Research On Distributed Differential Control System Of Electric Vehicle Based On SOSM Algorithm

Distributed drive electric vehicle cancel the traditional mechanical transmission device according to the distribution of the motor,and the advantages of high transmission efficiency and low noise have been actively researched by a growing number of experts and scholars and started to be promoted and applied in the market.Aiming at the stability control of distributed driven electric vehicles,this thesis designs an electronic differential control system of distributed driven electric vehicles based on SOSM algorithm,and tests its control effect on the lateral stability of vehicles.The designed electronic differential control system(EDS)selects the yaw rate and the center-of-mass lateral angle as the important state parameters for vehicle estimation.According to the research needs,a quarter vehicle two DOF model and a seven DOF model were built in the vehicle chassis lateral dynamics model.The contact force between the tire and the road surface is the maximum contact force between the vehicle system and the external environment,the judgment of which directly affects the prediction accuracy of the vehicle state parameters.In this thesis,the selection of semi-empirical Magic Formula tire model,combined with the vehicle's seven DOF model,can quickly obtain accurate model tire force output.The standard working condition of double shifting line is selected as the main demonstration road model in this thesis.At the same time,in order to obtain the ideal vehicle steering angle,the single-point preview driver model under Ackermannn steering theorem is selected to obtain the desired vehicle steering angle.At this stage,the expensive non-contact optical sensors can be utilized to measure the vehicle's center of mass deflection angle,however,due to the poor accuracy of the results,it is necessary to build a center of mass deflection angle observer to design the electronic differential control system.Based on SMC,it is also deduced by combining Lyapunov function and modern control theory.Because the FOSM algorithm is difficult to solve the system chattering problem brought by the algorithm itself,this thesis proposes the SOSM algorithm for motor drive torque distribution strategy control.In the verification analysis of the system control algorithm,the joint simulation of the model is carried out with the use of Matlab/Simulink and Car Sim,and the key state parameters of vehicle lateral stability,such as vehicle steering angle,yaw velocity,side angle of centroids and vehicle lateral acceleration,of electronic differential control system designed by FOSM algorithm and SOSM algorithm,were compared on dry road surface and wet road surface with high and low adhesion coefficient respectively.For the effect of vehicle stability control,the ?-? phase plane method can be seen that the designed electronic differential control system has good stability and applicability.Induction algorithm verification results: Distributed drive electric vehicle based on SOSM algorithm can maintain excellent path tracking ability,SOSM algorithm can effectively eliminate the chattering problem caused by sliding mode variable structure control system,control system robust.Comparing the response of the vehicle's various state parameters at 30km/h,80km/h,and 120km/h,the results show that the electronic differential control system effectively improves the vehicle's lateral stability.The fifth chapter is to build the HIL platform of the electronic differential control system.As the most accurate algorithm test method before the real vehicle test control system,this thesis studies the use of the research group to build a distributed drive HIL test platform.On one hand,the PC-side host computer imports the control system in Car Sim RT,builds the Lab VIEW stability control observation system,and uses LAN gigabit port to connect with data transmission.On the other hand,the lower computer utilizes the appropriate NI-PXI equipment to feedback the vehicle sensor signal and conducts HIL testing to verify the applicability and feasibility of the control system on the electronic differential control system designed and studied in this thesis,in hope of improving the lateral stability of the vehicle.