Adaptive fuzzy high-order sliding mode control for flexible air-breathing hypersonic vehicle

This paper proposes a multi-input multi-output (MIMO) adaptive fuzzy high-order sliding mode controller (FHOSMC) for the flexible air-breathing hypersonic vehicle (FAHV) longitudinal model. In order to suppress big uncertainties coming from flexible modes and make the system stably controlled, we design high-order sliding mode (HOSM) controller as the main controller to achieve system convergence in limit time, and adopt the fuzzy logic system (FLS) to generate adaptive parameters to adjust the control coefficients of HOSM controller online. In addition, tracking differentiator (TD) and nonlinear state observer (NSO) are designed to generate the high-order approximate commands and real-time derivatives of velocity and altitude respectively. The simulation results validate the effectiveness and robustness of the proposed controller.