A state and input constrained control method for air-breathing hypersonic vehicles

Besides nonlinearity, high coupling and parameter uncertainties, the design of a hypersonic flight control system still faces challenges due to the unstable dynamics under various flight conditions and to the presence of state constraints required by a scramjet. This paper presents a state and input constrained control method for the longitudinal motion of an air-breathing hypersonic vehicle through combining tensor product (TP) model transformation and the command governor approach. This method consists of three steps. Firstly, the paper applies the tensor product (TP) model transformation, making the state space matrices depend on the vector θ of time varying parameters. Secondly, it uses LQ (Linear Quadratic) method to design a set of controllers in the vertex of the TP model, and then, the controllers are checked with the parallel distributed compensation (PDC) controller design framework to ensure global stability and improving control performance. Thirdly, it introduces a command governor (CG) device for command optimization, which modifies the command signal to avoid state and input violations. The significance of this method mainly lies in its capability to avoid excessive flight constraints under various flight conditions. In order to demonstrate the effectiveness of this method, we carried out numerical simulations of the air-breathing hypersonic vehicle in its climbing phase which has state constraints and actuator constraints.