Robust Tracking Control of Electrical Driven Free-Floating Space robot Manipulators

This paper is concerned with robust tracking control of electrical driven free floating space robot manipulators with unmodeled uncertainties and external disturbances. The dynamics of the free-floating space manipulator system derived using virtual manipulator approach (VMA) uses only link angles as generalized coordinates, which is suitable for the controller design in joint space. Since joint coupling, unmodeled uncertainties, as well as external disturbances are treated as lumped disturbance, then a proportional plus derivative (PD) feedback control with disturbance observer (DOB) was developed and implemented at each joint of space manipulators including electrical and mechanical dynamics of motor. In addition, a feed-forward control consisting a simple predictor was added to reduce tracking error further. Simulation results from a six-link electrical driven space manipulators show that the developed controller achieves superior performance with less tracking error, especially when internal model uncertainties and large external disturbances are present