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Abstract-This paper describes the design of a nonlinear robust/adaptive controller for an air-breathing hypersonic vehicle model. Due to its complexity, a high fidelity model of the vehicle dynamics derived from first principles is used only in simulations, while a simplified model is adopted for control design. This control-oriented model retains most of the features of the high fidelity model, including non-minimum phase characteristic of the flight-path angle dynamics and strong couplings between the engine and flight dynamics, whereas flexibility effects are regarded as a dynamic perturbation. A nonlinear sequential loop-closure approach is adopted to design a dynamic state-feedback controller that provides stable tracking of velocity and altitude reference trajectories and allows to impose a desired trim value for the angle of attack. Simulation results show that the proposed methodology achieves excellent tracking performances in spite of parameter uncertainties.

Abstract-This paper presents the design of an adaptive flight control systems for constrained air-breathing hypersonic vehicle models. The proposed architecture comprises a robust adaptive nonlinear inner-loop controller, and a self-optimizing guidance scheme that shapes the reference to be tracked in order to avoid the occurrence of control input saturations. The scheme is explicitly designed to account for the presence of a state-dependent input saturation on the control loop for the vehicle longitudinal velocity, arising from physical limitations in the propulsion system. The approach is based on the integration of a previously-developed adaptive controller with a self-tuning pre-filter which shapes the reference command to maintain the control signal within feasible values. The reference command are left unaltered whenever there is sufficient control authority for stable tracking. Simulation results are provided to show the effectiveness of the method.