Base attitude disturbance minimizing trajectory planning for a dual-arm space robot

Space robots are playing an increasingly important role in on-orbit services. Affected by the coupling of dynamics, the base attitude of a space robot will deflect with the motion of its manipulators, which leads to unfavorable effect to the success of the mission. The trajectory planning problem for base attitude disturbance minimization of a dual-arm space robot will be studied in this article. Along the planned trajectory, the attitude of the base will keep unchanged when the end effectors of the manipulators arrive at the desired position. First, the dynamic equation of the dual-arm space robot is given, and the direct-inverse mixed dynamic equation is also derived. Then, the rotation trajectory of the manipulator joints is parameterized, and the attitude deflection of the base with respect to the given parameters is calculated based on the direct-inverse mixed dynamic equation. The particle swarm optimization algorithm is utilized to obtain the optimal trajectory. Finally, numerical simulations are carried out to verify the effectiveness of the method proposed in this article. Four cases are included, considering symmetrical or asymmetrical initial configuration and synchronous or asynchronous start of the dual arms. The simulation results show that, in each case, the method proposed can effectively plan the trajectory along which the base attitude will keep nearly unchanged before and after the motion of the dual arms.