Decoupling and Fast Estimation of RCS Disturbance and Fault

Focusing on the reaction control system disturbance and fault, a decoupling and fast estimation method is proposed. First, the finite-time unknown input observers are designed combining unknown input observers, sliding mode control reaching laws, and sliding mode observers to decouple the fault and realize fast and accurate disturbance estimation. The proof of the estimation error finite-time stability based on Lyapunov theory is given. Second, the obtained disturbance estimation is introduced into existing finite-time observers to achieve rapid and accurate fault estimation. Finally, the proposed method is applied to a reaction control system and the effectiveness of the method proposed in this paper is verified.