Event-triggered attitude control for hypersonic morphing vehicles using fixed-time control technique

This research discusses the attitude tracking issue for hypersonic morphing vehicles (HMVs) subject to multisource uncertainty and limited system resources. Hypersonic vehicles with variable-span wings can change the aerodynamic configuration according to various requirement segments. However, A morphing process will cause significant changes in aerodynamic coefficients, mass distribution, and inertial characteristics. Moreover, the additional forces and moments exist in the HMV model, impacting the attitude control. Therefore, a robust and fast flight control system is necessary for HMVs to stabilize the attitude angles in the presence of multisource uncertainty, which always consists of modeling inaccuracies, external disturbances, and coefficient perturbances. Considering such factors, the fixed-time control theory is employed to develop the flight control system with strong robustness and adaptation. Compared to the existing fixed-time control strategies with complex expressions to indicate the convergence time, the setting time of the proposed controller is more explicit and can be exactly preassigned in the design procedure. Fast attitude tracking can be achieved and accurately evaluated with the help of the proposed technique. Furthermore, to avoid excessive occupation of limited aircraft resources, a novel switched dynamic event-triggered technique is constructed, leading to a desired level of control performance with low resource consumption. The proposed event-triggering mechanism will strike a better balance between tracking accuracy and resource occupation than the commonly used triggered control methods, such as the fixed-threshold and relative-threshold event-triggering strategy. Finally, the event-triggered fixed-time controller provides an outstanding tracking performance, with the Zeno behavior avoided. The stability of the closed-loop system is proved by introducing the Lyapunov theory. Simulation results and comparisons validate the effectiveness and advantages of the developed control scheme.