An Adaptive LPV Integral Sliding Mode FTC of Dissimilar Redundant Actuation System for Civil Aircraft

This paper addresses three major issues in dissimilar redundant actuation system when operates in active/active mode. The first one is to reduce the effect of force fighting. The second one is to obtain precise tracking performance of the control surface. The third one is to induce fault tolerance in the presence of faults in hydraulic actuator. The proposed strategy is to design LPV integral sliding mode controller for each actuator in a dissimilar actuation system. The nonlinear dynamics of each actuator is first transformed into LPV form and employed tensor product model transformation to convert into polytopic LPV form. The integral sliding mode FTC is designed based on the LPV model of actuators. To induce the fault tolerance, the nonlinear injection term of proposed integral sliding mode control law is made adaptive subject to the severity of the fault. In order to verify the robustness of the proposed scheme, an external disturbance acting as an airload is applied at the control surface input. Finally, the proposed strategy is applied on the nonlinear model of system to validate the dominant performance as compared to existing methods in the literature. In the simulations, three types of faults in hydraulic actuator are considered and the performance of closed loop system is analyzed.