Abstract:

To address the problem of the degradation of actuation effectiveness caused by actuator deflection or fault in the attitude and orbit control system (AOCS) of spacecraft on orbit, an attitude fault tolerant and anti-disturbance control scheme is proposed based on a sliding mode controller with iterative learning law, in which the pseudo control input is used to design the sliding mode controller to ensure the AOCS tracks a reference trajectory precisely after some faults occur. By analyzing the Lyapunov stability, a novel adaptive iterative learning law is developed, which, in terms of the tracking error, determines some parameters in controller on line to deal with the actuator failure and external disturbance. Numerical simulation experiments show that the fault tolerant and anti-disturbance controller can ameliorate actuation malfunction and compensate the influence of external disturbance effectively.