| In recent years,with the rise of China and the rapid development of the national economy,people's awareness of environmental protection has gradually increased,aiming at traditional automobile exhaust emissions,consumption of fossil fuels and other issues have been worried.At present,pure electric vehicles with no emissions and no consumption of fossil-based fuels have been recognized as the development direction of future vehicles,among which four-wheel-drive electric vehicles are the most important research in the automobile industry because of their reasonable chassis design and spacious interior space.As one of the main components of electric vehicle chassis,suspension system directly affects the ride comfort and control stability of electric vehicles.The traditional passive suspension has the advantages of simple structure and low cost,but the vibration reduction effect is poor when driving under complex pavement conditions.The active suspension can adapt to the complex working conditions,and the vibration reduction effect is the best.Because of the complex design and high cost,it is only used in some high-grade cars.The semi-active suspension of magnetorheological damper which can not only adapt to complex working conditions but also achieve good damping effect has become a better choice in automobile suspension.In order to solve this problem,a cylindrical permanent magnet is designed and installed on the internal piston of the magnetorheological damper.The permanent magnet can provide a permanent static magnetic field so that the magnetorheological fluid is always in the state of solid state and will not settle.At the same time,in order to further improve the performance of semi-active suspension system,a superior control algorithm is designed for it,and the simulation model of two degrees of freedom 1/4 suspension and four degrees of freedom half vehicle suspension is built in the Matlab/simulink software,and the simulation test is carried out.This paper mainly carried out the following aspects of research:Firstly,the advantages and disadvantages of the traditional damper and the intelligent damper are compared.Based on the analysis of the working principle and dynamic characteristics of the intelligent magnetorheological damper,the structural design of the new magnetorheological damper is completed,its three-dimensional model is built and the virtual assembly of the new magnetorheological damper is completed.The main components are analyzed by finite element analysis and magnetic field analysis.Secondly,by studying the magnetic field distribution in the damping channel of the permanent magnet rheological damper,the magnetic field in the damping channel is superimposed by the superposition principle after calculating the magnetic field intensity generated by the coil and the permanent magnet in the damping channel respectively.Finally,by analyzing the mechanical properties of the damper,the mechanical model of the permanent magnet rheological damper is established,and the simulation model is built by Matlab/simulink software for simulation test.Then,according to the evaluation index of suspension system,the mathematical model of semi-active suspension system is established,and the simulation model of multi-degree-of-freedom semi-active suspension system is built according to the mathematical model.The simulation model of multi-degree-of-freedom suspension system is simulated and analyzed by random excitation.Lastly,based on the research of PID control strategy and whale optimization algorithm,WOA)learning,using WOA to adjust the relevant parameters of PID,build the two degree of freedom quarter suspension system model and four degree of freedom half car model controlled by PID,and carry out the simulation experiment of white noise input and impact signal input conditions,to verify the effectiveness of woa-pid control algorithm.The results show that woa-pid control algorithm can significantly improve the damping performance of suspension system. |
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