Research On Structure Design And Control Strategy Of Electromagnetic Mechanical Wedge Brake System For Passenger Cars

With the development of intelligent car in recent years,some traditional hydraulic components in automobile are gradually replaced by electronic mechanical parts.Increasingly,the brake mode of automobile is changing to the way of wire control.The brake by wire system includes the electronic hydraulic brake system(EHB)and the electronic mechanical brake system(EMB).On the basis of EWB,the brake by wire system is extended to the electronic wedge brake system(EWB).In this paper,a new type of brake by wire system is designed based on the characteristics of EMB and EWB.The new brake structure is called electromagnetic mechanical wedge brake(EMWB).By using the combined simulation technology of CarSim and Simulink,the braking performance of EMWB system is simulated and analyzed.The braking safety and comfort of EMWB system are mainly studied,which can provide reference for further development of brake by wire system.The main contents are as follows:(1)Design the Structure of EMWB actuator.This paper first summarizes the advantages and disadvantages of the electronic hydraulic brake system and the electromechanical brake system,and then completes the overall design of the EMWB system in view of the shortcomings of the existing line control brake system.For braking pedal simulator,a new type of EMWB pedal simulator is designed.In the aspect of braking execution mechanism,the design of braking execution mechanism based on electromagnetic braking is completed,the motor braking structure is added as backup mechanical braking structure,and the three-dimensional modeling of EMWB braking system is completed.(2)Verify the safety and comfort of EMWB system.Based on the structure model of EMWB system,the corresponding mathematical model is established,and the current characteristic model of EMWB braking motor is obtained.Referring to BFI evaluation index,the comfort of brake pedal simulator in EMWB system is simulated.According to the national standards GB 12676 and GB/T 13594,the safety of the executing mechanism in EMWB system is verified by simulation.Taking braking deceleration as reference,the stability of EMWB system during braking process is simulated and verified.(3)Verify the control strategy of EMWB system.After verifying the safety and comfort of EMWB brake system,the ABS control strategy of EMWB system is studied.For the current characteristics of electromagnetic brake and motor brake,PID fuzzy control is used to reduce the current error of EMWB system.For the pressure regulation mode of EMWB system,the control method of combined AEB and ABS braking is designed,the braking model is built in Simulink,the vehicle model is built in CarSim,and the EMWB strategy is simulated on four different road surfaces with different adhesion factors.The braking distance,braking time and braking torque changes are taken as the results to verify the reliability of EMWB strategy.The research results of this paper can enrich the structure of brake by wire system and provide theoretical basis and reference for the development of related products of brake by wire system.