On Robust Coordinated Compliant Control Design for Space Manipulators under Flexible and Uncertain Dynamics

Abstract

This paper presents a coordinated compliant control strategy for space manipulator systems to enable safe and robust target capture during on-orbit servicing and assembly missions. The proposed controller operates in two distinct phases: free-space motion and contact interaction. In the free-space phase, end-effector accurate trajectory tracking is required, while in the contact phase, the control objective shifts to force regulation, maintaining contact forces within safe bounds and ensuring stable interaction durations to enhance operational safety. A key feature of the developed method is its ability to provide a smooth and continuous transition between free-space and contact phases without requiring controller switching. Furthermore, the controller preserves the attitude stability of the chaser spacecraft during manipulation, mitigating mission-critical risks such as communication loss or solar panel misalignment. The approach explicitly incorporates the coupled rigid-body dynamics of the SMS and demonstrates robustness to various real-world disturbances. Simulation results validate the effectiveness of the proposed controller. Future work includes experiments, using the planar Space Robotics Emulator of our lab at the National Technical University of Athens to assess real-world readiness.