Research On Pole Distribution Of Vehicle Lateral Dynamic System

In order to propose Relaxed Static Stability control for all-wheel-drive electric vehicle,in this paper,the method to use second order system pole location for lateral vehicle dynamics research was proposed.Relaxed Static Stability uses the active yaw moment provided by the motors to conduct pole assignment,to improve the handling stability.The key point is using pole location to predict the performance of the vehicle dynamics.Numeric simulation was widely used in conventional lateral dynamics research.Although the conventional method could obtain the influence of parameter change on dynamics behavior,a large amount of simulations and discussion is in need to do it.But the pole method could put the pole distribution on different conditions into just one figure,the damping ratio and the frequency is easy to observe.It’s convenient to provide guidance for the engineering design and obtain Relaxed Static Stability control.In this paper,the 7 DOF nonlinear dynamic model with accurate tire nonlinear characteristics was built,including longitudinal,lateral and yaw movement of the body,as well as the rotation of four wheels.Based on the model,the handling dynamics behavior was obtained.According to the tire cornering stiffness observation,the 2 DOF time-vary model of the vehicle was built.Based on the comparison between 2DOF and 7DOF model,the accuracy of the 2 DOF model with tire cornering stiffness observation is verified.Based on it,the expression of pole locations are obtained.The judge method to predict the steering characteristics was obtained.The change situation of the pole location when the condition changes and the overall parameters change is obtained.Finally,based on an electric drive prototype vehicle,the theoretical results in this paper was validated.