An improved nonlinear model and adaptive fault-tolerant control for a twin rotor helicopter

This paper proposes an improved nonlinear model for a twin rotor helicopter and its robust adaptive strategy with uncertainties and faults. Firstly, a modified dynamic model is developed, in which coupling among axes is fully considered. This model scheme is useful for applications when the accuracy of original model can not be satisfied. Then, to preclude the performance degradation, a robust adaptive fault-tolerant control scheme is designed for the helicopter. Considering multiple faults, an online support vector machine controller is proposed to learn the state error caused by many factors. Since the error contains both dynamic uncertainties and partial disable faults, additional controllers are not required to get rid of the unwanted faults. Stability of the closed-loop system is analyzed with the Lyapunov stability theory. Finally, simulation is presented with multiple faults to verify the effectiveness and feasibility of the improved model and controller.