Robust adaptive approximate backstepping control of a flexible air-breathing hypersonic vehicle with input constraint and uncertainty

This article shows the controller design problem of a flexible air-breathing hypersonic vehicle in the presence of input constraint and aerodynamic uncertainty. A control-oriented model, derived from curve-fitted model, is reasonably decomposed into subsystems that include velocity subsystem, altitude and flight path angle subsystem and angle of attack and pitch rate subsystem. Then, dynamic inversion and robust adaptive control are integrated with approximate backstepping control philosophy to design the control scheme, in which the upper bounds of uncertainties are not to be known in advance and estimated by adaptive law. To tackle input constraints, auxiliary systems are constructed and the states of them are used for controller design and stability analysis. Moreover, a detailed stability analysis of the resulting rigid body system is carried out within the framework of Lyapunov theory. Finally, simulation results illustrate the property of the designed control strategy in handling input constraint and aerodynamic uncertainty.