Research On Control Strategy Of Vehicle ESP System Based On Road Adhesion Coefficient

With the gradual increase of the number of cars in China,car safety has become the most concerned issue for drivers and car manufacturers.The ESP system is one of the most important active security systems in the car,and plays a very critical role in the vehicle Stability control and trajectory tracking when the vehicle is steering.However,due to the very complex working environment of the vehicle,when the vehicle runs on different road conditions,there will still be insufficient adaptability.Based on this,according to the influence of different road adhesion coefficient on the function of vehicle ESP system,the ESP system is studied in this thesis.Firstly,the differential braking ESP control system with independent all-wheel braking is studied in the thesis.Based on the analysis of automobile stability characteristics and instability conditions,ESP system controls the stability of the vehicle by two selected control variables of yaw angular velocity and sidesaw Angle of the center of mass.Then,the Dugoff tire model,the seven-degree-of-freedom vehicle model,the two-degree-of-freedom monorail reference model and the braking torque model were established.And through the Matlab/Simulink module to establish the effectiveness of the model,as the foundation of simulation.Then on the basis of mainstream fuzzy controller and sliding mode controller designed respectively,through the analysis of automobile braking torque under different road conditions influence on the wheel slip ratio,and putting the tire-road friction coefficient into the input variables of the model,put forward the "fuzzy sliding mode variable structure controller based on tire-road friction coefficient",compared with the former two controller which has better control precision and road adaptability.In order to increase the comparability of the experiment,this thesis used PSO algorithm to set and optimize the key parameters of each controller.Finally,simulation tests of vehicle stability control under two road conditions of high adhesion coefficient and low adhesion coefficient were carried out under two modes of sinusoidal input of front wheel rotation Angle and step input,and the simulation results were evaluated by the cumulative deviation of the control variables.Through the comparative analysis of the test results,it is verified that the proposed controller is effective and has good adaptability to the road surface.It can improve the driving stability of the vehicle and reduce the occurrence of accidents,which provides reference for the research of the vehicle stability control system.