The Research On Yaw Stability Control Strategy For Distributed Drive Electric Vehicle

The rapid development of the automotive industry has provided convenience and pleasure for people's lives and work,but it also causes a series of problems such as environmental pollution,shortage of fossil energy and frequent traffic accidents.In recent years,many countries have actively developed pure electric vehicles.For the yaw dynamics control of distributed drive electric vehicle,the direct yaw moment control method has significant advantages.This method can timely adjust the driving torque of the wheels on both sides when the vehicle has a tendency of insufficient steering or over-steering,so as to improve the yaw stability performance when the vehicle is turning.Based on this technical,this paper has done the following work:(1)The establishment of the co-simulation platform of Carsim and Simulink.Firstly,the vehicle model was set up by Carsim software,which is more accurate.At the same time,the motor was modeled in Simulink software.By configuring the input and output interfaces of Carsim vehicle model,the establishment of the co-simulation platform was completed,which laid the foundation for the establishment and verification of the subsequent stability control strategy.(2)Analysis of vehicle dynamics and estimation of tire force.The main causes of vehicle instability were analyzed;Based on the deduction process of the ideal single-track model,it was concluded that the side slip angle and the yaw rate are the important parameters to determine the yaw stability of the vehicle;The HSRI tire model was established to analyze its characteristics,and the tire force model was established to estimate the tire lateral force which is difficult to measure in real vehicle test.Then,the reliability of the tire force estimation model was validated by Fish-hook working condition,which could be applied in the subsequent vehicle test.(3)Design of yaw stability control strategy.The three-layer mode control strategy was established in Simulink:the dynamic modeling layer calculated the actual value and the expected value of the variable,and the compensation torque formulation layer processed the deviation value of the variable,and then divided the vehicle running state into stable region,single control region,and joint control region according to the extension control theory.Then the weight of two-parameter control was established.Finally,an adaptive sliding mode control strategy was established to develop a suitable compensation torque,which combined the advantages of extension control and sliding mode control.The wheel torque distribution layer provided constraints for the compensation torque and distributed it appropriately to the four motors,so as to realize closed-loop control of the entire vehicle and improve the stability of the vehicle.(4)Simulation and experiment of stability control strategy.In the co-simulation platform,the control strategy was tested under the conditions of low-speed angle step and high-speed sinusoidal angle.The simulation results showed that the side slip angle and yaw rate of the whole vehicle are obviously corrected by the controller.Secondly,the test vehicle was converted into a four-wheel independent drive form.At the same time,the vehicle controller was built,and the signal acquisition device was designed.The rapid prototype test of the control strategy under the condition of serpentine winding was carried out.The test results showed that the real-time performance of the control strategy is good,and the response speed of vehicle parameters and the stability performance of the vehicle are obviously improved.