Switching Control Research Of Hypersonic Vehicle Based On LPV Model

Hypersonic vehicle is a vehicle that works in the near space area,usually has the ability of large flight envelope and hypersonic flight.The wing of some vehicles have a winglet telescopic structure,improve the ability to adapt the environment of flight.At the same time,the hyersonic vehicle has the characteristics of strong nonlinearity,intense fast time-varying,strong coupling and serious uncertainty.There also exists the problem of climb/cruise switching and mode switching of winglet telescopic.Therefore,the research on the modeling and mode switching control of hyersonic vehicle is challenging.This thesis focuses on the study of establishment of the linear parameter varying(LPV)model,design of switching controller based on LPV model and application of Switching Control in mode switching of winglet telescopic.Specific research contents are as follows:Firstly,the nonlinear mathematical model of the hypersonic vehicle has been built according to the domestic and abroad research data of hypersonic vehicle and the characteristics of variable winglets.In addition,considering the advantages of LPV model in dealing with non-linear model and the convenience of designing controller,the traditional LPV modeling methods are compared,and the LPV model of hypersonic vehicle is established.The accuracy of the modeling is verified by open-loop simulation,which lays a solid foundation for the research of flight control and switching control of aircraft.Secondly,due to the strong non-linearity and large envelope flight characteristics of hypersonic vehicle,the traditional LPV modeling method can not guarantee the accuracy of modeling and the computational complexity of the model at the same time,and the selection of the number of equilibrium points depends on the empirical selection method,which does not form a complete set of equilibrium point selection methods.Therefore,the gap measurement theory is introduced into the LPV modeling process,and an innovative polytopic LPV modeling method based on the number of optimal equilibrium points is proposed.At the same time,considering the accuracy of modeling and computational complexity,the optimization model of the optimal number of equilibrium points is established,the optimal number of equilibrium points is obtained,the selection algorithm of equilibrium points is further designed,and finally the polytopic LPV model is established.The open-loop simulation results show that the polytopic LPV model can better approximate the original non-linear model.Thirdly,considering the sudden change of flight state during mode switching,it is very easy to cause the instability of aircraft.Therefore,aiming at the switching process of climbing/cruising mode of hypersonic vehicle,the control effect of direct switching is analyzed,and the necessity of designing switching control law is explained.Considering the advantages of LPV model in modeling,a switched multi-cell LPV model is established firstly.Considering the effectiveness of non-fragile robust control in dealing with such problems as controller parameter perturbation,a non-fragile robust controller is designed for each sub-model.Considering the smooth switching between sub-models,a non-fragile robust LPV switching control based on smooth switching characteristic function is designed.The advantages and disadvantages of the control algorithm and direct switching control are analyzed by numerical simulation.Finally,based on the particularity of hypersonic vehicle,the influences of retracted winglets on flight control are studied in order to lay foundation for the control system of different winglet conditions.The switching LPV model of the wing is established.And the non-fragile robust LPV switching control method based on smooth switching characteristic function is applied to the switching process of the wing,aiming at the instantaneous jump of the aircraft state during the switching process from the retracted mode to the extended mode.Finally,the numerical simulation shows that the switching control method has good control effect and robustness for the small wing expansion mode switching.To sum up,this thesis researches the LPV modeling and switching control of hypersonic vehicle.A new LPV modeling method is proposed.Based on the LPV model,an improved switching control algorithm is proposed to ensure the smoothness and stability of the mode switching process.And the method is applied to the winglet expansion process.