Modeling Research on Road Used for Virtual Experiment of Tracked Vehicle

利用Matlab编程建立了用于履带车辆虚拟试验的三维随机路面模型,并对单道路面不平度进行了功率谱估计和不同单道相关性验证.创建了适用于Adams软件履带车辆模块(ATV)路面模型的三维路面节点生成通用算法.分别分析了三维随机路面和有确定外形路面网格数量对路面模型精度的影响.在随机路面上进行车辆直驶虚拟试验,结果表明,三维随机路面的虚拟试验结果与二维随机路面的有较大不同；三维随机路面可以模拟车辆垂向和侧向两个方向载荷的作用,优于二维随机路面.     

随机路面激励下车辆系统参数对汽车行驶平顺性的影响研究

基于汽车系统动力学和随机振动理论，建立了简化的人体-座椅、车身及车轮3-DOF车辆振动模型，采用线性滤波白噪声法建立了路面激励模型，并仿真分析了常见C级路面的不平度特性。以C级随机路面激励为车辆振动系统输入，运用变步长四阶Runge-Kutta法求解了车辆系统数学模型。在时域和频域两方面，仿真分析了座椅刚度、阻尼，悬架刚度、阻尼及轮胎刚度对座椅、悬架性能的影响，以及路面不平度和车速对座椅垂向加权加速度的影响。得出了座椅加速度、悬架动挠度、轮胎动载荷功率谱密度随座椅刚度、阻尼系数，悬架刚度、阻尼系数及轮胎刚度变化的规律。     

路面国际不平度指数的两种描述及其应用

为理解和应用路面国际不平度指数,研究了路面国际不平度指数的时间域和时间频率域描述。基于路面国际不平度指数的标准车辆模型,建立了路面国际不平度指数的时间域描述和车辆模型的运动微分方程。在空间频率域,建立了路面不平度功率谱密度表示;在时间频率域,建立了路面激励功率谱密度表示。通过路面国际不平度指数标准车辆模型推导出悬架动挠度速度的频率响应表示,建立了路面国际不平度指数的时间频率域表示,分析证明了路面国际不平度指数和路面激励功率密度等效。利用美国LTPP项目实测路面不平度数据,求取了路面国际不平度指数时间域和时间频率域的结果,通过两者对比说明了国际不平度指数时间频率域描述的正确性和有效性,对实测路面不平度数据引入中值滤波可更好确定时间频率域路面国际不平度指数。     

基于增广卡尔曼滤波并考虑车辆加速度的路面不平度识别

为实现车辆在实际加减速行驶工况下路面不平度的准确识别,提出了一种考虑车辆加速度、基于增广卡尔曼滤波算法的路面识别方法.以车辆纵向加速度作为已知输入,车身垂向振动和俯仰振动响应作为观测向量,设计增广卡尔曼滤波观测器估计路面不平度信息;求取固定位移窗长度内的国际平整度指数,实现了对路面的等级分类.仿真结果表明在典型非匀速工...     

一种带新型内置悬置系统的电动轮结构研究EI北大核心CSCD

针对现有轮毂电机驱动电动轮车辆非簧载质量增加及路面激励引起的轮毂电机气隙不均匀带来的车辆平顺性和舒适性恶化的问题,提出了一种新型内置悬置系统的电动轮拓扑结构方案。此方案通过设置橡胶衬套将轮毂电机与簧下质量弹性隔离,将电机转化为与簧上质量并联的质量,同时,利用橡胶衬套吸收路面传递给电机的振动能量,减小路面激励对电机气隙的影响,改善车辆垂向动力学特性。在建立新型电动轮车辆模型和分析悬置系统参数对车辆垂向性能影响的基础上,对有、无悬置系统的两种电动轮驱动方案进行了垂向特性对比分析。结果表明:设置橡胶衬套后,簧上质量加速度、轮胎动载荷、悬架动行程和定、转子相对位移等方面均有不同程度的改善,尤其是对定、转子的相对位移量的改善最为显著。     

基于道路友好性的重载汽车悬架半主动控制研究

车辆的平顺性和道路友好性是反应车辆悬架性能的2个重要指标。为改善重载汽车在道路行驶中的友好性,基于7自由度重载汽车动力学模型,建立了半主动悬架系统的运动方程,设计了半主动悬架最优控制器,考虑路面不平度的随机激励,以车辆平顺性和道路友好性为控制目标,提出了车辆悬架的最优半主动控制策略,并且给出了详尽的推导过程。仿真分析结果表明:当汽车以20m/s的速度行驶在C级路面时,车身和驾驶室垂向加速度有效均方根值分别减少了3.42%和46.4%,轮胎对路面的破坏减少了2.10%;半主动控制悬架有效地保证了车辆行驶的平顺性,同时可减小车辆对路面的冲击作用,改善了车辆的悬架性能。     

多种加速工况下车辆悬架系统非平稳随机振动特性研究

文章研究了车辆在多种加速工况下受到路面的非平稳随机激励,以及因此产生的非平稳随机振动响应特性。利用协方差等效法和滤波白噪声法建立车辆在不同加速度下所受到的道路激励模型,采用精细积分法求解1/4车辆模型在不同激励下车轮与车身的垂向加速度响应。结果表明,车辆通过同一等级路面时,路面非平稳激励、车身和车轮垂向加速度均会随行驶加速度的增加而呈现不同比例的增大。     

路面不平度对低路堤动应力的影响研究

基于正弦函数变化的路面不平度和两自由度的四分之一车辆模型,推导出车辆随机动荷载计算公式,研究路面不平度对车辆荷载作用下低路堤动力响应的影响规律。建立车-路耦合三维动力有限元模型,计算分析6种工况下不同路面不平度时车辆随机动荷载作用下低路堤的动应力,得出低路堤动应力均随路面不平度值的增加而增大,且与车辆附加动荷载系数m近似为线性关系;提出不同路面不平度时车辆随机动荷载作用下低路堤动应力计算模型,并对比有限元模型得到的低路堤动应力与应力计算模型得到的低路堤动应力。     

基于RBF神经网络识别路面不平度的研究

针对应用RBF神经网络识别路面不平度的输入选择、输入方案确定和识别效果评价3个问题,提出了一种解决方法。对RBF神经网络和训练过程进行了分析,选择车辆可以测试的车辆响应作为RBF神经网络输入,引入正交试验设计确定RBF 神经网络输入方案,采用相关系数和均方根误差作为RBF神经网络识别效果的评价指标。通过采用车辆和路面不平度系统4自由度平面模型仿真获得车辆响应和前轮路面不平度,应用RBF神经网络对常用路面等级和常用车速行驶下某汽车的前轮路面不平度进行了识别。结果表明,所提出的方法解决了基于RBF神经网络识别路面不平度的3个问题,可以用于其它神经网络识别路面不平度。     

基于MATLAB仿真的块石减速路面设计方法研究

块石减速路面因其造价经济和减速性能良好等优点,在农村公路建设中具有广泛的应用价值。针对目前块石减速路面平整度控制缺乏标准、设计指标模糊不清等问题,提出一种基于MATLAB仿真的块石减速路面设计方法。建立基于谐波叠加法的块石路面三维建模方法和1/4车辆模型进行仿真,通过分析车辆响应与路面不平度之间的关系,提出一种参数可调,理论可靠的仿真建模途径,并得到块石减速路面的有效设计方法。结果表明,通过该方法仿真生成的块石减速路面可以达到令驾驶员主动减速的目的,减速效果良好。     

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

A model of the relationship between a vehicle wheel and the unevenness of the road surface is defined. The wheel is considered to be of circular shape. For a given form of unevenness, the excitation functions are evaluated for the individual subsystems of the dynamic vehicle model having 5 degrees of freedom. The vehicle model traverses the uneven surface at a variable velocity. The model provides for the study of the complex dynamic phenomena which occur between the wheel and the unevenness. The response of the model also includes the dynamic stress on the drive when the wheel passes over the unevenness of the road surface.     

Simulation of the Interaction between Vehicle Wheel and the Unevenness of Road Surface

SUMMARY

A model of the relationship between a vehicle wheel and the unevenness of the road surface is defined. The wheel is considered to be of circular shape. For a given form of unevenness, the excitation functions are evaluated for the individual subsystems of the dynamic vehicle model having 5 degrees of freedom. The vehicle model traverses the uneven surface at a variable velocity. The model provides for the study of the complex dynamic phenomena which occur between the wheel and the unevenness. The response of the model also includes the dynamic stress on the drive when the wheel passes over the unevenness of the road surface.     

考虑弹性支撑边界条件的电动汽车-路面系统机电耦合振动特性分析

轮毂电机驱动电动汽车的簧下质量大导致轮胎动载荷增加,并且电机电磁力和转矩波动对车轮造成电机激励,进一步加剧车轮振动引起垂向振动负效应的问题。鉴于此,考虑电机的电磁激励,建立了电动汽车-路面系统的机电耦合动力学模型,推导了弹性支撑边界条件下路面结构的模态频率和振型表达式,以及路面振动引起的二次激励。计算了简支与弹性支撑边界条件下的路面模态频率,根据频率分布进行了截断阶数选取,并分析了边界条件、电机激励和车速对路面响应的影响。在此基础上,研究了不同行驶速度、路基反应模量及路面不平顺幅值下,激励形式对汽车车身加速度、悬架动挠度和轮胎动载荷的影响。结果表明：路面不平顺幅值越小,弹性支撑对路面响应的影响越大,弹性支撑边界条件下的路面响应较小,电机激励会引起路面响应的增加;弹性支撑边界条件下,路面不平顺幅值和路基反应模量越小,考虑路面不平顺、路面二次激励和电机激励的三重综合激励对电动汽车响应的影响越大,激励形式对轮胎动载荷的影响最大,对车身加速度的影响次之,对悬架动挠度的影响最小;电机激励导致轮胎动载荷增加,对路面破坏和寿命产生的负效应不容忽视。所建电动汽车-路面系统机电耦合模型及研究思路可为电动汽车垂向动力学分析提供参考与理论支持。     

Roadway Elevation Profile Generation for Vehicle Simulation

With a simplified approach for creating road surface elevation information for simulation of vehicle vertical response to roadway unevenness, roadways for single and parallel track simulations and averaged roads for variable velocity simulation are developed. Sets of correctly chosen random roadway slopes are averaged appropriately for the variable velocity simulation. The procedure generates approximately “white” slope spectral density roadways in the frequency ranges of interest, and the elevation profiles are representative of average road profiles. The method is simple in practice yet suffices for many parameter studies of suspensions and vehicle dynamics.     

Ride quality evaluation of a vehicle with a planar suspension system

The longitudinal connection between a chassis and a wheel in a conventional vehicle suspension system is commonly very stiff than the vertical connection. Such a mechanism can efficiently isolate vibrations and absorb shocks in the vertical direction but cannot sufficiently attenuate the impact in the longitudinal direction. In order to overcome such a limitation, a planar suspension system (PSS) with spring–damper struts in both the longitudinal and vertical directions is proposed so that the vibration along any direction in the wheel rotation plane can be isolated. In this paper, the dynamic responses of a vehicle with PSS due to a single bump and random road unevenness are investigated. The ride quality of the vehicle with PSS is evaluated in accordance with ISO 2631. A comparison with that of a similar conventional vehicle is conducted to demonstrate the promising potentials of the PSS in improving the vehicle ride quality.     

基于RBF神经网络识别路面谱的新方法

路面不平度是车辆行驶中振动的重要激励。为了识别路面不平度的功率谱密度函数(路面谱),提出了一种基于径向基函数(RBF)神经网络识别路面谱的新方法。该方法以7自由度汽车振动模型为基础,以MATLAB软件仿真得到的汽车车身质心垂直加速度谱为神经网络理想输入样本,以GB7031-86建议的路面谱为神经网络理想输出样本,应用RBF神经网络建立汽车车身质心垂直加速度谱和路面谱之间的非线性映射模型。另取一组仿真得到的车身质心垂直加速度谱代入已训练好的网络进行路面谱识别。结果表明:该方法具有较强的抗噪声能力和较理想的识别精度,识别的路面谱与拟合的路面谱吻合一致。     

Roadway Elevation Profile Generation for Vehicle Simulation

SUMMARY

With a simplified approach for creating road surface elevation information for simulation of vehicle vertical response to roadway unevenness, roadways for single and parallel track simulations and averaged roads for variable velocity simulation are developed. Sets of correctly chosen random roadway slopes are averaged appropriately for the variable velocity simulation. The procedure generates approximately “white” slope spectral density roadways in the frequency ranges of interest, and the elevation profiles are representative of average road profiles. The method is simple in practice yet suffices for many parameter studies of suspensions and vehicle dynamics.     

Effect of vertical and lateral coupling between tyre and road on vehicle rollover

The vehicle stability involves many aspects, such as the anti-rollover stability in extreme steering operations and the vehicle lateral stability in normal steering operations. The relationships between vehicle stabilities in extreme and normal circumstances obtain less attention according to the present research works. In this paper, the coupling interactions between vehicle anti-rollover and lateral stability, as well as the effect of road excitation, are taken into account on the vehicle rollover analysis. The results in this paper indicate that some parameters influence the different vehicle stabilities diversely or even contradictorily. And it has been found that there are contradictions between the vehicle rollover mitigation performance and the lateral stability. The direct cause for the contradiction is the lateral coupling between tyres and road. Tyres with high adhesion capacity imply that the vehicle possesses a high performance ability to keep driving direction, whereas the rollover risk of this vehicle increases due to the greater lateral force that tyres can provide. Furthermore, these contradictions are intensified indirectly by the vertical coupling between tyres and road. The excitation from road not only deteriorates the tyres’ adhesive condition, but also has a considerable effect on the rollover in some cases.     

Characterization of Longitudinal Road Unevenness in the Light of the International PIARC - EVEN Experiment 1998

The basic model of road pavement unevenness (homogeneous random function with Gaussian distribution function and simple power spectral density function) is generalized to cover real states of roads under traffic conditions, such as: independent characterization of long and short wavelengths unevenness, and consideration of non-homogeneity including appearance of individual large imperfections. The method of estimating relevant parameters is based on the interaction coupling between the traveling vehicle and the road. To justify the need for these generalizations, summarizing results are given of the International PIARC - EVEN experiment conducted in 1998 in three world regions (Arizona, USA, Hokkaido, Japan, and Netherlands / Germany). Total 47 road sections of different technological execution and different unevenness levels were tested using DYNVIA device.     

Biodynamic responses of seated pregnant subjects exposed to vertical vibrations in driving conditions

A pregnant woman's body is a very sophisticated dynamic system that is sensitive to whole-body vibrations in a sitting posture. While much effort has been devoted to vibration effects on non-pregnant seated persons, little research has been devoted to the biodynamic responses of seated pregnant women exposed to vertical vibrations, especially in driving conditions. In this study a thorough survey of lumped-parameter models for non-pregnant seated persons is implemented. According to the literature the mathematical models adequate for representing the increase in mass due to pregnancy are proposed and evaluated systematically. On the basis of an analytical study and experimental validation, the six-degree-of-freedom model modified from the non-linear model proposed by Muksian and Nash is recommended. In addition, the recommended pregnant model is further integrated with two-dimensional half-car and three-dimensional full-car models to assess the responses of pregnant drivers or passengers exposed to vertical vibrations due to road unevenness. It is believed that the study presented in this report provides a profound understanding of biodynamic responses of seated pregnant women and that it may offer vehicle engineers a good reference in the design of vehicle suspension systems.