Robust Control of Air-Breathing Hypersonic Vehicles With Adaptive Projection-Based Parameter Estimation

A robust controller with an adaptive projection-based parameter estimator is presented for the air-breathing hypersonic vehicles. First, a novel parameter-varying model is established wherein the number of variable parameters is significantly reduced. In this way, the problem of overparameterization is avoided, and the controller design procedure is simplified. Then, the framework of the controller is established based on the backstepping approach, in which a second-order filter is introduced to solve the problem of “explosion of terms”. In order to enhance the robustness of the controller, an adaptive parameter estimator is designed. The Lipschitz continuous dead-zone modification is used to solve the problem of parameter draft in the conventional adaptive control and a sufficiently smooth projection operator is introduced to guarantee the uniform boundedness of adaptive parameters. The simulation results show that the proposed robust controller achieves the stable tracking of the reference commands under the parameter perturbation, and the variable parameters are limited within the preset range.