Passivity based on Energy Tank for Cartesian Impedance Control of Redundant Free-Flying Space Robots with Elastic Joints

Abstract

This paper presents a Cartesian impedance control for free-flying space robots with elastic joints. In order to archive high dynamic behavior of the end-effector like a mass-spring-damper system, the control stiffness and control damping are computed online depending on the Cartesian robot mass matrix and thus time-varying. Therefore, in order to ensure passivity of the system the control law is extended using the concept of energy tank so that the system can achieve maximal performance and simultaneously shows stable behavior both in free motion and in contact with its environment. The proposed control method is very efficient and practicable. Furthermore, it is very robust with respect to dynamic parameter uncertainties, coupling dynamics, and can simultaneously provide good results in term of the dynamic behavior and position accuracy. Simulation results validate practical efficiency of the controller.