Adaptive Sliding Mode Controller Design for Fault Tolerant Flight Control System

In this study, a fault tolerant flight control system based on adaptive and sliding mode control scheme is proposed. The merits of adaptive and sliding mode control scheme are that (i) the magnitude of sliding mode controller gain can be reduced and (ii) the fault detection and isolation process is not required. Using the timescale separation principle, the aircraft system can be decomposed into fast inner-loop dynamics and slow outer-loop dynamics. Angular velocity components are used as virtual inputs for the slow dynamics, which are angular variables in the outer-loop control system. The inner-loop controller is designed to make the fast states, that is, angular velocities, follow the outer-loop control input trajectories using the aileron, elevator, and rudder to complete the maneuver. The stability analysis of the proposed control law is performed using Lyapunov theory and LaSalleYoshizawa theorem. To verify the effectiveness of the proposed control scheme, numerical simulation is performed for a high performance six degree of freedom nonlinear aircraft model. Simulation results demonstrate that the closed-loop system has good performance in spite of the actuator fault and the nonlinearity of aircraft system.