Adaptive Task-Space Control of Flexible-Joint Manipulators

Abstract

This paper considers the motion control and compliance control problems for uncertain rigid-link, flexible-joint manipulators, and presents new adaptive task-space controllers as solutions to these problems. The motion control strategy is simple and computationally efficient, requires little information concerning either the manipulator or actuator/transmission models, and ensures uniform boundedness of all signals and arbitrarily accurate task-space trajectory tracking. The proposed compliant motion controllers include an adaptive impedance control scheme, which is appropriate for tasks in which the dynamic character of the end-effector/environment interaction must be controlled, and an adaptive position/force controller, which is useful for those applications that require independent control of end-effector position and contact force. The compliance control strategies retain the simplicity and model independence of the trajectory tracking scheme upon which they are based, and are shown to ensure uniform boundedness of all signals and arbitrarily accurate realization of the given compliance control objectives. The capabilities of the proposed control strategies are illustrated through computer simulations with a robot manipulator possessing very flexible joints.