Nonlinear robust decentralized controller design for spacecraft attitude control system

This paper deals with the attitude control problem of the spacecraft with external disturbance torques and parameters perturbations. For this class of MIMO uncertain nonlinear system, based on a kind of nonlinear robust decentsalized control theory, a simple and easy-to-realize controller was designed. The proposed controller included integral actions for the compensation of the entire dynamics system assumed to be unknown. In addition, these integral actions ensured that the steady state error in the regulation of the output variables in some constant reference outputs was equal to zero. Simulation results are presented to show that, compared with nonlinear dynamic inversion controller, nonlinear robust decentralized controller designed is superior in resisting external disturbances and adapting the uncertainties of system model. In the closed-loop system, even if external disturbances and model uncertainties exist, precise attitude control can still be accomplished. Nonlinear robust decentralized controller can effectively improve robustness and adaptability of the spacecraft attitude control systems.