Combined Reference Governor and Anti-Windup Design for Constrained Hypersonic Vehicles Models

Abstract

Control of hypersonic vehicles is complicated by the presence of physical limitations on the inputs of the system, which limit the range of feasible reference trajectories that can be tracked without violating the constraints. Constraints on the fuel equivalence ratio arise as a result of thermal choking of the engine when the acceleration demand is too aggressive, whereas control surface deections have obvious physical constraints in place. The upper limit of the equivalence ratio is state-dependent and must be implemented as dynamic saturation, which necessitates anti-windup schemes to be included in the controller. In this paper, anti-windup strategies are proposed in combination with a reference governor that selects the reference inputs in order to avoid frequent occurrence of input saturation. The new controller is designed to be augmented to an existing adaptive controller which has been designed to provide adequate tracking of reference signals for an unconstrained model.