Fuzzy disturbance observer-based dynamic sliding mode control for hypersonic morphing vehicles

Abstract

This research discusses the attitude-tracking problem of hypersonic morphing vehicles (HMVs) in the presence of multi-source uncertainties. The hypersonic flight vehicle with variable-span wings is introduced. Considering the dramatic aerodynamic characteristic changes caused by morphing-span wings, strong robustness and great adaption are demanded. The sliding mode control technique is adopted to build the flight control system since the robustness is what the aircraft orders. In order to obtain fast attitude-tracking performance, the terminal function and adaptive laws are developed to achieve finite-time control with high adaptation to varying aerodynamic characteristics. For a hypersonic flight with guts, robustness enhancement is required. Therefore, a novel fixed-time disturbance observer is proposed to enhance the robustness against multi-source uncertainties. Unlike the existing finite-time observers, the settling time is independent of the initial conditions. Based on the disturbance observer and the adaptive technique, finite-time flight control is developed to provide strong robustness and adaptation, achieving uncertainty compensation. The effectiveness of the designed controller is revealed with the help of Lyapunov synthesis. Several flight scenarios are introduced to analyze the performance.