Disturbance rejection analysis of multiple impedance control for space free-flying robots

To increase the mobility of on-orbit robotic systems, Space Free-Flying Robots (SFFR) in which one or more manipulators are mounted on a thruster-equipped base, have been proposed. Unlike fixedbased manipulators, the robotic arms of SFFR are dynamically coupled with each other and the freeflying-base, hence the control problem becomes more challenging. In this paper, the Multiple Impedance Control (MIC) is developed to manipulate space objects by multiple arms of SFFR. The MIC law is based on the concept of designated impedances and enforces them at various system levels, i.e., the free-flying base, all cooperating manipulators, and the manipulated object itself. The object may include an internal angular momentum source, as is the case in most satellite manipulation tasks. The disturbance rejection characteristic of this algorithm is also studied. The result of this analysis reveals that the effect of disturbances substantially reduces through