既有公路桥梁不同车辆荷载连续到达过程模拟

车辆荷载是公路桥梁基本可变荷载,在各种组合中占很重要的地位.在分析评述目前国内外关于车辆荷载模型研究的基础上,依据我国现有的车辆荷载统计资料,假定车辆匀速通过桥梁,视行驶在桥梁上的n个车辆为一个车队,以截尾概率分布控制两个连续到达问距的最值,进而采用卷积方法来确定,n个不同连续到达概率密度函数.该方法可以考虑公路桥梁上的交通状况,确定不同跨径桥梁上行驶的最大车辆荷载数目,为建立合理的车辆荷载效应模型奠定了基础.     

一些常用的车头时距分布所对应的到达分布

车头时距分布和到达分布是交通流理论中两个重要的分布。对同一交通流，这两种分布是互相对应的，这种对应关系是很有实用意义的。但由于具体的时距分布的对应到达分布不易推出，至今仍缺乏这方面系统的论述。本文试图做此工作。     

基于抽样车辆轨迹数据的信号控制交叉口排队长度分布估计

排队长度是评价信号控制交叉口运行状态的重要参数之一。现有大多数基于抽样车辆轨迹数据的排队长度估计方法可以实现周期级排队长度估计,但是需要信号配时、渗透率或车辆到达分布等实践中难以获取的输入信息。此外,这类方法在低渗透率条件下往往难以确保估计结果的准确性和可靠性,极大地限制了其实用性。因此,提出一种抽样车辆轨迹数据驱动的时段级信号控制交叉口排队长度分布估计方法,可不依赖任何交通流理论模型和前述输入信息实现排队估计。首先,通过理论推导可以证明时段内抽样车辆的停车位置分布和排队长度分布之间可互相转化;然后,提出一种扩展的核密度估计方法来拟合并平滑抽样车辆停车位置分布,从而有效地适应不同日期和周期的轨迹叠加所带来的波动,提高方法的适用性;最后,基于前述推导和拟合的停车位置分布实现时段排队长度分布、平均排队长度和百分位排队长度估计。分别采用仿真和实证数据对上述方法进行验证和评价。结果表明,通过叠加5 d相同时段的抽样轨迹数据,15 min的平均排队长度估计误差仅为1.59 veh,相对误差仅为9%。同时,面向不同分析时长,只要给定超过100 veh抽样车辆的观测样本,无论渗透率高低,所提出的方法在定时或自适应信号控制交叉口都可实现时段排队长度分布的准确估计,其成果可进一步用于信号控制交叉口运行可靠性评估以及多时段定时信号控制的鲁棒优化。     

单一路径下基于固定到达时间的最优出发时间分布研究

针对动态交通分配领域动态OD难以准确预测的问题,根据不同目的出行的时间分布特征,建立基于出行类别的DTA研究新框架,并就此框架中基于固定到达时间的DTA子课题,研究单一路径下系统最优的出发时间分布问题。首先分析出行者费用的表示方法,然后结合Greenshields交通流模型,给出系统最优的出发时间分布的求解方法,最后设计实例探讨出行人数、路段长度以及费用参数比变化对最优出发时间分布的影响。本研究对制定错时上班、拥挤收费、流量控制等动态交通管理措施具有实际参考价值。     

基于高空视频图像的山地城市信号交叉口到达车辆运行特征分析

为明确山地城市信号交叉口到达车辆的运行特征及其影响因素,通过无人机采集4个位于山地城市的道路信号交叉口的高空视频图像数据,利用基于DataFromSky云平台的AI视频分析技术,获得车辆运行参数。基于车辆运行时空图,得到了交叉口直行道停止线前车辆停滞延误特征、停止线位置车头时距和车头间距统计特征,分析车头间距、停止线截面处速度及道路平均坡度之间的相关性。结果表明：不同路段同一排队位次和同一路段不同排队位次的车辆运行特征均有所不同,排队位次越靠前的车辆,停车点分布区间越集中,下坡路段整体停车位置分布范围比上坡路段大;无论是上坡、下坡,还是缓坡,排队位次越靠前的车辆停滞延误分布范围越大,而靠后的车辆停滞延误分布范围小,最大值出现在下坡路段;不同路段类型车头时距分布均集中于1.5 s,上坡路段的车头时距离散程度最大,但峰值比下坡路段和缓坡路段小;不同路段类型的车头间距分布均集中于10 m,上坡路段和下坡路段车头间距分布出现左偏现象,而缓坡路段车头间距分布更为集中;车头间距在上坡、下坡和缓坡路段均和车辆经过停止线位置处时的速度存在较强的正相关性;道路平均坡度与相邻2车车头间距存在正相关性。     

用于城区交叉口闯红灯预测的车辆轨迹特征参数分析

通过对比闻红灯预测算法的性能,选择出用于区分车辆走、停行为的车辆轨迹特征参数.为实现对交叉口车辆闯红灯行为预测,根据闯红灯车辆为在红灯亮起后通过停止线的车辆这一定义,提出闯红灯预测算法的两个主要功能:估计车辆到达停止线的时刻;预测车辆到达停止线后的走、停行为.研究结果表明:在速度、加速度、行驶时间和车头时距4个物理量中...     

信号控制交叉口实时延误计算与仿真研究

信号控制交叉口实时延误计算模型是实时自适应交通控制系统核心模型之一。在HCM2000中提出的延误模型的基本假设决定了其在计算实时延误方面的局限性。根据车辆延误产生的基本原理，建立了基于上、下游检测器数据实时车均延误计算模型，并对模型进行了平滑处理。Vissim仿真结果显示，在不同流量的情况下，笔者提出的模型比HCM的延误模型的计算结果更能反映真实延误值随车流量的波动而变化的趋势。仿真还发现，以2个周期为单位经移动平均处理后，模型计算结果与真实值吻合程度较好。最后，对模型的适用条件进行了分析。     

交叉口进口段车辆折算系数研究

采用交通渠化后引起了城市道路部分路段（交叉口进口段）的交通流特性有别于普通路段,针对这种变化,采用1种以路段通行能力为等价标准来计算车辆折算系数的方法,并通过实例进行了验算。推荐交叉口进口段的大型车车辆折算系数为3．0。     

基于申请通行记录的桥梁超限车辆荷载统计模型

根据广西区申请通行的超限车辆数据信息,基于概率统计理论,采用双峰正态分布和对数正态分布建立了该区五轴和六轴超限车辆总重和轴距的概率分布模型;根据一元正态线性回归理论,建立了总重与轴重的线性回归模型;分析了超限车辆总重和轴距之间的相互关系。根据建立的超限车辆荷载模型,采用蒙特卡洛(Monte Carlo)法各随机生成了10 000辆五轴、六轴超限车辆,通过对比随机生成的超限车辆与实际超限车辆对中小跨径简支梁桥产生的跨中最大弯矩效应,验证了按照本文方法建立的超限车辆荷载模型用以模拟实际超限车辆的可行性,同时也为五轴、六轴超限车辆过桥时桥梁的安全评估提供了基础数据。     

车辆荷载中车辆允许通过总重值的研究

本文通过对107国道实际运行线路车辆进行调查,统计分析了车辆的交通量、总重、轴荷分布及轴距等特征。以统计值为依据,选取两轴车进行研究,考虑两轴车以不同车间距组成的车队形式,根据其计算效应与公路设计荷载效应相等的原则,给出了两轴车总重的计算值,并通过比较跨中弯矩效应所得总重值与支座反力效应所得总重值,得出与支座反力效应相等时所得的车总重值为车辆允许通过总重值。同时,通过计算发现,同类型车辆以不同车间距组成的车队通过不同跨径的桥梁时,除个别区段外,车辆允许通过总重值随跨径的增大基本呈下降的趋势;对于同一桥梁跨径而言,该车队组合方式中车辆的允许通过总重值则随着车间距的增大,车辆总重呈逐渐增大的趋势。     

Evaluation of detection sensitivity and count performance of advanced vehicle detection technologies at a signalized intersection

This article evaluates the stop-bar detection and count performance of three advanced vehicle detection sensors under various environmental conditions at a signalized intersection. Continuing advancements to vehicle detection technologies and improvements to their detection capabilities to overcome issues from impacting conditions necessitates testing the performance of new and upgraded sensor products to evaluate their performance and identify the most suitable products for various climates and weather conditions. The three evaluated sensors were Autoscope Encore video, Iteris Vantage Edge 2 video, and Wavetronix SmartSensor Matrix microwave sensors. The three sensors performed with high detection sensitivity during ideal environmental conditions with up to 99.9% detection accuracy levels and are suitable for traffic monitoring centers that rely on remote access to the monitored sites and the collected data. However, they were affected by some extreme adverse weather conditions, mainly daytime and nighttime snow, daytime fog, dawn lighting, and strong winds (for high mounted devices). The selection of a sensor product will depend on the type of application and the priority given to the type of traffic data being collected. Overall, the Iteris video sensor performed with the highest detection sensitivity levels, with the Wavetronix Matrix microwave sensor performing similarly under most conditions (14 of 19 evaluated conditions). Autoscope video provided the highest count accuracies and also provides a much broader data collection capability. The results of this study will help transportation agencies in selecting suitable vehicle detection sensor technologies for future installations within their jurisdiction and improved data collection.     

A comparative study of equivalent modelling for multi-axle vehicle

In this paper, equivalent modelling methods of a multi-axle vehicle are presented and compared. Firstly, for the sake of comparison, a single-track model of a three-axle and a two-axle vehicle is developed, and then existing equivalent modelling derivations are presented and discussed. Next, the proposed model-based dynamic equivalence of force/moment at the centre of gravity (CG) is introduced and optimised. It represents the approximately equivalent steady-state and transient response of the yaw rate and side slip angle, which allows different cornering stiffness on the central and rear axle. Finally, to demonstrate how the proposed method is advantageous to the other equivalent models available in the literature, different simulation cases are compared in the dimension of time-domain, eigenvalues characteristics and frequency-domain. Furthermore, the proposed method is extended to any multi-axle vehicle configurations and a general expression is formulated.     

An optimal torque distribution control strategy for four-independent wheel drive electric vehicles

In this paper, an optimal torque distribution approach is proposed for electric vehicle equipped with four independent wheel motors to improve vehicle handling and stability performance. A novel objective function is formulated which works in a multifunctional way by considering the interference among different performance indices: forces and moment errors at the centre of gravity of the vehicle, actuator control efforts and tyre workload usage. To adapt different driving conditions, a weighting factors tuning scheme is designed to adjust the relative weight of each performance in the objective function. The effectiveness of the proposed optimal torque distribution is evaluated by simulations with CarSim and Matlab/Simulink. The simulation results under different driving scenarios indicate that the proposed control strategy can effectively improve the vehicle handling and stability even in slippery road conditions.     

An approach for the validation of railway vehicle models based on on-track measurements

This paper proposes an approach for the validation of railway vehicle models based on on-track measurements. The validation of simulation models has gained importance with the introduction of new applications of multi-body simulation in railway vehicle dynamics as the assessment of track geometry defects, the investigation of derailments and the analysis of gauging. These applications are not only interested in qualitative predictions of the vehicle behaviour but also in precise quantitative results of the safety and comfort relevant vehicle responses. The validation process aims at guaranteeing that the simulation model represents the dynamic behaviour of the real vehicle with a sufficient good precision. A misfit function is defined which quantifies the distance between the simulated and the measured vehicle response allowing to evaluate different models at different running conditions. The obtained modelling errors are compared to the measurement uncertainty estimated for one vehicle using repeatability analysis.     

A study of the environmental impacts of intelligent automated vehicle control at intersections via V2V and V2I communications

This article presents a novel intersection traffic management system for automated vehicles and quantifies its impact on fuel consumption and greenhouse gas emissions of CO₂ relative to traditional traffic signal and roundabout intersection control. The developed intelligent traffic management (ITM) techniques, which are based on a spatiotemporal reservation scheme, ensure that vehicles proceed through the intersection without colliding with other vehicles while at the same time reducing the intersection delay and environmental impacts. Specifically, the spatiotemporal reservation scheme provides each vehicle a collision-free path that is decomposed into a speed profile along with navigational instructions. The integration of the developed microscopic traffic simulator with instantaneous emission model, provides improved assessments of the environmental impact of traffic control strategies at intersections. The simulator architecture integrates several ITM algorithms, vehicle sensors, V2V/V2I communications, and emission and fuel consumption models. Each vehicle is modeled by an agent and each agent provides information depending on the specific vehicle sensors. The ITM system is supported by V2V and V2I communications, allowing the exchange of information among vehicles and infrastructure. The data include the estimated vehicle position and speed. Compared with traditional traffic management techniques, the simulation results prove that the proposed ITM system reduces CO₂ emissions significantly. The research also shows that these reductions are more significant when the traffic flow increases.     

Dynamic model for ride comfort evaluations of the rubber-tired light rail vehicle

The dynamic model was developed to evaluate vibration accelerations and ride comforts during the running of the Korean-standardised rubber-tired light rail vehicle. Ride comfort indexes were analysed and tested in accordance with UIC 513R by using the dynamic model and the actual vehicle in the test track. Based on the comparisons between analysis results and test results, the validity of the developed dynamic model was evaluated. It was verified whether or not the developed Korean-standardised rubber-tired light rail vehicle met the specified target specification on ride comfort. In addition, the influence of the wearing of guide wheels on ride comfort was estimated.     

汽车车门综合耐久试验台研制

介绍了一种乘用车车门的耐久试验台架,它以一台工业控制计算机为上位控制单元,以一台可编程控制器(PLC)作为下位控制单元。该设备能够实现对试验条件或工况的人-机交互设定;该设备中采用了小型机械手来开,关门锁,它能完整地模拟乘员上下车开关车门动作的全过程。     

某型矿用胶轮车动力源匹配的研究

随着矿山机械技术的不断提高,在矿山巷道的底板上,液压机械传动防爆无轨胶轮车被大量用来进行运输工作。然而,运输和自卸之间动力源的匹配应加以改善。本文中,在特定类型的防爆胶轮车的基础上,从上述问题出发,通过优化匹配变速箱和匹配动力源,有效提高了防爆无轨胶轮车的动力性能,验证了采用在折中匹配的基础上使用液力机械分流变矩器,以及修正变速箱换挡规律来提升柴油防爆胶轮车的动力性能的方案是合理有效的。     

越野汽车TCS冰雪道路试验研究

针对自主开发的越野汽车牵引力控制系统（TCS）进行了冰雪路面加速道路试验研究，完成了实际“驾驶员-车辆-道路”闭环环境下的TCS的软、硬件匹配。试验结果表明：牵引力控制系统能够有效消除驱动轮过度滑转，显著改善汽车的加速性和方向稳定性。     

Optimal controller design for a constrained polynomial vehicle system with an input-state linearized model

This paper presents a new controller design method based on a data-mining polynomial algorithm. We show application of a polynomial data-mining algorithm, where an input-state linearized polynomial vehicle model is developed for very low speed operation and, without introducing any processes with fudge factors, control inputs of a nonlinear system are obtained in the original coordinates. We verify the developed modeling method and controller design method through numerical experiments.