Adaptive backstepping control for air-breathing hypersonic vehicle with actuator dynamics

This paper investigates the flight longitudinal control problem of a hypersonic vehicle subject to input constraints and aerodynamic uncertainties. A modified control-oriented model is first derived with explicit consideration of the actuator dynamics property. Then, based on the novel dynamics model developed, adaptive backstepping controller and dynamic inverse controller are designed for the altitude subsystem and the velocity subsystem, respectively. To avoid the complexity problem residing in traditional backstepping control caused by the repeated derivations of the virtual control variables, the dynamic surface control technique is involved in conjunction with the backstepping control approach, and a novel second-order sliding-mode-based integral filter instead of the conventional first-order filter is employed. Additionally, in order to deal with actuator magnitude constraints, two auxiliary systems are constructed to generate certain compensating signals to guarantee tracking errors suitable for adaptive parameter estimation. It is proved that the proposed control scheme can guarantee that the tracking errors converge to an arbitrarily small neighborhood around zero in the presence of actuator constraints and aerodynamic uncertainties as well. Finally, numerical simulations are presented to demonstrate the effectiveness of the proposed control scheme.