| The vehicle ride comfort and handling stability has attracted more and more people's attention. Suspension performance is closely related with these two indicators. Conventional passive suspension can no longer satisfy the requirements of the automobile, However, the semi-active suspension damping adjustability can be achieved that can be better meet the driving requirements of motor vehicles. Compared with the active suspension, it has some benefits, such as simple structure, low cost and etc. Now it has become a hot research. In this paper, Magnetorheological semi-active suspension use magnetic rheological fluid effect to control the damping force of the shock absorber.In structural design, the paper chose magnetorheological(MR) damper as the research object, introduced the magnetic circuit design of MR damper, combined the structure and working characteristics of existing automotive hydraulic shock absorber and worked on the calculation and selection of the MR damper's cylinder, inflatable cavity, the effective length and est. Then, completed the design of the overall suspension. This suspension has a lower energy consumption, high reliability and a similar characteristics with active suspension based on a certain control strategy. It is a high performance, semi-active control system. It can monitor input information which come from sensors of the status of the body and wheel motion to make real-time response on road conditions and driving environment. It can provide fast, smooth and continuously variable damping force to reduce the vibration of the body and increase the adhesion between tire and the various road.In control research, the paper chose a mini-car as a reference model. First, according to vehicle dynamics theory to set up 1/4 car semi-active suspension control system dynamics model. Then, based on familiar with skyhook control algorithm, fuzzy control algorithm and fuzzy-PID control algorithm we designed skyhook controller, fuzzy controller and fuzzy-PID controller.In the conditions of various road for the road input and different driving speeds, we used Matlab/Simulink for simulation study of MR semi-active suspension and achieved good control effect. The results show that, Combined with relevant control algorithm, semi-active with MR damper suspension system effectively improved the car's ride comfort and handling stability. Then we compared and analyzed sprung mass acceleration, suspension deflection response and tire load response, the final study results show that fuzzy-PID controller has better control effect and can effectively improve the dynamic performance of vehicles compared with skyhook controller and fuzzy controller.
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