Control of a flexible air-breathing hypersonic vehicle based on adaptive mode suppression scheme

This paper presents an integral sliding mode controller combined with adaptive mode suppression scheme that is simulated on a longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV) to force the velocity and altitude to tack desired reference commands. Firstly, in order to over parametric uncertainties in flight, an integral sliding mode controller is designed for the rigid body of the FAHV. In addition, the aeroservoelastic effects caused by flexible modes may degrade the FAHV tacking performance or even bring about instabilities, and the frequency and damping ratio of the flexible modes can be uncertain and also vary during flight due to atmospheric heating. Then, a frequency estimator incorporates an adaptive notch filter are designed to accurately track and suppress an unknown or changing flexible mode online. Finally, simulations are presented to illustrate the effectiveness of the control strategies.