Guaranteeing prescribed output tracking performance for air-breathing hypersonic vehicles via non-affine back-stepping control design

This study develops a novel back-stepping controller with prescribed performance for air-breathing hypersonic vehicles (AHVs) utilizing non-affine models. For the velocity dynamics, a non-affine control law is addressed to achieve prescribed tracking performance. The altitude subsystem is rewritten as a strict feedback formulation to facilitate the back-stepping control system design via a model transformation approach. At each step of back-stepping design, performance functions are constructed to force tracking errors to fall within prescribed boundaries, based on which desired transient performance and steady-state performance are guaranteed for both velocity and altitude control subsystems. Furthermore, the exploited controllers are accurate model independent, which guarantees control laws with satisfactory robustness against unknown uncertainties. Meanwhile, the proposed control scheme can cope with unknown control gains. By the Lyapunov stability theory, the stability of the closed-loop control system is confirmed. Finally, numerical simulations are given for an AHV to validate the effectiveness of the proposed control approach.