Robust ADP-Based Sliding-Mode Fault-Tolerant Control for Nonlinear Systems with Application to Spacecraft

This paper considers a novel fault-tolerant control (FTC) scheme for a category of cascade nonlinear systems with mismatched uncertainties and unknown actuator faults. The robust adaptive dynamic programming (RADP) is used to design a novel optimal sliding surface (SS) off-line, which renders the corresponding sliding-mode dynamics able to obtain robustness of stability to mismatched uncertainties. Subsequently, a simple sliding-mode control (SMC) with the adaptive fault compensation is developed to guarantee reachability of the sliding mode. Then, it is proven that the weight errors of neural networks (NN) of RADP and the closed-loop system are stable based on Lyapunov stability theory. In the simulation section, this proposed scheme is used to deal with the attitude FTC of a spacecraft, and simulation results verify the effectiveness of the proposed novel control scheme.