| As an active safety technology, Electronic Stability Program(ESP) can improve the vehicle handling stability completely by monitoring the vehicle's state in real time and constraining the oversteering or understeering actively. ESP leads the progress of the future active safety technology. So it is essential to master the advanced technology about ESP, which means taking advantages in the competition of automotive safety market in the future. Therefore, studying of the theories and key technologies in developing ESP can not only have a great realistic significance in improving the ability of developing domestic automobile industry and shortening the gap between the technological levels of our country and developed countries, but also greatly accelerate the progress of automotive industry and other related industry. And it leads to applications widely in the future prospects.This thesis is associated with the fact subject. Basis on the summary of the domestic and foreign research achievements, this thesis has focused on the hydraulic modulator modeling and wheel cylinder pressure estimation algorithm conducted in-depth studies.The thesis based on the software of AMESim to build up hydraulic regulator model and made the model validated.Then,using the hydraulic modulator modeling to research wheel cylinder pressure estimation algorithm. Derived from the rate of change of wheel cylinder pressure of the mathematical model, and through the hydraulic modulator model simulation of the data on the rate of change of wheel cylinder pressure model parameters identification, finally get round cylinder pressure model. Test platforms of Vehicle Stability Control system have been built , through the real vehicle test and according to different operating conditions to verify the model. The following aspects have been studied in this thesis: Chapter 1 of this thesis for the Preface, introduction of electronic stability control system for the definition of theory and composition, and prospects for the development of key technologies. Thus described the application of academic and subjects the background of this thesis, give the main contents of this paper.Chapter 2 of this thesis introduced the software AMESim, Because of the AMESim has a more comprehensive library of hydraulic components and users can study on AMESim platform to research any components or system, such as steady-state and dynamic performance characteristics of the HCU model,and results can match the needs of this research,so this paper selected AMESim to set up HCU model.Besides the ESP control strategy, the HCU can decide the performance of the ESP system.Therefore, the establishment of a relatively high accuracy regulator hydraulic model for the whole thesis is essential. At a detailed analysis of the ESP hydraulic modulator working principle, set up at AMESim in ESP hydraulic regulator model, the main sub-modules throttle, solenoid valve, accumulator, piston pump and the brake pipe of the Math model carried out a detailed analysis of the various model parameter settings, the status of the ABS and ESP run simulation; and analysis of model parameters for the hydraulic properties of regulator. Finally,the hydraulic modulator model is correct at ABS and ESP mode had been separately verified.Chapter 3 of this thesis analyzed the current ESP yaw brake torque distribution strategy,then find that most ESP just using direct measurement methods. this paper put forwrd that estimation method to estimate the wheel-cylinder pressure, this method can greatly reduce the ESP system cost, speed up the popularization of ESP. Based on the analysis of the hydraulic modulator group characteristics, as well as summing up of hard and soft brake hose transmission characteristics based on the wheel cylinder system, application of fluid mechanics and other related knowledge to build a wheel-cylinder pressure change rate model; application has been proven hydraulic regulator model collection round cylinder pressure change rate model parameter identification data required for the successful identification of the model parameters.Set up the pressure estimation model in MATLAB \ Simulink.Through a variety of working conditions on the wheel cylinder pressure model for authentication, including simple decompression condition, cycle condition, stair pressurization condition, achieved better test results prove that the model is correct.Chapter 4 of this thesis, first of all had set up the stability control system development and experimental study of vehicle test platform, the test platform includes sensors, actuators, controllers and monitoring system of four parts. The software and hardware of stability controller are designed and developed independently. Experimental study on the stability control system is the key process of developing technologies, vehicle stability control test platform set up for the stability control system and part of the overall development of the precondition.Based on verification of the conditions necessary to develop experimental programs, the use of vehicle stability control system test platform to the required test data for pressure estimation model was verified and the amendment to a preliminary proof of the correctness of the algorithm . Gradually taking into account the complexities of system delays, so that the model can be more perfect, then pressure estimation algorithm can be used on real vehicle.Chapter 5 of this thesis is a content summary, and points out future research directions and priorities.Following conclusions have been found in this thesis:(1)Self-developed ESP system must have a hydraulic modulator that correctness in most condition. This article has been built up a model that can meet the needs.(2)Through a reasonable simplification of the wheel brake cylinder , analysised mathematical model of the wheel cylinder pressure , and used to cylinder pressure estimate, finally verify the correctness of this model by real test of the car.
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