Online Path Planning and Compliance Control of Space Robot for Capturing Tumbling Large Object

Abstract

This paper presents the path planning and coordinated control of a space robot with a manipulator for capturing a rotating large object. As the grasping point on a rotating large object is translationally moving fast, an appropriate strategy and coordinated motion control of the spacecraft base and robotic arm must be employed for approaching and tracking such a grasping point. In this paper, we propose a robust control scheme including the online path planning and compliance control for grasping such a target. The path planning is derived in a simple form that allows the desired end-effector trajectory to be easily modified in real-time using the newly updated states without complex numerical calculation. In addition, the compliance control allows the end-effector to track the planned trajectory or the moving grasping point, while using contact force feedback to reduce the end-effector position error from the grasping point when capturing the target. This end-effector motion is implemented by coordinated control on the spacecraft base and robotic arm, which can suitably alter their distribution of motion according to scenes using a weighted pseudoinverse matrix. Experiments are conducted to demonstrate the validity of the proposed path planning and compliance control.