Torque control in the joint of a space robotic arm

This paper deals with the torque loop control design in a joint prototype of a space manipulator. First a model of the joint for free and contact motion is proposed, pointing out the strong nonlinear behaviour in contact motion. Then the controller design for the free motion is dealt with and the robustness of the torque regulation loop with respect to the contact stiffness is examined. Guidelines are given to select a suitable control law according to robustness and performance goals, for both free and contact motion. The resulting control law is finally experimentally verified.