Disturbance Observer-Based Control of Spacecraft Attitude Dynamics Subject to Perturbations and Underactuation

Abstract This chapter deals with the stabilization of nonlinear spacecraft attitude dynamics by solely using magnetic actuation. The considered control problem possesses instantaneous underactuation due to the magnetic torque production mechanism. The aim is to design an observer-based control system by integrating an already existing magnetic sliding mode attitude controller with a nonlinear disturbance observer. In the observer-based controller synthesis, all major environmental disturbances and complete inertia matrix uncertainty are taken into account. It is proven that the obtained controller realizes sliding mode in the system, which implies robustness of the stabilization. An exemplary simulation verifies the theoretical deduction. Comparative simulation results indicate superiority of the ultimate controller to the baseline controller in terms of control effort and chattering while the same state responses are output by both control systems.