Study On The System Of Magnetorheological Semi-active Suspension And Its Control Strategy

With the development of society and technology, the demand of people on the car ride comfort and seat comfort is increasingly severe. Suspension is the most important coupling part in Vehicle, which will directly affect the performance of the comfort and safety of passenger. Although the traditional passive suspension can improve the ride comfort and operation stability in a certain extent, its structure parameters can not change automatically with the running state of the vehicles, which restricts its application greatly. Magnetorheological(MR) semi-active suspension uses MR technology to carry out the real-time adjustment of its damp. Due to its advantages of rapid response speed, wide dynamic range, low power consumption and comparatively simple structure, magnetorheological semi-active suspension has became the central of intelligent suspension, and has received considerable attention of many automobile manufactures. In this paper, the methods of theoretical and numerical simulation are used to study the dynamics characteristics of MR damper, the control strategies and subsystems of semi-active suspension. The main research work is as follows:(1) Make an overall introduction to the rheological mechanism of MR, the working mode of MR and the mechanical model of MR. In view of the deficiency of the parameter model and non-parameter model, the article established an improved Bouc-Wen model, then establish the simulation model of the shock absorber in Matlab/Simulink and analyze its performance. The results shows that the model can b e t t e r r e f l e c t t h e n o n l i n e a r h y s t e r e t i c c h a r a c t e r i s t i c s o f t h e s h o c k a b s o r b.(2) Based on the analysis of the mathematical model of road surface roughness and the theory of random road surface, the four wheel related time domain model is established. Through the reasonable simplification of the whole vehicle vibration system, we derived the seven degrees of freedom vehicle dynamics equation, and establish the mathematical models of the semi-active suspension. Finally, this paper makes a summarition to the performance evaluation indexes of the whole vehicle system, and then analyses the influence of each index on the vehicle ride comfort and operation stability.(3) According to the nonlinear structural characteristics of the suspension system, the paper analyses two kinds of control strategies. Then based on the whole control theory fuzzy control, the fuzzy PID control and variable universe fuzzy control are proposed and studies. We design their own fuzzy controllers and fuzzy control rules, and build their corresponding control subsystems. Finally, using Matlab software to simulate the three kinds of control strategies, the simulation results show that the three control strategies are effective, and they can improve the performance of goals in varying degrees. But the variable universe fuzzy control is more obvious, which can greatly improve the ride comfort and driving safety. It provides reference to researching and designing semi-active suspension.