Robust nonlinear control design with PI observer for an air-breathing hypersonic vehicle

This paper proposes a robust nonlinear control strategy for a model of an air-breathing hypersonic vehicle. The control objective is to provide robust velocity and altitude tracking in the presence of unknown parameter uncertainties and elevator couplings. The proposed approach takes the advantages of the dynamic inversion method to get a transformed description of the system and then a PI observer is introduced to reconfigure the transformed states together with the transformed unknown effects resulted from the modeling errors. Using the reconfigured transformed state for state feedback controller design and using the estimated unknown effects as a disturbance rejection, the whole control loop with the proposed control design is proved to be stable and robust. Simulations results demonstrate that the proposed control design achieves excellent tracking performance despite the presence of model uncertainties and nonlinearities.