Nonlinear Dynamic Analysis And Control Study Of Semi-vehicle Magnetorheological Suspension

As an important assembly of the vehicle,the suspension system plays a role in buffering the road excitation and determining the ride comfort and handling safety.The semi-active suspension system based on the magneto-rheological damper(MRD)has the advantages of low energy consumption,fast response speed,and continuously adjustable damping force,so it has a wide application prospect.However,because the magneto-rheological damper itself has a strong nonlinear hysteresis characteristic,with other nonlinear factors such as springs,tires,and external road excitation,there are a variety of complex nonlinear dynamic behaviors in the MR suspension system,such as bifurcation and chaos,which can lead to damage to parts,discomfort to passengers,and other negative effects.The analysis of the nonlinear dynamic characteristics of the MR suspension system and the design of chaotic vibration control strategies have important guiding significance for its practical application.In this thesis,through the combination of theoretical analysis and numerical simulation,the modeling,nonlinear dynamic analysis and controller design of the magneto-rheological suspension system are conducted.The main work are as following aspects.(1)To the half-vehicle MR suspension system,a systematic dynamic model is established.Based on the modified Bouc-wen phenomenological model of the MRD,the dynamic differential equation of the half-vehicle MR suspension system is established.In addition,the system state equation is written and the stability of the system equilibrium point is analyzed according to the Routh-Hurwitz criterion.(2)The nonlinear dynamic analysis of the half-vehicle MR suspension system is conducted to investigate the nonlinear dynamics of the system.With the relevant theoretical analysis of nonlinear dynamics,the response of the vehicle MR suspension system under the harmonic excitation at different amplitudes and frequencies is carried out.The system bifurcation diagrams,Lyapunov exponents,time histories,phase portraits and Poincaré sections are obtained through numerical analysis.The results show that there will be a variety of complex nonlinear dynamic behaviors,such as period doubling bifurcation,chaos,saddle-node bifurcation and hyperchaos.(3)To control the chaotic vibration,a novel sliding mode control strategy is proposed.The sliding mode error is obtained by taking the vehicle steady state as a reference.The sliding mode plane is constructed by introducing the proportion,integral and differential terms of the tracking sliding mode error.The strategy is compared with the traditional linear feedback control.The results show that the vertical vibration of sprung mass response of the vehicle is effectively reduced.The riding comfort of the vehicle is also improved.