| The development of the new four modernizations of automobiles has led to industrial transformation,and the trend of electrification has become unstoppable.Based on vehicle dynamics theory,Kalman filter algorithm and modern control theory,this paper takes distributed drive pure electric vehicle as the research object,studies tire force and other state estimation algorithms,and designs torque control strategies to maintain dynamic performance during starting acceleration and yaw stability at high speed;A virtual simulation platform was built using Car Sim and Simulink software for multi working condition verification,and the modification of the distributed drive real vehicle platform was ultimately completed,verifying the reliability and effectiveness of the algorithm.The specific research content of this article is as follows:(1)Architecture design and algorithm development of vehicle state parameters and tire force observers.Based on the reference coordinate system,a nonlinear seven degree of freedom dynamic model for vehicle driving is established,including vehicle handling dynamics model and wheel dynamics model.Considering the strong nonlinearity of the vehicle dynamics model,the unscented Kalman filtering algorithm in Kalman filtering theory is used to estimate the vehicle longitudinal/lateral speed,centroid sideslip angle,and tire force.Using Car Sim dynamics software to conduct vehicle parametric modeling,and the performance of the state observer is verified by setting the vehicle simulation test conditions.(2)Research on torque independent control of distributed drive electric vehicle anti-skid system.On wet and slippery roads in rainy and snowy weather,wheel slippage can easily lead to accidents and casualties.By analyzing the mechanical relationship between tire and road adhesion coefficient,an optimal slip rate calculation and road adhesion coefficient estimation algorithm are designed based on the Burckhardt tire model.Taking the optimal wheel slip rate under different road conditions as the target control input,using sliding mode variable structure control theory,the torque output of each driving wheel during vehicle starting acceleration is independently adjusted to effectively utilize tire adhesion and ensure the optimal starting acceleration performance of the vehicle.Verify the effectiveness of the controller by setting three types of road surfaces: single,docking,and split.(3)Yaw torque control strategy design for vehicles traveling at high speeds based on optimal torque distribution of drive wheels.The electronic stability control unit used in traditional vehicles can prevent vehicle instability by adjusting the four-wheel braking force to generate additional yaw torque,which can lead to speed loss and affect the driving experience.Utilizing the advantages of distributed drive torque independent control,the stability control form of traditional differential braking is changed through drive force adjustment.An objective function based on tire adhesion utilization is introduced,and the target yaw torque is optimally distributed considering tire adhesion limits and motor characteristics limitations.Through the joint simulation platform,the simulation of the vehicle’s handling and stability conditions during high-speed driving on high and low adhesion road surfaces was completed,verifying the reliability of the yaw stability control strategy.(4)Construction and site testing of distributed drive real vehicle platform.Based on the existing mass production vehicle models,the distributed drive structure transformation was completed,and then three typical handling and stability tests in national standards were conducted in a professional test site.Real-time vehicle status information was collected through handling and stability testing equipment carried on the real vehicle platform.Summarize and process the test data collected by the equipment,and verify the estimation accuracy of the vehicle state observer through comparative analysis;Based on the driver’s driving experience and the measurement results of actual vehicle status information,it is shown that the steering stability of the vehicle has significantly improved after the control algorithm is turned on,thereby verifying the feasibility of the stability control algorithm. |
