Sensor faults tolerance control for a novel multi-rotor aircraft based on sliding mode control

This paper deals with the controllers design using a novel siding mode control and proportional-derivative control for the trajectory tracking problem of a new multi-rotor aircraft, which experiences angular velocity sensor faults and external disturbances. The control system is divided into two parts: the inner loop for attitude subsystem and outer loop for position subsystem. For the inner loop, the angular velocity sensor faults, including bias, drift, loss of accuracy, and loss of effectiveness are considered as equivalent mismatched disturbances, while the system internal coupling, nonlinearity, and external disturbances are considered as equivalent matched disturbances. A novel sliding mode control approach is proposed for inner loop controller design, which includes a nonlinear disturbance observer to estimate both mismatched and matched disturbances, a novel switching surface based on the estimation of the mismatched disturbance to counteract its impact, a double power reaching law to attenuate the chattering problem, and a compensation for the matched disturbance to reduce the controller gains. The sensor faults are handled without fault detection and controller reconfiguration, making the method require less computation and easy implementation. The proposed method enhances the robustness without sacrificing the nominal properties. For outer loop, the proportional-derivative approach is used to design the virtual controller. The closed-loop system stability is proved by the Lyapunov theory. Finally, various simulation experiments are shown to validate the effectiveness, robustness, and the superiority of the proposed flight control scheme.