Constrained multi-observer-based fault-tolerant disturbance-rejection control for rigid spacecraft

This article develops a multi-observer-based fault-tolerant disturbance-rejection control strategy to solve the attitude stabilization problem of spacecraft subject to multisource complex disturbances, for example, external disturbance, measurement error, actuator fault, input constraint. First, two intermediate variables are introduced for multi-observer design, so that the synergistic estimations of attitude information, actuator fault and external disturbance are obtained simultaneously. Then, a fault-tolerant disturbance-rejection control strategy is proposed based on the estimations, and an augmented closed-loop system is derived. Afterwards, Lyapunov stability analysis is performed to prove the quadratic stability and robust (Formula presented.) performance, and corresponding conditions in terms of linear matrix inequalities (LMIs) is proved, where the input constraint is satisfied as well. Finally, numerical simulations of a spacecraft attitude control system are performed which demonstrate the effectiveness and superiority of the proposed multi-observer-based control strategy.