Robust Sliding Mode Control Law Design for the Lateral Model of a Helicopter

In this paper, the parameter robust design method and sliding mode control theory are combined to design the helicopter control system in the whole flight envelop with the uncertainties and nonlinearities considered. First based on the flying qualities and the constraint conditions of the measurable states, the partial pole assignment is realized by the parameter robust design method, accordingly the mapping relationship of the parameter space and the corresponding usable set is determined, which provides an effective method to design the equivalent scheduling control law in the whole flight envelop. Second based on the helicopter T -S model within the whole flight envelop, according to the parameter mapping law, the equivalent control law is designed using the parallel distributed compensation algorithm, which ensures the well dynamic performance the control system in the whole flight envelop. Finally the closed-loop system characteristic equation corresponding to the equivalent control law is used to construct the integral sliding surface. The switching is designed so that the system has the robustness against the uncertainties and disturbances. The simulations indicate that the proposed sliding mode control system is robust against the external disturbances, it has the strong disturbance-suppression capability and satisfies the dynamic performance requirements of the helicopter.