Disturbance-observer-based fault tolerant control for near space vehicles with input saturation

In this paper, the fault tolerant control scheme is proposed for near space vehicles (NSVs) with system uncertainty, unknown external disturbance, actuator faults and input saturation based on the sliding mode control (SMC). To eliminate the effect of external disturbance and system uncertainty, the nonlinear disturbance observer (NDO) is designed. Neural networks are employed to deal with actuator faults. Considering input saturation, a compensated tern is constructed in the control law. The stability of the closed-loop system is proved and all closed-loop signals are uniformly ultimately bounded via Lyapunov analysis. Simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.