Impedance Control of Free-Flying Space Robot for Orbital Servicing

One of the most important phases of orbital servicing by a space robot is capturing a target satellite. In this phase, there is the risk that contact will push the target and robot away from each other. Controlling the impedance of the manipulator effectively prevents this. For a free-flying space robot, however, conventional methods used for fixed base robots cannot be used because the motion of the base interferes with the manipulator motion. An impedance control method for a space manipulator arm is proposed, where the end tip of the manipulator is controlled as if a mass-damper-spring system fixed in inertial space. Possible applications in orbital servicing are also discussed.