Study On Dynamics Modeling And Control Of Supersonic Vehicle Considering Actuator Nonlinear Factors

With the change of modern war environment,there is an urgent demand for new types of aircraft such as missiles and drones to possess characteristics of high speed,high precision,high maneuverability and so on.As the core of aircraft stability and maneuverability,the attitude control system is a prerequisite for completing complex tasks.The performance of the actuator has a crucial effect on the attitude control of the aircraft.Due to the advantages of simple structure,convenient maintenance,single energy source,low cost,and light weight,electromechanical actuator(EMA)have been widely used in aircraft.However,nonlinear factors such as dead zone,friction,and backlash are widely present in EMA systems,which pose challenges to the dynamic response of EMA and aircraft attitude control.In addition,atmospheric disturbances also pose challenges to attitude control and flight safety.Therefore,this thesis focuses on improving the accuracy of aircraft attitude control under nonlinear factors of EMA by studying a supersonic missile and its EMA.Relevant research works are carried out through EMA modeling,nonlinear factors compensation,and aircraft attitude control considering nonlinear factors of EMAs,elastic vibration wind disturbance,etc.The main contents are as follows:1)Considering the parameters of EMA components,the EMA is regarded as an electromechanical system with two-stage reduction device.Based on the theory of electricity and the principle of Newton mechanics,the dynamics model of the electromechanical system of EMA is established.Frequency domain method is used to analyze the influence of the stiffness and inertia parameters of the EMA on the dynamics model.According to the analysis,the model is simplified into double-inertia model and rigid one,and the effectiveness of the model simplification is verified.2)By using the method of description function and numerical analysis,the influence of nonlinear factors on the EMA system is investigated.For dead-zone,an active disturbance rejection controller is designed which can treat the dead zone nonlinearity and other unmodeled dynamics as disturbances and compensate them in real time.The stability of the system is proved and verified.For friction,a continuously differential error feedback function was introduced to enhance the extended state observer,and a compound sliding mode control strategy based on the modified extended state observer was proposed,which achieved high precision position tracking and suppressed control chattering.A continuous nonlinear function is used to replace the nonlinear backlash model,and a new backlash backstepping compensation strategy based on modified tracking differentiator is proposed.This strategy improves the dynamic performance of the EMA and solves the differential explosion problem of the inversion method.3)The aircraft model under wind disturbance was modeled and simplified by Newton mechanics principle.The influence of dead zone nonlinearity of EMA on attitude control of the rigid aircraft model under the traditional controller is analyzed.In order to study the attitude control problem of rigid vehicle with dead zone,friction in the EMA,based on the principle of time scale separation,active disturbance rejection control strategy is proposed for both the EMA loop and the attitude loop,and the effectiveness and robustness of the control strategy under gust disturbance is verified by simulation.4)Based on Euler-Bernoulli beam theory and assumption mode method,the dynamic rigid-elastic coupled model of the aircraft is established.The aerodynamic-servo coupling mechanism and the influence of the backlash nonlinear factor of EMA on the attitude control of elastic aircraft is studied.A composite attitude control strategy,which using the backstepping control with the modified tracking differentiator method to compensate the backlash nonlinearity in inner loop,and the active disturbance rejection control with notch filters to suppress wind disturbance in outer loop is proposed to realize high control performance,effectiveness is verified by simulation.