Hybrid Impedance/Position Control of a Free-Flying Space Robot for Detumbling a Noncooperative Satellite

This paper presents hybrid impedance/position control of a free-flying space robot for detumbling a noncooperative satellite. Detumbling a noncooperative satellite by a single serial-link manipulator is achieved using a novel hybrid control scheme in which position-based impedance control in the direction normal to the surface of a noncooperative satellite realizes soft contact between the end tip of the robot's manipulator and the desired contact point on the satellite, while PID position control in other directions maintains the end-tip position and orientation at the same contact point. The hybrid control scheme utilizes vectors expressed in a reference frame fixed in a noncooperative satellite. Simulation results in a two-dimensional planar case show that our approach of using the proposed hybrid impedance/position control scheme succeeded in realizing zero angular velocity of a noncooperative satellite.