Robust model reference sliding mode control for flexible air-breathing hypersonic vehicle

This paper is concerned with the robust model reference sliding mode control (MRSMC) design problem for flexible air-breathing hypersonic vehicle (FAHV). This problem is challenging because of the inherent couplings between the propulsion system, the airframe dynamics and the existence of strong flexibility effects. A reference model, which can provide ideal dynamics, is designed for FAHV with parameter uncertainties and external disturbance, and the parameter uncertainties and external disturbance are not necessary to satisfy the so-called matched condition. A tracking error model is first proposed with respect to the reference model. An integral sliding surface is designed, and then a sufficient condition is derived to guarantee the global robust stability of the sliding dynamics on the specified surface in the presence of unmatched uncertainties and disturbance. The reachability of the specified sliding surface is guaranteed by the designed control law. Finally, simulations on the nonlinear dynamics of FAHV are given to show the effectiveness of the proposed control methods.