Study On Vehicle Handling Stability Based On Contact Analysis Between Tire And Three-Dimensional Spectrum

The study of vehicle-road coupling dynamics is of great significance for improving vehicle dynamics and road safety.In this paper,a three-dimensional road model that can reflect the micro-topography characteristics of the road surface is established to meet the needs of the refined road surface spectrum in the vehicle-road system.Based on the non-uniform grounding characteristics of the tire,a modified Lu Gre tire model is proposed to realize the re-development of the road surface model and the tire model in the multi-body dynamics software.Based on the rolling contact analysis of the tire and the three-dimensional road surface,the control of vehicle handling and stability are studied..Firstly,based on fractal theory,a three-dimensional pavement spectrum reconstruction method is proposed.According to national standards,the harmonic superposition method is used to obtain the unevenness data of the road surface.Then,by using random mid-point displacement method,the two-dimensional road spectrum is extended to three-dimensional pavement,which reflects the self-similar characteristics of the road surface.Meanwhile,compile the road data into Truck Sim software and implement the application of the three-dimensional model.By comparing the dynamic response of the vehicle under the two-dimensional pavement and the three-dimensional pavement,it is found that the vehicle has great difference in the lateral dynamic characteristics.Secondly,in order to accurately reflect the actual contacting between tire model and road surface,the paper analyze the vertical load distribute regulation in longitudinal and transverse direction of the tire contact patch,on these grounds,study the distribution form of non-uniform pressure in the tire/road contact surface.Based on this pressure distribution,a modified Lu Gre tire model is improved,and the effects of slip rate,sideslip angle,load offset on tire dynamics are analyzed to verify the accuracy of the improved tire model.Then,the tire model is re-developed to be embedded in the Truck Sim vehicle model,and the data interaction is realized throughjoint simulation with Matlab / Simulink.Finally,based on the digitalization of the three-dimensional road spectrum and the improved tire model in Truck Sim software,a multi-body dynamic model of a three-axle heavy vehicle is established to study the lateral dynamic characteristics of the vehicle.An angular step simulation test and a fishhook simulation test are designed to analyze the changes of the vehicle body yaw angle,yaw angular velocity and lateral acceleration,it is found that the vehicle rolled over under the input of a large steering wheel angle.In response to this phenomenon,a PID controller and a fuzzy PID controller are set up to control the braking force of the wheels during cornering.After that,the simulation tests are re-performed.The results show that the vehicle with the control strategy avoids the occurrence of rollovers,the fuzzy PID control effect is better than PID control,which provides the basis for the research on improving the handling stability of the vehicle.