Control And Simulation Of Vehicle Active Suspension With MR Damper Under Random Excitation

With the rapid development of global social economy,and the improvement of human living standards,people have higher and higher requirements for the comfort and safety of vehicles.The semi-active suspension system based on magnetorheological damper can improve the ride comfort and handling stability of vehicles.magnetorheological damper is widely used in structural vibration control and vehicle engineering because of its fast response speed and respond in milliseconds according to the magnitude of the current,especially in the field of vehicle semi-active suspension.The traditional passive suspension,though simple in structure,can not meet the vehicle ride comfort and handling stability at the same time.In view of this,this thesis uses Proportional-Integral-Differential(PID)control and fuzzy control theory to simulate and verify the 1/4 vehicle semi-active suspension system based on magnetorheological damper.(1)The desired output controller of magnetorheological damper of 1/4 vehicle semi-active suspension system is designed.According to Newton's second law,the dynamic models of passive and semi-active suspension of 1/4 vehicle with two degrees of freedom are established;according to the principle of road roughness,based on the integral white noise,the random road input model is established and the random road input response curve is obtained;according to PID control and fuzzy control theory,the desired output controller of magnetorheological damper of semi-active suspension system under random excitation is designed,the simulation model is built in Matlab/Simulink to get the desired force of suspension system.(2)The dynamic model of magnetorheological damper of 1/4 vehicle semi-active suspension system is established.According to the characteristics of the mechanical model of the magnetorheological damper,taking the forward model of the modified Bouc-wen magnetorheological damper as the research object,taking the current,relative displacement and speed of damper piston as input variables and the actual damping force as output variable,the Simulink simulation modules of the forward model are constructed,and gives different values of each input variable for simulation verification.The results show that the forward model has obvious nonlinear hysteretic characteristics.Using the characteristics of BP neural network self-learning to deal with nonlinear functions,an inverse model of BP neural network is established,which takes the parameters of the desired force of suspension system,relative displacement and speed of damper piston as input variables and the actual current of magnetorheological damper as output variable,the simulation modules are designed and implemented in Matlab/Simulink,which verifies the inverse model of magnetorheological damper feasibility.(3)The overall simulation of 1/4 vehicle semi-active suspension with magnetorheological damper under random excitation is carried out.Combining the forward and reverse models of magnetorheological damper with fuzzy-PID controller,the simulation modules of 1/4 vehicle semi-active suspension system are established and verified under random road excitation,the simulation analysis is carried out by combining the simulation curve of suspension performance evaluation index and the comparison curve between the desired force and the actual damping force.The results show that compared with the fuzzy-PID control,under the control of actual magnetorheological damping force,the acceleration of vehicle body is reduced by 27.41%,the dynamic deflection of suspension is reduced by 21.17%,and the dynamic load of tire is reduced by 27.83%.This shows that the actual damping force obtained from the conversion of the desired force to the magnetorheological damper is more significant,which significantly improves the ride comfort and operation stability of the vehicle.