Research on Impedance Control of Flexible Joint Space Manipulator On-Orbit Servicing

In this paper, the positional accuracy and contact force index requirements of the manipulator are analyzed according to the tolerance index of the space manipulator screwing. An position-based in Cartesian space impedance control strategy based on friction identification and compensation is proposed. By using joint friction torque compensation to improve the system control precision and setting the desired Cartesian position of the manipulator end point to control the contact force, this strategy solves the contradiction between the positional accuracy index and the contact force index requirement of manipulator during contact operating. The control algorithm is designed based on the system dynamics model, and the stability analysis of the control algorithm is given. The correctness of the control strategy is verified by simulation and on-orbit implementation. China's space manipulator has successfully completed the actual on-orbit servicing mission based on impedance control for the first time.