Research On Nonlinear Vibration Control Strategy Of Vehicle Magnetorheological Suspension System

As an important part of vehicle chassis,suspension system plays the role of buffering road excitation,which determines the ride comfort and handling safety of vehicles when driving.The semi-active suspension system based on magnetorheological damper(MRD)has the advantages of high frequency response,low energy consumption,continuous adjustable damping force and simple implementation,which has become the inevitable trend of research and development innovation in the intelligent automobile industry.However,the nonlinear analysis due to MRD hysteresis characteristics and chaotic vibration control of seven-degree-of-freedom(7-DoF)fullvehicle MR suspension system have not made breakthrough progress,which has become a research hotspot of scholars in recent years.In this thesis,the dynamic evolution process and chaotic vibration control of 7-DoF full-vehicle MR suspension system under the change of road excitation parameters are discussed by combining theoretical analysis and numerical simulation.The specific research contents are as follows:(1)The dynamic model of 7-DoF full-vehicle MR suspension system based on the improved Bouc-wen hysteresis model is established.Under harmonic signal,smooth pulse signal and random road signal,the vertical displacement acceleration of centroid,body attitude acceleration,tire dynamic force and suspension dynamic stroke are simulated and analyzed.The comfort and stability of suspension system are verified.Compared with passive suspension,the simulation results show that the MR suspension has a good inhibitory effect on the vibration in the vertical and pitching directions,and has a good response speed,which verifies the comfort and stability of the MR suspension system.(2)The nonlinear dynamic characteristics of 7-DoF full-vehicle MR suspension system are analyzed.The bifurcation diagram,phase plane diagram,Poincare section diagram and the maximum lyapunov exponent analysis method are used to reveal the evolution mechanism of bifurcation,chaos and other dynamic behaviors of the system under the influence of road excitation parameters.The simulation results show that the system produces complex nonlinear vibration with the change of excitation,including period doubling bifurcation,saddle node bifurcation,periodic window,chaos and so on.These nonlinear vibrations will seriously affect the driving stability,ride comfort and service life of the system components.(3)The improved sliding mode variable structure control strategy of 7-DoF fullvehicle MR suspension system is designed.Taking the ideal motion state of spring mass as sliding mode error,the sliding surface is constructed by introducing the proportion,integral and differential terms of the tracking sliding mode error.The simulation results show that the chaotic vibration is effectively suppressed under the improved sliding mode variable structure control strategy.The suspension has small impact response and low vibration intensity.Compared with the classical linear feedback control,it has the advantages of fast response speed and easy engineering realization,and the effect on vibration control is better.