Optimal Motion Planning for Free-Floating Space Robots Based on Null Space Approach

The kinematics of a free-floating space robot (FFSR) is more complex than that of a fixed-base robot, and hence its motion planning is more difficult. In this paper, the kinematics of the FFSR is introduced firstly. Then the null space approach is used to reparameterize the path: the direction and magnitude are decoupled and no direction error is introduced. And the Newton iterative method is adopted to find the optimal magnitude of the joint velocity. A plannar FFSR with a 2 DOFs manipulator is selected to test the algorithm and simulation results illustrate that the path following is realized prisely. Finally, deficiencies of the method and prospecsts for the future are summarized.