Anti-disturbance control of hypersonic flight vehicles with input saturation using disturbance observer

This paper proposes an anti-disturbance control scheme for the near space vehicle (NSV) based onterminal sliding mode (TSM) technique and disturbance observer method. To tackle the system uncertainty andthe time-varying unknown external disturbance of the NSV, a disturbance observer based on TSM technique isdesigned which can render the disturbance estimate error convergent in finite time. Furthermore, an auxiliarydesign system is introduced to analyze the input saturation effect. Based on the developed disturbance observerand the auxiliary design system, an anti-disturbance attitude control scheme is developed for the NSV usingthe TSM technique to speed up the convergence of all signals in closed-loop system. For the closed-loop system,the stability is rigorously proved by using the Lyapunov method and we guarantee the finite time convergenceof all closed-loop system signals in the presence of the integrated affection of the system uncertainty, the inputsaturation, and the unknown external disturbance. Simulation study results are given to show the effectivenessof the developed TSM anti-disturbance attitude control scheme using the disturbance observer and the auxiliarysystem for the NSV.