【作者】 薛长久；

【导师】 刘顺安；

【作者基本信息】 吉林大学 ， 机械电子工程， 2008， 硕士

【摘要】 本文结合吉林大学“985工程”二期汽车工程科技创新平台建设项目,就越野车主动悬架系统及其控制策略进行深入研究。论文提出基于伺服阀控伺服液压缸的液压主动悬架系统,建立了1/2车四自由度主动悬架系统的机械系统动力学模型和液压伺服系统动力学模型。综合考虑主动悬架系统各种控制方法,应用控制系统仿真软件Matlab6.5+Simulink,分别对最优控制、轴距预见控制和轴间预见控制电液主动悬架系统进行了仿真分析。仿真结果表明:最优控制电液主动悬架系统可有效的降低车身加速度,悬架动挠度和轮胎动位移,使车辆行驶平顺性和操作稳定性得到改善,从而验证了所提出电液主动悬架系统方案的可行性;轴距预见和轴间预见控制与最优控制相比较,前轮部分基本没有变化,后轮部分的性能有进一步的明显改善,并且轴间预见控制改善的效果更加明显。同时,运用多学科仿真软件AMESim分析了时变因素及模型简化时一些被忽略的非线性因素对主动悬架系统性能的影响。最后,在多功能液压实验台上进行了伺服阀控制液压缸实验,主要对伺服阀的空载流量特性和液压缸的位移动态响应特性进行了实验,实验结果表明,本文采用的伺服阀控液压缸结构能够满足本课题对主动悬架执行机构的要求。更多还原

【Abstract】 To maintain a good stability of off-road vehicle which is running when the road bumps. So we hope that the suspension of off-road vehicle not only can lower and make automobile possess good handing stability and ride comfort when it runs along straight line, speed up, brakes and turns, but also can improve the pass ability. And it should have an additional function that adjusts the height, to adapt to the need of transportation and battle.The suspension system is one of the most important devices of automobile. It links the vehicle body and wheel flexibly, in order to achieve the goal that make the vehicle running normally ,the suspension transfers the force and the moment between vehicle body and wheel, and mitigate the body vibrancy that is brought by impact force. It has been proved that the choice of suspension structure not only determine the pass ability, but also is subjected to the stability of steering. So the significance of designing excellent suspension system is very important. Now the researches into active suspension focus on two fields, one is the control theory and the other is the actuator, adopt different math models and control theories, to attain a good controlled effect.This dissertation mainly combined the Jilin University 985 automobile innovation project "The research on large working space of active and semi-active suspension ", It mainly made research into the active suspension control theory of off-road vehicle.Below are the main jobs of this dissertation:1 .This dissertation advances that using the technology of active-suspension on the off-road vehicle, and take the cylinders controlled by the electro-hydraulic servo valve as the actuator, And the active-suspension hydraulic servo system is designed according to the traits of suspension system of off-road vehicle and the variety of road, and fix on the primary parameters of hydraulic servo system and choose the primary elements with correlative technical parameters according to the structure coefficient of a kind of heavy off-road vehicle.2. The mathematical model for active suspension system of off-road vehicle is established, and then compute the transferable functions based on the parameter that acquired in chapter three, and establish the road surface model with filter white noise as the input.3. Do some research on the influence of factor change with time to the active suspension system. The factor includes road surface、speed、load and so on. Through analyzing the performance index curve through simulation, though factor change with time influence the system a little, all are controlled under the perfect range, this also show that the validity of using active control to the suspension.4.Generally considering characteristics of researching system and all kinds of strategies, mainly do some researches on optimal control and part preview control base on optimal theory, determine the controllable and observable facet of system, and systemic performance index is expressed with secondary model, calculate the matries Q、R、N with the motorial equation, figured out the suspension model based on full states feedback, build the performance function under the primary abilities, and get the control function U = -KX , At the same time respectively do some research on two ways of control which are wheelbase preview control and axial middle preview control, ratiocinate the state equations of different control ways.5.Use Maflab/Simulink to establish the simulation model of passive suspension and optimal active suspension based on the half of vehicle, and attain the active suspension simulation model of wheelbase preview control and axial middle preview control through do a little modification on the latter. Analyzing the performance index curve through simulation, we can know that use of optimal control hydro-electric active suspension in off-road vehicle brings a perfect result. the body acceleration、suspension working space、dynamic tyre displacement are all improved, able to ensure the need of stability of steering and pass ability of the vehicle. And wheelbase preview control and axial middle preview control improve the performance of latter part more efficiently.6.Do some experiments about cylinders controlled by the electro-hydraulic servo valve on the multifunctional hydraulic test bench, mainly research on flux without load and dynamic response of displacement of cylinder, the results of them indicate that cylinders controlled by the electro-hydraulic servo valve this dissertation used can satisfy the need of active suspension actuator of this project.更多还原