Robust Controller Design For Wind Resistance And Mode Switching Of Near Space Vehicle

Near space vehicle(NSV)is a vehicle that works in the near space area,usually has the ability of wide flight envelope and hypersonic flight.The NSV generally has vertical and horizontal launch two ways of takeoff.The wing has a winglet telescopic structure which improves the ability to adapt the flight environment.At the same time,the NSV has the characteristics of strong nonlinearity,intense fast time-varying,strong coupling and serious uncertainty.There also exists the problem of horizontal takeoff wind disturbance and mode switching of winglet telescopic.Therefore,the research on the NSV's horizontal takeoff wind disturbance and mode switching control is challenging.In this paper,the nonlinear model of the NSV is established first,and the horizontal takeoff wind disturbance resistance robust control and robust control of mode switching of winglet telescopic are studied.The main contents of this paper include:Firstly,combining with the domestic and abroad research data of the NSV,considering the complex and changeable flight environment and the characteristics of different modes of flight tasks,the atmospheric environment model and the engine thrust model in different flight modes are established according to the requirements of flight mission and the characteristics of winglet telescopic structure.Finally,the nonlinear model of the NSV is established.Moreover,the aircraft aerodynamic parameters' change of winglet telescopic is analyzed,which lays the foundation for the research of flight control system.Secondly,the NSV is designed with slender fuselage and Blended-Wing-Body technology.It has low lift coefficient at low speed and the problem of horizontal takeoff wind disturbance.Considering the sliding mode control method with the advantages in dealing with the uncertainty and good robustness,a sliding mode robust controller for equivalent model based on feedback linearization is designed.This paper theoretically proves the stability of sliding mode control,and simulation results show that the sliding mode controller is effective and has good robustness for the horizontal takeoff wind disturbance.Thirdly,to solve the problems of the uncertain parameters in the NSV's mode switching process and the disturbance in the controller switching process,a robust switching controller is designed to realize smooth switching between different mode controllers.Considering the robustness of sliding mode control and the universal approximation capability of fuzzy systems,a kind of fuzzy sliding mode control method based on fast double exponential reaching law is presented.The simulation results show that this method has a good control effect and robustness in the process of winglet telescopic controller switching.Finally,the influence of the aerodynamic parameters' change on the flight control system that arise from the winglet change during the winglet telescopic mode switching process is analyzed.Aiming at the NSV's winglet telescopic mode switching process,the neural network is trained to adaptively adjust the parameters of reach law of sliding mode control.Adaptive sliding mode controller is designed for telescopic winglet to realize the smooth switching between different modes.The simulation results show that this method has a good control effect and robustness.The research results of this paper provide an advanced design idea and an effective design method for the design of the flight control system of the NSV,especially the mode switching control.