Research On Coordinated Control Of Steering Stability Of Wheel Motor Driven Vehicle

Wheel motor four wheeled independent drive electric vehicle is a new energy vehicle that installs the driving motor into the wheel.It has the advantages of compact structure,quick response and accurate torque response,and high energy efficiency.The motor is loaded inside the wheel,the quality of the sprung is increased and the wheelbase is also changed,which affects the design of the whole chassis.At the same time,the torque of each wheel can be allocated at any proportion in the motor capacity range,so it has greater technical potential in the stability control system.The electric vehicle stability control system improves the vehicle handling stability and reduces the traffic accidents by restraining the excessive steering and the serious lack of steering.In order to improve the handling stability of electric vehicles,a stability control strategy based on direct yaw moment control and sliding mode variable structure control theory is designed in this paper.First of all,according to the characteristics of four wheel motor vehicle driving each wheel torque control,the linear dynamics model is established in this paper.7 degree of freedom independent drive electric vehicle and the ideal model of two degrees of freedom,analysis of the influence of vehicle load on wheel motor driving stability of vehicles.Based on Car Sim,a four wheel independent driving hub motor electric vehicle simulation platform is built,and Simulink is used to build control strategy model and carry out Car Sim/Simulink co simulation.Then the relationship between the side angle and the yaw rate of the centroid and the stability of the yaw angle is analyzed,and the yaw moment control analysis of the independent drive electric vehicle with hub motor is carried out.In this paper,the side angle of the centroid and the yaw rate are used as the control variables of the stability control system,and the double control control system is developed.The input of upper controller is all state parameters of vehicle during driving.Then the desired yaw moment is calculated according to the sliding mode variable structure control method.The lower level controller assigns the desired yaw moment of the upper controller to all motor executor under the constraint conditions,which is based on the minimum optimization algorithm of tire utilization.Sideslip angle and yaw rate of the two control variables based on the sliding mode variable structure control theory,the study of three different control parameters based on the control strategy of sideslip angle: sliding mode variable structure control,variable structure control,joint control,sideslip angle and yaw rate based on transverse sliding mode the yaw rate based on.Finally,in the Car Sim and Matlab/Simulink co simulation experimental platform of standard under the condition of double lane change electric vehicle stability control strategy,the specific effects of control parameters on the stability and the effect of different road conditions and the selection of control parameters is studied.The simulation results show the effectiveness and robustness of the stability control strategy of the electric vehicle.