Research On Control Problem Of Hypersonic Vehicle With Uncertainties

Hypersonic aircraft with high flying speed,large flight envelope characteristics,is attracting more and more attention in the field of aerospace technology.Because the hypersonic vehicle has many uncertainties factors,such as complicated flight environment,strong coupling effect between the engine and airframe,and incomplete experimental data.Therefore,we should take full account of the impact of the uncertainties in control design process,and ensure that the controller has sufficient adaptability and robustness.In view of the above problems,this paper discusses the influence of parameter perturbations on the characteristics of hypersonic vehicle,the modelling of hypersonic vehicle with uncertain parameters,the flight controller design in case of parameter perturbation and external disturbance.The main research contents and achievements are as follows:First of all,based on the hypersonic vehicle model data published abroad,a hypersonic vehicle dynamics model is established.The aerodynamic model,engine model and atmospheric environment model are analyzed thoroughly.The longitudinal nonlinear dynamic model of the hypersonic vehicle is obtained,and open-loop characteristics of the aircraft are analyzed,which provides the foundation for the following research.Secondly,the influence of parameter perturbation on the root characteristics of open-loop hypersonic vehicles is analyzed.The effects of single parameter perturbation and multiple parameter perturbations on the aircraft characteristics are analyzed respectively.Uncertainty modeling of hypersonic vehicle with uncertain parameters was carried out,and the uncertain parameter model was obtained,and uncertain boundary caused by parameter perturbation is analyzed in this model.Then,based on the established uncertain model,an adaptive sliding mode control method is designed through combining sliding mode differentiator,adaptive parameter estimation and sliding mode control.This method can theoretically guarantee the stability of the aircraft,in the case of the parameter perturbation.Simulation results show that the proposed method has better control performance than ordinary integral sliding mode control method.Finally,a robust adaptive sliding mode controller and a robust adaptive Backstepping controller are designed in the presence of composite uncertainties of parameter perturbations and external disturbances in aircraft model.The parameter projection operator is adopted in the robust adaptive sliding mode control method to ensure the boundedness of parameter adaptation,which helps to avoid the controller singularity problem.The adaptive robust compensation term is also adopted to suppress the unknown interference in control system.In the robust adaptive Backstepping control method,based on certain assumptions,separate control of speed and altitude is realized.According to estimation feedback of the upper bound of uncertainty,adaptive compensation to uncertainties is realized and the anti-interference ability of the controller is enhanced.At the same time,the upper bound of the derivative of virtual control instruction is adaptive estimated,which avoids the inherent problem of differential calculus explosion in Backstepping control.Simulation results show the effectiveness of the proposed control method.