Delta Parallel Robot — the Story of SuccessBy Ilian Bonev Special thanks to Prof. Reymond Clavel (École Polytechnique Fédérale de Lausanne) Matthias Ehrat (SIG Pack Systems AG), Marc-Olivier and Pascal Demaurex (Demaurex SA), Stephen Kelly (ABB Flexible Automation), Saburo Furuya (Hitachi Seiki Co.), Andrew Davies (Elekta Oncology System Ltd.), Karol Miller (University of Western Australia), Prof. Chris Watts (Dalhousie University) and Rick Stamper (Rose-Hulman Institute of Technology) It is in the early 80's when Reymond Clavel (professor at EPFL - École Polytechnique Fédérale de Lausanne) comes up with the brilliant idea of using parallelograms to build a parallel robot with three translational and one rotational degree of freedom. Contrary to opinions published elsewhere, his inspiration was truly original and does not come from a parallel mechanism patented by Willard L. Pollard in 1942, which at that time was not known to Professor Clavel. The latter calls his creation the Delta robot, without suspecting that at the turn of the century, it will establish itself as one of the most successful parallel robot designs, with several hundred active robots worldwide. In 1999, Dr. Clavel is presented with the Golden Robot Award, sponsored by ABB Flexible Automation, for his innovative work on the Delta parallel robot. Schematic of the Delta robot (from US patent No. 4,976,582) The Design The basic idea behind the Delta parallel robot design is the use of parallelograms. A parallelogram allows an output link to remain at a fixed orientation with respect to an input link. The use of three such parallelograms restrain completely the orientation of the mobile platform which remains only with three purely translational degrees of freedom. The input links of the three parallelograms are mounted on rotating levers via revolute joints. The revolute joints of the rotating levers are actuated in two different ways: with rotational (DC or AC servo) motors or with linear actuators. Finally, a fourth leg is used to transmit rotary motion from the base to an end-effector mounted on the mobile platform. and Presto. their major objective became to commercialize the parallel robot for the packaging industry. its workspace is the intersection of three right circular tori. and the European patent issued on July 17. The Delta robots available on the market operate typically in a cylindrical workspace which is 1 m in diameter and 0. The Delta Robot on the Market The history of the Delta robot marketing is long. these patents protect the invention in USA. The second one. Demaurex now claims to have sold some 500 Delta robots worldwide. concerning robots of larger dimensions. Canada.976. was sold to AID and later resold to DeeMed. After purchasing a license for the Delta robot in 1987. and most West European countries. the US patent issued on December 11. specializes in the surgical domain and manufactures a Delta robot used to carry a heavy (20 kg) microscope (SurgiScope). It all started in 1983 when the two Swiss brothers Marc-Olivier and Pascal Demaurex created the company Demaurex based in Romanel-sur-Lausanne. The Delta robot technology was consequently sold to . 1991 (EP 0 250 470). Switzerland. After several years. EPFL had already sold two licenses. The patents do not specify the way in which the Delta structure is actuated in order to incorporate the basic design as well as its variants (such as the Triaglide or the Linapod). and intriguing. The first one concerning the robots of small dimension (arm + parallelogram < 800 mm) was attributed exclusively to Demaurex in 1987. Four application versions were commercialized under the names of Pack-Placer. The company product went through a number of modifications.2 m high. before the transaction took place. Top-Placer. bought later by the Swedish Elekta. Demaurex's Line-Placer installation for the packaging of pretzels in an industrial bakery (courtesy of Demaurex) The patent on the Delta robot was bought by the brothers Demaurex from EPFL in 1996.582). Ideally. 1987 (WO 87/03528). This makes the Delta robot a perfect candidate for pick and place operations of light objects (from 10 gr to 1 kg). However. the design of the Delta robot is covered by a family of 36 patents of which the most important are the WIPO patent issued on June 18. Japan. complicated. Demaurex succeeded in occupying a major place in this new difficult market. The Patent As simple as it is.The use of base-mounted actuators and low-mass links allows the mobile platform to achieve accelerations of up to 50 G in experimental environments and 12 G in industrial applications. Line-Placer. Overall. This company. 1990 (US 4. since the company undertook the obligation not to enter the over 1. . Dr.161.992) which is again a Delta robot with linear drives. In the meantime. Humboldt-University at Berlin (courtesy of Prof. In addition. It is interesting. ABB acquired a license to manufacture Delta robots of larger dimensions. Renault Automation Comau introduced at EMO'99 in Paris their Urane SX milling machine which is remarkably similar to the Quickstep design. However. Demaurex may not produce robots of dimensions greater than that. Tim C.Medtronic at the end of 1999. As a result.200 mm). Demaurex announced its decision to produce robots of greater dimensions (almost 1. though. when it purchased the exclusive under 800 mm license. as well as with Mikron Technology Group for their Triaglide. It seems probable that Demaurex negotiated with the German GROB-Werke over the license to produce the TRIAGLIDE 5g. Elekta IGS entered negotiations over its Delta license with the Zurich based Global technology group ABB. both of which are Delta robots with linear motors.200 mm market. that the Krause & Mauser Group has a patent for their Quickstep 3-axis milling machine (US 6. Lueth) Before the SurgiScope transaction. SurgiScope in action at the Surgical Robotics Lab. Hitachi Seiki represents Demaurex in Japan. ABB Flexible Automation's IRB 340 FlexPicker (courtesy of ABB Flexible Automation) . In fact.Hitachi Seiki's Delta robots for pick-and-place and drilling (courtesy of Hitachi Seiki) Demaurex also licensed the Japanese company Hitachi Seiki to manufacture Delta robots of small dimensions for packaging (DELTA) and for drilling (PA35). and electronics industries. Presently.000 workers — a company big enough to offer Demaurex the so much needed access to the world market. designed especially for clean-intensive environments. Yet another highly-optimized version. In an attempt to ensure its long-term stability. One such modified Delta robot was built at the University of Maryland. NUWAR. The FlexPicker is equipped with an integrated vacuum system capable of rapid pick and release of objects weighing up to 1 kg. And it is thus. in order to gain a world market. Demaurex suddenly faced the decision of the Swedish giant ABB to enter this lucrative market. However. Two of the three Delta robot models offered by SIG Pack Systems. The SIG Group consists of three branches. Demaurex changed its line of production from naked Delta robots to complete robot cells. The attainable velocities are 10 m/sec and 3. the robot may be equipped with a motion controller and vision system by Adept Technology. modified version was constructed at the University of Genoa. A number of variants have been proposed in the literature but most of those that have been prototyped stay close to the original design. employs some 2. Demaurex will keep its name and even its two founders and CEOs. C33 and CE33 (courtesy of SIG Pack Systems) The Delta Robot In Academia The Delta robot design has attracted great interest not only in industry but also in university labs. Another. three different Delta robot models are offered by SIG Pack Systems. whereas the C23 and C33 are manufactured by Demaurex while the CE33 is fabricated by SIG Pack Systems. The robot comes in two versions. one of which is sealed.6 deg/sec (about 150 picks per minute). the small Demaurex started looking for a partner. corrosionresistant wash-down version. Three industry sectors were aimed — the food. The robot is guided with a machine vision system by Cognex and an ABB S4C controller. of which the SIG Pack branch. pharmaceutical. was built in the University of Western Australia. the parallelograms are replaced by equivalent mechanisms. After more than fifteen years as the sole player on the market. In that design.2 rad/sec². that Demaurex became acquired by the Swiss Group SIG at the end of 1999. Optionally.ABB Flexible Automation launched its Delta robot in 1999 under the name IRB 340 FlexPicker. and the accelerations are up to 100 m/sec² and 1. The NUWAR is claimed to reach accelerations of up to 600 m/sec² and differs from the other Delta robot versions in its non-coplanar arrangement of the axes of its rotary . only. D. Miller. J'automatise. Symp.. C. 4. And an even more original application of the Delta robot. EPFL. Miller. Bibliography Clavel. Symp. Molinari-Tosatti.. 8. 1999. And of course." ROBAUT. Boër. Vol. 1995. one of the latest inventions of that Group makes use of the same parallelogram concept in order to construct a robot with only orientational degrees of freedom (Argos). on Advanced Robotics (ICAR'92). G.. 1992. A classical Delta robot was also modeled at LIRM. June 16. pp.. 1992. Thesis. ETH Zurich. 3.976.. No. Parallel Kinematic Machines: Theoretical Aspects and Industrial Requirements.." Journal of Robotics and Mechatronics. as part of a decoupled 6-DOF haptic interface. 1997. Tokyo. Lausanne. Another linear version and two conventional Delta robots were fabricated in the scope of student projects at the University of Michigan (1. Miller. of Industrial Robots (ISIR'95). January-February 2000.. "Modeling of Dynamics and Model-Based Control of DELTA Direct-Drive Parallel Robot. and K. and MicroDelta 240) were built by the Parallel Robotics Group headed by Prof. Zakopane. K. September 27-29. pp. 49-54.571. several Delta robots (Delta 720. Another typical Delta robot was also constructed at the EPFL's Automation Institute. "On Accuracy and Computational Efficiency of DELTA Direct Drive Robot Dynamics Model. "Device for the Movement and Positioning of an Element in Space. "Experimental Verification of Modeling of Delta Robot Dynamics by Direct Application of Hamilton's Principle. Springer-Verlag. Japan. 2000." 13th RoManSy. pp. R. J.D. October 4-6." IEEE Int. "Position Controlling Apparatus.. on Microsystems. Trajectory Tracking Experiments. 1991. A more different application of a slightly modified Delta robot. Pollard. 1995. "Mechanics of New UWA Robot. Merlet. 491-496.. Fages. 568-571. they would have been placed in that fancy box by the rapid hand of a Delta robot. Parallel Robots. "La vérité sur les robots parallèles. Intelligent Materials and Robots.000 USD. No. . Their Delta Force Feedback Device is commercially available for about 20.-P. 2. 344-352. USA. 1995. R. and the University of Stuttgart. K. Switzerland. L. K. Poland.actuators." Robotersysteme. Japan.582." Ph. L. 4). Nagoya.286. Naturally. Chances are that next time you savour delicious chocolate candies. on Robotics and Automation (ICRA'95)." Int. K. 2. Conf. Linear Delta. 1942. 8. 1990. Stamper. June-July 1999. Astonishingly. "Model-Based Control of DELTA Direct Drive Parallel Robot. R." ROBAUT. Kluwer Academic Publishers. 1995.. J'automatise. Miller. Reymond Clavel... Miller.. MD... "The Proposal of a New Model of Direct Drive Robot DELTA-4 Dynamics. 17." 26th Int. Miller. Three linear-motor versions were also constructed at Ferdinand-von-Steinbeis Schule. 4. was implemented at Dalhousie University. Thesis. as a vegetable transplanting device. . Springer-Verlag." Ph. May 25-27. W. Singapore. was implemented at Tohoku University. K. pp. "A Three Degree of Freedom Parallel Manipulators with Only Translational Degrees of Freedom. July 3-6. Clavel. pp. December 11. pp. Vol." US Patent No. K. 4. 411-416. Miller. Smith (Eds). R. November 1-2. "Conception d'un robot parallèle rapide à 4 degrés de liberté. No. 2000. 4. No." Int. "Demaurex change de mains mais reste suisse. "The Lagrange-Based Model of Delta-4 Robot Dynamics. 532-537.." US Patent No. Japan. University of Maryland. The Delta robot remains without competitors in the sector of rapid transfer robots. the greatest concentration of Delta robot family members is found at its birthplace — l'École Polytechnique Fédérale de Lausanne (EPFL). Sendai. E. K. There is a haptic device built by EPFL's Virtual Reality and Active Interfaces Group. Conf.S. and Clavel. R.