Immersion and Invariance-Based Adaptive Coordinate Control for Space Manipulator

This paper investigates the coordinate control problem for a free-flying spacecraft equipped with a manipulator. A novel robust adaptive sliding mode controller modified by immersion and invariance theory is proposed to drive the spacecraft attitude and the manipulator pose to maneuver from the initial condition to the desired one in a fast manner, simultaneously guaranteeing the robustness against system uncertainties and external environmental disturbances. The nonconventional sliding mode surface and introduction of I&I theory eliminate the effect of chattering since the system dynamics evolve closer to its natural behavior. Moreover, the noncertainty equivalence principle based disturbance estimator avoids possible controller singularities. Stability analysis of the closed-loop has been rigorously proven with the Lyapunov theory. Numerical simulations demonstrating the effectiveness and robustness of the proposed control scheme are carried out on a model of a spacecraft equipped with a 2 degree of freedom manipulator.