| The brake system that has a great impact on ride comfort and handling stability is one of the most important subsystems of the car,which is the execution unit of Automatic Driving System as well.This paper concentrates on the simulation and experimental verification of Integrated Electro-hydraulic Brake(I-EHB)system,including the design of components and structure,the derivation of mathematical modeling and transfer function,the experiment and simulation of I-EHB system,the control system design of I-EHB,and the strategies and co-simulation of Autonomous Emergency Braking(AEB)system based on I-EHB.The contents of this paper are:(1)A new program of electro-hydraulic brake system is designed and those basic brake function,failure backup braking,advantages and disadvantages are discussed.In addition,the mechanical subsystem,the hydraulic subsystem and the solenoid valve are analysed and the mathematical model is established respectively.Then the model is simplified and linearized based on simulation,and the transfer function is deriverd by assuming that I-EHB is in equilibrium.(2)The experimental bench of I-EHB system was built and the open-loop experiment was carried out with the motor torque as input,for testing the open-loop response characteristics of the I-EHB.Furthermore,the Simulink model is established by the mathematical analysis,and the AMESim model is established by structure of I-EHB.Analyse the advantages and disadvantages of them,then simulate and analyse the dynamic characteristics of the solenoid valve using Simulink,and the dynamic characteristics of pressure and flow of I-EHB system using AMESim respectively.The effect of target pressure,solenoid valve cross-sectional area,ball screw lead,and pipe diameter on I-EHB system are discussed.(3)The system leakage diagnosis program is designed according to the structure of I-EHB and the characteristics of its hydraulic circuit.A real braking intention recognition method based on support vector machine is designed.This method can identify the driver’s braking intention online based on pedal data,so that the target brake pressure obtained by booster curve will be corrected by the intention spotted.Besides,the incremental pressure PID control algorithm is designed to improve the pressure response speed,and the double-loop PID control algorithm is designed to solve that the putt can not return in single-loop control.The experimental results show that the problem is solved successfully.(4)The control strategy of Autonomous Emergency Braking system based on I-EHB system is studied and designed,which including the dangerous target identification,the collision time calculation,the time-threshold determination,the time-based collision grading,and the calculation of target brake pressure.Then the feasibility of the control strategy is verified based on the co-simulation using Carsim,AMESim and Simunink. |
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