ON CONTROLLING ROBOTS WITH REDUNDANCY

Recently there has been considerable interest in increasing the applic ability and utility of robots by developing manipulators which possess kinematic and/or actuator redundancy. This paper presents a unified a pproach to controlling these redundant robots. The proposed control sy stem consists of two subsystems: an adaptive position controller which generates the Cartesian-space control force F is-an-element-of R(m) r equired to track the desired end-effector position trajectory, and an algorithm that maps this control input to a robot joint torque vector T is-an-element-of R(n). The F --> T map is constructed so that the ro bot redundancy (kinematic and/or actuator) is utilized to improve the performance of the robot. The control scheme does not require knowledg e of the complex robot dynamic model or parameter values for the robot or the payload. As a result, the controller is very general and is co mputationally efficient for on-line implementation. Computer simulatio n results are given for a kinematically redundant robot, for a robot w ith actuator redundancy, and for a robot which possesses both kinemati c and actuator redundancy. In each case the results demonstrate that a ccurate end-effector trajectory tracking and effective redundancy util ization can be achieved simultaneously with the proposed scheme.