Research On Four-wheel Independent Electric Drive Vehicle Steering Control Strategy

Compared with the single motor driven electric vehicle,Multi-wheel independent electric drive vehicle has more advantages and greater prospects of application and development because of its structure and control characteristics.The research on the technology of multi-wheel independent electric drive vehicle control system attracts a large number of scholars and enterprises,among which the steering control system has become a hot research and has made many achievements.The core of the multi-wheel independent electric drive vehicle steering control system is the electronic differential control system.The common electronic differential control system is based on Ackermann-Jeantand steering model for the derivation of the mathematical relationship to get the desired torque value of the inside and outside drive wheel,so as to realize the differential function of inside and outside wheels.However,there is a poor stability in this kind of electronic differential control system in high-speed.For the problem addressed above,a four-wheel independent electric drive vehicle steering control system is designed in this paper,in which the vehicle's two front wheels provide driving power and responsible for electronic differential system,while the two rear wheels responsible for the direct yaw moment control system in order to improve the vehicle stability at high speed.The electronic differential control system is realized by Ackermann-Jeantand steering model and fuzzy control.And the direct yaw moment control system is realized by the two degrees of freedom vehicle model and fuzzy control.Electronic differential system model,direct yaw moment control model and the permanent brushless DC motor speed control model are built in Matlab/Simulink and the four-wheel independent electric drive vehicle model is built in CarSim.The four-wheel independent electric drive vehicle steering control system simulation about steering wheel step angle input and sinusoidal double lane change condition are carried out by the joint simulation of Matlab/simulation and CarSim,showing that the four-wheel independent electric drive vehicle steering control system perform good in different speed and curves,which proved the feasibility and effectiveness of the designed steering control system.