Yaw Stability Control Of In-wheel Motor EVs Based On Curve Following

With the increasingly prominent problems of automobile safety,road traffic accidents and environmental pollution,Advanced Driver Assistant System of new energy vehicles has become a hot research in recent years.As an important part of Advanced Driver Assistant System,Adaptive Cruise Control System has been widely used and popularized,but it has the characteristics of poor applicability under high speed curve,especially the problem how to ensure yaw stability of the vehicles.Therefore,it has great significance to do research on yaw stability under curve following.Based on the existing research results,chosing in-wheel motor EVs as the object,this paper studies yaw stability control of the vehicles under curve following.And the following research work are done:1 Firstly,a hierarchical structure of yaw stability control based on curve following is designed.On this basis,the CarSim is used to establish the model of the front car and ego car respectively,set the simulation environment conditions and define the input and output variables.Also,selecting type of in-wheel motor and establishing its model,then the corresponding control methods and strategies are established by using Matlab/Simulink.Finally,the research of this paper is verified by joint simulation of CarSim and Matlab/Simulink.2 A coordinated controller based on MPC algorithm is designed to solve the multi-objective coordination problem of the following curve and yaw stability control.The three degree of freedom model of the vehicle is established,coupled of transverse and longitudinal.Through the state feedback decoupling and combined with the longitudinal following safety distance model,the required control object prediction model is obtained after the integrated and discrete processing.On the basis of longitudinal tracking,yaw stability and comfort,the relevant constraints and targets are designed.Finally,the optimal control sequence in control horizon is given by rolling optimization.3 The control principle of vehicle yaw stability is analyzed,and the typical wheel torque distribution method of in-wheel motor EVs is summarized.According to the optimal control variables from the upper controller,and combined with the characteristics of motor and hydraulic braking,the control strategy of yaw stabilitybased on in-wheel motor EVs is formulated with the use of the torque optimal allocation algorithm.At the same time,the control strategy of yaw stability based on hydraulic differential brake and the control strategy of yaw stability based on the average distribution of motor torque are set up according to the characteristics of hydraulic braking and motor.On the basis of the designed simulation road and simulation scheme,the control effect of three strategies is verified through joint simulation.