Robust fault-tolerant tracking control for a near-space vehicle using a sliding mode approach

In this study, a flight fault-tolerant control scheme based on an adaptive sliding mode technique is proposed. First, a control allocation of a near-space vehicle (NSV) attitude dynamics is analysed, and actuator fault modelling is introduced. Then, a modified sliding model tracking control approach, using a continuous strategy of integral sliding mode control, is designed to improve the position tracking precision. This scheme can solve the chattering problem without loss of robustness and control accuracy. Actuator fault and unmeasurable external disturbances are compensated for by an integral action term. To verify the effectiveness of the proposed control scheme, a numerical simulation is performed for an NSV attitude system, which is a non-linear aircraft model with six degrees of freedom. Simulation results demonstrate that the closed-loop system has good performance in spite of the actuator fault and system disturbances.