Adaptive compliance control for redundant manipulators

This paper presents two adaptive schemes for compliance control of redundant manipulators. The first scheme is developed using an adaptive impedance control approach for torque-controlled manipulators, while the second strategy is an adaptive admittance controller for position-controlled manipulators. The proposed controllers are very general and computationally efficient since they do not require knowledge of the manipulator dynamic model or parameter values of the manipulator or the environment, and are implemented without calculation of the inverse dynamics or inverse kinematic transformation. It is shown that the control strategies are globally stable in the presence of bounded disturbances, and that in the absence of disturbances the ultimate bound on the size of the system errors can be made arbitrarily small. The capabilities of the proposed admittance controller are illustrated through laboratory experiments with a Robotics Research Corporation seven degree-of-freedom (DOF) manipulator