Adaptive Control of an Aeroelastic Airbreathing Hypersonic Cruise Vehicle

Abstract

This paper describes an adaptive linear quadratic (ALQ) altitude and velocity tracking control algorithm for the longitudinal model of a generic airbreathing hypersonic flight vehicle. The vehicle design is inspired by a set of mission requirements broadly accepted for a hypersonic cruise vehicle intended for both space access and military applications. The vehicle, CSULA-GHV, has an integrated airframe-propulsion system configuration and resembles an actual test vehicle. The complete aerodynamic and scramjet engine data, including the coupling between the two, have been developed by both flow theoretic models and by using an integrated aero-propulsion CFD model in FLUENT. A set of nonlinear longitudinal equations of motion for the vehicle which include both an inverse-square-law gravitational model and the centripetal acceleration, as well as the CFD-generated aerodynamic, propulsion, and coupled aeropropulsion data are developed and used for control design. The certainty equivalence principle is used to combine the adaptive law with the control structure of the standard linear quadratic (LQ) regulator. For comparison, the traditional LQ and ALQ control laws are applied to a high fidelity model that includes unmodeled dynamics (structural modes) as well as actuator dynamics. Simulation results demonstrate the eectiveness of ALQ control over traditional LQ control in tracking altitude and velocity commands in the presence of aerodynamic changes and actuator failures.