Considering the problem of trajectory planning for Free-Floating Space Robot(FFSR),a particle swarm optimization(PSO) based on minimum torque trajectory planning scheme is presented.By analyzing the dynamic equation of system,an optimal control algorithm is applied to FFSR trajectory planning,in which the driving torque of manipulator joint angles is considered as the objective function.Moreover,the high order polynomial is used to approach the trajectories of the joint angles.To achieve the optimal trajectory,the PSO algorithm is implemented so that the planned joint angle trajectories are smooth and continuous.Numerical simulation results show that the proposed methodology is effective and available for solving FFSR trajectory planning problem.With accomplishing the space robot attitude adjusting mission,the driving torque is reduced to the least. free-floating;space robot;dynamic equation;particle swarm optimization;minimizing torque