Robust non-fragile state feedback attitude control for uncertain spacecraft with input saturation

This paper investigates the robust non-fragile state feedback attitude control problem for uncertain spacecraft, and the problem explored here is subject to H_∞ performance constraint, quadratic stability, external disturbances, controller perturbation and control input saturation. The model of spacecraft attitude control system is introduced and transformed into a state space form with parameter uncertainty. Based on Lyapunov theory, sufficient conditions for the existence of robust non-fragile state feedback controller are given based on linear matrix inequalities in terms of additive perturbation and multiplicative perturbation. Then, the design of non-fragile controller subject to required constraints can be regarded as a convex optimization problem based on linear matrix inequalities. By solving linear matrix inequalities to obtain an optimal feasible solution which satisfies all the constraints of the problem and optimizes the objective function, the controller gain matrix can be obtained exactly. Based on the obtained controller, the spacecraft attitude control problem can be solved. The simulation results also demonstrate the effectiveness of the proposed control method.