Study On MR Semi-active Suspension Based On Identification Of Driving Road Condition

The viscosity and yield stress of MRF changes rapidly with the change of electric current intensity, moreover, this change is continuous and reversible, so MR technology has created a new way of developing a generation of automotive semi-active suspension system. However, restricted by the identification of driving road condition, real-time optimal damping ratio mathematical model of the suspension system, damping characteristic control law of MR shock absorber, and so on, there has not been continuously controlleed MR shock absorber for semi-active suspension system of real-time optimization damping match under different driving conditions. At present, most of them are shift-selected, costly and hard to be widely used. With the development of auto-industry and the increase of driving speed, higher requirements of driving safety and riding comfort are put forward. In this paper, some research was conducted, aiming at the problems of MR semi-active suspension system. The innovations are as follows:(1) With ride vibration analysis based on 1/4 model of vehicle suspension, the model of damping characteristic simulation, the relation of body vibration acceleration, travel speed and vehicle’s parameters, the identification model of driving road condition was built, based on vibration acceleration and travel speed.(2) With vehicle smoothness analysis, vibration acceleration and wheel dynamic load, the joint optimal objective function of damping ratio was established; by the constraint of suspension dynamic flexibility, the model of real-time optimization damping ratio of semi-active suspension system was deduced.(3) With mechanics performance analysis on MRF under the action of an applied electric current, the study on the rheological properties of MRF in damping channel using parallel plate model was carried, the optimization design methods of the key parameters of the magnetorheological damper were established, and the damping characteristic mathematical model of MR shock absorber, based on the electric current controlled and the vibration acceleration of automobile body, was built.(4) With the real-time optimization match damping as the controlling target, the control law of electric current in different driving conditions was established, based on the damping characteristic mathematical model of MR shock absorber.With MATLAB/Simulink,the characteristics of the magnetorheological semi-active suspension system and the indexes of vehicle riding comfort evaluation had been simulated, and compared with the simulation features of the passive suspension.The computer simulation analysis shows that the model of real-time optimization damping ratio of semi-active suspension system and control law can meet the requirements of driving safety, riding comfort and manipulation stability. The research has important theoretical and application value for the design and development of MR semi-active suspension.