Barrier Lyapunov function-based adaptive control for hypersonic flight vehicles

Abstract

This paper presents an adaptive control strategy for hypersonic flight vehicles (HFVs) subject to parametric uncertainties, external disturbances and faulty actuators. Besides the guaranteed tracking performance, the main novelty of this study is to strictly constrain the flight states, which are crucial to hypersonic flights, such as the bounded angle of attack required by the scramjet. To achieve this, the disturbed control-oriented model of HFVs with uncertain parameters and faulty actuators is first rewritten into a parameterized form, based on which novel adaptive controllers are then designed for velocity and altitude subsystems. By introducing barrier Lyapunov functions to design procedures, specific tracking performances of velocity and altitude are guaranteed, while the other flight states of angle of attack, flight path angle, pitch angle and pitch angle rate can be kept within the prescribed ranges. Command filters are employed in the back-stepping design for altitude subsystem to limit the magnitudes of virtual controls and to avoid the complicated analytical calculations. In addition, an adaptive inverse is integrated into the adaptive control scheme to sufficiently compensate for the unknown dead-zone nonlinearity in elevator. It is shown that the developed control system regulates the tracking errors within some neighborhoods of zero, which become sufficiently small by proper adjustments on design parameters. Finally, the numerical simulation is provided for comparison and verification purposes.