一种动态OD矩阵估计算法的研究及应用

OD矩阵是智能交通的重要研究领域之一,是微观交通仿真、城市交通规划、管理和控制等的关键数据.本文将微观交通仿真与交通信号机监控系统相结合,提出一种基于极大熵法的动态OD估计算法.分析路段交通流的动态变化.为提高OD估计的精度,给出一种历史OD矩阵的递推方法.仿真结果表明本文方法是有效、可行的.     

智能交通动态调度优化模型与评价方法

为了降低大城市市民出行成本,缓解公交企业运力压力,提出一种智能交通出行OD(Origin Destination,出行地和目的地)的公交调度优化算法,以公交出行OD客流预测和计划排班发车时间间隔为出发点,运用公交出行OD客流推导理论,构建智能交通出行OD的公交调度优化模型。通过获取个人OD数据,利用单条线路公交OD方法,实现全市公交OD矩阵推算。根据全市公交出行OD推算结果,求解公交调度模型,解决智能交通调度多目标规划和公交线网优化问题。通过仿真模拟试验,分析智能公交排班计划评价指标,计算车辆营运效率占比:自动排班仿真数据为79%,实际运营数据为73%;统计车辆高峰时段与全天营运车次占比:自动排班仿真数据为36.75%,实际运营数据为37.37%,满足智能公交计划排班评价指标的要求,实例证明模型和算法具有实用性和可靠性。     

微观交通再现仿真系统研究与开发

为了再现过去某段时间的交通状况,提出一个微观交通再现仿真系统,主要由车辆生成模型、OD分配模型和车辆初始分布模型组成。仿真系统对车辆仿真进行了再现分析,能够有效展示各路段上的交通流量、车辆密度、车辆的行驶速度,真实再现路段上的交通流状况。选取上海市中环路的实际采集数据进行仿真验证,结果表明微观交通再现仿真系统真实再现了交通流的时空变化。应用该系统能够为交通道路规划与管理提供技术支持,并能对各种交通参数进行比较和评价。     

基于GA-Transmodeler的动态OD矩阵估计方法*

采用系统仿真与遗传优化算法相结合的方法完成离线状态下多时段OD矩阵的估计。系统仿真旨在对多时段的动态OD矩阵实现连续动态交通分配,以得到在各个时段的OD流量对观测路段的分配比例矩阵,遗传算法则通过种群内个体的交叉、变异等遗传算子求解最优条件下的OD矩阵。仿真结果表明,这种仿真优化结合的方法能够充分体现动态交通流的延续性,且遗传算法具有较强的全局收敛性。     

交叉口车辆左转避撞行为建模与仿真

由于无法对交叉口车辆左转的各种控制策略进行实地测评, 在提出了交叉口车辆左转运动轨迹模型的基础上, 建模了两种主要的车辆左转避撞行为。采用C#语言设计开发了交叉口微观交通仿真系统, 实现了车辆在交叉口左转避撞行为的动态模拟和分析。结果表明不同交通需求状况下合理设置左转避撞行为可以有效降低车辆平均延误时间、车辆启停次数等指标适合于不同交通控制策略的模拟和评价。     

基于O-D矩阵估计的路网交通流量仿真模型

为了将交通出行需求对路网交通流量的影响进行动态的量化分析,提出了一个基于O-D矩阵估计的路网交通流量仿真模型。利用O-D矩阵估计的重力模型计算方法、复杂网络理论和路段阻抗模型,构建了路网模型;在人们出行总是选择路段阻抗最小路径的假定下,设计了出行需求的路网流量映射算法;基于离散事件仿真,在PC系统上实现了路网流量仿真系统。仿真结果表明：该仿真系统可以根据各交通子区域出行需求的变化,精确模拟路网流量和交通状态的动态演进。     

微观仿真信号交叉口车辆运动的实现与研究

主要介绍了对信号交叉口的车辆运动的微观仿真研究的思路及具体实现中遇到的问题与思考。首先概述了国内外信号交叉口控制系统和微观仿真系统的发展与现状，接着介绍该文所要实现的信号交叉口微观仿真软体的总体思路和程序流程，并针对各组成部分具体详细说明了实现的方法，进一步探讨了用计算机如何对车辆运动进行描述。最后，构想了在微观仿真平台上研究路口公交优先控制方案并展望了今后的发展。     

车辆产生仿真模型

从满足交通仿真需求角度分析了车辆产生模块建模的特点,提出了详细的车辆产生仿真模型,该模型能准确细致地仿真初始车辆产生的全过程,为交通仿真模型真实的反映路网交通状态奠定了基础.     

基于物联网视觉的大型拥堵车辆调度系统设计

针对道路拥堵车辆调度问题,设计了一种基于物联网视觉的大型拥堵车辆调度系统,分析了系统的总体结构,给出了系统的ZigBee协调器模块、车载传感器节点、图像采集处理模块以及无线传输模块的硬件结构,详细介绍了拥堵车辆调度算法流程,并给出了车辆调度最佳路径算法代码,实现了大型拥堵车辆的有效调度;实验结果说明,所设计系统可获取有效的交通车辆拥堵图像,实现交通拥堵的高效调度.     

城市交通系统的微观仿真研究

基于微观交通模型,将面向对象方法与可视化技术运用到城市交通系统的微观仿真研究中,开发了一套具有一定实用价值的交通仿真软件。仿真结果表明,车辆运行动画与人的直观交通经验一致。该方法可用于对一般的规模庞大的道路交通网络的研究。     

车联网中RFID模型

RFID模型是车联网仿真的基础和核心模型之一. 目前交通仿真模型不能满足车联网无线通信及协同交互等方面的需求、且缺少RFID模型. 为此, 建立了RFID系统的读写器和电子标签模型. 给出了读写器Agent和电子标签Agent结构及实现. 根据自动机理论, 建立了读写器、电子标签和主机之间通信时异构通信协议数据帧格式的有限状态机模型, 解决了异构数据帧统一处理问题. 作为模型应用和验证实例, 基于VC++ 2010平台, 开发了RFID交通数据采集读写器优化布设仿真软件. 结果表明, RFID模型较好地逼     

Evaluating traffic effects of a route guidance system by dynamic simulation

This paper will present how to evaluate the global traffic effect of a telematic route guidance system by using a developed simulation tool, DYNEMO. A mesoscopic model, that gathers the merits of both macroscopic and microscopic traffic models, has been applied in this tool for dynamic traffic simulation. The communication between vehicles and the telematic infrastructure inside a road network is simulated by decision points that able to give last traffic messages, as vehicles pass by them. The evaluation will be made from the traffic aspect, safety aspect and consumption as well as emission. We will illustrate the approach by using the city road network of Braunschweig in Germany as an example of implementing a kind of route guidance system like EURO-SCOUT.     

A Survey on Visual Traffic Simulation: Models,Evaluations, and Applications in Autonomous Driving

Virtualized traffic via various simulation models and real-world traffic data are promising approaches to reconstruct detailed traffic flows. A variety of applications can benefit from the virtual traffic, including, but not limited to, video games, virtual reality, traffic engineering and autonomous driving. In this survey, we provide a comprehensive review on the state-of-the-art techniques for traffic simulation and animation. We start with a discussion on three classes of traffic simulation models applied at different levels of detail. Then, we introduce various data-driven animation techniques, including existing data collection methods, and the validation and evaluation of simulated traffic flows. Next, we discuss how traffic simulations can benefit the training and testing of autonomous vehicles. Finally, we discuss the current states of traffic simulation and animation and suggest future research directions.     

道路网元胞自动机交通流仿真研究

对于交通流移动对象的模拟,论述了现有模型的不足,并提出基于道路网的元胞自动机模型（RN-CA）。该模型不仅模拟移动对象在交通流中的行为,还引入不同类型道路和车辆情况下的发车、跟车、超车和矫正模型,使模拟更精确、可靠。采用Dijkastra算法,综合考虑道路长度、车道数、流量、平均速度等因素动态计算最优行驶路径。对于行车时间预估,采用模拟加预估的方式,综合考虑当前和历史路况。为了改进系统的性能,系统采用可调节线程数目的模拟方式。     

Environmental Protection in Scenic Areas: Traffic Scheme for Clean Energy Vehicles Based on Multi-agent

The low-carbon environmental protection and traffic congestion are two primary issues that people focus on highly and need to be solved efficiently. Under the circumstance, this paper designs a transportation simulation system for clean energy vehicles in scenic area based on multi-agent. From the view of introducing clean energy electric vehicles with limited funds and unlimited funds, we investigate the optimal introduction scheme and the optimal traffic scheme of clean energy vehicles to alleviate air pollution and tourist overcrowding. Combined with the specific circumstances of a famous scenic spot in China, we conduct the simulation and propose many countermeasures and suggestions to improve traffic scheme of clean energy vehicles.     

A general framework for modeling shared autonomous vehicles with dynamic network-loading and dynamic ride-sharing application

Shared autonomous vehicles (SAVs) could provide low-cost service to travelers and possibly replace the need for personal vehicles. Previous studies found that each SAV could service multiple travelers, but many used unrealistic congestion models, networks, and/or travel demands. The purpose of this paper is to provide a method for future research to use realistic flow models to obtain more accurate predictions about SAV benefits. This paper presents an event-based framework for implementing SAV behavior in existing traffic simulation models. We demonstrate this framework in a cell transmission model-based dynamic network loading simulator. We also study a heuristic approach for dynamic ride-sharing. We compared personal vehicles and SAV scenarios on the downtown Austin city network. Without dynamic ride-sharing, the additional empty repositioning trips made by SAVs increased congestion and travel times. However, dynamic ride-sharing resulted in travel times comparable to those of personal vehicles because ride-sharing reduced vehicular demand. Overall, the results show that using realistic traffic flow models greatly affects the predictions of how SAVs will affect traffic congestion and travel patterns. Future work should use a framework such as the one in this paper to integrate SAVs with established traffic flow simulators.     

城市交通路口车辆排队系统仿真及优化

针对城市路口车辆排队系统数据不稳定、时效性差的缺点,提出了利用Flexsim仿真技术模拟路口车辆排队系统的方法.论文首先通过分析现场数据,得出车辆排队系统排队规则、车辆排队系统服务时间;然后,利用ExpertFit拟合分布软件拟合排队系统车辆到达时间间隔函数,并利用排队系统函数进行模型仿真;最后,根据模型仿真结果分析,提出优化方案.结果证明,Flexsim仿真技术能有效地模拟路口交通的堵塞情况,对改善路口交通状况有较好效果.     

基于通用触发器系统的地面交通仿真

通过分析地面交通仿真所面临的问题，构建了一个以车辆和虚拟交警为智能Agent的多Agent系统，并利用通用触发器模型解决多Agent之间的通信和协调问题，从而实现对地面交通的仿真。定量分析了引入虚拟交警和通用触发器模型后，系统通信过程中信息量的变化，同时设计了地面交通的实验模型对该仿真方法的有效性进行了验证。     

Deployment of a fully distributed system for improving urban traffic flows: A simulation-based performance analysis

Distributed, cooperative systems dedicated to road traffic self-organization are very attractive, but present some drawbacks. In particular, their cooperative nature makes them fairly inefficient when working with a reduced number of partners. This situation typically corresponds to the deployment stage, during which only a few vehicles cooperate. This time period cannot be avoided when pushing a new system to the market. We are interested in two features that are important for this kind of system: traffic jam detection and traffic alert transmission. For the first feature, we present a theoretical model that anticipates the proportion of equipped vehicles that allows an acceptable level of traffic jam detection, and we validate this model by simulation. For the second feature, we examine two ways to improve the system behaviour when the proportion of equipped vehicles is very low; their efficiency is tested through simulation. This study is innovative because the simulation platform we developed can take into account the directional behaviour of wireless communications in urban context for a low computational cost.