LESO-Based Dynamic Surface Control for a Hypersonic Flight Vehicle

A linear estended state observer (LESO)-based dynamic surface controller is proposed in this paper for the cruising control problem of a hypersonic flight vehicle (HFV) with model parametric uncertainties and external disturbances. First of all, the longitudinal model of the HFV is denoted, and the decoupling of the altitude and velocity is realized via the nonlinear dynamic inversion (NDI) technique. Then, combining with the conventional back-stepping technique, a tracking differentiator based on the inverse hyperbolic sine function (IHSTD) is adopted to attain the derivatives of the virtual control laws, which avoids the problem of “differentiation explosion”. And then a LESO is designed for the precise estimation and compensation of the “lumped disturbance” containing parametric uncertainties and external disturbances, which tremendously improves the ability of the disturbance rejection of the system. Finally, the stability of the proposed approach is analyzed by means of the Lyapunov stability theory. The exploited approach guarantees the asymptotic stability and robustness of the system, and the simulation results demonstrate the validity of the proposed method.