Fuzzy adaptive fault-tolerant control for quadrotor helicopter

This paper proposes a fuzzy adaptive sliding mode control for accommodating large actuator fault and maintaining system stability. Boundary layer is employed to smooth control discontinuity and eliminate control chattering. However, if the thickness of boundary layer is chosen too big, the tracking accuracy will be degraded. Whereas, if the boundary layer thickness is too small, control chattering will be stimulated and system stability will also be affected. With this consideration, a fuzzy logic based boundary layer is designed together with the proposed adaptive control scheme to maintain system stability. The on-line adaptive control scheme can seamlessly change control gains to make a compensation in the presence of actuator fault. When there is a trend to overestimate the control gain, the fuzzy boundary layer will be triggered to enlarge boundary layer thickness to ensure system stability. In such a way, larger actuator fault can be accommodated within the proposed control scheme. The effectiveness of the proposed control strategy is validated through a simulation based on a quadrotor helicopter under two different fault scenarios.