Study On Switching Control Of Vehicle Hybrid Electromagnetic Active Suspension Based On LQR Control

In recent years,people rely more and more on the car as a means of travel,so the requirements for its comfort and safety are higher and higher.Because the damping stiffness of the passive suspension system is not adjustable,it can not adapt to the changing road conditions,and is gradually replaced by semi-active suspension and active suspension.Active suspension replaces the spring force and damping force of passive suspension with the actuating force generated by actuator.Its biggest advantage is that it can provide the desired damping force in real time with the change of vehicle motion state and external excitation.Therefore,it can improve the ride comfort and handling stability of the vehicle better.Among them,the electromagnetic suspension system with superior controllability has been widely studied by scholars.The current research on the electromagnetic active suspension focuses on vertical dynamics control,neglecting the change of vehicle body attitude under the condition of acceleration or high speed steering,which leads to the deterioration of vehicle dynamics performance.To solve the above problems,this paper designs a vehicle hybrid electromagnetic active suspension switching control strategy based on LQR control.According to the vehicle performance requirements under different driving conditions,the active suspension control objectives are divided,and the control parameters under different driving conditions are optimized by IAHP.The main contents of this paper are as follows:Firstly,the vehicle dynamics model is established.The differential equation of the whole vehicle is deduced according to Newton’s second law,and the dynamic model of seven degrees of freedom of the whole vehicle is established.At the same time,the excitation model of four wheel random pavement and long slope convex block pavement is built based on the wheelbase characteristics,which lays the foundation for the subsequent controller design and dynamic performance simulation analysis.Secondly,the paper designs the switching control method of hybrid electromagnetic active suspension system based on LQR control.According to the internal and external loop architecture control theory,the hybrid electromagnetic active suspension switching control method is designed.The control mode of the outer ring is divided according to different working conditions and performance requirements.The weight coefficient in performance index is determined by the analytic hierarchy process,and the control parameters of different working conditions are optimized;vector variable is used The mathematical model of PMSM is established and the current replacement control algorithm of inner ring linear motor is designed.Finally,the effectiveness of switching control algorithm is verified.The paper analyzes the control effect of switching control strategy in the condition of uniform linear motion,deceleration belt,emergency braking,single convex block road and fishhook by using the joint simulation of casim and matlab/simulink.The hardware in loop test platform is built.The effectiveness and feasibility of the control system are verified by comparing with the test results.The simulation results show that the switching control method of hybrid electromagnetic active suspension system based on LQR control has a great improvement effect on the ride comfort and stability of the vehicle in the emergency and non emergency conditions.Compared with passive suspension,the vertical acceleration of vehicle body with hybrid electromagnetic active suspension is reduced by 13.56%,pitching angle acceleration is reduced by 16.26%,the acceleration of inclination angle is reduced by 17.39%,pitch angle is improved by 11.40%,and the inclination angle is improved by 9.37%;the maximum dynamic travel value of suspension and dynamic load of tire are slightly deteriorated,but in a reasonable range;in emergency control Under the dynamic condition,the peak value of vertical acceleration,vertical displacement,pitch angle acceleration and pitch angle of the body are optimized by 15.78%,12.53%,8.27% and 7.35%,respectively.Under the fishhook condition,the peak value of body vertical displacement and inclination angle are improved,and the overshoot of the side inclination is also reduced.The simulation results show that the proposed switching control strategy is effective,and the hardware in loop test results are basically consistent with the simulation results.The correctness of the hardware in loop test strategy and the feasibility of the switching control strategy are verified.