Prescribed performance sliding mode control for high-speed morphing vehicles based on high-order fully-actuated systems

To address the attitude control problem for High-speed Morphing Vehicles (HMVs) under strong coupling, parameter perturbations, and multi-source disturbances, this paper proposes a prescribed performance Super-Twisting Sliding Mode Control (STSMC) method based on High-Order Fully-Actuated Systems (HOFAS) modeling. Firstly, a high-order attitude dynamics model of the vehicle is established using the HOFAS approach. Through dynamic extension and variable elimination, the unmodeled dynamics induced by aerodynamic/structural coupling are mitigated, and the nonlinear dynamic equations are transformed into the HOFAS form. Through the parametric design for the characteristic polynomial coefficient matrix, the decoupling of state variables and separation of control are achieved. Secondly, to handle the lumped uncertainties arising from time-varying aerodynamic parameters during morphing and external disturbances, while also considering the dynamic response characteristics of the actuators, a super-twisting sliding mode controller based on Prescribed Performance Control (PPC) is designed. By constructing time-varying performance boundary functions, the controller robustly constrains attitude control errors and the asymptotic stability of the system is proven using a Lyapunov function. Finally, the performance of the proposed attitude controller is verified through Model-in-the-Loop (MIL) simulations and Hardware-in-the-Loop (HIL) experiments. The results demonstrate that the proposed method significantly reduces control chattering and validates its real-time performance and engineering practicability on an embedded platform.