Cartesian Control of Space Manipulators for On-Orbit Servicing

This paper is focused on Cartesian control of a free-floating space manipulator in the post-grasping phase so as to bring the tumbling non-cooperative satellite to rest. First, a coordination control for the space manipulator, which is mechanically connected to target satellite, is developed so that the space manipulator moves the target according to a desired velocity trajectory while regulating the attitude of the its base to a desired value. Then, a time-optimal velocity trajectory through which the tumbling satellite is brought to rest from its initial angular velocity subject to the constraint that magnitude of the torque interaction between the target satellite and the manipulator end-effector remains below than a safe value is derived. The control method is validated by simulation.