Trajectory Planning of Free-Floating Space Manipulators With Spacecraft Attitude Stabilization and Manipulability Optimization

This article focuses on trajectory planning of the free-floating space manipulator (FFSM), so that the end-effector trajectory tracking and the spacecraft attitude stabilization are achieved simultaneously. A novel spacecraft attitude stabilization constraint with the time-decaying term and the time-varying gaining parameter is constructed, such that not only is the designed constraint satisfied at the initial instant but also the spacecraft attitude can converge into the small neighborhood of the desired attitude. Two constraints on joint accelerations are constructed, such that the constraints on joint angles/velocities/accelerations and the requirement on the end-effector trajectory tracking are both satisfied. Besides, for the cost function with the control efforts and the manipulability optimization, it can be equivalently converted as a strictly convex quadratic function. Correspondingly, the trajectory planning problem of the FFSM at the acceleration level can be formulated as a constrained convex quadratic programming problem. The proposed trajectory planning algorithm avoids the dynamic singularity of the FFSM. The effectiveness of the proposed algorithm is validated by the simulation results.