Predefined-time fault-tolerant control of a fixed-wing aircraft with asymmetric damage

In this paper, a practical predefined-time backstepping fault-tolerant attitude controller is proposed for fixed-wing aircraft with asymmetric damage, multiple actuator faults, model uncertainty, and angular acceleration disturbances. First, a detailed analysis is performed to investigate the impact of 40 % right-wing loss on aerodynamic data and structural parameters. Subsequently, a comprehensive nonlinear aircraft model incorporating asymmetric damage and actuator faults is established. Second, an improved predefined-time stability criterion is introduced to develop a practical predefined-time fault-tolerant control architecture. The control architecture is composed of a predefined-time backstepping attitude angle controller, a predefined-time incremental backstepping angular rate controller, a predefined-time filter and a predefined-time nonlinear disturbance observer. Specifically, the attitude angle controller and angular rate controller ensure that the attitude angle and angular rate can track the desired commands within a user-defined time after wing damage and actuator failures. The predefined-time filter is employed to avoid “explosion of complexity” in the backstepping controller design. The disturbance observer is used to estimate the lumped disturbances and provides them to the angular rate controller for compensation, thereby further enhancing the robustness of the controller. Strict Lyapunov stability analysis demonstrates that the closed-loop control system is practically predefined-time stable, with the stabilization time independent of the initial states. Finally, numerical simulations verify the effectiveness and superiority of the proposed method.