基于MATLAB汽车主动悬架的仿真分析

机械设计制造及其自动化论文，论文编号:JX1308  论文字数:22045.页数:55

 摘     要
 悬架是汽车的重要总成之一，它保证车轮或车桥与承载系统（车架或承载式车身）之间具有弹性联系，并能传递载荷、缓和冲击、衰减振动以及调节车辆行驶中的车身位置等，对于汽车的行驶平顺性和操纵稳定性有直接的影响。
 目前，汽车上普遍采用的是由弹性元件和减振器组成的被动悬架。被动悬架由于系统参数固定，对操纵稳定性和行驶平顺性等这些相互冲突的设计要求只能选择折衷方案，这对在多变的环境中工作的汽车来说，被动悬架难以满足期望的性能要求。主动悬架能够根据路面的情况在车轮和车身之间主动及时的调整和产生所需的悬架控制力，以抑制车身的振动，使悬架处于最优减振状态，同时,达到改善汽车行驶平顺性和操纵稳定性的目的。可以说，这是未来汽车悬架发展研究的一个重要方向。因此，本论文就针对这方面的问题进行建模、仿真研究。
 本论文首先根据牛顿定理，运用车辆动力学理论，建立了被动悬架以及基于四分之一车体的二自由度主动悬架系统的动力学模型。考虑到路面扰动输入对悬架控制的重要影响，将路面输入与主动控制信号一同作为输入量，进一步简化了微分方程，将微分方程转换为状态方程的表达形式。并建立了路面输入分别为正弦信号、阶跃随机信号以及白噪声信号的路面不平度数学模型，实现仿真。同时，概述了悬架性能的三个评价指标，即车身垂直加速度、车轮相对动载荷、悬架动挠度。并通过软件Matlab7.0/Simulink构建出汽车悬架控制系统仿真模型图，其中包括路面输入模型，汽车被动悬架模型，PID控制主动悬架模型。运行仿真模型图即可实现不同路面输入信号的悬架系统的仿真。最后，根据不同控制方法下的几种不同路面激励信号，对悬架性能评价指标的仿真结果进行深入分析。
本论文可以为主动悬架的实验研究以及产品开发提供理论基础和数值参考。
关键词：车辆工程  主动悬架  MATLAB  建模  PID控制  仿真

Abstract
 Suspension is an component of the important assembly of the automobile, it guarantees to contact with a flexible between the wheels or axles and bearing system (or load-frame body), and can transfer loads、relax impulsion、reduce vibration and regulate the body position of the vehicle in traffic, and have a direct impact on ride comfort and operate stability.
 At present, vehicles generally used the passive suspension, which is consisted of the flexibility components and the shock absorber. Due to the suspension system’ parameter was fixed, it chooses compromise for the conflicting design requirements, such as the operate stability and ride comfort and so on, but as to the automobile in volatile work environment, the passive suspension is difficult to satisfy anticipant performance requirements. According to the road situation, the active suspension can adjust to and produce the necessary suspension control between the wheels and the body in a timely, which contain the body’s vibration, so that the suspension keep in the optimal damping state, at the same time, and achieve the purpose on improve the ride comfort and operate stability of the vehicle . It can be said that, this is an important direction of the development research of the automobile suspension in future. Therefore, aim at this problem, the paper put up for modeling, simulation study.
    Firstly, according to the Newton theorem, the paper use the vehicle dynamics theory, and set up the dynamics model of the passive suspension and the second freedom active suspension system based on a quarter of the body. Taking into account an important impact of the road surface disturbance to enter for the suspension control, and enter the road input and the initiative to control signals with input, as to further simplify the form of the differential equations. And translate the differential equations into a form of expression of the state equations. And establish the road roughness mathematical model of the road input signal for sine, step random and white noise signal, and achieve the simulation. At the same time, outlined the three evaluation index of the suspension performance, such as the body vertical acceleration, the relatively dynamic load of the wheel, the suspension dynamic deflection. And build the simulation model plans of the control system of the automobile suspension by the Matlab7.0/Simulink software, including the importable model of the road, the passive suspension model, the active suspension model of the PID control. And run the simulation model map to achieve the simulation of the different input signal of the suspension control system. Finally, according to several different road of the incentive signal under the different control means, and analysis the simulation results of the evaluation index of the suspension performance in-depth.
 This paper can provide theoretical foundation and numerical reference for the experimental research and product development of the active suspension.
Keywords: Vehicle engineering   Active suspension  MATLAB   Modeling 
PID control   Simulation
目  录
目录 1
中文摘要 3
Abstract 4
第一章   绪论 5
 1.1  研究背景 6
 1.2  研究的目的与意义 7
 1.3  研究的主要內容及方法 7
第二章   悬架的概述及类型 9
 2.1  悬架的概述 9
 2.2  悬架的类型 9
2.2.1  被动悬架 10
2.2.2  半主动悬架 11
2.2.3  主动悬架 12
2.2.4  各种悬架性能比较 14
第三章   悬架的系统建模与性能评价 15
     3.1  引言 15
     3.2  汽车主动悬架的工作原理 15
 3.3  汽车主动悬架的动力学模型 16
       3.3.1  常用的基本车体模型的简化及假定条件 17
       3.3.2  基于四分之一车体的被动悬架动力学模型的建立 18
       3.3.2  基于四分之一车体的主动悬架动力学模型的建立 19
     3.4  随机路面模型 20
       3.4.1  路面不平度的功率谱密度 20
       3.4.2  空间谱密度与时间谱密度的转化 21
     3.5  悬架的性能评价标准 24
第四章   主动悬架PID控制理论的研究 25
     4.1  PID控制的简介 25
     4.2  PID控制原理 26
     4.3  主动悬架系统的PID控制 27
     4.4  PID控制的参数整定 29
第五章   悬架的建模及仿真 30
 5.1  仿真环境介绍 30
 5.1.1 MATLAB的简介 30
 5.1.2 SIMULINK的技术简介 31
 5.2  主动悬架仿真控制模型的建立 32
第六章   悬架的仿真过程及分析 41
 6.1  车辆悬架仿真过程 42
 6.2  车辆悬架仿真结果分析 42
 6.2.1  不同控制方法下的簧载质量加速度的比较 43
 6.2.2  不同控制方法下的悬架动挠度的比较 46
 6.2.3  不同控制方法下的悬架动载荷的比较 49
 6.3  本章小结 53
第七章   结论 54
参考文献 56
致谢 57