Fixed-Time Dynamic Surface Control for Hypersonic Morphing Vehicle with Uncertainties Based on Fixed-Time Disturbance Observers

We investigate the attitude control problem for hypersonic morphing vehicles with uncertainties. Firstly, the fixed-time dynamic surface control (FDSC) is applied to improve the tracking performance in morphing phase. Subsequently, to enhance the robustness of FDSC, a fixed-time disturbance observer (FDO) is used to estimate the uncertainties resulted from external disturbances and unmodelled dynamics. The semiglobal fixed-time stability of the attitude control system is proved via Lyapunov approach. Finally, some simulations are carried out to demonstrate the feasibility of the proposed control method.