A Task-Priority-Transition-Based Obstacle Avoidance Strategy for Space Manipulator

This study put forward a real-time motion control scheme for space manipulator to avoid collisions with complex space environment during performing tracking task. Considering the situation where obstacles locate on the desired trajectory, the proposed strategy is based on the idea of task priority transition to realize the main mission of obstacle avoidance and the minor mission of trajectory tracking. An on-line detecting method is employed to obtain the closest position on the space manipulator system to the obstacles. Depending on the variation of the minimal distance to the obstacles, the priority orders of obstacle avoidance and end-effector tracking are transformed continuously to deal with the conflict between tasks. The effectiveness of the proposed strategy is verified via two simulation cases on a seven-degrees-of-freedom kinematical redundant space manipulator system. The simulation results demonstrate the proposed method ensures the space manipulator avoid collisions with multiple obstacles in the workspace, while achieving smooth and continuous movement.