Research On Lateral Stability Control Of Four-Wheel Independent Steering And Driving Electric Vehicle

With the increasing awareness of environmental protection and the continuous shortage of energy reserves,electric vehicles,which are vigorously promoted by the state,have entered our lives.When the four-wheel independent steering drive electric vehicle is turning,due to the high integration degree of each system,improper control may cause the vehicle to be unstable and unnecessary traffic accidents.Therefore,how to carry out integrated control of four-wheel drive torque,steering angles and yaw moment,and improve the vehicle lateral stability control ability has become an important research topic.This paper relies on the “Major Science and Technology Research Project of Jilin Province(20170201005GX)” and the “Outstanding Youth Talent Fund Project of Jilin Science and Technology Department(20170520097JH)” to conduct research on the lateral stability control of four-wheel independent steering drive electric vehicles.Firstly,the vehicle dynamics characteristics are analyzed.According to the vehicle lateral stability control requirements,the vehicle's longitudinal motion,lateral motion,yaw motion and four wheel rolling are considered to establish a seven-degree-of-freedom vehicle dynamics model.When the vehicle stability is controlled under extreme conditions,the tire may enter a non-linear region.Therefore,the Pacejka tire model is selected to characterize the trend of tire force in the nonlinear region.The vehicle model was built using CarSim commercial software,and the B-Class Hatchback was used as the prototype vehicle to set the CarSim vehicle model parameters.Secondly,the control system is analyzed,and the vehicle lateral stability controller is designed based on the hierarchical control structure.In the upper control process,the total longitudinal force,the total lateral force and the total yaw moment are introduced as the pseudo control amount,and the model predictive control method with time-varying parameters is used to complete the design of the upper controller,and the total longitudinal force is optimized.Lateral force and yaw moment.The lower layer control takes the optimal tire utilization rate as the control target,and designs the tire force distribution controller based on the weighted pseudo-inverse control distribution method to realize the distribution control of the longitudinal force and lateral force required for each wheel.For longitudinal force distribution,the sliding mode control is used to control the driving or braking torque of the four wheels with the optimal slip ratio.When the wheel lateral forceis distributed,the tire inverse model is used to determine the rotation angle of each wheel to realize the control of the steering angles.Finally,based on the joint simulation platform of CarSim and Matlab/Simulink,the simulation algorithm proposed in this paper is simulated.The results show that the proposed control algorithm can reduce the tire utilization rate of the four wheels of electric vehicles,improve the adhesion margin of each tire,and finally realize the tracking control of the longitudinal speed,lateral speed and yaw rate of the vehicle.