Adaptive higher order super-twisting control algorithm for a flexible air-breathing hypersonic vehicle

A novel adaptive higher order super-twisting control algorithm (AHOSTC) is proposed for a flexible air-breathing hypersonic vehicle (FAHV). Firstly, the nonlinear control-oriented model (COM) is processed using input/output feedback linearization method. Therefore, significant flexible effects aroused by slender fuselage and strong coupling between propulsion and aerodynamic of FAHV could be considered during the application of model-based control techniques. Secondly, an adaptive control gain L is incorporated into normal higher order super-twisting algorithm (HOSTA) via dilation rescaling to improve speed of response and attenuate chattering, in the meanwhile, the matched disturbances can be compensated and the finite-time convergence can be achieved. In addition, gain L could be adjusted by the presented novel adaptive law automatically, especially when Lipschitz constants of disturbances are unknown and time-varying. Furthermore, the stability of adaptive law is analyzed via Lyapnuov criteria. Ultimately, compared with normal HOSTA, the proposed AHOSTC is able to enhance robustness and respond speed, while minimizing effects of chattering efficiently. Simulations on longitudinal model of FAHV are carried out to compare AHOSTC with normal HOSTA. The results demonstrate the superiority and effectiveness of AHOSTC under different simulation conditions, external disturbances and parametric uncertainties.