Research On Electronic Differential Control System Of Electric Test Vehicle With Four Wheels

As an outstanding representative of pure electric vehicle,hub-motor electric vehicle has attracted much attention and become a research hotspot of many automobile manufacturing enterprises and scientific research institutions due to its convenient and flexible chassis structure layout,better chassis active control and faster control response and other technical advantages.When the car is running in a turning direction or on a complicated road surface,the driving distance of the left and right driving wheels is different.The traditional internal combustion engine automobile and the centralized drive electric vehicle all use the mechanical differential mechanism to realize each drive wheel rotation at different speed.However,hubmotor electric vehicles do not have mechanical differential mechanism,but instead coordinate the control of the driving wheels by means of electric control,that is,electronic differential control system.Based on D2 P rapid prototype development platform,the electronic differential control system of four-wheel hub electric test vehicle is studied in this paper.The Ackermann&jeantand steering model was used to analyze the target speed of each driving wheel under different steering angles and driving speeds,that is,the differential speed relationship.Then the target speed of the four driving wheels is sent to the four motor controllers through CAN bus,so as to realize the electronic differential control of the four-hub electric test vehicle.Firstly,according to Ackermann&jeantand steering model and mathematical model of hub brushless dc motor,the differential steering model,motor control model and electronic differential system model are built,and then simulated and analyzed respectively.Secondly,the D2 P rapid prototype development platform was used to realize the electronic differential control strategy,and the modeling software Moto Hawk was used to build Ackermann&jeantand steering model,accelerator pedal model,gear switch model,brake switch model and CAN model.Then,the electric system of the test vehicle is designed and arranged.Finally,the main function modules of the test vehicle were tested separately,and then the electronic differential control system of the test vehicle was tested.Test results show that using experimental D2 P rapid prototyping platform as a four wheel hub electric vehicle controller,it can perform data reading and sending,and satisfies the requirement of experimental basic operation,and build on the platform of the test on the electronic differential control strategy can realize,when the steering wheel Angle is 360 °,respectively with 10 km/h,20 km/h,30 km/h,different running speed of 40 km/h,four-wheel actual speed can be a very good follow goal realization of differential speed,maximum control error within-5.62% ～ 3.37%;At the same speed at 25km/h and the steering wheel Angle is 180°,270°,360° and 450° respectively,the actual speed of the four driving wheels can well follow the target speed to realize the difference,and the maximum control error is within the range of-1.79%～0.92%.At a speed of 25km/h,turn the steering wheel continuously from 0° to 362.1° to the left within 19.18 s,and the differential response time is about 0.31 s.