Comfort enhancement by an active vibration reduction system for a flexible railway car body

In order to improve the ride comfort of lightweight railway vehicles, an active vibration reduction system using piezo-stack actuators is proposed and studied in simulations. The system consists of actuators and sensors mounted on the vehicle car body. Via a feedback control loop, the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment, which is directly applied to the car body by the actuators. This bending moment reduces the structural vibration of the vehicle car body. Simulations have shown that a significant reduction in the vibration level is achieved.     

行驶质量评价指标的回顾和展望

道路作为满足公众行驶需要的一种特殊产品,其好坏的根本量度之一就是行驶质量评价指标。由于这个指标取决于道路的破损情况,因此将其与道路表面的粗糙度特征建立回归关系才方便应用。自从20世纪60年代以来,确定行驶质量指标的主要参数就不断演变。先是人工实测车辙,破损及修补面积,再是各种仪器实测的路面平整度,比如国际平整度指数,IRI。本文在大量的研究基础上,指出了现行主要参数的不足,并提出了一个确定行驶质量指标的新参数,既乘客所直接感受到的竖直方向上的加速度的变化率,JERK。     

公路卧铺客车平顺性随机输入行驶试验研究

讨论了公路卧铺客车平顺性随机输入行驶试验方法和评价标准，并通过试验来分析试验方法和评价标准，认为卧铺客车平顺性随机输入行驶试验方法与普通客车相比主要应注意正确建立坐标系，且认为ISO2631评价标准暂时不能用于严格评价卧铺客车的平顺性。     

基于遗传算法的车辆半主动悬架控制系统参数优化

遗传算法(Genetic Algorithm,GA)是一种基于自然群体遗传演化机制的高效优化算法,它能模拟自然界生物进化过程,依据适者生存,优胜劣汰的进化规则,采用人工进化的方式对目标群体进行遗传操作,不断得到更优群体。文章根据遗传算法基本思路,在MATLAB/Simulink中搭建了基于遗传算法的车辆半主动悬架参数优化模型,利用该算法对半主动悬架控制系统参数进行了优化,并对优化结果进行了仿真分析,结果表明,优化后车辆簧载质量加速度均方根值降低31.1%、悬架动挠度均方根值降低11.2%、轮胎动载荷均方根值降低7.1%,车辆平顺性得到提升。     

某乘用车平顺性调校及虚拟验证研究

基于某乘用车前期平顺性目标设定与分解,详细地介绍了其平顺性调校的方法和过程,运用主观评价手段对车辆的平顺性进行了调校,并对调校前后的参数指标建立了动力学虚拟样机。利用仿真方法展开定性验证,结果表明车辆平顺性在调校后满足前期平顺性目标,为底盘调校及悬架设计提供了较好的工程参考。     

铰接式自卸车橡胶弹簧悬架系统试验研究

采用模拟随机输入路面谱激励室内台架试验的方法,对装有新型橡胶弹簧悬架系统的某型号铰接式自卸车进行台架试验研究,以评价橡胶弹簧悬架系统的减振性能和整车行驶平顺性。试验结果表明由于橡胶弹簧悬架系统某些参数匹配不合理导致该车行驶平顺性很不理想,通过优化悬架及座椅的刚度和阻尼参数,可提高整车行驶平顺性,并给出了座椅弹簧的优化结果。     

面向平顺性仿真的越野汽车动态模型

首先根据越野汽车的结构特点和平顺性试验方法建立越野汽车静态模型;然后把平顺性虚拟测试过程视为变化的系统,从集合观点建立其动态模型,并把多种越野路面包括在模型中。测试结果表明,该建模方法可以用来表征不同越野车型随时间和空间变化的激励与响应特征,扩大了越野汽车平顺性虚拟测试系统的适用范围。     

松软路面突变性对车辆垂向振动的影响

为了在越野行驶车辆平顺性仿真系统中实时动态反映车辆的振动特性,提出了基于小波变换的松软越野路面突变性描述方法并分析突变性对车辆垂向振动的影响。通过小波变换对路面奇异点进行测定和定位,把越野车辆平顺性仿真系统看作是在有限时间内受到随机载荷激励的动力系统,分析其受路面突变载荷的车辆的垂直振动响应方差。结果表明,小波变换能较准确地判定路面奇异点并对其定位,可为越野车辆平顺性虚拟测试系统提供路面随机输入。     

基于心率变异性的乘坐舒适性评价

文章在传统乘坐舒适性评价的基础上研究心率变异性(HRV)对乘客在站姿、坐姿状态下乘坐舒适性进行评价的可行性。以某品牌纯电动公交车为研究对象,采集试验车辆选定位置处X、Y、Z三个方向的振动加速度信号,并采集受试乘客站姿、坐姿两种状态下的生理信号,并利用不同数据处理方法进行处理,最后得到站姿、坐姿状态下的对应指标如时域分析下的均方根值、HRV三角指数(HRVti);频域分析中的标准化低频分量与高频分量之比(nLF/nHF);非线性分析中的散点椭圆拟合短半轴与长半轴之比(SD1/SD2)、样本熵(SampEN),结合受试乘客主观评价得到舒适性评价。通过研究可知HRV分析,可以作为传统乘坐舒适性的评价补充。     

Dynamic ride sharing using traditional taxis and shared autonomous taxis: A case study of NYC

This study analyzes the potential benefits and drawbacks of taxi sharing using agent-based modeling. New York City (NYC) taxis are examined as a case study to evaluate the advantages and disadvantages of ride sharing using both traditional taxis (with shifts) and shared autonomous taxis. Compared to existing studies analyzing ride sharing using NYC taxi data, our contributions are that (1) we proposed a model that incorporates individual heterogeneous preferences; (2) we compared traditional taxis to autonomous taxis; and (3) we examined the spatial change of service coverage due to ride sharing. Our results show that switching from traditional taxis to shared autonomous taxis can potentially reduce the fleet size by 59% while maintaining the service level and without significant increase in wait time for the riders. The benefit of ride sharing is significant with increased occupancy rate (from 1.2 to 3), decreased total travel distance (up to 55%), and reduced carbon emissions (up to 866 metric tonnes per day). Dynamic ride sharing, wich allows shared trips to be formed among many groups of riders, up to the taxi capacity, increases system flexibility. Constraining the sharing to be only between two groups limits the sharing participation to be at the 50–75% level. However, the reduced fleet from ride sharing and autonomous driving may cause taxis to focus on areas of higher demands and lower the service levels in the suburban regions of the city.