Pneumatic Muscle

Handling Machining Assembly ControlM M M Pneumatics Electronics Mechanics Sensorics Software Hesse The Fluidic Muscle in Application 150 practical examples using the Pneumatic Muscle Chinese English French German Russian Spanish Blue Digest on Automation 54178 Hesse The Fluidic Muscle in Application Handling Pneumatics Stefan Hesse The Fluidic Muscle in Application 150 practical examples using the Pneumatic muscle Blue Digest on Automation Blue Digest on Automation © 2003 by Festo AG & Co.KG Ruiter Straße 82 D-73734 Esslingen Federal Republic of Germany Tel. 0711 347-0 Fax 0711 347 2155 All texts, representations, illustrations and drawings included in this book are the intellectual property of Festo AG & Co.KG, and are protected by copyright law. All rights reserved, including translation rights. No part of this publication may be reproduced or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior written permission of Festo AG & Co.KG Preface How does a muscle actually function? Is it technically possible to reproduce a muscle? This question has already robbed many an inventor and project manager of sleep. What is possible mechanically and is it chemically and physically feasible? As far back as 1872, the German professor Franz Reuleaux (1829-1905) described a flexible, pneumatic actuator. Since then all sorts of things have been tried: Muscles on the basis of memory metal, electrochemical actuators, polymer gels and electric motors combined with high ratio subminiature gears. To date, only very few solutions have found their way into everyday industrial life. Many are on hold in laboratories. Amongst the few durable solutions is the Fluidic Muscle from Festo, which is the principle performer in this book. It consists of an advanced high performance material and creates powerful and fast movements in a new way. An old idea has caught on in a high-tech era. Since the muscle can also be operated using water, it is probably more apt to speak of a fluidic actuator in general rather than a pneumatic muscle, even though compressed air will primarily be the medium used. In this book, a disproportionate view of the Fluidic Muscle will generally be shown in order to highlight its importance. In reality, a Muscle with an internal diameter of, for example, 10 mm takes up relatively little space. This is also an advantage when it comes to subsequent installation into existing machine structures. It is probably too early to fathom all the areas where the Fluidic Muscle will one day be in use. Nevertheless, this artificial Muscle is an actuator with a very interesting future for various reasons and there are already a number of applications with encouraging positive results. All the same, it is still in a status nascendi. This book is intended to provide suggestions for the use of the Muscle and to explain its function, point out the advantages and disadvantages and to provide an idea of suitable areas of application. I should like to thank Thomas Dehli, B.Sc. (Civil Engineering) and Manfred Moritz (both Festo) for their kind support with writing of this book. Stefan Hesse Preface Contents 1 Membrane construction in nature and technology . . . . . . . . . . . . . . . . . . . . . 9 2 Example: Biological muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 Technology and characteristics of the Fluidic Muscle . . . . . . . . . . . . . . . . . . 20 4 Muscle-type construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.1 Lifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 5.2 Gripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 5.3 Pressing and punching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 5.4 Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5.5 Clamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.6 Adjusting and positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 5.7 Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.8 Arm and leg movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 5.9 Checking and testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 5.10 Driving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 5.11 Oscillation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 5.12 Braking and stopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 5.13 Transporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 5.14 Distributing and branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 5.15 Machining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 5.16 Unwinding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 5.17 Dosing and portioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Index of technical terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 1 Membrane constructions in nature and technology By membrane we understand a thin, two-dimensional structure of a certain elasticity, which can be subjected to tension and stabilised by means of a gas air or fluid (water). The sheathing, outer medium and filler form a constructional system. In biology, a membrane refers to a skin, which for the most part grows into a porous septum and permits the movement of matter in both directions. All cell walls for example, are grown in the form of a membrane. Blood vessels are an example of this. More “constructional” membranes for example, are the vocal sacs of the aquatic frog. These consist of very strong cellular tissue and are pressurised by internal pressure, thereby forming an inflated spherical shape. The soft bodies of snails, worms and caterpillars typify tubular constructions stiffened by internal pressure. The sealing skins in this case are formed in such a way that when combined with the internal excess pressure, a shape typical of a particular species is produced. Membranes therefore play an extremely important role in living things. In the case of plants, there are for instance the epidermal water blisters (part of the epidermis) of the stems of crystalline plants. These cells are also subject to high internal pressure and they stabilise their form in this way. Pneumatic inflatable buildings are designed according to this principle. In technology, the term “pneu” refers to a system, whereby a sheathing which is purely subject to tension covers a filling. Typical pneus are air balloons, soap bubbles, inflated buildings, tyres, firehoses and domed membranes in the form of canopies for highly sensitive radar scanners. In these cases a state of tension exists in the homogenous membrane which is equal in all directions. Pneumatic lifting cushions in ring-shaped or rectangular form also come under this heading. These expand if compressed air is applied. This expansion effect is for instance used for lifting, gripping, sealing and pressing. Cushions of this type are made of synthetic reinforced rubber, polyurethane, neoprene coated polyamide, also reinforced with steel-cord or aramide, as well as other materials and fillers. However, the function of such cushions different to that of the Fluidic Muscle from Festo, because in this case the action of expansion is converted into tensile force, as you will see. An application for a cushion is shown in fig. 1-1. The cushion lifts a support plate. Pressures of up to 7 bar are applied (depending on design and size) and fairly high stroke forces are generated. In the pressureless state, the height of the cushions is greatly reduced. Cushions of this type can also be stacked. In this case, the stroke is increased in line with the addition of individual strokes. This method can for example be used to lift damaged aircraft or tanks. However, the cushion itself is without a guide and requires external elements for guiding or displacing. Many applications are purely for limited occasional use in emergency systems, accidents, lifting and sealing functions and are therefore not subject to continual frictional wear. 1 Membrane constructions in nature and technology 9 Fig. 1-1 Lifting plate with pneumatic cushion drive 1 2 3 4 5 6 7 Pneumatic cushion Lifting plate Guide bush Guide column Stop bush Base plate Inlet connection piece 4 3 1 2 5 6 7 Wherever objects are retained with the help of frictional forces, frictional wear to a lesser or greater extent is the result, with a corresponding effect on service life. Rubber tubing on the other hand is used for a wide range of different functions in industry. In the past, fire hoses were often used by joiners and cabinet makers as a means of supplying energy in bonding presses. Fig. 1-2a shows an example of how tubing can be installed in helical form in order to clamp cylindrical or slightly conical objects. Even a minimal expansion in tubing diameter under pressure is sufficient for the execution of a clamping function. Fig. 1-2 Membrane constructions in industrial use a) Tubular clamping device for round parts b) Peristaltic tubing pump c) Rolling bellows cylinder d) Bellows cylinder e) Strip bellows f ) Pneumatic clamping strip a) b) e) c) d) f) 10 1 Membrane constructions in nature and technology Stroke In the case of the pump shown in fig. 1-2b, rollers create a peristaltic effect by pressing the tubing using a floating pressure point. Diaphragm and rolling bellows cylinders are often used to generate a pressing force or motion. Like bellows cylinders (fig. 1-2d), these can be purchased off the shelf. Bellows cylinders are also often used in pneumatic spring systems or installed to generate high press forces. They are attached via connecting parts made of metal or plastic, which also facilitate the supply of air. Bellows cylinders do not require any seals which require replacing due to wear and are absolutely maintenance-free. Compressed air cushions in elongated form on the other hand are used for retaining, gripping and pressing, e.g. in special devices. Attempts have also been made to equip finger-type membrane structures with several chambers. By varying the pressure in the immediately parallel chambers, a finger gripping movement can be achieved. This principle is shown in fig. 1-3. However, a gripper of this type can only be used for relatively lightweight components. Moreover, the life expectancy largely depends on the degree of friction on the gripping surfaces. Fig. 1-3 Gripper on the basis of tubing fingers with several chambers [1] An interesting design comes from the Czech engineer Julius Mackerle who, more than 30 years ago, designed a wheel, whose tread consists of inflatable rubber elements (fig. 1-4). The rolling movement is achieved by means of targeted pneumatic actuation of the individual chambers, so-to-speak a sequence of numerous small propulsion movements. Compressed air is distributed into the wheel hub via hand lever valves. If full pressure is applied via supply line B, chamber 4 expands and creates an anti-clockwise torque in relation to the axis of rotation of the wheel. At the same time, chambers 1 and 2 are connected to atmospheric pressure via control segment C so as not to build up any rolling resistance during the turning of the wheel. Chamber 3 is closed and at that instant acts as a pneumatic spring. 1 Membrane constructions in nature and technology 11 Fig. 1-4 Creation of a rolling movement by means of inflatable rubber elements [2] 10 A, B, C Fixed control channels 9 8 11 1 to 12 Pneumatic chambers 7 A 12 C B 5 6 1 2 3 4 12 1 Membrane constructions in nature and technology 2 Example: The biological muscle The automation of production has brought major changes in its wake, which are intended to replace brains and muscles by means of technical constructs. This requires computers robots, machines of all types and also artifical muscles. Biological muscles serve as the model construction here, because they have an advantageous mass/performance ratio. They are capable of flexible and smooth movements and the connection of levers (bones) via the tendons is effected in an extremely compact way and because in the human body for example, they exist in great numbers in sustained working order. The altogether 656 muscles in a human being make up 40% of body weight. The eye muscles for example, contract more than 100 000 times a day. Hence there is a great deal of research and also some success on the way to developing an efficient artificial muscle. As long as 50 years ago, the discovery of polymer gels and their extraordinary characteristics was made. Stimulation by means of external stimuli due to ionic diffusion did in part cause dramatic differences in concentration and as such osmotic pressure differences. This causes a solvent to be created in or emitted by the gel, which is associated with changes in form. In the USA, NASA in collaboraton with Jet Propulsion Laboratories, has developed a type of plastic muscle. Formal memory composites, which change in shape during a change in temperature, have been used for technical gripper hands on a trial basis. However, their use is associated with a constant need for the material to be heated and cooled to ensure a properly functioning gripping action. In order to increase the minimal travel of the “muscle wires” made of nitinol (nickel-titanium alloy), V. Hayward (Montreal) has drawn the thin wires into a helix-type web covering discs (fig. 2-1). This is made up of 12 capillary wires. Whilst this marginally reduces the tensile force, the metal fabric is nevertheless capable of contracting or bending as a whole across a greater length. The change in length of an individual wire is in the region of approximately 3% of the nominal length. Fig. 2-1 Canadian helix meshing made of memory wire – a tensile actuator 1 2 3 4 Disc Pneumatic spring Memory wire Connecting flange 1 2 3 4 2 Example: The biological muscle 13 Even artificial muscles for nanorobots of the future have already been considered. Imagine a number of nano tubes bundled into a fibreous web and then making use of their expansion as they are electrically charged. In the case of some of these projects, their applicability is probably still far off in the distant future because of far too limited service life. However, it is also chemo-physically possible. An electrochemical muscle is shown in fig. 2-2. Electrical energy is converted into stroke force F by means of a chemical process. The element ressembles a metallic bellows with hermetic encapsulation. With an operating distance of 0 to 5 mm, an ultimate force of 0 to 300 N is reached or 3 kN with a 16 mm operating distance. Fig. 2-2 Electrochemical actuator (Friwo Silberkraft) F H2 H2O R In the USA, work has started with the building of robots that move with biological muscles – using mouse muscles. These can be grown from a single cell in a test tube and are then combined with silicon and steel. The energy is gained from a weak sugar solution, in which the muscles have to be “bathed” [3]. However, this is not suitable for the industrial market for the time being. Machine builders and designers have long been faced with the task of actuating levers in a combination of upper and forearm, whereby they can naturally only fall back on conventional drives. To illustrate this, fig. 2-3 shows some of these solutions. 14 2 Example: The biological muscle Fig. 2-3 Technical substitute for muscles in an upper and forearm system 1 2 3 4 5 6 7 8 9 10 11 Upper arm Forearm Working cylinders Electric motor Spindle-nut drive Worm and wheel Solenoid Tension spring Motor Harmonic gear drive Pneumatic rotary vane motor 1 3 2 5 4 6 8 7 9 10 11 The latter shows that mechanical drives can only be realised with the involvement of increased installation space, more mass and impaired movement behaviour (jerky start, jolting impact in end position). Apart from this, movements cannot be connected to a supporting structure as smoothly as is the case in reality with a lightweight biological system. A segmented form of motion such as is the case with triceps and biceps which form an antagonistic muscle pair can really only be found on a solenoid drive, which is combined with a tension spring. But how does this function with a biological muscle? Virtually half of human body weight is made up of the muscular system. Muscles are excitable, contractable organs. In order to perform a to and fro movement they need to exist in pairs, since they can only generate and transmit tensile forces. As you can see in fig. 2-4, these are biceps and triceps (agonist and antagonist, muscle and counter muscle). The muscles used to move the forearm are located on both sides of the humerus. A muscle comprises numerous fibre bundles, which are encased by a connective tissue membrane like a stocking. Between the fibre bundles are the blood vessels acting as supply lines to the muscle and nerves. The latter receive the commands from the central nervous system which cause the muscle to operate. 2 Example: The biological muscle 15 Fig. 2-4 Muscle configuration in the human arm 1 2 3 4 Bicep Tricep Humerus Ulna 3 1 L K 2 4 k l In order for the muscles to work, brief and powerful contractions of the muscles are required. Due to the length of the arm, they cause long-range but less powerful movements of the forearm. The universally known lever principle applies Force K • Force arm k = Load L • Load arm l Biological muscles are therefore short-stroke machines. They generate a great deal of force across a short distance. The biological muscle performs the most work (the product of displacement force and displacement distance of an object), when it reduces itself by roughly 10% of its length. However, most muscles are able to contract by up to 30% with a minimal load. In order to meet various different requirements, nature has also created different types of muscle (Fig. 2-5). Fig. 2-5 Muscle types a) Ordinary muscle b) Pennate muscle 1 Muscle fibre 2 Tendon 3 Connective tissue membrane 3 1 2 a) 2 2 b) 16 2 Example: The biological muscle With an ordinary muscle, the muscle fibres run from the tendon at one end to the tendon at the other end. The pennate muscle on the other hand is made up of short transversely running fibres, which produces a large force with a small distance. Muscles of this type are particularly prevalent in insects and crustaceans, e.g. for the powerful actuation of the claws of a lobster. But how is it possible to come anywhere near to an industrially (and also medicinally) applicable replication of biological muscles? As in the case of all major wars, the need for prostethes for hands, arm and legs that have been lost increases. This triggered the search for a practical means of powering artificial hands. As a result, an artificial arm was developed at the Orthopaedic Centre in Heidelberg in 1948, which is operated by means compressed air. The artificial hand shown in fig. 2-6 also forms part of this. The fluidic actuator is an expanding body, which swivels the finger into a firm grip when inflated. A tension spring is built-in to open the finger. Up until 1965, more than 350 people had benefitted from this development. Fig. 2-6 Artificial hand from the Orthopaedic Centre in Heidelberg (1948) 1 2 3 4 5 6 Gripper housing Flexible fluidic actuator Wooden finger Return spring Connecting flange Compressed air line 1 2 3 5 p Compressed air p 6 4 An interesting design is the McKibben muscle. Muscle replacement plays a major role in the development of artificial hands. In the mid fifties of the last century, the American J. L. McKibben developed a rubber segment muscle, which was to assume the role of the drive (fig. 2-7). 2 Example: The biological muscle 17 Fig. 2-7 Artificial hand with McKibben muscle 1 Rubber muscle 2 Cable control 3 Anthropomorphous five-finger hand 1 3 2 The secret of this muscle is in the fact that a network of non-expandable fibres has been inserted around the coating contour via a rubber tube. Under pressure, this muscle swells and shortens by approximately 20% since, due to its properties, the material of this fibrous net cannot yield. This creates considerable tensile force.On the prosthesis, the arm is moved and the bending of the phalanx triggered. However then as now, the supply of compressed air represents a problem in the case of mobile applications of this type. The muscle is known as a McKibben muscle or as a rubbertuator (rubber actuator). In Japan, a pedipulator (walking machine) with artificial rubber muscles was created for research purposes as far back as 1969 at the Waseda University of Tokyo (Humanoid Robotics Institute). By means of appropriate actuation of the two-legged apparatus, walking was facilitated via rubber muscles (fig. 2-8). Already then, the Japanese were convinced that the humanoid robot would be a reality in the 21st century. Experiments were therefore carried out with programs for biped walking. Today, the interest in new fluidic actuators on a membrane basis continues unabated and so a 5-finger hand has been developed, whose design and dimensioning is based on the human hand. Fluidic actuators have been developed to represent the phalanxes, whose principle is illustrated in fig. 2-9. These actuators are very small and can be completely integrated into each finger of the artificial hand. They are operated by means of compressed air at 3 to 5 bar and generate forces of up to 10 N. Frequencies of up to 10 Hz are reached during the stretching/bending cycles. The actual fluidic actuators consist of small chambers that change in size if a fluid (gas, liquid) is pumped in or out [4]. 18 2 Example: The biological muscle Fig. 2-8 Walking machine WAP-1 with artificial rubber muscles (1969) Fig. 2-9 Flexible fluidic actuators (IAI Research Centre, Karlsruhe) a) Expansion sequence b) Contraction sequenc 1 Swivel plate 2 Flexible fluid chamber 3 Pilot pin 1 2 3 a) b) In order to render a muscle based on the principle of a diaphragm actuator suitable for demanding industrial use, a high performance composite rubber material is required, which consists of numerous high loadable fibre strands for tensile force. The Fluidic Muscle from Festo is made of such a material and is now available in the form of a tensile actuator. 2 Example: The biological muscle 19 3 Technology and characteristics of the Fluidic Muscle The Fluidic Muscle is a diaphragm contraction system, i.e. tubing, which shortens under pressure. The basic idea lies in the combination of flexible tubing which is impervious to fluids and an integrated covering consisting of strong fibres in rhomboidal form (fibre structure). This creates a three-dimensional grid structure. In its capacity as an actuator, it can be operated both with compressible and with non compressible fluids such as clarified water. As with other components subject to tension, the construction principle is characterised by the fact the only normal tension occurs in the component, which is evenly distributed across the entire cross-sectional area. This facilitates designs of a high load bearing capacity or generation of force using a minimum of material. Constructions subject to tension are generally easier to design than those subject to pressure or bending, because there is no risk of instability. High strength fibres are available for this purpose, which are not usual in the compressed air sector. In the Fluidic Muscle, these characteristics have been fully translated into a standard product. The combination of a supple, flexible covering for maximum tensile strength, filler material (air, other gases, fluids) and the surrounding medium (generally atmospheric air) form the constructional system. The Muscle is of cylindrical shape and the force/mass ratio is approximately 400:1. The shortening of the longitudinal axis is directly proportional to the filler volume. The tension in the walls of thin spherical or cylindrical surfaces depends on their size. The bigger the sphere or cylinder, the greater the tensions if an internal pressure p2 is applied. The Laplace principle (if it really does originate from Laplace) is true of the sphere (fig. 3-1): σ = (p2 – p1) · r · 1 2 Fig. 3-1 Crash situation of a thin-walled hollow body r p1 p2 p2 p1 Voltage 20 3 Technology and characteristics of the Fluidic Muscle The same law applies for a cylinder, but without factor 1/2. Cylinders are curved in one direction and spheres in two directions. Since the pressure is therefore held in one direction as a result of the tension, double the tension is created. A cylinder with a hemispherical end piece usually cracks at its ends if it is inflated to the point of bursting [5]. The principle of a diaphragm contraction system in cylindrical form is explained in fig. 3-2. Tubing which is impervious to fluids is provided with a covering made of strong fibres in rhomboidal form. These form a three-dimensional grid structure thereby reinforncing the tubing. When air is admitted, the grid structure changes in shape through expansion and a tensile force is created in the axial direction. The greater the internal pressure, the more the Muscle is shortened. Fig. 3-2 Equilibrium of forces system on a diaphragm contraction system disregarding the elastomer tensions and fibre expansions ∆FU p p p FZ ∆FU 2α ∆FL 2α ∆FL ∆FU d FZ ∆U Stroke L ∆FU The following applies: tan α = ∆FU ∆U = ∆FL ∆L 2 · ∆FU = p · d · ∆L π ·d · ∆FL = p · π d2 + FZ ∆U 4 FZ = p · FZ = 0 → α0 = arccos → = α0 = 54.7° 3 Technology and characteristics of the Fluidic Muscle   21  1  3 √   π 2  3 · cos2α – 1 ·d  4 1 – cos2α Symbol definition: d FZ ∆FL ∆FU ∆L p ∆U α αo Muscle diameter Tensile force Change in tensile force Circumferential force Change in length Internal pressure of Muscle Change in circumference Semirhomboidal angle Neutral rhomboidal anglel Fig. 3-3 is intended to assist you in understanding the above formulae and how they function [5]. First of all, let us look at the extreme cases. Fig. 3-3 Correlation between volume and length of a cylinder with a helical covering of fibres, if the fibre angle changes 1.0 A Relative volume 0.8 70° 60° 50° 40° A Exploded area B Slack area C Line of contraction 0.6 B 0.4 80° C 30° 20° 0.2 0 0 0.2 0.4 0.6 0.8 1.0 Relative lenght If the length is zero, there is no volume. The cylinder has degenerated into a disc. The fibres would run in circular form without any pitch. If the cylinder is expanded to maximum length, it becomes a line and equally does not have any volume. The cylinder achieves the maximum volume roughly in the middle of the two extreme cases at a fibre angle of 54.7°. This is the neutral angle, at which an increase of internal pressure would lead with equal probability to a lengthening as well as a thickening of the cylinder. In other words, at this fibre angle, the tensile force has dropped to zero. The typical force pattern of a Fluidic Muscle during a contraction can be seen in the diagram in fig. 3-4. Working strokes of up to 25 % of the nominal length of the Muscle can be achieved. Initially, acceleration is powerful and the approach to the required position gentle. The tensile force is greatest at the beginning of the contraction and then decreases to zero virtually in line with the stroke. In 22 3 Technology and characteristics of the Fluidic Muscle contrast with this, a “rigid” pneumatic cylinder produces the same force throughout the entire stroke, which is why it needs to be cushioned in the end position so that the velocity does not have to be decelerated suddenly. Fig. 3-4 Force/contraction diagram for the Fluidic Muscle 1 Muscle with diameter of 10 mm 2 with diameter of 20 mm 3 with diameter of 40 mm 6000 5000 3 Force in N 4000 3000 2 2000 1000 1 0 –5 Expansion in % 0 5 10 15 20 25 Contraction in % A comparison of the Fluidic Muscle with a working cylinder using an identical piston diameter clearly shows the advantage of the Muscle with regard to the initial force. Fig. 3-5 illustrates this fact quite convincingly. Fig. 3-5 The tensile force illustration is convincing 1 Pneumatic cylinder 2 Fluidic Muscle 3 Loading weight 1 2 3 10 x G G Stroke force Stroke Stroke force Stroke 3 Technology and characteristics of the Fluidic Muscle 23 It is also an important feature when assessing applicability, although the conditions vary depending on load. The following overview (Table 1) shows some characteristic cases. Table 1 Load cases using the Fluidic Muscle p v = const. p1 = const. Lifting of load from a supporting surface Force-free coupling is only possible, if the load to be moved rests on a firm base. In this state, the Muscle is not elongaged or compressed. Lifting/lowering of a freely suspended load In a pressureless state, the load consisting of a freely suspended mass leads to an elongation of the Muscle. In this state the Muscle develops maximum forces with optimal dynamics and minimal air consumption. Absorption of movements using a constant volume or constant pressure When changed, the Muscle behaves like a spring. The preloading force of these “pneumatic springs” and their spring constant can be influenced and this results in different spring characteristic curves. The ambient temperature should also be observed in each case. Continuous use at more than 60 °C is not recommended with the standard material, since this leads to premature aging of the rubber elastomer. However, the Muscle may be briefly (for a few seconds) subjected to a temperature in excess of 60 °C. 24 3 Technology and characteristics of the Fluidic Muscle In the case of dynamic use, the Muscle can also be operated at temperatures below + 5 °C, since it warms up after a few stress cycles due to the compressed air. However, if the Muscle is subjected to static load, lesser force values will be achieved than those within the recommended temperature range, since more energy needs to be generated in order to expand the more rigid diaphragm. The composition of rubber and elastomer can be changed by the manufacturer in exceptional cases in order to facilitate its use in temperatures below 5 °C or over 60 °C. However, this may also change other Muscle characteristics such as material resistance. How is the key data for a particular application calculated? The working range of the Fluidic Muscle is represented in a force/contraction diagram (fig. 3-6). The diameter-dependent range of application is defined by the following limits: • Limit of maximum permissible elongation (left) • Limit of maximum achievable force (top) • Limit of maximum operating pressure (right, dropping) • Limit of maximum change in shape (right, vertical) Fig. 3-6 Working range of the Fluidic Muscle with an internal diameter of 20 mm Force compensator Max. operating pressure Force (N) Max. elongation Permissible working range Max. deformation Contraction [%] When selecting a Muscle, the stress points must be within the permissible working range. Example A constant load of 80 kg is to be lifted force-free from a pallet over a distance of 300 mm. Compressed air is available at 6 bar. Which Fluidic Muscle is to be selected for this (diameter, nominal length)? 3 Technology and characteristics of the Fluidic Muscle 25 Step 1 Determine the size according to the maximum load to be lifted. Given a force of F = 800 N, a Fluidic Muscle 20-... can be used. Step 2 Enter the two load points in the diagram. These are points F = 0 N at pressure p1 = 0 bar and F = 800 N at pressure p2 = 6 bar. Step 3 From the diagram, read the contraction of the Muscle in percentage. The change in length corresponds to a contraction of 10%. Step 4 Calculate the nominal length of the Muscle. The nominal length NL is obtained from the stroke divided by the contraction (as factor). Therefore NL = 300 : 0.1 = 3000 mm. With this result, you would need to ascertain that the room height is in fact available. If lifting is envisaged via a loose roller, then the necessary Muscle stroke and force are doubled. Conversely this means that a 1.5 m Muscle would be sufficient, although it would need to generate twice the force. This solution is shown in fig. 3-7. However, this is immediately associated with additional mechanical expenditure. Fig. 3-7 Alternative solution to reduce the nominal length Stroke Stroke 26 3 Technology and characteristics of the Fluidic Muscle Designers should use the calculation program “MuscleSIM” to configure a Muscle. Due to the Muscle’s hysteresis behaviour, the graphic configuration using the force/contraction diagram may vary when compared with the results determined via the software tool. The calculation with the use of the simulation software is simple: • Definition of load • Input of project data (stroke, forces, pressure) • Suggested Muscle data (nominal length, degree of contraction, total mass, assembly length) • Output of parts list data A decision in favour of the Fluidic Muscle is generally more or less consciously compared with a pneumatic cylinder. This is why the most important advantages and disadvantages are listed in Table 2 below. Table 2 Comparison of Fluidic Muscle and pneumatic piston system Advantages compared to a piston cylinder • With an identical diameter considerably higher (initial) maximum force • Superior media resistance • Considerable less mass per force unit • Possibly reduced purchase price depending on comparative product • Easy to position by means of pressure regulation, also intermediate positions • Impervious as hermetically sealed • For many applications reduced compressed air consumption • Any actuator length easy to produce • Highly dynamic operation possible, high acceleration • No stick-slip characteristics • Suitable for clean rooms and contaminated environment • Silent positioning • Can be operated by means of air and water • No need to use lubricants Disadvantages compared to a piston cylinder • Considerable increased assembly lengths for required stroke • Maximum force is reduced down to zero depending on stroke, which can can however also be an advantage (dependent on application) • Pressure forces cannot be directly generated • Double-acting function is not possible • Guidance of load not possible; if necessary, requires additional technical expenditure • Aging of rubber material; service life is dependent on the degree of contraction and operating temperature • Vulnerable with regard to sharp edged external damage and welding splashes; if necessary protective covers are to be provided • Risk of aneurysm or cracks forming if overloaded, therefore not overload-proof 3 Technology and characteristics of the Fluidic Muscle 27 In addition, the resistance of the elastomer base material (chloroprene) is to be taken into account. The following rough estimation can be used as a basis: Media resistance Good: Aging, weather, flame retardance Usable: Acetone, petrol, alkaline solutions, mineral oils, ozone, hot air, cold, acids, water (warm) Poor: Benzene, chlorine, steam, ester, tetrachloroethylene, pyralene Mechanical characteristics Good: Wear, bending, expanding, viscosity, tensile strength Usable: Elasticity, deformation resistance Poor: Electrical insulation The maximum operating frequency depends on numerous parameters: • The stroke required • Contraction (degree) of the Muscle • Load, pressure, temperature, valves and air supply • Design of the application (cushioning of load, stop, mechanical springs for return stroke, etc.) Subject to correct configuration, frequencies of 3 Hz are possible without impairing service life. In order to achieve high stress cycle figures, the Muscle should on the one hand be configured in a way that contraction of 10% is not exceeded and on the other hand that it is provided with open interfaces at both ends so as to facilitate flushing as well as quick exhausting of the Muscle. Otherwise the Muscle would overheat as a result of the permanent compression of the same air volume. IncidentaIly, in living things too each muscle movement is associated with heat generation which already starts at the beginning of a contraction and outlasts this. For velocity characteristic values, the same as for frequency applies. Tests were conducted under nominal conditions (room temperature, Ln = 10 x internal diameter, 6 bar, Muscle unattached at one end without additonal load). Minimum speed is approx. 0 m/s, maximum speed is 1.5 m/s for MAS–10 and 2 m/s for MAS–20 and MAS–40. Service life is dependent on load, which is obtained from the thermal load, the set change in deformation and the additional load. The load component (thermal) can be reduced by means of specific pressurising at both ends and the service life is significantly extended as a result of this. 28 3 Technology and characteristics of the Fluidic Muscle An assortment of peripheral components is available for the mechanical attachment of the Muscle. Fig. 3-8 illustrates these components which, depending on a particular application, can be attached at both ends of the Muscle. Fig. 3-8 Peripheral components for the attachment of a Fluidic Muscle to machine structures (Festo) 1 2 3 4 5 6 7 8 9 10 11 12 13 Blanking adapter Radial adapter Axial adapter One-way flow control valve Quick connector Quick-Star push-in fitting Barbed fitting Threaded rod Foot mounting Rod clevis Rod eye Coupling piece Rod clevis with threaded rod The Muscle can be produced in nominal lengths of up to 9000 mm as required by the customer. The reinforced tubing is either clamped and therefore releasable or the ends are permanently moulded to connecting components. Fig. 3-9 illustrates the construction of the Muscle for both versions. The Fluidic Muscle is currently available in the following nominal diameters: 10, 20 und 40 mm. Fig. 3-9 Fluidic Muscle versions a) Clamped attachment of the diaphragm b) Fluidic Muscle with permanently moulded connections 1 2 3 4 5 Locking nut Clamping cone Muscle tubing Relaxed state Contracted state 3 1 2 Stroke a) 6 3 4 5 Stroke b) 3 Technology and characteristics of the Fluidic Muscle 29 The actuation of Fluidic Muscles is simple and yet quite fascinating. The Muscle reacts to the smallest of pressure changes and can be operated at pressures of between 0 bar and pmax. = 6 bar (with a Muscle of 10 mm diameter up to 8 bar). The proportional correlation between length change and filling volume permits intermediate positioning without costly control electronics simply by means of controlling the internal pressure. Because of the hysteresis phenomenon, the positioning accuracy can if anything be described as approximate. A good way of describing this is low-tech/low-cost positioning. The Fluidic Muscle is ideally suitable for sensitive application since it does not have any built-in electrical or electronic components and the actuator is hermetically sealed. This is particularly important for applications in areas subject to explosion hazard. The control system too can be realised purely with pneumatics. The service life of the Fluidic Muscle is shortened in extreme operating conditions. The following factors in particular have a negative influence: • Increasing contraction h in percentage • Increasing additional load m in kilogrammes • Increasing ambient or operating temperatures in degree Celsius An initial approximation of this is graphically illustrated in fig. 3-10. Fig. 3-10 Load-independent service life pattern C (n = number of stroke cycles) Service life C in n stroke cycles Mass m = O Mass m = max 0 5 10 15 20 25 30 Contraction h in % 30 3 Technology and characteristics of the Fluidic Muscle The following generally applicable advice can be derived from this: • Do not economise with the nominal length of the Muscle! • Service life is contraction-dependent. Less contraction extends life expectancy. • Pressure applied at opposite ends (“flushing”) reduces the operating temperature of the Muscle (recommended for frequencies greater than 2 Hz; Muscle MAS-...-MO...). The compressed air consumption of a single-acting pneumatic cylinder is reduced because compressed air is only required during the working stroke. This also applies in the case of the Fluidic Muscle which, with an identical force to that of a conventional pneumatic cylinder requires roughly only 40% of the energy. Since the Muscle does not have a piston, the internal volume can be further reduced by a filler material. This additionally reduces air consumption and usually does not affect the functioning and service life of a Muscle. A filler material of this type is shown in fig. 3-11. However, in the case of highly dynamic applications, it should be remembered that insufficient exchange of air may lead to undue heating of the Muscle. Fig. 3-11 Muscle with built-in filler material 1 Fluidic Muscle 2 Filler material 1 2 Finally, safety also needs to be taken into consideration when using the Fluidic Muscle. A Muscle under pressure has enormous energy potential. A sudden release of this energy, e.g. due to bursting of the reinforced tubing as a result of incorrect use, can considerably accelerate individual components of the Muscle. Any work on the Muscle must therefore only be carried out in the unpressurised state [13]. 3 Technology and characteristics of the Fluidic Muscle 31 Table 3 lists the most important technical data of the currently available sizes of the Fluidic Muscle. Table 3 Technical data of the Fluidic Muscle product range Type Maximum permissible operating pressure Maximum permissible operating frequency Connection thread Internal diameter of reinforced tubing Maximum permissible offset of connections Maximum permissible elongation Maximum contraction Permissible temperature range Maximum stroke force at 6 bar**) Maximum permissible useful load (freely suspended) Maximum hysteresis Maximum relaxation Permissible speed minimum maximum Theoretical air consumption at 1 HZ*) Normal leakage Repetition accuracy Materials Connecting flange: Reinforced tubing: Adhesive: MAS-10-... 8 bar 3 HZ M10 x 1.25 10 mm MAS-20-... 6 bar MAS-40-… 2 HZ M16 x 1.5 20 mm M20 x 1.5 40 mm – Angular offset < 1° – Lateral offset < 2 mm pro 100 mm nominal length 3% of nominal length***) 20% of nominal length***) +5 °C ... +60 °C 400 N 30 kg less than 5% less than 5% (at room temperature) less than 10% (at maximum temperature) 0.05 m/s 1.5 m/s 10 l/min less than 1 l/h less than 3% Al (anodised); St (galvanised); NBR Chloroprene, aramide Loctite 243 0.05 m/s 2 m/s 75 l/min 0.05 m/s 2 m/s 600 l/min 1200 N 60 kg 4000 N 120 kg 25% of nominal length***) *) **) ***) Nominal conditions: At 6 bar, nominal length 10 x diameter, maximum elongation Limited due to stroke force protection Nominal length = Visible range of unloaded reinforced tubing 32 3 Technology and characteristics of the Fluidic Muscle Configuration example Lifting a constant load. A constant load of 80 kg coupled force-free is to be lifted from a base across a distance of 100 mm by means of a Fluidic Muscle. The operating pressure is 6 bar. Required is the size (diameter and nominal length) of the Fluidic Muscle (for other loading cases, see calculation program “MuscleSIM”). Parameter conditions Required force in neutral position Required stroke Required force in contracted state, approx. Operating pressure Values 0N 100 mm 800 N 6 bar Solution method Step 1 Establishing the size of the Fluidic Muscle. Determine the suitable Fluidic Muscle diameter on the basis of the required force. The required force is 800 N, therefore a MAS-20-… is selected. Step 2 Entering the load point 1. The load point 1 is to be entered in the force/displacement diagram of the MAS-20-…. Force F = 0 N Pressure p = 0 bar Step 3 Entering the load point 2. The load point 2 is to be entered in the force/displacement diagram. Force F = 800 N Pressure p = 6 bar Step 4 Taking a reading of the change of length. The change of length of the Fluidic Muscle is to be read between the load points on the X-axis (contraction in %). Result: 10.7% Contraction Step 5 Calculation of nominal length. A required stroke of 100 mm produces the nominal length of the Fluidic Muscle, divided by the contraction in %. Results: 100 mm/10.7 % ~ 935 mm. Step 6 Result: The nominal length of the Fluidic Muscle to be ordered is 935 mm. A MAS-20-N935-AA is required in order to couple 80 kg force-free and lift this by 100 mm (see also diagram on page 25). 3 Technology and characteristics of the Fluidic Muscle 33 4 Muscle-type construction This is to be primarily regarded as a load-justified interface. Load types such as pressure, shearing, torsion and bending are not applicable. In such cases, force reversal often is a useful solution. The Fluidic Muscle is primarly a tensile actuator and should be used as such. Designations and permissibe displacement are outlined in fig. 4-1. Non parallel and angular offset attachment of Muscle ends are unfavourable and can be avoided by means of angularly flexible connecting components. Eccentric loads and torsional forces must be avoided. Fig. 4-1 Designations and permissible deviations for installation NL Nominal length vL Elongated length G Weight force kL Contracted length P Permissible parallelism error (less than 2 mm per 100 mm nominal length) W Angularly flexible interface α Permissible angular error (< ± 1°) M Torque (M = 0 Nm) E Load eccentricity (E = 0 mm) NL vL kL E G G G α P M G G W The maximum permissible elongation is 3% of the nominal length This is given with a Fluidic Muscle of 10 mm diameter if a freely suspended additional load of 30 kg is applied. 34 4 Muscle-type construction If the Muscle is subject to a static load for an extended period (more than 500 hrs), a relaxation effect sets in. This means that the Muscle lengthens, i.e. that at a constant internal pressure and given position, the force slightly decreases. At room temperature, this relaxation is less than 5% for all three diameters, at 60 °C it is less or equal to 10%. The Fluidic Muscle is a tensile actuator and therefore only transmits tensile forces. As with other tensile media such as ropes, chains and belts, there is no motion guidance and this has to be created additionally. This is not necessary in the case of a pneumatic cylinder, since piston and piston rod operate simultaneously within a linear guide. All guides require additional components, which increase labour and costs. The mass/performance ratio is therefore slightly less favourable. A number of options for motion guidance are illustrated in fig. 4-2. Fig. 4-2 Guides for Muscle movements a) Internal guidance via a compression rod b) External compression rod guide c) External guidance via a tensile plate 1 2 3 4 5 Fluidic Muscle Compression rod pushing Compression spring Guide column Base plate 5 1 1 2 1 2 3 4 3 5 a) b) c) As fig. 4-2 shows, the compression rod elements can also be realised, if the guide, the fixed point and the movable Muscle end are selected accordingly. Another option is a scissor mechanism, for instance to guide the load on a lifting device. This is illustrated in fig. 4-3. Lifting devices of this type are usually fitted to an overhead traversing carriage. The scissor mechanism is designed in duplicate, with a centrally built-in Fluidic Muscle. 4 Muscle-type construction 35 Fig. 4-3 Motion guide using scissor mechanism 1 2 3 4 5 6 Hinge Fluidic Muscle Compressed air line Scissor arm Gripper unit, Container to be gripped 3 1 p p Compressed air 2 4 Stroke 5 6 Various other lever mechanism solutions are also possible as shown in Fig. 4-4, where the lifting motion is performed along a straight line using an articulated arm. This arm can be doubled in mirror-image form, thereby creating a planar four-link chain. The advantage of articulated mechanisms of this type compared with other longitudinal guides is that, in the direction of movement none of the guide components extend upwards. This is crucial in the case of low room heights. However, the disadvantages of both applications also have to be considered, in particular the limited stroke height and the additional guide components. Fig. 4-4 Motion guide with parallelogram linkage 1 1 2 3 4 5 6 7 Ceiling rail Castor Fluidic Muscle Parallelogram Load retainer Load hook Operating and guide lever 2 3 4 5 7 6 36 4 Muscle-type construction Another possibility is shown in fig. 4-5. Four laterally rigid bands are arranged at 90° to each other. The bands are fitted on a winding roller with internal torsion springs for independent winding. One or several Fluidic Muscles act on the lifting frame and generate the lifting force. The bands simultaneously protect the Muscle against mechanical damage. Fig. 4-5 Stroke stabilisation using four laterally rigid bands 1 2 3 4 5 Frame Fluidic Muscle Band roller Band Lifting frame 1 2 3 4 5 However, many mechanical structures do not require a special motion guide, since guides are built-in and merely the appropriate feed points need to be created. The same applies for the configuration of Muscles, where only the spring action is required, as shown in the following example. Fig. 4-6 illustrates a leisure device, an “air hopper” as a product study (B. Osko and O.Deichmann), where the Fluidic Muscle is used as a spring. The spring force helps to achieve longer leaps and higher jumps because part of the kinetic energy from the preceding jump is returned with the next jump. The constructional solution is based on the function of kangaroo tendons. However, moving forward by jumping with both legs without falling over rather takes some getting used to. Even on skateboards, wheel suspensions have been cushioned using Fluidic Muscles with the aim of directing and cushioning the tilting movements [6]. 4 Muscle-type construction 37 Fig. 4-6 Air hopper (Festo) 1 Shoe, Boot 2 Fluidic Muscle 3 Spring plate 1 2 3 There are numerous constructional possibilities of creating pneumatic actuators which, in the combination of muscle and compression spring, correspond to the function of single-acting cylinders. Fig. 4-7 and 4-8 illustrate some examples of this. A Fluidic Muscle with a diameter of 20 mm can for example be used here. The advantage is in the high force (1200 N) and the extremely fast response. Fig. 4-7 Compression spring cylinder with Muscle retraction 1 Cap 2 Round housing with 42 mm diameter 3 Compression spring 4 Fluidic Muscle 5 Locking ring 6 Bush 7 Stem 8 Compressed air connection 6 7 1 2 3 4 5 8 1 38 4 Muscle-type construction The cylinder shown in fig. 4-7 has a guided stem, to which the mechanical components can be attached. The compression spring or a spring contact assembly are located inside the Muscle (spring force approx. 700 N). The Muscle cylinder shown in fig. 4-8 is designed for clamping functions and can be constructed in either pulling or pushing mode depending on which side the force is received. The basic body is attached to the machine table, for which slotted guide rails can be used for protection. The whole barrel body is displaced when compressed air is applied. The spring in this case is used purely to reset the Muscle so that virtually the full Muscle force comes into effect. Fig. 4-8 Barrel-Muscle cylinder 1 Basic body of 42 mm diameter 2 Screw cap 3 Locking ring 4 Moving barrel 5 Compression spring 6 Fluidic Muscle 7 Connection thread 8 Compressed air connection 3 4 5 6 2 7 8 2 1 1 A cost effective motion unit is obtained by using a standardised guide unit (FEN-...) and a Muscle as an actuator instead of a pneumatic cylinder (fig. 4-9). Moreover, there is a choice of selecting a unit with sliding or ball bearing guide. In addition a displacement encoder can be attached if required. The guiding accuracy is excellent, as protection against rotation is obtained by means of the double guide. A unit of this type is suitable for numerous applications in automation, preferably for short distances. 4 Muscle-type construction 39 Fig. 4-9 Standard guide unit with built-in Fluidic Muscle a) Sliding bearing guide b) Ball bearing guide 1 2 3 4 5 6 Fluidic Muscle Guide rod Sliding bearing guide Ball bearing guide Compression spring Yoke plate 6 1 5 4 2 3 2 a) b) 5 Fig. 4-10 lists some variants for the connection of the Muscle to pneumatics. The permissible number of strokes of these varies according to time unit. In the circuit diagram shown in fig. 4-10b it should be noted in particular that the valves are mounted as closely as possible to the Muscle. Added to this, the connection and tubing diameters should be as large as possible. For circuit configuration, the familiar principle for pneumatics applies as set out in [14] and [15]. Fig 4-10 Pneumatic circuit diagrams for the connection of a pneumatic Muscle 2 3 2 a) Air supply with radial or axial adapter (frequency up to 0.5 Hz) b) to d) Air inlet with axial adapters (frequency from 0.5 Hz) 1 2 3 4 5 6 7 Fluidic Muscle MAS-...MC Fluidic Muscle MAS-...MO 3/2-way valve Non-return valve Quick exhaust valve Flow control valve 5/2-way double-pilot valve 2 1 b) 4 1 3 1 3 a) P A R 2 4 1 1 3 5 1 3 12 A P 5 R 6 c) d) 40 4 Muscle-type construction The Muscle can also be operated using vacuum, which can of course only be effected indirectly, as shown in fig. 4-11. The fixed end of the Muscle is open and can be connected to atmosphere and possibly supplemented with a silencer. A vacuum exists on the outer side of the Muscle. If this is applied, then the stem retracts, since the internal pressure of the Muscle is greater. The return stroke (advancing) is down to the spring force. However, an external force uncoupled from the process can also be effectively deployed. Fig. 4-11 Muscle operation using vacuum 1 2 3 4 5 6 7 8 Housing Connection to atmosphere Fluidic Muscle Vacuum connection Stem Spring plate Return spring Locking nut 5 6 7 1 3 8 2 4 Lastly, the behaviour of forces and distances (strokes) if several Fluidic Muscles are conneced in series or parellel is also of interest. This is illustrated in fig. 4-12. Both the forces (parallel connection) and the distances (series connection) can be accumulative. In the case of series connection, you would need to consider whether to use a correspondingly long Fluidic Muscle. However this is only possible if the direction of the action of forces is uniform. A number of different applications can also be seen in Fig. 5.1 at page 44. A frequently asked question is whether the radial expansion of the Muscle can be used for clamping tasks. Applications of this type should be rejected and this not only because the surface is used as a wearing course, but because the fibrous structure within the rhomboidal pattern is displaced. This further increases frictional wear. The Fluidic Muscle has been optimised purely for use as a tensile actuator. 4 Muscle-type construction 41 Fig. 4-12 Connection of pneumatic Muscles Forces F Displacements s s 3F Parallel connection 3F Series connection F 3s If gripping tasks are nevertheless realised by means of tensioning the outer surface as illustrated in the example shown in fig. 4-13, then rapid wear is to be expected. A Muscle-based design of a gripper of this type is shown in fig. 5-16. Even so, the engineering expenditure in the case of this construction is still relatively little. Fig. 4-13 Gripping of a part using the lateral surface a) Totally unsuitable application b) Suitable for continuous operation 1 1 Fluidic Muscle 2 Workpiece 3 Guide rod 2 3 a) b) 42 4 Muscle-type construction The applications shown in fig. 4-14 should be similarly evaluated. These refer to the generation of an internal force for tube bending. In order for a tube to remain round during bending and to prevent it from buckling, thin walled tubes are filled with sand and plugged or a tightly wound coil spring is introduced and pulled out again after the tube has been bent. The removal of dents from tubes is an individual mechanical application that could perhaps be considered. Fig. 4-14 The Fluidic Muscle as a supporting force generator a) Bending of tubes b) Removal of dents in tubes 1 3 1 Tube bending device 2 Dented tube 3 Fluidic Muscle 2 b) a) A slightly better situation would be achieved, if the membrane were to be shaped into a cushion instead of being covered by strong fibres in rhomboidal form. An inflatable “semicushion” could then be used for clamping functions which were previously impossible with Fluidic Muscle. Fig. 4-15 illustrates some applications for cushions of this type. Fig. 4-15 Workpiece clamping using a pad-type Muscle a) b) c) d) Gripper Clamping device Clamping of tubes Semicushion element 5 7 6 4 1 2 c) 11 4 12 1 Semicushion 2 Object to be gripped or clamped 3 Base plate 4 Compressed air line 5 Bar code reader 6 Lighting 7 Rotary joint 8 Adjusting angle 9 Base plate 10 Retaining plate 11 Inner body 12 Attachment eye 1 a) 2 8 4 2 3 10 9 b) 1 d) 9 2 10 1 11 4 Muscle-type construction 43 Gripping as shown in fig. 4-15a does not cause the gripped object to be accurately centred in the gripper device. The contact force can be regulated via pressure. Idle strokes without counterforce are to be avoided. The gripped object must not have any burrs or sharp edges.Other than that, cushion elements of this type are maintenance-free and thus occasional visual inspections suffice. If these pad-type Muscles are attached to a suitable multifacetted body, then internal gripping of tubes for example, can also be realised as shown in fig. 4-15d. In conclusion, Table 4 lists a few recommended applications. Table 4 A few recommended applications of the Fluidic Muscle Characteristic Reduced mass, slim design Area of application Aviation, mobile technology, car construction, dynamically motive devices such as effectors for robots, robotics in general, highly dynamic devices such as cutting units, simulators For high acceleration requirement, lifting equipment, clamping devices, simulators, gripping technology, safety and locking systems, initial force/mass ratio of 400:1 Clean room, biomedicine, sewage works, sewage treatment technology, areas subject to explosion hazard, woodworking Accurate positioning at reduced speeds, technology, rehabilitation equipment, humanoid robots Highly dynamic cutting and sorting processes Gentle retracting into a required (end) position Intermediate positions via pressure regulation possible without displacement encoder Use in environments subject to dust and contamination High initial force and acceleration Hermetic seal, high media resistance Stickslip-free movement High cycle rate Degressive force curve (force/displacement pattern) Pressure/length curve Sturdy design 44 4 Muscle-type construction 5 Applications 5.1 Lifting The considerable force developed by a Fluidic Muscle and its stick-slip free movement make it an interesting option for many lifting tasks. Serial connection and the loose roller principle may be used to increase the stroke. Fig. 5-1 illustrates a few assembly suggestions (the Muscle is shown enlarged). These solutions are used in the manually operated manipulator sector. With some installations, the Muscle can be conveniently housed in cantilever boom axes and vertical columns. Generally, sufficient room is also available for parallel connected Muscles in order to increase force. What stroke heights can be expected with different transmission variants? Fig. 5-1 Possible assembly variants for the Fluidic Muscle [7] 5 a) Simple configuration b) Doubling of stroke via a loose roller c) Twin configuration and loose roller d) Parallel superposed configuration to increase stroke 6 4 8 L1 3 L1 2 H2 2 Variant 1 b) 1 Variant 2 7 6 L1 3 2 H3 F H4 c) Variant 3 d) L2 Variant 4 a) 5 H1 5 Applications 1 2 3 4 5 6 7 8 Suction cup Control unit Fluidic Muscle Carriage Return pully Cantilever boom axis Connection plate Air supply line H Stroke L Length of contraction membrane With a contraction of 20%, the following stroke H is obtained for the variants shown: L1 45 H1 = 0.2 ⋅ L1 H2 = 2 ⋅ 0.2 ⋅ L1 H3 = [(0.2 ⋅ L1) + (0.2 ⋅ L2)] ⋅ 2 H4 = (0.2 ⋅ L1) + (0.2 ⋅ L2) The following should be used to compare all the assembly variants of the load balancers shown in fig. 5-1 during their lifting actions: L1 = 2000 mm, L2 = 1400 mm Muscle size MAS 40 (= 40 mm internal diameter) Operating pressure 6 bar Contraction 9% or 20% of initial length With these assumptions, the following data is obtained if the load is not freely suspended: Contraction 9% Variant 1 (Fig. 5-1a) 2 (Fig. 5-1b) 3 (Fig. 5-1c) 4 (Fig. 5-1d) Stroke in mm H1 = 180 H2 = 360 H3 = 612 H4 = 360 Force F in N 3900 1950 1950 7800 Contraction 20% Stroke in mm 400 800 1360 800 Force F in N 1800 1800 1800 3600 Forces can be increased by the simple method of using several parallel bundled Muscles. Even in this case, movements can still be finely reproduced. Fig. 5-2 shows yet another constructional design of a load balancer. The entire stroke unit can for instance be attached on a traversable ceiling track. Fig. 5-2 Drive system for a balancer using a flat belt for load lifting 1 2 3 4 5 6 7 8 9 Circular guide Siding bearing Fixed return pulley Ceiling attachment Traversable return pulley Fluidic Muscle Base plate Flat belt Suspensed load 4 3 5 6 7 1 2 FA 8 FG Weight force FA Drive force 9 FG 46 5 Applications The suspended load can be balanced by means of pressure regulation thereby creating a seemingly weightless state for the handling object. The less the mass of the moving part, the more dynamic the operation and this is further facilitated by the Fluidic Muscle. A Fluidic Muscle working in parallel has been attached in front of and behind each of the roller devices. The Muscles are inserted in a guide barrel and mounted on the right of the base plate. With this design, the maximum stroke height of the load is four times the Muscle stroke. It should be pointed out that the stroke force decreases over the distance, which is why the Muscles are provided in pairs in the example shown. Fig. 5-3 illustrates a manually guided manipulator, which also balances the suspended load using a Fluidic Muscle, provided that appropriate pressure control is available. Depending on the load ratios, one or more Muscles should be provided depending on load ratios. The Muscle drive can be easily accommodated in the vertical column which is a basic requirement. There is also a safety aspect to the dual use of Muscles. In the event of one of the Muscles failing, the second Muscle must ensure a minimum force. In contrast with the already shown manipulator solutions, the cantilever boom axis motion is balanced forcewise. The end effector can be moved within a relatively large working space. Fig. 5-3 Hand-guided manipulator with Fluidic Muscle 5 1 2 3 4 5 6 7 8 9 10 Rotary joint Arm Rotary axis of gripper End effector Tie-rod Parallelogram drive linkage Fluidic Muscle Vertical column Ball bearing Basic rotary axis 1 2 6 3 4 7 8 7 9 10 5 Applications 47 Although, without an increase in distance, the Muscle stroke is a relatively small, simple lifting gear can be quite easily constructed. Fig. 5-4 shows such a device for the handling of stone slabs. Fig. 5-4 Lifting gear with cantilever boom axis 1 a) Lifting gear b) Circuit diagram 14 2 4 1 Cantilever boom axis 2 Carriage with compressed air production 3 Electric cable 4 Fluidic Muscle with 20 mm nominal diameter 5 Air supply line 6 Ejector 7 Handle 8 Disc suction cup 9 Stone slabs 10 Directional control valve 11 Vacuum suction generator 12 Vacuum filter 13 Finger lever valve 14 Vacuum actuator 1 2 4 3 11 3 11 13 5 6 2 12 7 1 8 10 9 a) b) The compressed air is generated locally and is used for lifting and also for vacuum generation via a venturi nozzle. The load can be easily manipulated, since the moving part is low in weight and therefore has favourable dynamics. Load balancing, i.e. the compensation of weight forces is effected smoothly without sudden movements, since the lifting actuator operates stick-slip free. The Fluidic Muscle can be used cost effectively for many in-house devices. Fig. 5-5 illustrates such a device, whereby a gumming unit is lifted for cleaning purposes. This unit is equipped with lateral trunnions as a means of load attachment in the form of a double hooked suspension gear. Other boxes can be lifted and transported in a similar manner, e.g. moulding boxes in a foundry. The basic construction is also fairly universal. Imagine for example a device with gripping jaws for handling cast girders or a device with suction cups to grip wooden boards, panes of glass or furniture. 48 5 Applications Fig. 5-5 Lifting gear for a gumming unit 1 2 3 4 5 6 7 8 9 10 Ceiling running gear Fluidic Muscle Handle Air supply line Double-hook retainer Gumming unit Locating strip Flow control valve Hand lever valve Pressure regulating valve 1 4 2 8 9 3 5 10 6 7 Another interesting area of application is that of scissor-type elevating platforms as illustrated in the two examples shown in fig. 5-6. The weight force of the lifting plate is generally sufficient to ensure the lowering action and the lifting force is generated by a Fluidic Muscle. This can also be used pairwise to increase force. Constructionally, the Muscle is relatively easy to accommodate and to mechanically connect. Fig. 5-6 Scissor-type lifting platform with Fluidic Muscle drive a) Lifting platform with single scissors b) Lifting platform with twin scissors 1 2 3 4 Lift platform Fluidic Muscle Scissor drive Base frame 1 F 1 F 3 2 4 3 2 2 F Weight force a) b) 5 Applications 49 Fig. 5-7 illustrates a sample solution for a device used to lift pallets incrementally so that the upper workpiece position always reaches a defined unloading point. A ball bearing runs in a guide barrel and is protected against rotation by means of a bolt, which runs with a slotted hole; the Fluidic Muscle is also attached to this bolt and is protected within the barrel. Four drives of this type are configured on the lifting station. Fig. 5-7 Lifting platform for flat pallets 1 2 3 4 5 6 7 8 9 Flange plate Fluidic Muscle Guide barrel Guide slot Ball bearing Counter weight Workpiece stack Ratchet Flat pallet 7 A p h7 h6 h5 h4 h3 h2 h1 1 2 3 h1 to h7 Defined lifting levels p Compressed air 4 8 9 B 5 6 The pallet is deposited on the spot. Due to the weight force, the ratchet elements then move downwards from the top position A. When passing the edge of the pallet, the ratchets engage and clip underneath the pallet when the down position B is reached. The various lifting levels are controlled purely via the pressure within the Muscle. 50 5 Applications Levelling devices for stacked plates, sheets of paper or cardboard section can be found on many processing machines. The withdrawal or deposit levels should remain constant even though the stack height continually changes. Fig. 5-8 shows a solution for this.The height is controlled by means of pressure within the Fluidic Muscles. In order to create an adequate stroke, three Muscles are connected in series, whereby the combined contraction distances of the Muscles make up the overall stroke. The disadvantage here is that the compressed air connection point changes position on two of the Muscles. An additional base plate guide may be dispensed with if the configuration shown is repeated on the rear side. Fig. 5-8 Regulation of stacking levels using the Fluidic Muscle 1 2 3 4 5 6 7 Fluidic Muscle Paper stack Stacking frame Return pulley Hoisting rope Base plate Double-grooved cable roller 7 2 1 5 3 4 6 A less common application of the Fluidic Muscle is shown in fig. 5-9. This involves the lifting of a safety glass hood, which protects items on exhibit. If these are to be removed, then the Muscle lifts the hood including the built-in lighting system so that the items on display can be accessed. Four cables are fitted to the corners of the hood, which guide the hood during the lifting action. These are attached to the ceiling and to the base plate of the showcase, to prevent the lifting hood from swivelling and hold the base plate in the designated position. Since the showcase is suspended and free-standing, it has no support. 5 Applications 51 This design can of course also be used for other devices, which are used to lift hoods and covers, safety hoods for laboratory workplaces, test rigs and special workplaces in the medical sector. Fig. 5-9 Lifting devices on show cases 1 2 3 4 5 6 7 Fluidic Muscle Electric cable Guide cable Lighting system Glass hood Base plate Exhibit 1 2 3 7 6 5 4 Fig. 5-10 illustrates a swivel device for the feeding of an automatic cleaning machine. The module to be cleaned is moved upwards by means of a swivel arm until it is adjacent to a window opening on the sealing sleeve. A high torque is required in order to move the overhanging arm, which can be developed by means of a pair of Muscles with a diameter of 40 mm. This movement is transferred to the arm via a chain wheel. An identical drive is located on the other side of the machine. Both swivel arms are permanently connected via the pick-up platform and therefore move synchronously. Fig. 5-10 Loading device on an automatic cleaning machine 1 2 3 4 5 6 7 8 9 Fluidic Muscle Drive chain Swivel arm Chain wheel Steel bearing Module to be cleaned Pick-up platform Contact seal Cleaning nozzles 8 9 4 3 5 5 1 3 6 2 7 52 5 Applications 5.2 Gripping Grippers are used for the temporary retention of workpieces, packages and other physical objects and are generally attached to arms positioned within range. For reasons of dynamics, it is desirable that these should be as light as possible. However, a major part of the gripper weight consists of the drives. The Fluidic Muscle, being a compact, powerful tensile actuator, is ideally suited for gripping technology. A few application suggestions are therefore set out in this chapter. In the case of the gripper shown in fig. 5-11, workpiece protecting rubber elements are used as gripper jaws, which bulge during the retaining grip. The necessary force is generated via Fluidic Muscles. The rubber elements are wearing parts and can be easily exchanged. The “clamping fingers” can be attached in the diagonal oblong holes provided in the two base plates, so that they can be easily adjusted to variably sized objects to be gripped. The gripper is characterised by a favourable mass/performance ratio. However, the gripping distance with this design which is set for one object size is minimal. Fig. 5-11 Clamping grippers [8] 1 2 3 4 5 6 7 8 9 Gripper flange Air supply line Base plate Fluidic Muscle Spacing bolts Tie rod Guide bush Rubber body Object to be gripped 2 1 3 4 5 F Gripping force 6 7 8 F 9 F A larger gripping area is achieved with the following designs. In the case of the gripper shown in fig. 5-12, the Fluidic Muscle is used as a direct drive. The force/displacement ratios can be mechanically influenced by varying the hinge points. A tension spring is required to open the gripper jaws, although a compression spring could also be configured via the Muscle. All in all, a sturdy gripper is available for numerous tasks. 5 Applications 53 Fig. 5-12 Angle gripper 1 2 3 4 5 Gripper housing Fluidic Muscle Tension spring Gripper finger Gripper jaw 1 2 3 4 5 The gripper represented in fig. 5-13 is a long stroke gripper. Similarly, in the case of this gripper, the Muscle operates against a tension spring. The main movement is transferred to a traction mechanism (toothed belt), which moves the gripper fingers operating along a twin circular guide. This gripper is relatively wide and the Muscle can therefore be built-in laterally. Also, the gripper jaws are exchangeable and can be repositioned via selectable hole positions to permit adjustment of the gripping range to suit different sizes of object to be gripped. Internal gripping is also possible, although the gripping force is then predetermined by the tension spring force. Fig. 5-13 Long stroke gripper 1 2 3 4 5 6 7 8 9 10 11 Connection flange Fluidic Muscle Tension spring Toothed belt Return pulley Base plate Gripper jaw connection Internal gripper jaw Exchangeable gripper jaw Object to be gripped Linear guide 3 4 1 2 p 5 6 A Gripper jaw for part A B Gripper jaw for part B p Compressed air 11 7 B A 10 8 9 54 5 Applications Fig. 5-14 illustrates the principle of a multiple gripper, which can grip four objects and subsequently alter the distance between the gripper. For example, object such as ceramic tiles spaced at certain intervals on a conveyor belt. After the gripping process, the sliding blocks move inwards so that the parts are positioned closely together at the depositing point such as a flat pallet. The reverse process is also required in technology. A servomotor can be deployed at the swivel arm to make the adjustment. However, a lightweight Fluidic Muscle is used in the example shown. The spacing of the sliding blocks and therefore the objects to be gripped is set via the pressure. A second Muscle can also be provided instead of the tension spring. Fig. 5-14 Adjusting gripper with Fluidic Muscle drive (basic representation) 1 2 3 4 5 6 7 8 9 Sliding block Fluidic Muscle Twin guide rods Lever Tension spring Single Gripper Gripper housing Swivel arm Gripper jaw 4 3 1 6 5 8 4 1 9 2 3 7 Vacuum suction cups generally cannot be used to grip empty pallets because, although particularly in other countries, the framework size of the pallets is standardised, the positioning of the slats is not. The gripper shown in fig. 5-15 therefore grips the outer contours of the pallet. The clamping plates are guided at four points by means of a guide rod and opened by means of four compression springs, i.e. two on each gripper side. A Fluidic Muscle provides the clamping force and is located in the centre of the gripper. The deciding factor in favour of using the Muscle was the reduced mass, total insensitivity to dirt and high force (700 N, 20 mm Muscle diameter, 120 mm stroke, 1100 mm nominal Muscle length). 5 Applications 55 Fig. 5-15 Empty pallet gripper (Schmalz) 1 F 2 F 1 2 3 4 5 6 7 8 Connection flange Air supply line Fluidic Muscle Transport pallet Clamping plate Linear guide Compression spring Lateral slat 7 6 F Gripping force 8 3 4 5 How objects can be gripped via an internal bore assuming these are dimensionally accurate, i.e. have close tolerances, is discussed in the next example. Fig. 5-16 shows an internal gripper based on an external collet chuck. An conical wedge generates the gripping force FG when the Fluidic Muscle is activated. However, the taper on the cone must not lead to automatic locking, since the spring force of the multislotted collet chuck is required as a reset force. The Muscle stroke can be relatively small, since a high initial force is required. The clamping stroke of the chuck is minimal and is generally within a range of just 0.2 to 0.3 mm. Fig. 5-16 Internal bore gripper 1 2 3 4 5 6 Collet chuck Fluidic Muscle Workpiece Conical wedge Air supply line Attachment thread 5 6 1 FG Gripping force 2 3 FG FG 4 56 5 Applications There are many other possible solutions for operating a gripper by means of a Fluidic Muscle. Fig. 5-17 illustrates another variant. The gripper is of simple mechanical design, of lighter weight than comparable grippers and yet more powerful in retaining an object. The gripper fingers are mechanically coupled to synchronise the jaw movements. Provided that the Fluidic Muscle is fitted sufficiently close to the centre of rotation of the finger, even a short Muscle is adequate to execute the clamping motion. The efficiency of the gripper is excellent, since frictional resistance only has to be overcome in the circular pivots of the gripper fingers. However, this design does not permit opening angles of 90° per finger and different gripper kinematics would need to be selected. Fig. 5-17 Simple angle gripper 1 1 2 3 4 5 6 7 8 Gripper flange Gripper housing Tension spring Gripper finger Gripper jaw Workpiece Fluidic Muscle Rod for motion synchronisation 9 Finger stop p Compressed air 2 8 5 6 9 p 7 3 4 It is of course possible to replace heavy pneumatic cylinders with Fluidic Muscles in the case of many other gripper concepts. Yet another example is portrayed in fig. 5-18. This is a gripper which needs to be set above the object to be gripped. The gripping elements are held open by means of a tension spring and the Fluidic Muscle clamps the workpiece. Possible objects to be gripped are bars, bottles and for instance standing shafts. Fig. 5-18 Enveloping gripper 1 1 2 3 4 5 6 Tension spring Gripper base Fluidic Muscle Air supply line Gripper jaw Rotatable ring 2 3 4 5 6 5 Applications 57 5.3 Pressing and punching The Muscle is ideal when used for the actuation of a small press, e.g. for a table press using a toggle lever mechanism, because a high force is exerted via a short stroke. In the design shown in fig. 5-19, a press force of approximately 30 000 N is achieved with a stroke of 10 mm, using a Muscle with a diameter of merely 40 mm. Fig. 5-19 Pneumatic table press with twin toggle lever system 1 2 3 4 5 6 7 Yoke Fluidic Muscle Column Toggle lever mechanism Forming or cutting tool Block Tension spring 1 2 3 4 6 7 5 Whilst the force of the Muscle decreases with an increasing working stroke, it is characteristic of the toggle lever mechanism that the force at the dead point tends towards infinite. This leads to a certain compensation in the course of the force curve. The motion is therefore smooth and thus also has a positive effect on the punching result. 58 5 Applications Moreover, noise is greatly reduced. Since the Muscle can only generate tensile forces, a reset force is required for the toggle lever mechanism which, in the example shown, is generated by means of a tension spring. Other than that the Muscle is leak-free and is not subject to any frictional wear. Furthermore, when compared with a pneumatic cylinder, it only requires 40% of the energy for an identical force. The pressing-in of bearings in major repair subassemblies is carried out by means of mobile presses, which are attached to a cable or balancer arm (fig. 5-20). These are guided manually by sight. The lighter such a C-frame pressing machine is, the more dynamically and easy it is to be positioned within a given area. This is why the use of a Fluidic Muscle is advantageous. The two Muscles are accommodated on both sides of the press frame. A compression spring may be used to reset the press plate. A similar method may also be used to construct mobile dismantling units. Fig. 5-20 Assembly press 1 Cable or chain pulley block suspension 2 Air supply line 3 Fluidic Muscle 4 Press arm 5 Rod clevis 6 Press plate 7 Assembly module 8 Assembly bench 9 Assembly component 10 Back support 11 Operating handle 12 Press frame 13 Compression spring 1 3 2 13 4 5 11 12 9 6 7 10 8 5 Applications 59 A small table press powered by a Muscle is shown in fig. 5-21. A toggle lever mechanism is interconnected between the Muscle and the upper tool section for the force transmission. As mentioned in fig. 5-19, the action of the Muscle forces and the toggle lever are superposed in the course of the press stroke. Two small single-acting pneumatic cylinders are attached because the Muscle cannot generate any pressure forces. The workpiece closed smoothly and without jerking, as there is no piston friction with the Fluidic Muscle. The press generates relatively high forces within a small area and can be universally used in a workshop. Fig. 5-21 Small press for assembly and forming operations Yoke Toggle lever mechanism Upper tool section Guide rod Lower tool section Fluidic Muscle Retract cylinder Tool clamping element Base plate Transmission of force on toggle lever 11 Force curve for Fluidic Muscle 1 2 3 4 5 6 7 8 9 10 4 1 8 7 9 2 4 6 6 Action of force 10 11 8 3 5 9 Path Dead point Handling units using an articulated arm (industrial robot) generally cannot be used for the pressing-in of tight fitting parts due to the load bearing capacity of the joints. Percussion devices are available for this, which are basically pneumatic hammers on a reduced scale that can for instance press-in a dowel pin by means of a repeated punching action. In this case, the flux of force is not required to close via the articulated arm of the robot. The percussion device outlined in fig. 5-22 is lightweight and can realise a high striking frequency. The striking energy is generated by the spring and the acceleration of mass of the percussion element. Vibrationwise, the percussion device is decoupled from the flanged piece via several elastomer springs. 60 5 Applications Fig. 5-22 Pneumatic percussion device 1 2 3 4 5 6 7 8 Air supply line Valve Connection flange Base plate Percussion piston Elastomer spring Compression spring Fluidic Muscle 8 p Compressed air 1 2 7 p 3 4 5 6 In the case of printing or book binding machines, it is often necessary for material to be printed or glued to be pressed on to rollers. An adjustable presson force is therefore required. The press-on motion should be gentle and without any sudden changes. Because of its motion behaviour, the Fluidic Muscle is particularly suitable for this function. The configuration illustrated in fig. 5-23 should be regarded as an example for any similar cases. Fig. 5-23 Paper sheet guide plate press 1 2 3 4 5 6 Fluidic Muscle Material to be printed Retract spring Guide Sheet guide plate Exiting conveyor 4 5 1 3 2 6 5 Applications 61 Fig. 5-24 illustrates some press components such as have already been manufactured for various applications. Whereas in the variants shown in fig. 5.-24a and b, the Fluidic Muscle is used to release the tension, figs. 5-24c and d illustrate design variants where the central shaft (thrust bolt) advances when the Muscle contracts. Muscle actuators combined in this way achieve extremely high forces in relation to their size. With an operating pressure of 6 bar and contraction of 8%, seven Muscles of a diameter of 40 mm produce a total force of approximately 28 000 N. Fig. 5-24 Press components using the Fluidic Muscle as a force generator 1 a) Individual component with bevelled flange mounting b) Press component with rod eye coupling c) Unit using four Muscles d) High-force element with seven Fluidic Muscles 1 2 3 4 5 6 7 8 Pressure plate Compression spring Fluidic Muscle Rod eye Pressure head Square thrust bolt Mounting plate Thrust bolt 4 5 c) 6 7 2 3 a) b) d) 8 An installation from the texile and clothing industry is illustrated in fig. 5-25. This also involves pressing, but in this cases the “smooth pressing” of garments. The press is used for ironing, flattening, pressing and heat-set finishing. The press arm and press table can also be equipped with a formed press shoe. A multi-part link arrangement is attached in order for the upper press plate to open fast and wide and a Fluidic Muscle (or two in parallel) is used as the drive, which operates against the tension spring to open the press. 62 5 Applications Fig. 5-25 Ironing press for garments 1 2 3 4 5 6 7 Base plate, form Table Fluidic Muscle Swivel arm Tension spring Press arm Coupling element 70° 6 7 p Compressed air 1 2 3 4 5 p 5.4 Pumps Pumps of all types are important machines for the conveyance of pure, contaminated, aggressive and mildly gassing fluids. Reciprocating piston pumps are frequently used, which typically have a displacement element either in the form of a piston or a diaphragm. Whereas the single-acting type only facilitates one displacement action per double stroke, two displacement actions per double stroke can be achieved with the double-acting type. A piston pump of this type is shown in fig. 5-26. A special feature is the actuation by means of an integrated Fluidic Muscle. When expanding, the Muscle not only acts as a tensile actuator, but also as an additional displacement element, because the diameter increases during contraction. This solution is also made feasible because the Muscle material is insensitive to water, waste water and other contaminated fluids. Apart from the disc piston or piston seal, no other components are subject to frictional wear (valves excepted). A pump of this type can be widely used, e.g. in mining, as a cooling water pump or recycle pump. It is considerably lighter which facilitates manual implementation, e.g. in the building trade and is not subject to leakage. 5 Applications 63 Fig. 5-26 Piston pump with Fluidic Muscle (Messrs. Gründer & Hötten) 1 2 3 4 5 6 Ball valve Air supply line Cylinder Fluidic Muscle Ball valve Suction line 1 p1 2 3 4 p2 5 6 If water can be pumped, then equally the evacuation of air must also work. This involves the creation of a vacuum. Fig. 5-27 shows a functional diagram of a vacuum pump, whereby a pressure of approximately – 0.6 bar can be achieved. The piston is moved by two Fluidic Muscles. Proximity sensors supply signals for the return. The air is evacuated in two stages and vented to atmosphere. A 3/2-way valve is activated via a process signal and switches the vacuum to the suction cup. In the other position, the suction cup and the supply line are switched to air circulation. Fig. 5-27 Vacuum pump with Fluidic Muscle actuation (functional diagram) 1 2 3 4 5 6 7 Cylinder Ring magnet Piston Vacuum reservoir Vacuum suction cup Object to be gripped Proximity sensor 5 4 6 2 1 3 7 24V 0V 0V 24V 64 5 Applications 5.5 Clamping High force and short distances are characteristic basic requirements for clamping devices. These coincide perfectly with the capacity of the Fluidic Muscle, which generates considerable initial force. This can be directly transmitted to the object to be clamped or additional transmission mechanisms can be interconnected to reverse the direction of force action and increase force. A few examples are shown below. Fig. 5-28 illustrates a tensile actuator specially developed for clamping. This can be installed for tensile or pressure action. In the clamping example, the clamping force F is generated by a set of cup springs. The Fluidic Muscle is used to release the clamping action. In addition, the force of the piston (annular surface x pressure) can be added to this to support the Muscle. A separate supply port is provided. The clamping force F varies depending on how the individual forces (FM diaphragm force, FF Spring force, FK Piston force, FKi Piston force at the spring end of the piston) takes effect. A major advantage is the small size of the clamping element compared to conventional pneumatic cylinders. The use of a hydraulic working cylinder can therefore be dispensed with in many cases. The slightly inclined construction of the clamping unit leads to a pullingdown effect during clamping whereby the workpiece is not only clamped but at the same time pressed against the supporting surface. Fig. 5-28 Tensile actuator with Fluidic Muscle [9] 1 2 3 4 5 6 7 8 9 10 11 Workpiece Clamping counter support Hollow piston Cap Support Supply port for piston Set of cup springs or screw cup springs Fluidic Muscle Housing Supply port for Muscle Locking ring 6 7 1 3 2 8 9 10 4 11 5 p1 p2 p3 F F F F = FM - FF - FKi F = FM + FK - FF - FKi F = FF 5 Applications 65 By means of a simple “adaptor mechanism”, the tensile actuation can also be made into a gripper or internal clamping device as illustrated in fig. 5-29. The clamping action is effected by means of spring force. The actual gripper head could be designed in an easily detachable form so that different gripper heads could be used if required. Fig. 5-29 Internal clamping device 1 2 3 4 5 6 7 8 Housing Fluidic Muscle Set of cup springs Piston Piston rod Attachment flange Clamping lever Workpiece 1 2 3 4 5 6 7 8 Another problem is keeping belts tensioned. This has been the case for as long as belt drives have existed, since belt drives lengthen slightly during operation. Numerous solutions are therefore available. Fig. 5-30 illustrates how a Fluidic Muscle can also be used here. It is used as a pneumatic spring to tension toothed belts. The belt operates a concrete vibrator, i.e. the environment is subject to considerable concrete dust. In the case of pneumatic cylinders used in the past, dust settled on the piston rod and gradually damaged the wiper seal. 66 5 Applications The Muscle is much better equipped to cope with this, since it is a closed system. Moreover, it absorbs any unavoidable impact much better since it does not need to overcome any component friction. Fig. 5-30 Belt tensioning device The retention of reels of material often requires axial devices, which can be used for internal clamping. A shaft axis of this type is shown in fig.5-31. A Fluidic Muscle concealed inside is used as a tensile actuator. This principle can also be used for other internal clamping functions. The tubular casing complete with countercones is divided into three so that an expanding action can be created. Diameter D expands and in this way clamps against the internal wall of a sleeve or a reel of material. Spring clips hold together the segments in the unclamped state and also effect the return stroke of the segments. Fig. 5-31 Design of a shaft axis 1 2 3 4 5 Spring clip Casing Fluidic Muscle Clamping cone Supply port 2 1 5 3 View A 4 D 4 1 5 Applications 67 Fig. 5-32 illustrates a clamping device where, because of the limited installation length available for the Muscle, the hinge points have been moved very close to the centre of rotation of the clamping arms in order to slightly increase the small stroke of the Fluidic Muscle. The clamping arms have been mechanically coupled to ensure that the clamping elements close centrally. Fig. 5-32 Clamping device for ring flange 1 2 3 4 5 6 7 Clamping jaw Workpiece Fluidic Muscle Clamping arm Retract spring Clamping table Air supply line 1 2 5 3 4 6 7 Fig. 5-33 illustrates two clamping options using a Fluidic Muscle. In one solution, pipes and rods are moved along on an angled roller conveyor. If the Muscle is released, the pipe can be moved on manually, since there is a rolling friction on all points of contacts. During the cutting-off process, the clamping arm is pressed with great force against the pipe. Fig. 5-33 Clamping devices a) Holding of piping on a cutting off device b) Clamping a casting 1 2 3 4 5 6 7 8 Clamping object Angled roller Plain roller Clamping arm Fluidic Muscle Frame Tension spring Pressure disk 3 1 2 5 4 8 1 7 6 a) b) 68 5 Applications It is possible to imagine many other constructional modifications of this basic device, such as the clamping of cuboidal objects. Often only a small clamping stroke is required so that a much shorter Muscle is needed that can be easily accommodated in a clamping device. Fig. 5-34 shows a device used for the welding together of conveyor ends. This is a press with heatable plates, which are pressed together by two Fluidic Muscles. The Muscles are loose and are not suspended in the U-shaped retainers of the plates until the conveyer belt ends have been inserted and clamped with the cone of the locking nut. The pressure lines for the Muscles are then connected and the compressed air switched on. This device is simple and lightweight and therefore easy to transport. Fig. 5-34 Press for welding conveyor belt ends (simplified representation) 1 2 3 4 5 6 7 8 Fluidic Muscle Upper plate Lower plate Supporting plate Heating cable Conveyor belt Belt clamp Handle 8 1 2 3 7 4 5 6 The Fluidic Muscle designed in the form of a pressure element can be easily built into a clamping device. Fig. 5-35 illustrates a design example. The construction of this device is extremely simple. As with a pneumatic cylinder, the Fluidic Muscles are screwed into an appropriate basic component. Much smaller Fluidic Muscles are selected compared to the pneumatic cylinders, as they can generate much higher forces. This provides more space at the clamping point, making it easier to monitor and the Muscle is not damaged by wood splinters. 5 Applications 69 Fig.Bild 5-35 Clamping of a timber log on an articulated-arm drilling machine 1 2 3 4 Drilling or cutting tool Clamped object Angled support Base plate of clamping device 5 Fluidic Muscle 6 End stop 4 1 2 5 3 6 On a profile bar machining system, the semi-finished products are to be pressed onto a steel-plate conveyor by means of a rubber coated pressure roller using the force F (fig. 5-36). The material passing through is of different dimensions, although a defined contact force F is to be maintained. A tension spring cannot do this, since the contact force changes according to the spring constant if the height of the material changes. If a Fluidic Muscle is used, then the force F can be adjusted via the pressure. This would also function with a pneumatic cylinder, but not with stick-slip free movement and without a certain cushioning effect. Fig. 5-36 Contact roller for incoming plastic or other profiles 1 Fluidic Muscle 2 Precision pressure regulating valve (LRP...) 3 Pressing roller 4 Profile bar 5 Machine frame 6 Support 7 Plate-chain conveyor 1 5 F 3 4 2 6 70 5 Applications Similarly, quick clamping and ventilating is an important function on high performance automatic punching machines. During the intermediate venting, the pressure roller of the feed unit is to be briefly vented during each working cycle. The punching tape is therefore force-free so that the pilot pins in the tool can correctly align the tape. Roller feed devices are therefore mechanically or pneumatically ventilated at intermediate intervals, for example using ventilating periods of 10 ms and opening travel of 0.3 to 3 mm. If this intermediate ventilating is realised solely by means of a pneumatic cylinder, then an operating frequency of maximum 3 Hz is achieved. This corresponds to a stroke rate of 180 cycles per minute. The dynamics of this process can be improved if ventilating is assumed by a Fluidic Muscle, whereby maximum cycle rates of 7 Hz can be achieved. This corresponds to 420 cycle rates per minute, a rate which can so far only be achieved by the Muscle. The higher frequency is facilitated by the minimal mass and friction of the Muscle. In the example given, the stroke for ventilating is 3 mm and requires a high force, since the Muscle operates against the roller pressing cylinder (Fig. 5-37). Two Muscles with a diameter of 40 mm have been used (nominal length 120 mm, force for a 3 mm stroke 3500 N). System design-wise, the intermediate ventilating via the Muscle is a very simple and consists of only a few individual components. Fig. 5-37 Intermediate ventilating of a feed roller 1 2 3 4 5 6 7 8 9 Automatic punching device Fluidic Muscle Pneumatic cylinder Pressing roller Upper tool section Pilot pin Punching tape Lower tool section Feed roller 1 2 3 4 5 6 7 8 9 The tying down of loads with ropes often entails the use of tension jacks, spring and rubber straps. This clamping function can also be envisaged with the use of a Fluidic Muscle as a pneumatic spring. Fig. 5-38 illustrates a simplified example. In this case, the Muscle is equipped with a plug-in coupling. The compressed air for the clamping action is derived either from the on-board compressor of the heavy-goods vehicle or by means of a foot pump. 5 Applications 71 Fig. 5-38 Bracing cable with Fluidic Muscle 1 2 3 4 5 6 7 8 Bracing cable Fluidic Muscle Foot pump Tubing Plug-in coupling Loading surface Load Transport pallet 1 3 2 7 8 4 5 6 Slightly more space is involved to stabilise air-filled spatial structures. A membrane building of this type consists of inflated sections, which are longitudinally held in place by Y-supports. Fig. 5-39 shows a cut-out view of such a three-point node. The equilibrium of forces is ensured by means of cables and assisted by Fluidic Muscles. Fig. 5-39 Bracing of a membrane building (Festo) 1 Bracing cable 2 Spatial structure, Air-inflated building 3 Y-support 4 Fluidic Muscle 5 Tensile actuator 1 5 4 3 2 72 5 Applications The air pressure within the Muscles varies between 0.3 and 1 bar and continually and infinitely regulates the tensile force. In this way and with the help of sensors and master computer control, the building reacts to any load diversities as a result of wind load, snow and solar radiation. For example, if the wind load hits a side wall of the building, then the Muscles responsible for this wall react with an increase in tensile force. The Fluidic Muscle in this case is used as an adaptive tensioning component. Production systems processing strips or webs of material generally also have to ensure a constant identical tension during unwinding? On the band feed system shown in fig. 5-40, the band runs across guide rollers and is kept taught by means of a tensioning roller. Fig. 5-40 Band feed system with controllable tensioning roller 1 2 3 4 5 6 7 8 9 Band, Web of material Guide roller Tensioning roller Clevis foot mounting Fluidic Muscle Muscle attachment Inductive proximity sensor Proportional valve Swivel arm 1 4 2 9 3 7 5 5 8 6 This is pulled against the band by the Fluidic Muscle. The swivel arm motion is monitored by a proximity sensor and the pressure within the Muscle is specified by a proportional pressure regulating valve. 5 Applications 73 Objects to be clamped are not always rigid objects such as for instance in the case of packaging machines, where the end of a width of film, e.g. stretch film, needs to be retained. In the past, various different, generally mechanically elaborate, mechanisms have been developed for this purpose. Fig. 5-41 illustrates a principle of action, which works in a completely different way. Fig. 5-41 Clamping of stretch film a) Design principle b) Clamping process p 1 1 Film width 2 Compression spring 3 Fluidic Muscle F Muscle clamping force p Compressed air 1 2 3 3 a) b) F The film is placed against the coils of a slightly relaxed compression spring, whereby it enters between the coils. The Fluidic Muscle then generates force F and the spring is (almost) compressed up to the block length, thereby firmly clam-ping the stretch film. One advantage, apart from a mechanically simple solution, is that the force F is infinitely adjustable via the pressure p. In the example given, one Fluidic Muscle of an internal diameter of 10 mm is sufficient. One special type of clamping involves clamping systems, which need to become automatically effective in the event of power failure and for example stop reciprocating slidess. With safety systems of this type, springs are usually used as the active components, which are released during a power failure. 74 5 Applications An example of a mechanism of this type is shown in fig. 5-42. If the compressed air supply is blokked during an emergency, then the tensile force of Fluidic Muscle stops and the spring returns the clamping cam or clamping strip into position. The vertical slide is wedged as a result of this and therefore cannot drop. Fig. 5-42 Safety clamping system 1 2 3 4 5 Vertical slide, rail Guide rail Fluidic Muscle Clamping cam Tension spring p 1 2 3 4 5 The Fluidic Muscle could also be visualised in the form of a belt-tensioning actuator in a car (fig. 5-43). Up until now, actuation has been effected pyrotechnically. A pressure wave created as a result of a collision drives the piston operating within a tube, which then produces a tensile force. However, this only works provided that the piston system is not deformed during an accident. The solution using the Fluidic Muscle also requires a very fast valve apart from the Muscle and pressurised reservoir. If the crash sensor registers frontal impact, this causes the belt tensionsing control to react and opens the valve. The gas enters into the Muscle, which immediately develops a high tensile force. The system is explosion-proof and exhibits favourable force/displacement behaviour. However, a material composition would have to be selected which ensures full operational reliability even at temperatures down to – 30 °C. 5 Applications 75 Fig. 5-43 Application idea using a Fluidic Muscle as a belt tensioner [10] 1 2 3 4 5 6 Safety belt Belt locking clip Guide roller Fluidic Muscle Valve Gas cartridge 1 2 3 4 5 6 5.6 Adjusting and positioning The adjustments of components from one end position into another, often also using defined intermediate positions, very frequently occurs in automation. Before presenting some examples, a few basic possibilities are outlined below of how the Muscle can be used in machine stuctures. A reversal of the Muscle as shown in fig. 5-44h, is also possible. However, the diameter of the guide roller must be 10 times greater than the internal diameter of the Muscle. The roller should have a closely fitting contact surface in order to accommodate the radial expansion of the Muscle. However, the friction between roller and Muscle membrane does reduce service life; during testing, 50 000 stress cycles were achieved before the Muscle failed. 76 5 Applications Fig. 5-44 Actuation of components using the Fluidic Muscle a) Adjusting motion using stroke enlargement b) Actuation using force amplification c) Swivel angle adjustment d) Actuation of a rotary axis using twin Muscles e) Pressing rod element f ) Parallel connection for force amplification g) Slide unit h) Roller operation i) Actuator with spring return k) Torque amplification l) Linear movement a) b) c) d) e) f) g) h) i) k) l) A few topical applications and ideas are set out below. In the solution shown in fig. 5-45a, the width of the transport channel is set to the product width whereby, at a certain pressure level, a corresponding position of the control element is set. If products are to be guided into a specific output channel, then a sorting gate can be incorporated as shown in fig. 5-45b, which uses contra-operating Fluidic Muscles. Ten or more intermediate positions can be achieved even with a fast changeover. A fast switching valve is required for rapid changeover. A valve of type MHE 2 can be used here, which switches a flow of 100, 200 or 400 l/min within 2 ms and has symmetrical switch-on and off times. 5 Applications 77 Fig. 5-45 Width adjustment of a conveyor length a) Guide rail adjustment on one side b) Guide rail adjustment on both sides 1 2 3 4 5 6 Container product Guide rail Fluidic Muscle Conveyor belt Reset spring Linear guide p1 p2 p3 p4 3 p∩ 1 2 5 p Compressed air 6 4 p1 ... p∩ a) 1 2 4 3 p1 p2 b) 5 6 78 5 Applications Fig. 5-46 illustrates Fluidic Muscles (diameters 10 mm, length 150 mm) in the form of a drive for a manual hydraulic control unit. The hydraulic valve, for example for controlling a crane, hoist trolley or a construction vehicle is thereby remotely controllable. Radio remote control and pneumatics now permit the remote control of on-site functions such as the loading and unloading of a lorry. The depositing of a load can then be monitored and controlled from the immediate vicinity. The Fluidic Muscle is ideally suited as a drive in this case, since it permits stick-slip free movements and does not involve any external guides which could become dirty and require special maintenance. Standard pneumatic cylinders are subject to vibration during movement due to friction in the seals, which is detrimental to sensitive control. The permissible temperature range for Fluidic Muscle operation is generally around +5 °C to +60 °C. This would mean that the solution can only be used for indoor applications. For external use, a Muscle material would have to be used that can be exposed to temperature of – 30 °C. Fig. 5-46 Actuation of a joy-stick 1 2 3 4 5 Fluidic Muscle Hydraulic valve Reset spring Joy-stick lever Proportional pressure regulating valve 1 3 4 2 5 Fig. 5-47 illustrates the coupling of a slide to a Muscle drive. With this configuration, a slide stroke of 125 mm achieves a cycle time of 0.75 s. A second Muscle can also be used instead of a reset spring. Again, intermediate positions can also be approached via pressure in this case. Since this configuration involves a larger stroke, this also increases positioning errors. 5 Applications 79 Fig. 5-47 Slide drive using a Muscle 1 2 3 4 5 Fluidic Muscle Rocking lever Retract spring Linear guide Slide 3 p 1 2 p Compressed air 5 4 In sewage systems and similar installations in agriculture, coarse matter in waste water to be treated is frequently retained by means of grids and subsequently removed separately from time to time. The retaining grid therefore has to be movable. The example shown in fig. 5-48, uses several swivel arms arranged in parallel, each of which is actuated by a Fluidic Muscle. The return stroke is effected by the dead weight of the several metre wide grid. In the example, the decision to use the Muscle was taken, because it is better equipped to deal with the high air humidity than other drives. Moreover, the outlet level between channel and grid is sufficiently accurately and infinitely adjustable. Fig. 5-48 Swivel grid in a sewage treatment plant a) Grid closed b) Grid open 1 2 3 4 5 6 Fluidic Muscle Swivel arm Sewage channel Retaining grid Acceptable flow Roller 1 4 2 5 6 3 4 h Outlet level a) b) 80 5 Applications Fig. 5-49 illustrates a suggestion for the precision positioning of large loads. The support plate for load retention rests on an air cushion so as to limit friction to a minimum during movement. The load can be moved by means of corresponding pressure control of the fluid actuators and the orientation can also be changed to some extent. Since the movements are stick-slip free, minor correcting movements at low speeds are also not a problem. Fig. 5-49 Multiaxis precision positioning of a clamping support plate 1 2 3 4 Fluidic Muscle Air jet plate Base frame Clamping plate 5 1 4 2 3 2 4 Fig. 5-50 represents the actuation of a barrier. A total of four Fluidic Muscles is used, i.e. two on each side. The decisive factor was simple speed control, particularly in the end positions of the swivel motion. The force development characteristics are ideal for this task, i.e. high initial force and minimal end force when the barrier reaches the vertical axis position. This solution is of course only suitable if compressed air can be easily supplied from an adjacent building. 5 Applications 81 Fig. 5-50 Actuation of a barrier 1 2 3 4 5 Barrier Toothed belt Fluidic Muscle On-board toothed pulley Housing p Compressed air 4 1 2 3 5 p1 p2 If the Fluidic Muscle is introduced into a media flow, then its change in diameter can be used to regulate the flow velocity of flowing media. This principle is shown in fig. 5-51. The void pipe cross section of diameter D is restricted by means of the Muscle diameter d. The Muscle diameter is a function of the applied pressure p1. The following correlation exists: Fig. 5-51 Flow velocity regulation using the Fluidic Muscle 1 Fluidic Muscle 2 Retaining strut 3 Pipe p Compressed air 1 A2 d2 2 3 p1 p1 d2 A1 v1 d1 A2 v2 v3 d3 Q A3 82 5 Applications d1 d2 At a constant flow rate, the ratio of the flow velocity is the inverse of the flow cross sections. The flow rate equation is as follows: Q = A1 · v1 = A2 · v2 = A3 · v3 whereby A2 = f(p1). Another example is the infeeding of bulk material on a filter press which requires a constant throughput level height on a conveyor. However, height h is not a constant, but must be adjustable. In the solution shown in fig. 5-52, the excess material is pushed away by means of a wiper blade. A Fluidic Muscle paired with a tension spring is used as a drive for this wiper. The plate is therefore infinitely adjustable in line with process specifications. The drive is sturdy and insensitive to the demanding environment. Fig. 5-52 Adjustment of throughput level on a conveyor belt a) Section through the conveyor length b) Side view of conveyor 1 2 3 4 5 6 7 Frame Fluidic Muscle Tension spring Wiper blade Conveyor bulk material Guide plate Conveyor belt 1 2 3 4 6 h Level of material 7 a) 6 h 4 5 7 b) 5 Applications h 83 Of a completely different type is the mechanism shown in fig. 5-53, with which a mirror can for instance be used for tracking in order to measure solar radiation simply by adding a basic swivelling axis. The Muscle generates a constant diffraction of the articulated joint structure against a tension spring so that the end effector carries out an infinitely adjustable motion. The control of the pressure within the Muscle is predetermined by a program control system. An antagonistic Muscle pair could also be used and the spring omitted. The Muscle is an excellent choice for this application, since minimal Muscle strokes are sufficient and outdoor use is not a problem Fig. 5-53 Principle of an articulated joint structure used for position tracking of a mirror 1 Mirror 2 Articulated joint mechanism 3 Fluidic Muscle 4 Tension spring 1 2 3 4 The connection and disconnection of rotary movements requires couplings to establish a form-paired connection using claws or other drivers or force-paired 84 5 Applications using friction discs. Fig. 5-54 illustrates a suggestion of how the adjusting motion can be effected by means of a coaxially configured pneumatic Muscle. The movable coupling disk is connected to the drive shaft via a pin and oblong hole. A better and more powerful effective solution of course would be a multiple spline profile which is also possible. The coupling rotates with the drive shafts and the spring force is coupled. The release of the connection is effected by means of the pneumatic Muscle. The required compressed air is supplied internally via the drive shaft. Fig. 5-54 Switchable friction coupling 10 1 2 3 4 5 6 7 8 9 10 11 Friction lining Coupling disc Clamping cone Compression spring Fluidic Muscle Frame Drive shaft Compressed air channel Multiple spline profile Coupled Uncoupled 11 8 9 7 1 2 3 4 5 6 5.7 Handling It is obvious that because of their ability to react quickly, Fluidic Muscles can also be used as drives for handling units. Fig. 5-55 illustrates a handling device, which removes components from a machine and deposits these at a different point. Four Fluidic Muscles have been built-in around the upper section. The swivel plate with the lifing unit and the suction cup can therefore be deflected within the area around the centre point of the ball joint. Simple pressure changes within the Muscles suffice to effect angular motion of the swivel plate in four directions in clearly defined values. An additional Muscle is used for the up and down movement of the suction cup. Here too, the precise position is realised in relation to pressure achieved. As with a biological structure, the extensor and flexor form an antagonistic muscle pair. 5 Applications 85 Fig. 5-55 Withdrawal device for small parts 1 Fluidic Muscle with diameter of 10 mm 2 Ball jointed shaft 3 Swivel plate 4 Compression spring 5 Lifting unit 6 Suction cup 7 Workpiece 8 Muscle for lifting 9 Centre of rotation 10 Supply port 10 1 9 2 A A p4 3 Section A-A 4 8 p3 3 p1 p2 B B 5 p5 5 z 6 7 X Section B-B 4 A similar solution is shown in fig. 5-56. Here, a pneumatic cylinder with through hollow piston rod is used for the movement in the the Z-axis. In this way, the required vacuum (or compressed air if an ejector is used near the effector) can be guided through the piston rod. The stroke movement is monitored by means of cylinder sensors. The advantage here is that the magnitude of the Z-motion is not dependent on a muscle contraction and can therefore be selected for a respective task using the appropriate stroke. Moreover, the height of the handling module is less than that in the solution shown in fig. 5-55. 86 5 Applications Fig. 5-56 Handling module with 3 degrees of freedom (Tripod) 1 2 3 4 5 6 7 8 Base plate Fluidic Muscle Ball joint Pneumatic cylinder Sensor or cylinder sensor Swivel plate Vacuum suction cup Hollow through piston rod p1 p2 p3 p4 1 2 p Compressed air 3 8 p5 p6 4 5 6 7 Z Important and often technically complex handling processes are arranging and sorting tasks. By “arranging” we understand a process, whereby an object is aligned from a random into a specified orientation or direction of movement . “Sorting” on the other hand refers to the separation of a quantity of parts into different sorts. Dimensions and other characteristics can be chosen as parameters for sorting. Both in the case of arranging and sorting high piece rates. Fig. 5-57 illustrates how cuboidal workpieces enter into the arranging station at even intervals. The workpieces are then to continue separately in orientation A and B. 5 Applications 87 Fig. 5-57 Arranging of workpieces 1 2 3 4 5 6 7 Feed conveyor Workpiece queue Sensor Fluidic Muscle Oscillating arm Parallel conveyor Frame A 4 A and B Workpiece orientation 3 5 B 1 2 6 7 An optical sensor senses the incoming workpieces and supplies a signal to a fast switching valve MHE 2 via a PLC. This actuates the two Fluidic Muscles, which then move the slide. Incorrectly orientated parts are immediately pushed on to the parallel conveyor. Since the Fluidic Muscle is capable of extremely quick contraction and relaxation, very high throughput rates can be achieved. In a similar experimental setup, a maximum operating frequency of 47 Hz has been achieved, i.e. 47 arranging sequences per second. Highly dynamic motion sequences of this type are not achievable with piston drives. The automatic joining of matching pairs “bolts in holes” generally requires the compensation of small angle and position errors. Joining mechanisms are therefore used which are equipped with elastomer elements and which ensure a passive compensation. Because of its excellent characteristics, the Fluidic Muscle could also be used. 88 5 Applications Fig. 5-58 demonstrates a design solution for this. The compensation mechanisms consists of two function units. The upper row of bearings permits the compensation of positional errors x and the lower ones of angular errors β. Fig. 5-58 Joining mechanism p 1 2 3 4 5 6 7 Basic body Fluidic Muscle Positional compensation x Angular compensation β Gripper Joining part Basic assembly part 1 2 p Supply port 3 4 3 5 6 x 4 7 β In passive mode, the Fluidic Muscles act as springs whose characteristic is changeable. This could even change its characteristic during a joining action, which is not not possible with conventional joining mechanisms. The functioning of joining aids of this type is always dependent on the availability of a joining chamfer on the base part and/or on the joining part. 5 Applications 89 It would also be possible to set up an active operating mode, i.e. a precision adjustment of the gripper would be realised according to sensor information in the required steps. Each of the four Fluidic Muscles fitted would need to be individually controllable. The vibration-absorbant behaviour and stick-slip free compensating movements are particularly favourable in this case. The required Muscle stroke is minimal which is also why a reasonable height of the installation is achieved. If the pressure is allowed to pulsate throughout the Muscles, a vibrating movement (wobbling) is achieved on the gripper, which additionally assists the joining process or attachment of the joining part. Artificial muscles can also be used to advantage for the automatic transfer of objects. A certain task within a conveyor length may for instance consist of forwarding incoming material sections (solid material, pipes, semi-finished profiles) to the right or left, depending on the command from a master controller. One possible solution is to incorporate deflectors in the conveyor section (fig. 5-59) by installing several levers in pairs along the section. The actuation of these deflector levers can be easily realised by means of Fluidic Muscles, since these can generate a high force at the beginning of the deflecting motion. If none of the objects are deflected, then the parts simply continue along on the conveyor. Fig. 5-59 Deflector 1 2 3 4 Feed section Workpiece Deflector lever Fluidic Muscle 2 3 1 4 90 5 Applications Another solution for this problem is shown in fig. 5-60. In this example, a section of the conveyor length can be tilted to the right or the left so that parts can roll off of their own accord. Since the parts in question are large and heavy, the rolling movement needs to be decelerated at the end. A Fluidic Muscle in the form of a spring function has been used in this instance. The spring characteristic can be influenced by pressure control so that the stop impact is smoothly absorbed which is particularly important in the case of heavy workpieces. Tilting feed limiting devices of this type are generally hydraulically operated. Thanks to the high force generated by the Muscle, the less costly pneumatic Muscles are in many cases adequate. Fig. 5-60 Tilting separator with Fluidic Muscle 1 1 2 3 4 5 6 Object Tipping receptacle Roll-off track Stop Muscle as spring Fluidic Muscle 2 3 4 6 5 With the ever increasing speed of production systems, a fast allocator may also become a necessity. The feed limiting device shown in fig. 5-61 virtually “shoots” the components into the roll-off track. The capacity of the allocator is limited by the moving-along process of components in the magazine, i.e. the law of gravity. However, the moving-along process can be accelerated, e.g. by means of a compressed air jet. Applications are also possible in the bulk and loose material handling sector. For example, the discharge of pourable material from hoppers may be hampered if arching occurs. This means that an arch effect is created which can stop the flow altogether. This has traditionally been corrected by means of mechanical components such as swivel arms or advancing and retracting round or square bodies, which were built-into the zone precisely where the arching effect occurs [11]. A technically simple solution is the installation of a Fluidic Muscle as shown 5 Applications 91 Fig. 5-61 Fast allocator 1 2 3 4 5 6 7 Magazine chute Workpiece Roll-off track Allocating segment Stop Frame Fluidic Muscle 1 2 3 4 5 7 6 in fig. 5-62. Continual contractions of the Muscle regularly disturb the force patterns within the bulk material and thus prevent an arching effect. However, bulk material must not be inclined to agglomorate into lumps under pressure surges since this would lead to the opposite effect. Trials should therefore be carried out beforehand and the bulk material must not exhibit any visible abrasive characteristics. Fig. 5-62 Bulk material vibrator in a funnel-type hopper 1 2 3 4 Hopper Fluidic Muscle Arch effect zone Bulk material p 1 2 3 4 92 5 Applications If it is not possible to fit a device inside the hopper, then the Fluidic Muscle can be fitted externally. This creates vibrating hopper walls, as shown in fig. 5-63. In this way the bulk material is continually agitated and therefore more easily discharged. Fairly short Fluidic Muscles are generally quite adequate for this, since there is no need for large strokes (amplitudes). The vibrations should be less than 1 Hz. The undesirable arching effect is generally the result of a reduction in the cross-sectional area on the discharge cone of the hopper. Fig. 5-63 Bulk material hopper with vibrating walls to prevent an arching effect 1 2 3 4 5 6 Hopper Bulk material Arching effect zone Fluidic Muscle Frame, Conveyor 1 2 3 4 5 6 5.8 Arm and leg movements Artificial beings and replicas of man and beast are a booming industry in leisure and adventure parks, film and theatre, in research, in fairgrounds (fun fairs, ghost trains), in short in entertainment as a whole. Moving statues have existed since antiquity. Today however, as lifelike and natural as possible movements are required for androids and for instance of replicas of prehistoric animals in museums and travelling exhibitions as well as giant figures made of lego bricks. Up until now, numerous small pneumatic cylinders have been installed in order to move extremities and to bend vertebrae. However, the realisation of smooth and gentle movements is associated with major difficulties and cannot be satisfactorily achieved. The Fluidic Muscle can be ideally used to simulate arm, leg and finger movement. This improves motion, mass and installation space requirement. 5 Applications 93 Movements become more flowing and resemble the biological example. Fig. 5-64 shows articulated arms, capable of planar and spatial movement. Intermediate positions can be easily progammed with sufficient accuracy by means of simple pressure control. Arms with pneumatic actuators may in future also play a role in the service robot sector. At the world exhibition EXPO 2000, giant blades of grass were made to move to and fro although there was no wind. This was achieved using Fluidic Muscles. Fig. 5-64 Motion mechanisms based on the example of extremities a) Planar-mobile structure b) Spatially mobile construction 1 2 3 4 5 6 7 8 Fluidic Muscle Toothed belt Valve Arm join Support tube Effector connection flange Ball joint Joint plate 1 2 3 4 5 6 a) 1 7 8 1 5 b) 3 A less complex arm construction for a man-like figure is shown in fig. 5-65. Only two Fluidic Muscles are used in this case and the reset motion is executed by means of synthetic bands. Fig. 5-65 Example for a simple android arm 1 2 3 4 5 Upper arm Shoulder joint Synthetic band Forearm Fluidic Muscle 1 2 3 4 5 94 5 Applications Likewise, android hands can be actuated via a Fluidic Muscle [12]. In fig. 5-66, the finger movements are created pneumatically. The phalanxes bend each articulated finger uniformly in line with a gripping contour. A stiff elastic band transmits the movement and a tension spring represents the counterforce to the Fluidic Muscle. The fingers close via the tensile spring force. Fig. 5-66 Android hand 1 2 3 4 5 Flat rigid synthetic band Phalanx Joint Linear guide Fluidic Muscle 4 3 2 5 p p Compressed air 1 5-Finger gripper hands with articulated fingers have already been created for laboratory trials. In this case, the actuation is effected by several Fluidic Muscles, whose movements are transmitted to the fingers via cables. The motion sequences are extremely smooth and quiet thanks to the use of proportional controllers in use and the hand model can even be remotely controlled via the Internet since it is coupled with an embedded web server. This is illustrated in the block diagram shown in fig. 5-67. A compressor can be used as a possible source of compressed air or a compressed-air bottle in the case of mobile devices. Fig. 5-67 Block diagram for a hand model (as per Grunz) electrical TCP/IP Transmission Control Protocol/Internet Suit of Protocols Network protocol Standard for data exchange in heterogenous networks pneumatic Proportional controller Articulated finger hand Embedded Web-Server TCP/IP Compressed air mechanical Client Browser Air supply Finger The forward movement of legs is also a topical object for research. Walking machines are currently being constructed at many research institutes and universities for study to determine how four-legged animaloids behave in normal and extreme situations and how leg movements can best be coordinated. 5 Applications 95 One constructional suggestion is shown in fig. 5-68, but there are many other solutions. Fluidic Muscles and an electric motor are used as drives. The motor could also be replaced by a pair of Muscles. One important advantage again is the reduced “Muscle weight” and the supple movements. Six legged insectoides also already exists, which have been successfully made to walk by means of 42 Fluidic Muscles (Research Centre for Computer Science, Karlsruhe). The Air-Bug walking machine for instance is equipped with a pair of antagonistic Muscles for each joint, which facilitate position, torque and rigidity control. Since the rigidity is created by means of the Muscle’s transmission behaviour, there is no need for additional control and thus no additional computing time. Fig. 5-68 Leg construction of an insectoid walking machine 1 2 3 4 5 Electric motor Gear mechanism Swivel axis Fluidic Muscle Leg 1 2 3 4 5 96 5 Applications A movable Column which forms a section of a vertebra for robotic animals or a man machine for adventure parks is illustrated in fig. 5-69. The Fluidic Muscles operate in pairs as flexors and extensors. This construction could form part of the mechanism for artifical beings deployed in technical museums, mobile exhibitions and films as well as an advertising medium. Fig. 5-69 Simulation of a vertebra movement 1 Fluidic Muscle 2 Vertebra section 3 Joint interface p Pressure 3 1 2 p1 p2 These days, combat robots probably also come under the heading of entertainment. These fight one another in an arena by means of remote control just like the gladiators of ancient Rome once did. A typical feature of these mobile robots is that they are equipped with a “weapon”, with which they can put the enemy device out of action. Fig. 5-70 shows a “combat shears” construction from the Fig. 5-70 Combat shears used in a robot game 1 2 3 4 5 6 7 8 9 Secateurs Sliding guide Fluidic Muscle Radio receiver Directional control valve Pressure regulator Compressed air bottle Spindle motor Compression spring 1 9 4 5 3 6 7 2 8 5 Applications 97 arsenal of martial weapons. Secateurs have been converted to form the actual weapon. This can be extended; an electric motor with a spindle drive is used for this purpose. All actions are effected via radio control. 5.9 Checking and testing Nowadays most products are tested in endurance testing units until they fail and special problem-specific equipment is required for this. It soon became apparent that equipment of this type can be far more easily constructed if a Fluidic Muscle is used as a tensile actuator. Fig. 5-71 shows a diagram of two test rigs for office chairs. The high Muscle force is cleverly used to lift the loading weight via cables and pulleys. In one case, the back rest is tested and in the other the contiuous load bearing capacity of the seat. The arms of the chair are bent to breaking point. Fig. 5-71 Continuous testing unit for office chairs a) Test rig for back rest b) Continuous load test for seat 1 2 3 4 5 6 7 8 Test specimen Holding device Cable Fluidic Muscle Balancing weight Loading weight Guide Frame 1 8 3 6 4 2 7 5 a) b) Instead of complex force measuring technology and control loops, the tensile force is limited by means of easily changeable balancing weights. These simply lift-off if the tension mechanism exceeds the maximum force. The load bearing capacity of the seat could be similarly tested by simulating the body weight of a human being and continually depositing this with impetus (sitting down) and then lifting it again (getting up). 98 5 Applications The changing length of the Fluidic Muscle could also be used to roughly determine the pressure in a compressed air line. A scale with pointer reading could be used for this as shown in fig. 5-72a. Fig. 5-72 Pressure gauges a) Gauge pointer b) Visual indicator 1 2 3 4 5 Pipeline Fluidic Muscle Protective tubing Weight Scale 1 5 2 3 5 2 3 4 4 a) b) An even simpler method is available if only a rough indication is required for monitoring purposes. The pressure levels of 2-4-6 can be indicated by the colour markings red-yellow-green in an inspection window. An instrument of this type would be sturdy and is not affected by environmental pollution or vibration. Lastly, fig. 5-73 illustrates an example from material testing using a heavy test specimen. The test specimen moves continually from one side to the other. Once a line has been traversed, the test unit moves on by one line. This results in a meander-type test run during which the entire surface is tested. The lateral movement of the test unit could also be created by a pair of Muscles. The traversing rate can be effected smoothly without jerking. The disadvantage is that fairly long Muscles would be required for longer traversing distances. In that case, a reversal of direction using a cable (or toothed belt) should to be provided. 5 Applications 99 Fig. 5-73 Surface testing of heavy objects a) Assembly drawing b) Circuit diagram 1 1 2 3 4 5 6 7 8 Test unit Linear unit Test object Fluidic Muscle Carriage Non-return valve H-QS-... Quick exhaust valve SUE-... Precision regulating valve LRP-... 9 Solenoid valve CPE 14-... 2 3 4 250 kg 5 a) 6 7 9 8 b) 5.10 Driving Drives generally consist of a “motor” (in this case a Fluidic Muscle) and a gear unit in order to convert the movement generated by the motor into a usable form of movement for the equipment, machine or other devices to be driven. This can be rotational or linear, continuous or discontinuous as well as in continually the same or changing direction. Fig. 5.74 illustrates some mechanical converters, 100 5 Applications i.e.ratchet indexing mechanisms, spindle drives with large pitch, a drive via swash plate and systems using a crank shaft for continuous rotation. Fig. 5-74 Rotary drives using Fluidic Muscles for motion conversion a) Indexing motion b) Reciprocating rotation c) Rotation using crankshaft (see also fig. 5-75) d) Swash plate a) b) c) d) Fig. 5-75 shows a crankshaft drive based on Fluidic Muscles. The side view corresponds to the principle shown in fig. 5-74c. This is a “three-cylinder machine” for a speed of approximately 20 to 200 revolutions per minute, which operate either in forward or reverse motion subject to the actuation of the individual Muscles. Air distribution is ensured by means of a special valve. 5 Applications 101 Fig. 5-75 Crankshaft drive using Fluidic Muscles (Festo) 1 2 3 4 5 Fluidic Muscle Crankshaft Drive shaft Controller Rotary encoder p1 p2 p3 1 p Compressed air 5 4 3 2 However, a drive of this type is generally mainly used in areas subject to explosion hazard or applications where compressed air is the only source of energy available, such as for instance in the woodworking industry, in the waste water treatment sector, paint factories or oil refineries. As part of a feasibility study, a three-wheel town vehicle for two people standing was designed as a functional model, where the drive was effected by means of Fluidic Muscles and a crank shaft. Even in the wheel suspension there was room for a Fluidic Muscle. However the effective range is minimal since only minimal quantities of compressed air supply can be carried (fig. 5-76). Fig. 5-76 Muscle-operated town vehicle (Viererbl, F., Scholl, P.) with active Muscle wheel suspension and speed dependent tilting technique 102 5 Applications Fig. 5-77 illustrates the principle of a rotary drive without crankshaft. This is a 36 Muscle motor of modular design, whose individual drives have a cummulative effect. The conversion into a linear drive motion is effected by means of a spindle-nut system as previously shown in fig. 5-74b. Fig. 5-77 Muscle-powered car with rotary drive built without crank shaft Fig. 5-78 provides a sketch of how a hand-held screwdriver can be operated by means of compressed air. This hand-held screwdriver is lightweight because it is without a rotating motor using metallic components. The actuators can be built into the two handle halves. The pneumatic Muscle drives the screw shaft via a pawl and ratched wheel. The latch can be reversed thereby facilitating clockwise and anti-clockwise rotation. The torque is high despite the small actuator diameter and can be easily adjusted by means of a change in pressure. This drive operates more quietly than that of other rotary power tools. Given a Muscle diameter of 20 mm and that the point of application of force is 30 mm outside of the screw shaft axis, a torque of M = 1000 N x 0.03 m = 30 NM can be assumed. By comparison, the tightening torque of for instance a screw M8 is approximately 22 Nm. Other free-wheeling mechanism can of course also be used instead of the pawl system. A drive principle that has previously been used for flying machines is that of the radial-type engine. Star-shaped individual piston drives are configured around a crank, all of which are connected to driving rods. The to and fro moving masses of the driving rods and pistons represent a complex dynamic system. However, if you visualise the low mass Fluidic Muscles as drives in a radial-type configu- 5 Applications 103 Fig. 5-78 Pneumatic hand-held screwdriver 1 2 3 4 5 6 7 8 Fluidic Muscle Handle Pawl Ratchet wheel Shaft Screwdriver sprocket Air supply line Control button 8 2 1 3 7 4 M 1 5 6 ration (fig. 5-79), then this greatly simplifies matters. Instead of a single-bank radial motor as shown, a twin or multiradial motor configuration is possible, which then generates a higher torque. Several single-bank radial systems would then act on one universal crankshaft. 1 Fig. 5-79 Radial-type motor with Fluidic Muscle drive 1 Compressed air distribution control 2 Crank pin 3 Fluidic Muscle 4 Flywheel 5 Air supply line 2 3 4 5 104 5 Applications A Muscle as a door opener? Is such a thing possible? The Fluidic Muscle is sufficiently powerful to open sliding doors. Fig. 5-80 illustrates a retrofitted example. A rocker bar operates between rollers and transmits the motion. The door is closed by means of an applied load. However with a slightly inclined slide rail, the closing action can be effected solely by means of gravitational force. The advantage is that the door remains unchanged and only a pair of rollers need to be fitted to the door surface. The door can be opened automatically, if a sensor is used to detect approaching vehicles such a for instance a fork-lift truck. In this case, the sensor signal triggers the switching of a directional control valve for the compressed air. Fig. 5-80 Pneumatic sliding door opener 1 2 3 4 5 6 7 Wire cable Counterweight Roller Swivel arm Fluidic Muscle Slide rail End stop 6 1 3 7 8 4 2 5 Numerous other Muscle applications are also possible for linear movements, although one needs to get used to the idea that a piece of “rubber tubing” in the machine now acts as a drive. This process of rethinking takes time, but is quite easy to achieve. A to and fro movement can be realised by using two reciprocating Fluidic Muscles. The saw with 50 mm stroke illustrated in fig. 5-81 attains a sawing frequency of 160 strokes per minute. The Muscles can be configured in parallel with the guide and also coaxially provided that these are built-into the round guide for protection, which is required in any case. In the example given, the feeding movement for the sawing process is provided by a conveyor system, e.g. via corrugated or rubberised rollers, between which the sawn sections are conveyed. 5 Applications 105 Fig. 5-81 Saw actuation (plan view) 1 2 3 4 5 6 7 8 Fluidic Muscle Round guide bush Guide rod Saw blade Conveyor Log Roller conveyor Hollow bar (variant) p1 1 p2 2 8 5 6 7 4 3 2 p Compressed air Step-by-step locomotion too can be realised, based on the example of the earthworm. The earthworm braces itself against the inside of a hole by means of bristles. The body of the worm is encased by two muscle layers, i.e. externally by the ring musculature and internally by the longitudinal musculature. Both of these can be reproduced by the Fluidic Muscle. Fig. 5-82 illustrates the construction of such a locomotion system for equipment which operates within barreltype mechanical systems such as used for the inspection internal piping surfaces. The locomotion is worm-like and copied from the biological original. A complete step ∆s is shown in fig 5-83. The drive can be bidirectionally controlled and is capable of unlimited movement (provided that the “umbilical cord” is sufficiently long). It can be constructed with a very small diameter and achieve very fast step sequences. The two clamping heads are joined to the Fluidic Muscle via a flexible connection. Fig. 5-82 Earthworm-type motion system based on a Fluidic Muscle basis 1 2 3 4 5 6 Clamping jaw Pipe Clamping piston Fluidic Muscle Compression spring Joint 1 2 3 4 5 6 a, b, c Control air supply lines a b c 106 5 Applications Fig. 5-83 Motion sequence of a pipe runner with Fluidic Muscle actuation ∆s Displacement step ∆s The two heads are briefly clamped in order to ensure the position. Then either the compression spring or the Muscle comes into operation in order to realise the next step. For inspection work, the upstream clamping head would need to be equipped with a miniature camera and a miniature lighting system. Even electronic components could be accommodated as “filler bodies” inside the Muscle. 5.11 Vibrating systems The Fluidic Muscle can be operated at cycle rates of up to 90 Hz. As such and allied with the high initial force of the system it is ideally suited for vibratory drives. Fig. 5-84 illustrates various vibratory systems using a Muscle drive. Conventional electromechanical flyweight or magnetic drives have previously been used for this. The linear vibratory channel shown in fig. 5-84c is driven at a frequency of 75 Hz, which is infinitely adjustable from 10 Hz to 90 Hz. The projectile motion of the parts on the chute is predetermined by the angle 5 Applications 107 of inclination of the leaf springs. The same applies for the spiral chute hopper shown in fig. 5-84b. The Muscle force is centrally coupled via a ball bearing. This is essential since this results in a stroke/rotary movement of the attached hopper. The tangential attachment of several Muscles to the bowl-type vibratory feeder is also a possibility as can be seen in section in fig. 5-84a. Fig. 5-84 Vibratory systems using a Fluidic Muscle drive a) Tangentially distributed drives b) Vibratory spiral chute hopper with central Muscle drive c) Vibratory conveyor drive 1 2 3 4 5 6 7 8 9 Leaf spring or bar spring Fluidic Muscle Conveying chute Vibrating hopper Vibrating plate Ball bearing Base plate Connecting frame Suspension bracket 2 4 1 6 8 9 9 7 2 1 5 1 a) b) 9 1 3 2 1 c) 108 5 Applications In contrast, the oscillating table shown in fig. 5-85 executes purely vertical vibrations and can be used for testing and checking tasks. The clamping plate is guided via four low-friction column guides. The Fluidic Muscles operate against the compression springs or a set of cup springs. If a gyrating movement is to be generated, a spherically moving support would need to be incorporated centrally. The Muscles then need to be actuated individually in a predetermined pattern in order to generate the required vibratory behaviour. Similar pneumatic drives are also required in equipment which is used to separate tangled items. Low frequency vibrations with high amplitude are particularly effective here. Fig. 5-85 Vertical vibratory table for testing and checking tasks 1 2 3 4 5 6 7 8 Clamping plate Compression spring Fluidic Muscle Mounting flange Linear guide Ball bearing Guide column Column base 1 2 5 6 3 7 8 4 The entertainment and leisure industry is aiming for ever more lifelike effects in simulators. In the optical/visual field, this has already been quite successfully achieved and also with the use of the acoustic channel. What has been missing so far is the transmission of oscillations to the body in line with the required effects. One technically feasible and effective solution is to replace cockpit seats and other seating facilities with the Fluidic Muscle. This is fitted as a seat oscillator in order to generate spatial movements as shown in fig. 5-86. The seat rests on a central support with a spherically movable head and a bearing spring. The stick-slip free movements of the Muscles and the high achievable stroke frequencies meet the simulation requirements very well. In the fun and entertainment industry, a new dimension could be added to video games and screen films by means of a simple pneumatic construction and thereby heighten the quality of the experience. 5 Applications 109 Fig. 5-86 Oscillating seat for simulation purposes 1 Chair, Pilot seat, Car driver seat 2 Safety belt 3 Joystick for simulator operation 4 Foot rest 5 Base plate 6 Central support with compression spring 7 Fluidic Muscle 1 2 3 4 6 7 5 The device shown in fig. 5-87 is intended for mixing the contents of a barrel. An antagonistic Muscle pair has been configured for each tilting axis (X and Y). Depending on the Muscle actuation, the tilting movements can be effected individually around each axis and also superposed, which leads to a tumbling motion of the base plate. The movement pattern and the timing rhythm can be continually changed for each program. The applied loads are absorbed by means of appropriately sized rotary axis bearings. On a reduced scale, a mixer of this type could be useful in the laboratory sector. Fig. 5-87 Barrel shaker using four Fluidic Muscles 1 Barrel 2 Supporting plate 3 Muscle for tilting vibrations around the Y-axis 4 Base plate 5 Muscle for tilting vibrations around the X-axis 6 Rotary axis 1 A B 6 2 3 Y A and B Tilting movements 5 4 X 110 5 Applications The oscillating seat shown in fig. 5-86 is in principle also a model for the vibration test bench. The oscillating plate rests solely on the centrally configured compression spring. Depending of the timing of activation of the four Muscle actuators, different types of oscillation are achieved for the vibrating plate. The amplitudes of the vibratory movement can also be influenced. The entire test bench is buffered against the floor by means of vibration dampers. Compared with other drives, the Fluidic Muscle variant is also of advantage with regard to energy. Its mechnical construction is extremely simple. The table is for example used for vibration testing on car seats. Fig. 5-88 Vibration test bench 1 Attachable device for test module 2 Vibrating plate 3 Compression spring 4 Fluidic Muscle 5 Adjusting foot with integrated vibration damper 6 Base frame 1 2 3 4 6 5 Vibratory systems are generally spring/mass systems. Vibratory machines such as vibrating screens and attachment vibrators are generally actuated by means of rotating loads designed in the form of an unbalancing drive. This leads to high shock loads in the bearings at the targeted high accelerations. Vibrators are used in the building industry and in founderies in order to compress concrete and non binding earth such as gravel and sand. The vibrations reduce the surface tension and the internal friction of the matter and these settle more densely in accordance with the law of gravity. Fig. 5-89 illustrates an example of how a pneumatic drive can be used for this purpose. The Fluidic Muscles operate against the applied load of the vibrating plate. The use the Fluidic Muscle results in other operating characteristics of the reciprocating drive. 5 Applications 111 Fig. 5-89 Compression of bulk material 1 2 3 4 Moulding box Foundry sand Vibrating plate Fluidic Muscle 1 3 2 4 5.12 Braking and stopping Short distances and high forces are characteristic of the process of braking. Stopping is usually coupled with a locking action. Short strokes are generally also sufficient to advance any corresponding components. The Fluidic Muscle is suitable for both of these, since it is lightweight and requires only minimal space. The following examples provide a few ideas for applications. First example: A lifting station has been incorporated into a roller conveyor section which lifts the goods from a transfer pallet. In the event of power failure or damage, the load needs to be secured at that momentary level to ensure that it does not drop. Fluidic Muscles have therefore been built into the lifting platform which retract a locking pin. In an emergency, the compression spring operates and slides the stop into the notched rail. The installation of these Muscles requires a minimum of space. The operational environment is subject to dust, but this does not impair the Fluidic Muscles and this represents a considerable advantage. 112 5 Applications Fig. 5-90 shows the installation of Muscles into the lifting station. Fig. 5-90 Blocking device 1 2 3 4 5 6 7 8 9 Conveyed goods Transfer pallet Roller conveyor Lifting platform Compression spring Fluidic Muscle Lifting unit Stop pin Notched rail 1 2 3 8 4 9 5 1 7 6 2 3 A further example: The unwinding or rewinding of, for instance, a strip of sheet metal necessitates a constant unwinding speed to ensure a smooth and even entry into a workstation. However, the tensile force F on the sheet metal strip changes during the unwinding process depending on diameter. The unwinding speed therefore needs to be continually regulated via a retarder. At low speeds this therefore requires highly sensitive regulation and a stick-slip free drive, which can be easily realised by means of a Fluidic Muscle. It is clearly a much better solution than a piston cylinder for this application, since the regulation can also very easily be effected via a proportional valve. Fig. 5-91 shows a diagram of the described application. A Fluidic Muscle with a diameter of 40 mm and a nominal length of 250 mm is used (force approx. 500 N, stroke 2 mm). This application is suitable for all systems where a band-type material is to be unwound, rewound or wound, such as for metal surface refinement and the manufacture or processing of coated and uncoated metal strips. 5 Applications 113 Fig. 5-91 Retarder on an unwinding device 1 1 2 3 4 5 6 7 8 Reel Fluidic Muscle Diverter pulley Roller lever Force sensor Proportional sensor Reel hub Brake jaw 2 3 5 p1 4 F F Withdrawal force p Compressed air 7 8 6 p The production of sausages requires artificial sausage skin to be supplied which moves via guide rollers. So that these rollers can be quickly decelerated for process engineering purposes, A Fluidic Muscle can be accommodated in the hollow bearing of the roller. The Muscle does not rotate with the roller so that the compressed air can be supplied at a fixed point. The constructional solution is shown in fig. 5-92 and should be regarded as an example for similar bearing mounted cases. Fig. 5-92 Braking of a guide roller 1 2 3 4 5 6 Guide roller Ball bearing Frame Fluidic Muscle Brake disc Protection against rotation with torque resistance 1 2 5 3 6 4 p Compressed air p 114 5 Applications Fig. 5-93 illustrates a drum brake whose brake force is generated by means of compression springs or a set of cup spring. The brake is vented by means of Fluidic Muscles, which can generate high forces across a short distance. This mechanism can also be used as an emergency brake system. In the event of energy failure, the pneumatic actuators become de-energised and the spring then act as brake actuators. Fig. 5-93 Braking mechanism for drum brakes 5 1 Brake lining 2 Brake disc, drum 3 Compression spring, set of cup springs 4 Fluidic Muscle 5 Frame 3 1 2 3 4 5.13 Transporting In-house transport generally involves the transporting of packaged goods for the purpose of storage and removal from storage or temporary storage. In many cases belt conveyors are used for this. Although installations of this type are relatively simple mechanically, they nevertheless require actuators and tensioning drives of different types. This also includes maintaining the tension of pulleys and conveyor belts. If the tension is incorrectly set, then the frictional entrainment of the belt is impaired. Fig. 5-94 illustrates some solutions where the Fluidic Muscle has been used as an actuator. The use of the Muscle for belt tensioning has been considered because it is extremely durable and provides adaptable cushioning. 5 Applications 115 Fig. 5-94 Solutions for belt tensioners a) Shifting of guide roller b) Tension actuator on the conveyor belt support c) Vertical belt pull d) Belt tightener in a cleaning machine 1 2 3 4 5 6 Fluidic Muscle Guide roller Conveyor belt Burled belt Belt tightener Tensioning roller 3 a) 1 b) 4 6 2 1 5 2 5 1 c) d) The problem of frictional forces also arises in the case of a retarding roller conveyor (fig. 5-95). The advantage of conveyors of this type is that the objects transported do not build up any dynamic force if they are stopped on a section of the belt and accumulate. The conveyor belt shown in the example is used solely to drive the conveyor rollers. This occurs when pressure is applied to the Fluidic Muscle. When the conveyed goods reach a sensing switch, the compressed air is then switched off. The contact rollers on the swivel arms are disengaged and the conveyor drive belt is no longer in contact with the actual conveyor rollers. Conveying is not continued until a process signal by-passes the sensing switch. Fig. 5-95 Retarding roller conveyor with pneumatic deactivation 1 2 3 4 5 6 Conveyed goods Roller conveyor Conveyor drive belt Pneumatic sensor Contact roller Fluidic Muscle 1 2 4 p Compressed air line 3 5 6 p 116 5 Applications A different type of transport problem is solved with the installation shown in fig. 5-96. A sliding pawl fitted to a carriage, pushes heavy girders on a slide rail. The sliding pawl is raised by means of counterweight. The pawl moves down again with the return stroke and then engages in the next girder arriving at the standby position. Since the girders are long, several carriages are provided which simultaneously move in parallel. Transfer steps of various lengths can be executed, e.g. to engage on the other T-section of the girder. Fig. 5-96 Girder transfer device 1 2 3 4 5 6 7 8 Double T-girder Slide rail Sliding pawl Adjustable stop Fluidic Muscle Weight Carriage rail Carriage 1 2 3 4 5 7 6 8 The distribution of streams of goods can be effected on a horizontal level via parallel configured sorting lines. This is also possible vertically, which represents a saving in costly production area. However, the various storage levels must be individually approachable. The principle of distribution organised in this way can be seen in fig. 5-97. A Fluidic Muscle has been fitted on each side of the conveyor, which sets the conveyor in three positions via pressure. This process can also be effected automatically if a laser scanner is for instance used to read clear-text information or graphic codes and generates the adjustment comands. The applied load of the swivelling conveyor can be slightly reduced by means of a balancing weight or via spring force. The force ratios correspond entirely to an arm system as shown in fig. 2-4 on page 16. 5 Applications 117 Fig. 5-97 Distribution of streams of goods 1 2 3 4 5 Conveyor Sorting storage conveyor Barcode reader Fluidic Muscle Conveyed goods 2 3 4 F 1 g Acceleration due to gravity m Mass S Centre of gravity 5 S mg If slightly adhering bulk material is being fed along a belt conveyer, this may require a cleaning device whereby residual material adhering to the conveyor belt is removed by means of a scraper using pressed-on rubber or steel wiper strips. Fig. 5-98 illustrates an example of this. Here the Muscle assumes the function of a spring whose spring force can be set according to requirements via the pressure. It is also possible to gradually approach the contact pressure which gives the best results. Fig. 5-98 Double scraper on a conveyor belt 1 2 3 4 5 Discharge drum Conveyor belt Scraper strip Fluidic Muscle Frame 5 2 3 4 1 118 5 Applications The conveyor belt shown in fig. 5-99 can be moved horizonally with the help of two Fluidic Muscles. The belt is advanced to the loading surface once the lorry has backed up against the loading ramp. Depending on the lorry position, a traversing path is realised via the pressure, taking into account the loading surface. The actual conveyor belt is supported on sliding rods with which it can be positioned against the fixed frame. This linear guide as well as the Fluidic Muscles are arranged appropriately in parallel, in contrast with the illustration, thereby saving in height. For larger displacement paths, the loose roller method could be used, as shown previously in fig. 3-7. Fig. 5-99 Variable conveyor belt 1 2 3 4 5 6 7 Package Conveyor belt Loading surface Linear guide Fluidic Muscle Loading ramp Base frame 1 3 2 4 7 5 6 In the case of longer conveyor belts, the rectilinear course of the belt is for instance effected via a combination of tensioning and controlling rollers which need to be horizontally adjustable. A sensor unit, e.g. a through-beam sensor combination, controls the run of the conveyor belt. If required, the control roller is repositioned by a small angle β, whereby the belt is set exactly to centre. The system operates continuously and is represented in a simplified form in fig. 5-100. 5 Applications 119 Fig. 5-100 Rectilinear control of a conveyor belt a) Design of controlling roller system b) Conveyor course c) Belt edge sensing 1 2 3 4 5 6 Control roller Return roller Conveyor belt Through-beam sensor Swing frame Fluidic Muscle 3 1 1 +β –β a) 5 6 2 4 b) c) In fig. 5-101, a different solution is suggested for the same problem. In this case, the discharge roller of the conveyor is variably configured. The slide has sufficient play to facilitate a slight inclination of the roller axis which does not get jammed. A Fluidic Muscle is fitted on both sides of the belt which clamps the roller via a lever and at the same time ensures a rectilinear motion by means of unequal movement at either end. Fig. 5-101 Rectilinear motion of belt edge 1 2 3 4 5 6 Optical Band feed sensor Conveyor belt Tensioning roller Slide Lever Fluidic Muscle 2 1 3 4 p Compressed air 7 p 6 5 120 5 Applications Objects such as packages, canisters and containers often need to be briefly retained during transport in order to control the flow of objects. The device shown in fig. 5-102 can be used for this purpose. Its design is incredibly simple and its function immediately recognisable. If the Muscle contracts, the retaining wedge is displaced and the throughflow width is restricted. If an object is present at that point, it is pressed against the lateral guide and thereby retained. Since the Muscle is very fast, this process can be effected extremely rapidly once the start signal is emitted. Fig. 5-102 Retaining device for conveyed goods a) Free through-flow (plan view) b) Retaining device activated 1 2 3 4 5 6 7 Flat-plate conveyor Lateral guide Package Retaining wedge Fluidic Muscle Compression spring Housing and guide 7 4 6 a) 5 1 2 3 b) 5.14 Distributing and branching In mass production, product streams often need to be guided into several channels, which may entail allocating according to number of units or separating into types. This requires a sensor to determine the sorting characterics. The sensor signal then causes the controller to switch a sorting gate. Fig. 5-103 illustrates an example of this. The sorting gates using Fluidic Muscle actuation are particularly fast switching thereby ensuring excellent function even in the case of closely spaced products on the feed line. A relatively short pair of Muscles is adequate here, provided that the connection point is close to the swivel point of the sorting gate. 5 Applications 121 Fig. 5-103 Fast switching sorting gate (top view) 1 2 3 4 5 Sensor, camera Swivel gate Fluidic Muscle Sorting channel Feed line 1 2 7 3 4 5 6 A similar process is adopted for the distribution of bulk materials. Fig. 5-104 shows a sample solution, whereby a distribution chute can be set at two inclination levels. The acceptable flow is switched to either one of the two distribution belts. Adjustment is effected by means of a Muscle and Countermuscle. The hermetically sealed Fluidic Muscle tolerates the dusty environment much better than other drives. Fig. 5-104 Distribution system for bulk material 1 2 3 4 5 6 Feed conveyor Rocking chute Distribution conveyor Fluidic Muscle Support plate Stop 2 1 6 4 3 3 5 2 6 4 122 5 Applications 5.15 Machining As far as machining equipment and devices are concerned, there are numerous possibilities for using a Fluidic Muscle to advantage either as a drive for main and in particular for auxiliary movements. The following examples are therefore merely representative of numerous other applications. Bending is given as an initial example. Sheet metal panels in the car industry for instance, need to be bent in different ways. This requires high forces which can be generated stick-slip free by a set of Fluidic Muscles. The profile panel is pulled against a fixed former via tie rods as shown in fig. 5-105. Special presses of this type have been constructed before now for the profile forming of door frames for cars, with which 12 Muscles with a nominal diameter of 40 mm and a total force of 1.2 tonnes bend the profile frame in approx. 20 seconds. These bending presses comprise two contra-rotating plates which operate synchronously around a common centre of rotation. The upper and lower section of the bending former are attached to the lower rotating plate and the articulated points for the Muscles to the upper rotating plate. The profiles are drawn into the spatial bending former both via the rotary movement and the tensile force of the Muscles. The use of the Fluidic Muscle leads to a clearly more cost effective technical solution. Fig. 5-105 Bending device for sheet metal profile frames 1 2 3 4 5 6 7 Bending former Fluidic Muscle Overhead attachment Sheet metal profile Tie rod Spherical washer Nut 3 2 5 1 4 7 6 In the case of grinding and polishing processes, the specification of a precise and above all constant surface pressure determines the quality of the operation. A stroke-dependent specification is generally not possible since the grinding and sanding discs are subject to continual wear. The Fluidic Muscle is ideally suitable as a force generator for surface pressure, since this is easily adjustable and the conversion into motion is effected stick-slip free. Fig. 5-106 illustrates the operational principle of a device of this type. In this example, the workpiece is fed manually underneath the tool. The device can however also be attached to 5 Applications 123 automated production lines. In the case of polishing, the polishing agent must be automatically applied in precisely dosaged quantities and the surface temperature must not rise excessively. Fig. 5-106 Grinding and polishing device 1 2 3 4 5 6 7 8 9 10 11 12 Articulated arm Counterweight Tension spring Grinding/polisher drive unit Polishing disc Workpiece Sliding cross table Handle Support Fluidic Muscle Lacquer layer Locating pin 2 1 4 3 7 6 5 11 12 8 10 9 The examples below deal with the cutting of materials, which often entails the design of special presses. In the case of the device shown in fig. 5-107, the relatively high Muscle force is further amplified via eccentric discs. These discs are provided with slots on both sides to accommodate the arms which connect a pair of force generators, i.e. the Muscle and return spring. The base frame is available off the shelf and can be selected from a catalogue for standardised tool construction. The drive is attached to the top of the guide column in the form of a yoke. Fig. 5-107 Cutting press with twin eccentric disc mechanism 1 2 3 4 5 6 7 8 Fluidic Muscle Eccentric disc Yoke Column guide Tool Compression spring Tension spring Base plate 1 2 3 7 6 8 5 4 124 5 Applications Somewhat different is the device shown in fig. 5-108, which is used for rapid cutting of long thin strips. In this case, the force of the Muscles is transmitted via a toggle lever mechanism, However, the dead point is traversed so that a cutting sequence is executed with each individual stroke. An excellent cutting output is achieved thanks to the high reaction speed of the Muscle. The tension spring could also be replaced by a Muscle. Fig. 5-108 Cutting device with cutter bar 1 Fluidic Muscle 2 Cutter bar 3 Cutting base or counterblade 1 2 3 The separation of material can also be effected by means of rotating saw blades. Fig. 5-109 illustrates an application of this type. Items of a defined length are to be cut off from a plastic profile. A pendulous cutting device is moved by a pair of Muscles; the plastic profile in a guide is displaced manually and retained during the cutting sequence. The necessary protective devices are not illustrated. The Muscle drive ensures a constant feed movement and the reversal point of the pendular motion is adjustable via the pressure. 5 Applications 125 Fig. 5-109 Device for separating of plastic profiles 1 Motor 2 Saw blade, Separating blade 3 Profile material 4 Guide 5 Fluidic Muscle, 6 Frame 5 1 6 3 4 2 The cutting device illustrated in fig. 5.110 is of a greatly reduced size which is located more closely to hand tools. In this example, the force of a Fluidic Muscle is amplified via a semi-toggle lever joint towards the end of the blade movement. The two blade arms are synchronised via a pin and slot in the frame plate. Fig. 110 Simple cutting device 1 2 3 4 5 Blade Blade arm Fluidic Muscle Tension spring Frame 1 2 3 4 5 126 5 Applications A different cutting device is shown in fig. 5-111. This is used for the continuous separating of film into small strips. Only one cutting unit is portrayed. Depending on film width, several devices may be set up in parallel. The blade arm is moved into position by means of a Muscle and CounterMuscle. The slightly springy flexibility of the blade arm is desirable with this application. The device is of very simple construction. Fig. 5-111 Film cutting device 1 2 3 4 5 6 7 Fluidic Muscle Cutting blade Cutting roller Film Return roller Blade arm Fixed stop 6 3 2 1 7 6 2 3 4 5 Fig. 5-112 illustrates a blade cutting device for the separation a relatively soft material in strip form. The blade moves into an intermediate position for prior notching of the material, i.e. position line (a). After a specified number of notching sequences, the material is cut through to position line (b). Each return stroke is executed by means of spring force. This device is again of simple construction and reaches the intermediate position with an accuracy of ± 0.3% in relation to nominal length in the case a pulsed application and if the position is specified as pressure. Due to the hysteresis, a value of 3% applies in other cases, again in relation to nominal length. The cycle time for 5 double strokes is 2.2 s for 15 mm (notching) or 25 mm stroke (cutting). 5 Applications 127 Fig. 5-112 Cutting unit using a Fluidic Muscle drive a) Upper cutting (notch) position b) Through cutting (off ) position c) Rest position 1 2 3 4 5 6 7 8 Lifting plate Compression spring Fluidic Muscle Base plate Soft material Conveyor section Blade Guide column 7 1 2 c a b 8 7 1 3 5 4 6 Lastly, a saw table is illustrated in fig. 5-113. Here again, a drive using a Fluidic Muscle is provided. Its jerk-free movement characteristics are particularly ideal in this case. The return stroke of the saw table is performed by a pneumatic cylinder. With clever design, the Muscle can be largely accommodated within the machine table. It requires far less installation space than other conventional drives and produces comparable forces to a hydraulic drive. The material to be sawn is retained in conjunction with a contact device. Fig. 5-113 Saw table drive 2 1 2 3 4 5 6 7 8 9 Saw unit Contact device Workpiece Table Fluidic Muscle Retract cylinder One-way flow control valve Solenoid valve Precision pressure regulating valve F 1 3 4 5 F Contact force 6 7 8 2 2 12 82 11 33 12 82 10/12 1 3 9 128 5 Applications 5.16 Unwinding In the case of the winding and unwinding of tape or wire, constant tensioning of the material to be wound is generally a crucial factor. However, this varies continually since the coil constantly changes in mass and even the residual stress during the expansion of the material has a different effect on the band run. The familiar compensator roller control, also known as jockey roller control, consists of controlling rollers which are part of the electrically driven winding device. This senses the slack in a textile band and keeps it constant. The influencing factor on the drive therefore leads to a regular movement of the continually moving material to be processed. Fig. 5-114 illustrates one of many options. The pressure within the Fluidic Muscle is taken as a measure for the slack. In order to maintain this constant, an electric motor is activated which lets the friction belt for the coil drive run at a correspondingly fast speed. Fig. 5-114 Compensator roller control using multiple roller guide 1 2 3 4 5 6 7 Unwinding coil Jockey roller Fluidic Muscle Reel stand Drive motor Friction belt Regulator 1 6 2 3 5 4 7 In the case of the solution shown in fig. 5-115, the drive motor is directly connected to the reel shaft and generates the variable torque M. Here again, the pressure is evaluated within the Fluidic Muscle and the resulting signal is used to activate the motor. 5 Applications 129 Fig. 5-115 Jockey roller control 1 Jockey roller 2 Fluidic Muscle M Driving torque 2 M 1 F = const 5.17 Dosing and portioning These two terms describe the allocation of products of an indeterminate shape such as dough, granulate, fertilisers etc. For this type of process, the Fluidic Muscle can be used purely as a force generator or alternatively as a sensitive dosing device if appropriate sliding apertures are either specifically opended or restricted. Nowadays, most processes in industrial bakeries are executed automatically. This includes the dividing and shaping of dough and in particular the production of dough portions of identical volume. The design of the device required for this corresponds to that of a press. The dough mass is supplied in a channel, at the end of which a “punching tool” is located. The mass is then pressed through a 130 5 Applications die, after which the shaped dough is moved on by a conveyor belt for further processing. A process of this type forms the basis of the illustration shown in fig. 5-116. Fig. 5-116 Portioning of dough 1 2 3 4 5 6 7 8 Compression spring Column guide Frame Fluidic Muscle Die Extrusion punch Dough portion Conveyor belt 1 4 2 3 5 6 7 8 Particularly in agriculture, the building materials industry and in the chemical industry, bulk materials are often discharged and supplied from hoppers. Usually the discharge of bulk material is to be controllable. The volume flow is often set fairly approximately by means of simple slides or flaps. The use of pneumatic cylinders merely allows ON/OFF settings, which generally is not sufficient nowadays. Infinitely adjustable slides or flaps however can be easily realised by means of a Fluidic Muscle drive. Fig. 5-117 illustrates a solution for the supply of animal feed, where a counterweight acts as reset force. The Muscle is unaffected by environmental pollution such as occurs in agricultural premises. 5 Applications 131 Fig. 5-117 Flap control system for animal feed supply a) Discharge blocked b) Discharge volume via pressure control p 5 1 2 3 4 Fluidic Muscle Counterweight Swivel flap Hopper container 1 p Compressed air 4 3 a) 2 b) Of a slightly different and technically more complex design is the slide for the supply of bulk material as shown in fig. 5-118. Here, the slide operates within a linear guide. When selecting a guide you should make sure that it does not have a tendency to collect residue from powder or granulate, but instead features self-cleaning characteristics (vertical guide, swivel plates). Fig. 5-118 Slide control for bulk material 1 2 3 4 5 Hopper Slide Fluidic Muscle Linear guide Retract spring 1 2 4 3 5 132 5 Applications In conclusion, let us have a look at how abrasive material can be fed towards an automatic sanding device in dosaged form. The hopper outlet can be regulated by means of a swivel plate as illustrated in fig. 5-119. The width of the gap is a measure of the flow rate. The setting can be adjusted via the pressure in the Muscle. The specifications are transmitted to a proportional pressure control valve in the form of setpoint values and this sets the pressure accordingly. The swivel plate is closed by means of spring force. As in the case of all feed hoppers, it is essential to make sure that the pourability of the material is given and that no arching of the granulate occurs within the hopper. If necessary, vibrators are to be provided (see figs. 5-62 and 5-63), Page 91 and 92. Fig. 5-119 Dosing of abrasive granulate 1 2 3 4 5 6 Abrasive granulate Hopper Swivel plate Tension spring Fluidic Muscle Proportional pressure regulating valve 1 2 4 3 6 5 Setpoint MPPE Actual 5 Applications 133 Glossary Actuator Also known as drive, which converts (electrical) signals into mechanical movements via pneumatic, hydraulic or electrical means, e.g. a pneumatic cylinder. Aneurysm A locally restricted curved projection in arteries which has been theoretically transferred to the Fluidic Muscle in the form of arterial-type flexible tubing. A non-reinforced balloon is subject to aneurysms. Aramide A reinforcing fibre made of aromatic polyamides used for the Fluidic Muscle. This has a minimal expansion coefficient and is used for components subject to thermal stress that need to exhibit high dimensional stability. The fibres are lighter and sturdier than glass fibres and achieve strengths of 3000 to 4000 N/mm2 with approx. 2% elongation after fracture. Axial adapters Connector elements for the attachment of a Muscle to a machine structure, using coaxial compressed air supply. Blanking adapters Connector element in the form of blanking piece without compressed air connection, but threaded for connection to other components. Chloroprene A plastic material of the elastomer group used for the Fluidic Muscle. This remains soft with rubber-like elasticity during normal temperature and is created by means of synthetic rubber vulcanisation. Contraction Contraction of the Muscle if pressure is applied, whereby the Muscle shortens and develops a pulling force. Cushion In pneumatics an inflatable round, rectangular or ring-shaped body with diaphragm surfaces. Under pressure, the upper and lower side curve into a convex body, thereby creating considerable stroke forces in relation to size. For reasons of strength, the diaphragm is generally reinforced with high-tenacity fibres. Degree of contraction Ratio of nominal length/contracted length. The smaller the contraction ratio, the longer the service life of the Muscle. 134 Glossary Diaphragm Thin-walled, flexural, tension-susceptible covering which is often stabilised by means of gas pressure (air pressure) and as a result, capable of accepting external loads or of delivering forces. The cover, external medium and filling combine to form a construction system. In the case of the Muscle the covering is combined with a fibreous grid. Elongation Synonym for an expansion of the Muscle Expansion A Muscle expands if an external force is applied which leads to an elongation (lengthening). The external force is for example a freely suspended load. Force compensator A set of cup springs integrated into the Muscle connection, which are permanently preset to a maximum force value. If this force is exceeded, this causes the excess compressed air to be released. Hysteresis behaviour Behaviour of a material which, during a reversible process such as being loaded or unloaded, exhibits a direction-governed change, for example a change in length. Installation length Length of a Muscle in a pressureless state with connecting elements at both ends (nominal length plus 2 times length of connector elements) or specified as “installation length contracted”. Interface Type of connection of a Muscle to a machine structure using connectors, adapters or similar. Motor Generic term for motion-generating machines (lat. “mover”), which convert a given type of energy into a mechanical kinetic energy. Every pneumatic cylinder is therefore also a motor. In the narrower sense, a motor these days is understood to be a revolving rotary actuator, e.g. an electric motor. Revolving movements can also be achieved pneumatically, i.e. via a Fluidic Muscle, if the contractions act upon a crankshaft. Glossary 135 Muscle contraction, biological The conversion of chemical energy into a mechanical operation. During the process of contraction a connection is established between two muscle proteins (actin and myosin form actomyosin). Operating frequency Number of load changes per time unit in an application using the Muscle. In this book, it is specified in Hertz (Hz), i.e. in actions per second. Overload protection See force compensator Peristaltic A medical term. A movement carried out by the walls of hollow muscular organs, whereby the individual sections of an organ contract in a wave-like sequence, thereby transporting forward the contents of the hollow organ. Pneu A system, also a constructional system, whereby a covering which is subjected solely to tension envelops a filling. Typical pneus are air balloons, air bladders, soap bubbles, skin sections of man and beast, inflatable buildings, tyres, fire hoses and of course the Fluidic Muscle. Preload force Force on a non-activated Fluidic Muscle, which leads to lengthening by a maximum of 3% of the nominal length and a constriction of the Muscle. Radial adapter Connector elements for the attachment of a Muscle to a machine structure with lateral compressed air supply. Relaxation effect Time-delayed effect after a cause, such as a slight elongation of the Muscle with a static load and after a certain time. Spring characteristic curve This indicates the dependence of the spring travel s on the spring force F and can be progressive, linear or degressive. Springs with a progressive characteristic curve become “harder” with increasing load and those with a degressive characteristic curve “softer” with increasing load. 136 Glossary Spring constant This indicates the required spring force F in order to reach a spring travel f of 1 mm with a particular spring, e.g. a pneumatic spring G. In the past this was referred to as spring rate. Stick-slip effect Juddery or jerky movement of slides and rotary tables during very slow movement, which, in conjunction with elastic deformation, is created as a result of a change between static and sliding friction. Stroke length A change in Muscle length between two mechanically fixed load points. The stroke length is smaller than the distance possible during maximum contraction. Surface Muscle Designation for a “semi” compressed air cushion. The surface muscle consists of a solid flat base plate with mounting holes, through which a round or oval diaphragm protrudes if pressure is applied, thereby developing a pressing force. Glossary 137 138 [1] Kato, W.: Mechanical Hands Illustrated, Survey, Tokyo 1982 Literature [2] Litinetzkij, I. B.: Bionika (russ.), Verlag Bildung, Moskau 1976 [3] Brooks, R.: Menschmaschinen, Campus Verlag, Frankfurt/New York 2002 [4] Pylatiuk, Ch.: Entwicklung flexibler Fluidaktoren und ihre Anwendung in der Medizintechnik, Med. Orth. Techn. 120(2000)6, S. 186-189 [5] Vogel, S.: Von Grashalmen und Hochhäusern – Mechanische Schöpfungen in Natur und Technik, Wiley-VCH, Weinheim/New York 2000 [6] Dale-Hampstead, A.: Der pneumatische Muskel von Axel Thallemer, Verlag Form, Frankfurt am Main 2001 [7] Hesse, S.; Schmidt, U.; Schmidt, H.: Manipulatorpraxis, Braunschweig/Wiesbaden, Vieweg Verlag 2001 [8] Hesse, S.: 99 Beispiele für Pneumatikanwendungen, Festo, Esslingen 2000 [9] Hesse, S.; Krahn, H.; Eh, D.: Betriebsmittel Vorrichtung, Carl Hanser Verlag, München 2002 [10] Zeichen, G. u.a.: Case Studie Pneumatischer Muskel, TU Wien 2001 [11] Hesse, S.: Praxiswissen Handhabungstechnik in 36 Lektionen, expert verlag, Renningen 1996 [12] Iovine, J.: Robots, Androids, and Animatrons, McGraw-Hill, New York 2002 [13] Bedienungsanleitung Fluidic Muscle, Festo, Esslingen 2001 [14] Deppert, W.; Stoll, K.: Pneumatische Steuerungen, Vogel Buchverlag, Würzburg 1994 [15] Deppert, W.; Stoll, K.: Pneumatik-Anwendungen, Vogel Buchverlag, Würzburg 1990 Literature 139 A Index of technical terms Adjusting gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Agonist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Allocator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Android arm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Angle gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Antagonist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Arching effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Arranging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Articulate joint structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Articulated finger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Artificial being . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Artificial hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Assembly press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Attachment vibrators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Automatic sanding device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Balancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Barrel shaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Barrel-Muscle cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Bellows cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Belt tensioning device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Belt-tensioning actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75, 116 Bending device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Biological muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Blocking device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 Bracing cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Bulk material vibrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Cantilever boom axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Clamped attachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Clamping device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65, 68 Clamping gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Combat robot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Compensation mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Compensator roller control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Compressed air consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Contact roller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Conveyor belt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83, 119 Counter muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Crankshaft drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Cushion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Cutter bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Cutting device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Cutting press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 B C 140 Index of technical terms D Deflector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Diaphragm contraction system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Dismantling unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Distribution belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Door opener . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Double scraper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Doubling of stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Dough portion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Drum brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Emergency brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Empty pallet gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Endurance testing unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Enveloping gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 External collet chuck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Fast switching valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Feed roller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Filler material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Film cutting device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Filter press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Flap control system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Flow velocity regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Fluidic actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Force/contraction diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Friction coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Girder transfer device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Gripper head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Guide rail adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Guide roller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76, 114 Hand-held screwdriver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Handling module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Handling unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Intermediate ventilating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Internal bore gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Internal clamping device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 Internal gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Ironing press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Jockey roller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Joining mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Larger stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 E F G H I J L Index of technical terms 141 Leg construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Lever principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Lifting gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Lifting plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Lifting platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Linear vibratory channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Load case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Loading device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Long stroke gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 M Manipulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Manual hydraulic control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 McKibben muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Media resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Membrane building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Membrane contraction system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Motion guidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Multiple gripper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Muscle/work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 MuscleSIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Muscle motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Oscillating seat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Oscillating table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Pad-type Muscle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Paper sheet guide plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Parallel connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Parallelogram linkage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Pedipulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Percussion device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Pipe runner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Piston pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Pneu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Pneumatic hammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Polishing device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Precision positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Press component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Press-on motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Pressure gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Radial-type motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Rectilinear control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Rectilinear motion of belt edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 O P R 142 Index of technical terms Relaxation effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Retaining device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Retarder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Retarding roller conveyor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 S Safety clamping system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Saw actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Saw blade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Saw table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Scissor mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Scissor-type elevating platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Scraper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Series connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Service life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Shaft axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Single-bank radial motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Slide drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Small press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Sorting gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 Sorting gate using Fluidic Muscle actuation . . . . . . . . . . . . . . . . . . . . . . . 121 Sorting storage conveyor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Spatial structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Spindle-nut system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Standard guide unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Stretch film . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Stroke stabilisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Supply of bulk material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Support plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Supporting force generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Swivel device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Swivel grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Table press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Tensile actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Test unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Tilting separator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Toggle lever mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Town vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Tripod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Unwinding device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Vacuum pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Vertical vibratory table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Vibrating wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 T U V Index of technical terms 143 Vibration test bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Vibratory conveyor drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Vibratory spiral chute hopper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 W Walking machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18, 96 Width adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Wiper blade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Withdrawal device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Working range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 144