Typically in the kinematic control of manipulator arms the task of guiding the end effector along a trajectory is governed by equality constraints, all other tasks being considered secondary. This is a major cause of difficulty when other, often more important constraints are encountered, for example, joint motion limits, workspace boundaries, or obstacles. To overcome this problem the notion of an imaginary end effector connected to the real end effector via imaginary (or virtual) actuators is introduced. These imaginary actuators act as slack variables in the constraint equations. This enables the real end effector to deviate from its desired path in order to allow other constraints to be satisfied. Imaginary actuators can also be used to maintain control of an arm when it is driven beyond its kinematic range, or into singular configurations.
Unable to display preview. Download preview PDF.
- Beckley, L., Kovesi, P., and Owens, R. (1990). The Use of imaginary Actuators in Kinematically Redundant Mechanisms for Obstacle Avoidance. Proceedings of The Third National Conference on Robotics, Melbourne, June 3–6.Google Scholar
- Klein, C.A. and Huang C-H (1983). Review of Pseudoinverse Control for use With Kinematically Redundant Manipulators. IEEE Transactions on Systems, Man and Cybernetics, SMC-13–3, pp. 245–250.Google Scholar
- Kovesi, P.D. (1984). Kinematic Control of High Dexterity Manipulator Arms. Master of Engineering Science Thesis, Department of Mechanical Engineering, University of Western Australia.Google Scholar
- Liegeois, A. (1977). Automatic Supervisory Control of the Configuration and Behaviour of Multibody Mechanisms. IEEE Transactions on Systems, Man and Cybernetics, SMC-7–12, pp. 868–871.Google Scholar
- Ribble, E. (1982). Synthesis of Human Skeletal Motion and the Design of a Special Purpose Processor for the Real Time Animation of Human and Animal Figure Motion. M.Sc. Thesis, Ohio State University, Department of Electrical Engineering. p. 74.Google Scholar
- Trevelyan, J.P., Kovesi, P.D., and Ong, M.C.H. (1984). Motion Control for a Sheep Shearing Robot. First International Symposium on Robotics Research, eds M. Brady and R. Paul, Cambridge, Mass. MIT Press, pp. 175–190.Google Scholar
- Velletri, P. and Kovesi, P.D. (1990). Controlling Robot Manipulators at Motion Limits. Proceedings of The Third National Conference on Robotics, Melbourne, June 3–6.Google Scholar
- Wampler, C.W. (1986). Manipulator Inverse Kinematic Solutions Based on Vector Formulations and Damped Least-Squares Methods. IEEE Transactions on Systems, Man and Cybernetics, SMC-16–1, pp. 93–101.Google Scholar
- Whitney, D.E. (1969). Resolved Motion Rate Control of Manipulators and Human Prostheses. IEEE Transactions on Man Machine Systems MMS-10–2. pp. 47–53.Google Scholar