Disturbance observer based backstepping control for a hypersonic vehicle

Considering the longitudinal nonlinear model of a hypersonic vehicle including uncertain disturbances, a nonlinear controller based on backstepping method and dynamic inversion method is proposed for solving the tracking control problem. In order to facilitate the control design, the flight vehicle model is decomposed as velocity subsystem and flight path angle subsystem. The command filter is utilized to avoid the problem of “explosion of complexity” which occurs in backstepping method. In order to suppress the disturbances, a novel disturbance observer is proposed for estimating them during the tracking process. A Lyapunov-based stability analysis indicates that the tracking errors are uniformly bounded. Finally, the simulation results demonstrate that the proposed method can achieve superior tracking of velocity and flight path angle references in the presence of uncertainty of the general and aerodynamic parameters.