Asymptotic tracking control for hypersonic flight vehicles using exact disturbance observers

In this paper, the asymptotic tracking control problem of hypersonic flight vehicles (HFVs) is investigated by using exact disturbance observers (EDOs). In most of disturbance observer (DO) based approaches for the control of HFVs, it usually requires that the uncertainties and their time derivatives have a priori constant upper bound, and only obtains a bounded tracking result rather than an asymptotic one. However, assuming the state-related uncertainties have constant priori upper bound might be very restrictive before the system stability is proved. To remove such restrictive assumption and achieve exact disturbance estimation, a novel EDO design methodology is proposed. And based on the EDO, an asymptotic control scheme is developed to achieve exact tracking of the HFV system. The stability of the closed-loop system under the EDO-based control scheme is proved via Lyapunov theory, and the effectiveness is numerically validated.