Identification And Intelligent Optimization Of Vehicle Chaos Under Consecutive Speed Bump And Engine Combined Excitation

To avoid traffic accident caused by over speed,the consecutive speed bumps are widely set to key section.The height of consecutive speed bump is low,the effect on driving comfort is slight and the risk of direct hazard to vehicle is small.Considering nonlinear characteristics are ubiquitous in modern vehicle suspension,which may generate chaos under road speed bumps and engine vibration combined excitation.The pseudo random and initial state sensitivity of chaos is likely to inflicting many adverse effects on vehicle.To solve the problem,a considering engine vibration five freedom degrees vehicle model is established.Based on image and numerical value the chaotic state is identified and the effect of system parameters on vehicle chaotic state is analyzed.To inhibit the chaos of the vehicle,vehicle suspension parameters are optimized by genetic algorithm and vehicle is controlled by nonlinear feedback control based on particle swarm optimization algorithm.The main research content is as follows:(1)Speed bump and engine excitation coupled with vehicle speed model are established,while five degrees of freedom nonlinear vehicle model is built according to the simplify rules and related research.(2)Chaos state of vehicle is illustrated under variety of system parameters via bifurcation diagram,time history diagram,phase track diagram,poincaré section graph and maximum Lyapunov index of vehicle system.(3)The influence of system parameters on vehicle chaos state is analyzed.Utilizing the vehicle system maximum Lyapunov exponent to measure the vehicle chaotic degree,the parameters of chaotic degree smaller range is determined,which provided foundation of parameter selection for vehicle and speed bump.(4)Vehicle suspension parameter is optimized by genetic algorithm.Vehicle suspension parameter kf2?kr2?cf2?cr2 is adjusted to minimize vehicle system maximum Lyapunov exponent namely to minimize vehicle chaotic degree.(5)Vehicle system is feedback controlled by taking advantage of piecewise quadratic function,the best feedback coefficient feedback control is searched based on particle swarm optimization.According above research,the chaos characteristics of vehicle with consecutive speed bumps and engine combined excitation is revealed,the passive of chaos under different speed and the effects of system parameters on the vehicle chaos state is analyzed.The chaos of vehicle is suppressed by applying the optimization of vehicle suspension parameters based on genetic algorithm and the feedback control based on particle swarm optimization.