【作者】 马镯；

【导师】 裴润；

【作者基本信息】 哈尔滨工业大学 ， 控制科学与工程， 2007， 硕士

【摘要】 制动系统建模是车辆动力学研究的重要内容。它的研究对分析车辆动态特性,进行底盘控制系统的开发和控制器设计具有重要的意义。车辆制动系统的构成根据配置的不同而不同。由于防抱死制动系统(Anti-lock Braking System, ABS)已成为车辆的基本配置之一,且是其它制动系统结构的基础,因此,本文的研究是在轿车ABS结构基础上开展的。通过建立高精度的液压制动系统模型,为提高制动压力和轮胎作用力的估计精度,进行基于模型的防抱死制动控制、牵引力控制和车辆稳定性控制方法研究提供模型和分析基础。为使本文的结构清晰,便于分析和讨论,本文第二章阐述了当代轿车液压制动系统的结构特征,确定了本文将要讨论的系统结构,并对其工作原理进行了简要介绍,为后续的液压制动系统的建模进行了必要的知识准备。本文第三章讨论了制动系统中制动踏板、真空助力器、制动主缸、液压调节器、制动液压管路和制动轮缸等元件的机理模型,给出了各元件的动力学数学描述。由于液压调节器对制动系统模型精度影响较大,因此,本文的这部分工作是在实验平台上针对具体的液压调节器进行的,主要分为两部分内容。一是将常开/常闭电磁阀模型简化为节流阀模型,根据伯努力方程,推导出了常开/常闭阀的流量与阀流量系数、制动主缸压力、制动轮缸压力和低压储能器压力的关系;二是根据液压传动原理和回液泵以及制动轮缸的特性曲线,得到了回液泵和制动轮缸的静态模型。液压制动系统模型参数包括几何尺寸类参数、制动液特性参数(制动液密度、弹性模量)、结构特征参数(质量、容积、弹簧刚度、阀口面积)以及反映系统和元件性能的参数(摩擦、阻尼系数、阀口流量系数,摩擦阻力)。如何针对具体的制动系统确定模型参数是制动系统建模研究中亟待解决的问题。本文首先用实际车辆的制动回路以及车辆动力学仿真软件、实时仿真系统建立了车辆液压制动系统测试、分析和实验平台,在此基础上,讨论了以实际输出与模型输出之间的误差平方和最小为判别准则的参数辨识方法,给出了参数辨识结果。仿真和实验结果表明,本文给出的制动系统模型在制动系统增压、保压和减压过程中均有较高的精度。路面附着系数估计在制动控制中对确定控制参数极其重要,是车辆状态估计的重要内容。本文在以上工作基础上,通过对液压模型的简化,讨论了基于制动轮缸压力估算路面附着系数的方法,并在实验平台上对估计方法进行了验证。结果表明,基于制动轮缸压力的路面附着系数估计方法是可行的,并具有较高的实时性。更多还原

【Abstract】 Brake system modeling is an important content in the research of vehicle dynamics. It is of great significance in the analysis of vehicle dynamic characteristics, development of chassis control system and design of controller.The vehicle brake system constitution is different from each other according to the configuration. As the Anti-lock Braking System (ABS) has become one of the basic configurations in vehicle and is the basis of other brake system structures, the research is carried out based on ABS structure. A high-precision hydraulic brake system model is built, to improve the accuracy of tire pressure and brake force estimation. It also provides model and analysis foundation for anti-lock brake control, traction control and vehicle stability control.To make the structure of dissertation clear and ease the analysis and discussion, the structural features of hydraulic brake system that will be discussed is represented in the second chapter. The system structure and working principle is introduced briefly, which provides necessary knowledge preparation and structure description for the modeling of hydraulic brake system.In the third chapter of dissertation, the mechanism model of the brake pedal, vacuum booster, master cylinder, hydraulic regulator, hydraulic brake pipes and wheel cylinders are discussed and the mathematical description of the dynamic components is given. As the hydraulic pressure regulator model has great impact on model accuracy, therefore, this part of work is carried out on the experimental platform for specific hydraulic pressure regulator. It is mainly divided into two parts. First, the model of open / close solenoid valve is simplified to throttle model, and the relationship between the valve flow ratio and flow coefficient, master cylinder pressure, wheel cylinder pressure, and accumulator is deduced based on the Bernoulli equation. Second, according to the hydraulic principle, hydraulic pump and wheel cylinder characteristic curve, the static models of the pump and the wheel cylinder are obtained.The parameters of hydraulic brake system model include parameters like geometry, brake fluid parameters (brake fluid density, elastic modulus), structural parameters (quality, volume, spring stiffness, valve orifice area), and parameters to reflect the components performance (friction, damping, valve discharge coefficient, etc). How to identify the parameters of a specific brake system model is a key problem in the brake system research. This dissertation first uses actual vehicle brake circuit, vehicle dynamics simulation software and real-time simulation system to build an experimental platform for hydraulic brake system test and analysis. Based on this, the parameter identification method using the actual output and model output error sum of squares minimum criterion is discussed and the identification of the parameter results are given. Simulation and experimental results show that the brake system represent in the dissertation has high precision in the process of“Apply”,“Hold”and“Release”.Road adhesion coefficient estimation is extremely important to determine control parameters in brake control. It is an important part of vehicle state estimation. By means of a simplified hydraulic brake system model, the road adhesion coefficient estimation method is discussed based on the wheel cylinder pressure. The estimating method is certificated on the experiment platform and the simulation results show that the method is feasible and is real-time.更多还原