Modeling And Analysis Of Automotive ABS Hydraulic Modulator

Anti-lock Braking System (ABS) is an important safe technique for automobile, for it ensures optimum stability and stopping performance during hard braking. ABS has been widely used in China. Hydraulic modulator is an important component of ABS system. It influences the performance of ABS remarkably. The mass production of hydraulic modulator has over twenty years in broad. The various techniques of hydraulic modulator have developed maturely. The theory models and various manufacture crafts are very stable, and the product quality is reliable. But the research on hydraulic modulator has a widening gap between China and broad.Based on the aboard achievements of China and abroad, this paper researches on the hydraulic modulator modeling and parameter analysis, ABS control logic and ABS simulation, combined with a type of ABS hydraulic modulator.In Chapter One, it introduces ABS development course and development directions, analyzes ABS working principle and basic configuration and introduces the research status quo of ABS hydraulic modulator. In the end, the main task of the paper is indicated.In chapter two, the hydraulic modulator working principles and basic configurations are researched; the hydraulic modulator model is founded and validated with the test experience model. For modeling easily, according as the ABS hydraulic schematic, the author found the hydraulic modulator model in AMESim software. For AMESim has various hydraulic components and can receive the simulation results by four modes: founding the model scheme,IV selecting submodels,identifying the model parameters and running, it provides a big advantage for the hydraulic modulator research. By the validating with the experience model, it proves the credibility of the model with the software.In chapter three, by setting several values with one parameter and comparing the simulation results, it can analyze the effect of the parameter with the simulation results. The effects of the hydraulic restrictor,the inlet solenoid valve and the outlet solenoid valve on the wheel chamber pressure and flow rate are analyzed, and different parameter settings produce different wheel chamber pressurizing and decompressing speed. The effects of low pressure reservoir parameters on the pressure and piston displacement are analyzed, for it ensures that low pressure reservoir will not be permeated or the pressure will not be high. The effects of pump parameters on the pressurizing speed are analyzed. The cracking pressure of inlet valve has very important effects on the low pressure reservoir.In chapter four, several usual ABS system control logics are compared and the limited logic is selected as this paper's control logic. The control course of the limited logic is analyzed in the high and low adhesion coefficient road. By identifying the road adhesion coefficient, different control logics are adopted in the high and low adhesion coefficient to get good control results. The limited control logic is implemented by MATLAB/Simulink, the input signals come from the CarSim vehicle model and the output control signals go to the AMESim hydraulic modulator model.In chapter five, the advantages of AMESim,Simulink and CarSim is analyzed in different fields: AMESim in the mechanical and hydraulic modeling,MATLAB/Simulink in the control logic modeling and CarSim in the vehicle modeling. The advantages of different software can be exerted by co-simulation.The interfaces of the software are mounted to implement co-simulation in Simulink environment. CarSim vehicle model and AMESim hydraulic modulator model exist as S functions in Simulink. The co-simulation environment has good control results by ABS simulations in the high and low adhesion coefficient roads. The effects of hydraulic modulator parameters on the ABS control results are analyzed, such as: identifying the road adhesion coefficient,ladder pressurization and the values of limits.