Research On Acceleration Slip Regulation System For Electric Vehicles With In-wheel Motors

The in-wheel motor is a special motor integrated on the wheel side of the vehicle.Due to its various advantages,it is very suitable as a power source for electric vehicles.This article aims at electric vehicles driven by in-wheel motors.On the premise of ensuring the vehicle's operational stability and driving safety,a set of acceleration slip regulation system is designed with the goal of the best longitudinal acceleration performance.The research focuses of this article are as follows:(1)A vehicle speed estimation method based on information fusion technology is designed to realize the real-time calculation of the wheel slip ratio.The method is based on a seven-degree-of-freedom vehicle model and the HSRI tire model.Compared with traditional Kalman filtering and Unscented Kalman filtering,the Cubature Kalman filtering method with better performance is adopted.At the same time,the singular value decomposition method is used to solve the non-positive problem of covariance matrix in the filtering process.(2)A road recognition method based on fuzzy theory is designed to estimate the current road adhesion coefficient and the optimal slip rate.The method takes the current slip rate and the utilization slip coefficient as inputs,and outputs the identified peak slip coefficient and the optimal slip rate.When blurring,the slip rate was further subdivided.Based on the Burckhardt tire model,the adhesion characteristic curves and parameters of 8 standard roads were obtained,which improved the recognition accuracy of the fuzzy road recognizer.Based on the analysis of the basic principles,control requirements,and control methods of the electric vehicle's acceleration slip regulation system,a PID control algorithm that integrates vehicle speed estimation and road recognition is designed.In order to improve the adaptability of the designed acceleration slip regulation system,three improvement ideas are adopted:the target slip rate is modified according to the vehicle speed to ensure the lateral adhesion performance of the vehicle at a high speed;the driving torque is adjusted by the principle of low selection between Left and right wheels to reduces the yaw moment of the vehicle on the divided road surface and improves the steering stability.The PID control parameters are optimized by sections to improve the control effect of the acceleration slip regulation system on the road with different adhesion coefficients.