Hierarchical motion planning at the acceleration level based on task priority matrix for space robot

This paper addresses the motion planning problem for a free-floating redundant space robotic system at the acceleration level considering the strict task priority. The robot is primarily expected to track the prescribed trajectory together with various other tasks, e.g., regulating the base attitude, avoiding collision with obstacles and respecting the joint constraints. Then, the planning problem is reformulated as strictly hierarchical quadratic least-square problems containing both equality and inequality and solved with the proposed task-priority algorithm based on the combination of the task priority matrix method and the active-set method. Besides, a novel velocity-related dynamic potential function is also designed to obtain a smoother motion when approaching obstacles, and further relaxed to the one-dimensional inequality to take full advantage of the robot capacity and dexterity. Simulation results have validated the proposed motion planning strategy imposed on the dual-arm space robot.