This paper aims to rectify a perceived imbalance between theory and experiment in the research literature on the control of flexible manipulators. Additionally, this paper reflects the common-sense notion that judicious arm design can simplify a control task, making it more tractable, thereby leading to greater physical insight into the theoretical control problem. The theme, based on previous experi ence with flexible manipulators, is a novel 3-DOF flexible manipula tor, the Rotabot, designed and constructed at the Oxford University Robotics Laboratory. The arm is an experimental "concept" design for a full-sized industrial flexible arm, where the tractability of the final control problem has been a major design driver. As Part 1 of a two-part series, this paper describes the different design features of the Rotabot. Part 2 explains the controller design.
The kinematic and dynamic properties of the arm are evaluated, and the key design properties are demonstrated by simulation. Afull model that includes transmission compliance is presented, which forms the basis of the controller in Part 2. Experimental results derived from extensive identification exercises are used to confirm the arm properties predicted by simulation.
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References
1.
Armstrong, B.S.R.1988. Dynamics for robot control: Friction modeling and ensuring excitation during parameter identification. Ph.D. thesis, Department of Computer Science, Stanford University.
2.
Arocena, J.I.1992. Characterisation and control of a flexible robot subject to torque ripple. Ph.D. thesis (OUEL 1952/92), Department of Engineering Science, Robotics Research Group, University of Oxford.
3.
Arocena, J.I., Daniel, R.W., and Elosegui, P.1993 (June 25-27, Toulouse). End-point control of compliant robots. Second Int. Symp. on Exp. Robot. London: Springer-Verlag .
4.
Asada, H., Kanade, T., and Takeyama, Y.1982 (April). Control of a direct-drive arm. Technical Report CMU-RI-TR-82-4, The Robotics Institute, Carnegie-Mellon University.
5.
Balas, M.J.1977 (Blacksburg, VA). Active control of flexible systems. Symp. on Dynamics and Control of Large Flexible Spacecrafts. American Society of Aernoautics and Astronautics.
6.
Cannon, R.H., Jr., and Schmitz, E.1984. Initial experiments on the end-point control of a flexible one-link robot. Int. J. Robot. Res.3(4)62-75.
7.
Christian, A.D.1989. Design and implementation of a flexible robot. M.Sc. thesis, Artificial Intelligence Laboratory, Massachusetts Institute of Technology.
8.
Daniel, R.W., and Cook, I.C.1983 (October, London). The relationship between trajectory sensitivity and manoeuverability as a design aid for revolute fixed-arm industrial robots. IEEE Colloquium in Control Theory in Robotics. Los Alamitos, CA: IEEE.
9.
Daniel, R.W., and Irving, M.A.1987. Evaluation of control techniques for in-reactor manipulators . Technical Report CEGB contract R/RER/DSD/TD 464, Robotics Research Group, Department of Engineering Science, University of Oxford.
10.
Daniel, R.W., Irving, M.A., Fraser, A.R., and Lambert, M.1987 (Santa Cruz, CA). The control of compliant manipulator arms. Proc. of the Fourth ISRR. Cambridge, MA: MIT Press.
11.
Daniel, R.W., and Sharkey, P.M.1990 (Honolulu, HI). Chaos in high performance digital robot controllers. Proc. of the 29th Conf. on Decision and Control. Los Alamitos, CA: IEEE.
12.
Dubrowsky, S., and Gardner, T.N.1975 (May). Dynamic interactions of link elasticity and clearance connections in planar mechanical systems. Trans. ASME, J. Engineering Industry97:652-661.
13.
Elosegui, P.1992. Analysis of the compliant motion achievable with an industrial robot: Identification, feedback, and design. Ph.D. thesis (OUEL 1899/91), Robotics Research Group, Department of Engineering Science, University of Oxford.
14.
Fraser, A.R., and Daniel, R.W.1991. Perturbation Technique for Flexible Manipulators. Boston: Kluwer Academic.
15.
Gevarter, W.B.1970. Basic relations for control of flexible vehicles. Am. Inst. Aernoaut. Astronaut. J.8(4).
16.
Kanoh, K., and Lee, H.G.1985 (December, Ft. Worth, FL). Vibration control of a one-link flexible arm. Proc. of the 24th Conf. on Decision and Control. Los Alamitos, CA: IEEE.
17.
Kazerooni, H.1988 (October, Tokyo). Statically balanced direct-drive manipulator for constrained maneuvers. IEEE Int. Workshop on Intell. Robots and System Programs. Los Alamitos, CA: IEEE.
18.
Khatib, O.1993 (December, IRIAM, France). Toward a new generation of force-controlled robot manipulators. Proc. of ORIA '91. Elsevier.
19.
Kuwahara, H., Ono, Y., Nikaido, M. and Matsumoto, T.1985 (June). A precision direct-drive robot. Proc. of the American Control Conf, pp. 722-727.
20.
Lambert, M.1987. Adaptive control of flexible systems. Ph.D. thesis (OUEL 1707/87), Department of Engineering Science, University of Oxford.
21.
Liégeois, A., Dombre, E., and Borrel, P.1980. Learning and control for a compliant computer-controller manipulator. IEEE Trans. Automat. Control.25(6):1097-1102.
22.
Maples, J.A.1985. Force control of robotic manipulators with structural flexibility. Ph.D. thesis (SUDAAR-549), Guidance and Control Laboratory, Department of Aeronautics and Astronautics, Stanford University .
23.
Mason, M.T.1981. Copmpliance and force control for computer-controlled manipulators. IEEE Trans. Sys. Man Cybernet.11(6):418-432.
24.
Pfeiffer, F., and Gebler, B.1988 (April, Philadelphia, PA). A multistage-approach to the dynamics and control of elastic joints. Proc. of the IEEE Int. Conf. on Robot. and Automat. Los Alamitos, CA: IEEE.
25.
Rivin, E.U.1984 (June, Toronto). Compliance breakdown for robot structures. Proc. of the 7th Symp. on Engineering Applications in Mechanics., pp. 56-67.
26.
Rivin, E.U.1988. Mechanical Design of Robots. New York : McGraw-Hill.
27.
Salisbury, J.K.1980 (December, Albuquerque, NM). Active stiffness control of a manipulator in Cartesian coordinates. Proc. of the 19th IEEE Conf. on Decision and Control. Los Alamitos, CA: IEEE.
28.
Schmitz, E.1985. Experiments of the end-point position control of a very flexible one-link manipulator. Ph.D. thesis, Guidance and Control Laboratory, Department of Aeronautics and Astronautics, Stanford University.
29.
Singer, N.C.1989. Residual vibration reduction in computer-controlled machines . Ph.D. thesis, Artificial Intelligence Laboratory, Massachusetts Institute of Technology.
30.
Suehiro, T., and Takase, K.1985 (September, Tokyo). Development of a direct-drive manipulator: ETA-3 and enhancement of servo stiffness by a second-order digital filter. Proc. of the 15th Int. Symp. on Industrial Robotics.
31.
Sweet, L.M., and Good, M.C.1984 (December, Las Vegas, NV). Redefinition of the robot motion control problem: Effects of plant dynamics, drive system constraints, and user requirements. Proc. of the 23rd IEEE Conf. on Decision and Control. Los Alamitos, CA: IEEE.
32.
Thomson, W.T.1988. Theory of Vibrational Analysis with Applications, 3rd ed. London: Unwin-Hyman .
33.
Tsang, T.T.C.1990. The application of predictive control to flexible robot arms. Ph.D. thesis (OUEL 1842/90), Department of Engineering Science, University of Oxford.
34.
Whitney, D.E.1982. Quasi-static assembly of compliantly supported rigid parts . ASME J. Dyn. Sys. Measur. Control104.
35.
Yoshikawa, T.1990. Foundation of Robotics: Analysis and Control. Cambridge, MA: MIT Press.
