| The brake quality is one of the key and important qualities of vehicle.It is a complicated and dangerous working condition to apply the brake in the high speed turning.In this process,due to the action of centrifugal force,The load of the wheel on the inner side of the bend is reduced and the load of the outer wheel is increased.The effect of longitudinal deceleration under the load of the front axle wheel will be increased,The rear axle load will be reduced,making the car oversteer or understeer occurs,so that the car is easy to lose the stability,resulting in traffic accidents.The purpose of turning braking control is to improve the handling stability of the vehicle in cornering.In this paper,The control strategy of cornering braking is studied.The main research contents are as follows:(1)Application of vehicle dynamics simulation software CarSim to build model of suspension system,steering system,tire model,brake model,a vehicle simulation model than can reflect the running state of the vehicle,it lays foundation for the research of brake control curve.(2)Research on ABS control strategy.The design of the two kinds of ABS control strategies: ABS fuzzy PID control strategy and ABS logic threshold control strategy,selection of high adhesion and low adhesion road,high speed braking simulation test on the design strategy,to verify the validity of the model.In order to improve the stability in different road when braking,build a road recognition model in Matlab/Simulink software,through the open road and linking Road,on the road recognition design of the control strategy for high speed emergency braking simulation test,verify the validity of road identification model.(3)Braking control strategy research of automobile curve.Differential braking control(Active Braking Control)is a kind of active control method,which is used to change the running state of the vehicle according to the needs of different wheels.Through the analysis of the braking force of the automobile in the curve,It is concluded that the differential braking can improve the stability of the vehicle.The proposed change control method of wheel slip ratio target value when cornering brake control brake pressure is reduced,a wheel slip ratio target value,corresponding yaw moment to adjust the vehicle running state,The method to build automobile braking control model as the control target to slip in Matlab/Simulink software based on the automobile braking control algorithm was determined.(4)In order to verify the validity of the design curve control algorithm,this paper uses CarSim combined with Matlab/Simulink simulation software,The use of cornering brake control simulation are carried out at different turning radius,high adhesion and low adhesion road,In order to further illustrate the effectiveness of the curve control algorithm,selection in the driving simulator hardware in the loop test rig for braking the test again,Through the analysis of the results,verify the effectiveness of the proposed control logic,To solve the vehicle cornering braking instability problems,improve the stability performance of vehicle turning braking. |
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