SLIDING MODE FAULT TOLERANT CONTROL OF QUADROTOR UAV WITH STATE CONSTRAINTS UNDER ACTUATOR FAULT

Actuator faults and state constraints are the main factors that degrade the performance of quadrotor unmanned aerial vehicle (UAV). In this paper, a robust non-linear active fault tolerant control algorithm based on non-singular fast terminal sliding mode control (NFTSMC) and asymmetric barrier Lyapunov function is designed for a quadrotor UAV system with actuator fault and unknown external disturbance while specifically considering state constraints. Firstly, since the uncertainty of fault magnitudes, an adaptive estimator is applied to estimating the severity of actuator faults. Then, a novel NFTSMC is proposed. In virtue of the proposed method, the system can not only own strong robustness but also reach the original value in a short finite-time. In addition, aiming at the phenomenon of state constraints in the actual flight of quadrotor aircraft, the asymmetric barrier Lyapunov function (BLF) is introduced to guarantee the constraints not to be violated. Finally, the effectiveness and superiority of the proposed control scheme are verified by contrast simulation and comparison experiments.