Control of a space robot with flexible members

Abstract

Dynamics and control of a space robotic system with flexible members during an object manipulation task is studied here. Flexible members such as solar panels of space free flying robotic systems and their flexible joints during a manoeuvre may get stimulated and vibrate. Therefore, such vibrations will cause some oscillatory disturbance forces on the moving base and manipulated object, which in turn produces error in the position and speed of the manipulating end-effectors. These flexible members are classified into active and passive elements, to study the ways of controlling the vibration effects of such members. In this paper, considering a multiple arm space robotic system with flexible joints and flexible solar panels, the system dynamics is partitioned into two rigid and flexible bodies, motion, and a practical model for control implementations on compounded rigid-flexible multi-body systems is developed. Then, based on a designated path/trajectory for a space robotic system, the multiple impedance control is extended to perform an object manipulation task by such complicated rigid-flexible multi-body systems. Finally, a space free flying robotic system is simulated which contains two 2-DOF planar manipulators with flexible joints, and a rotating antenna and a camera as its third and fourth arm, appended with two solar panels. Obtained results reveal the merits of proposed controller to successfully perform the manipulation task and effectively suppress the vibration of flexible elements which will be discussed.