A novel strategy for a 7-DOF space manipulator transferring a captured target with collision avoidance

Abstract

This paper presents a collision-free transferring strategy for space manipulator in the static environment. The entire trajectory is planned based on acceleration to improve the smoothness. Firstly, the improved bidirectional alternating search strategy and the variable-step search strategy are applied to A* algorithm to find a collision-free linear acceleration trajectory of the captured target in Cartesian space effectively and rapidly. Then, the collision between the accessories carried on the target and the space robot is avoided by adjusting the attitude of the target in the aforementioned trajectory. Tracking-differentiator (TD) is adopted to achieve the smooth transition between the adjacent expected attitudes of the target. In addition, considering the posture of the manipulator during the task, an acceleration potential field is established to guide the arm-angle within the safe range all the time. Finally, the performance of the trajectory planning strategy is verified by simulation.