Connected and Autonomous Vehicles (CAVs) Challenges with Non-motorized Amenities Environments

With the deployment of Connected and Automated Vehicles in the coming decades,road transportation will experience a significant upheaval.CAVs(Connected and Autonomous Vehicles)have been a main emphasis of Transportation and the automotive sector,and the future of transportation system analysis is widely anticipated.The examination and future devel­opment of CAVs technology has been the subject of numerous researches.However,as three essential kinds of road users,pedestrians,bicyclists,and motorcyclists have experienced little to no handling.We explored the influ­ence of CAVs on non-motorized mobility in this article and seven various issues that CAVs face in the environment.

Analysis of conflict factors between pedestrians and right-turning vehicles at signalized intersections

Due to the fact that there is no protected signal phase for right turns at most signalized intersections, the conflict between pedestrians and right-turning vehicles is one of the most common conflict types for pedestrians. A pedestrian safety analysis of the common right-turn mode at four-phase signalized intersections is presented. Relative risk is used as a measure of the effect of behaviors. The analysis mainly includes five pedestrian factors that affect the conflict process between pedestrians and right-turning vehicles. Pedestrians tend to have a higher risk of being involved in conflicts in the following six situations: crossing with others, running over the crossing, entering the intersection, being near the exit lane, crossing in the middle or at the end of a green light when the right-turn lane is shared, crossing at the beginning of a green light or red period when the right-turn lane is exclusive. It is easier for pedestrians to get priority when crossing the street in the following situations: running over a crossing, entering the intersection, being near the entrance lane, and not using the crosswalk. However, pedestrians are more inclined to yield to right-turning vehicles when pedestrians are crossing in the middle of the green light time. Some measures to alleviate the conflict are put forward according to the conclusion. Video observations also indicate that a clear pedestrian waiting area must be marked for both pedestrian safety and right-turning vehicle efficiency at major flat intersections, particularly when the arms cover the lateral dividing strips.

Investigation and Optimization of Priority for Non-motor Vehicles in the Old Urban Area of Nanchang

Under the background of"people-oriented"thought and"green transportation",the idea of"priority for non-motor vehicles"came into being,which can improve the riding environment of non-motor vehicle riders to a certain extent.According to the current situation of priority for non-motor vehicles in the old urban area of Nanchang,through field investigation,questionnaire investigation and interview,this study summarized the existing problems,and put forward optimization suggestions for these problems,in order to provide reference for areas with similar conditions.

Factors Influence Hanoians’ Choice of Non-Motorized Transport Mode to Access Bus Stations

Hanoi’s rapid urbanization has led to a surge in private vehicle ownership, particularly motorcycles, amidst inadequate public transportation infrastructure. Despite government efforts, many still prefer motorized transport, citing mobility and safety concerns, exacerbated by insufficient pedestrian infrastructure. This study examines the motivations behind this reliance on motorized vehicles, particularly motorcycles, in Hanoi. Findings reveal safety and convenience as primary factors driving motorized transport use, especially for accessing bus stations. Economic incentives could promote non-motorized travel and public transport adoption. Policy implications highlight the importance of addressing economic factors and improving access infrastructure to manage motorized vehicle reliance and foster sustainable urban mobility in Hanoi.

Delays caused by motorized vehicles unable to clear intersections in China: Graphical analysis

In many Chinese cities,motorized vehicles （M-vehicles） move slowly at intersections due to the interference of a large number of non-motorized vehicles （NM-vehicles）.The slow movement makes a part of M-vehicles fail to leave intersections timely after the traffic signal tums red,and thereby conflicts between vehicles from two directions occur.The phenomenon was analyzed graphically by using the cumulative vehicle curve.Delays in three cases were modeled and compared：NM-vehicle priorities and M-vehicle priorities with all-red intervals unable to release all vehicles,and longer all-red intervals ensuring release all vehicles.Marginal delays caused by two illegal behaviors that occasionally happened in mixed traffic intersections were also investigated.It is concluded that increasing the speed of M-vehicles leaving intersections and postponing the entering of NM-vehicles are the keys in mathematics,although they are uneasy in disordered mixed traffic intersections due to a dilemma between efficiency and orders in reality.The results could provide implications for the traffic management in the cities maintaining a large number of M-and NM-vehicles.

Vehicle conflict resolution algorithm at non-signalized crossing based on inter-vehicle communication

A vehicle conflict detection and resolution method is proposed based on the concept of vehicle infrastructure integration （VII） system to prevent vehicle accident beforehand at blind cross- ing. After analyzing traffic conflict characteristics and vehicle collision scenarios at intersection, a vehicle dynamics model and an inter-vehicle communication method are discussed. In the inter-vehi- cle communication environment, the relative relationship between two encountered vehicles are de- signed. Then vehicle conflict detection and resolution algorithms under two conflict scenarios are put forward to represent the conflict-free movements of vehicles with adjusting vehicle velocity at cross- ing. Finally, simulation studies are carried out and the results prove that the proposed algorithms are effective for vehicle conflict resolution at blind crossing.

低空空域无人机运行安全保障技术研究综述

低空空域飞行活动日趋频繁,无人机类型多样且性能差异较大,飞行过程中易与建筑物或其他航空器发生飞行冲突。为实现低空空域的规范化、安全化、精细化和智慧化管控,需不断提升保障无人机运行安全的技术手段,例如冲突风险探测、安全风险评估等。文章从无人机的轨迹预测与意图识别、低空空域飞行冲突探测、低空空域风险评估及预警告警等3方面进行了研究。首先,总结了在无人机轨迹预测和意图识别方面的研究成果和面临的问题挑战;其次,基于低空空域冲突探测形式,分析不同探测方法的优缺点;随后,围绕低空空域风险评估及预警告警技术,分析当前研究需要解决的核心问题;最后,对无人机冲突探测和风险评估技术等方面进行了展望。

基于动作条件交互的高效行人过街意图预测

城市化的进程不断加速,人车冲突问题已成为现代社会亟待解决的重大难题。复杂交通场景下,行人横穿马路行为导致交通事故频发,准确、实时地预测行人过街意图对避免人车冲突、提高驾驶安全系数和保障行人安全至关重要。本文提出基于动作条件交互的高效行人过街意图预测框架(efficient action-conditioned interaction pedestrian crossing intention anticipation framework,EAIPF)来预测行人过街意图。EAIPF引入行人动作编码模块增强多模态动作模式下的表征能力,挖掘深层骨架上下文信息。同时,引入场景对象交互模块挖掘与对象交互信息,理解交通场景中高级语义线索。最后,意图预测模块融合行人动作特征和对象交互特征,实现行人过街意图的鲁棒预测。所提出的方法在两个公共数据集JAAD和PIE上验证算法性能,准确率分别达到了89%和90%,表明本文方法可以在复杂交通场景下准确预测行人穿越意图。

基于轨迹数据的非机动车左转信号灯安全效应评估

【目的】对城市交叉口采用的左转非机动车信号灯设施进行交通安全性量化评估。【方法】提出一种基于拓展碰撞时间(extended time to collision,ETTC)指标的左转非机动车信号灯安全效应评估方法。针对现有的碰撞时间(time to collision,TTC)指标不适于评估交叉口左转非机动车冲突的问题,考虑非机动车车辆尺寸与加速度对交通冲突的影响,采用拓展碰撞时间指标,评估交叉口非机动车交通冲突。收集长沙市4个信号交叉口的视频大数据,利用视频软件Tracker提取车辆微观轨迹后,开展案例分析。【结果】左转非机动车信号灯在时间上明确了非机动车的通行权,其设置能显著降低非机动车冲突率,在平峰、高峰时段非机动车冲突率分别降低了40.11%、25.27%。在直行相位末期、左转相位即将启亮时,设置组的左转非机动车在待行区等待,冲突率降为0;而对比组近50%的非机动车违规左转,冲突严重。设置左转非机动车信号灯的改善效果随非机动车流量的增大呈先增加后降低趋势,而随机动车流量的增大呈逐步波动下降趋势。【结论】本研究揭示了非机动车左转信号灯的设置对减少交叉口交通冲突的影响,可为城市交叉口非机动车交通安全管控提供有益参考。

冲突探测与解脱机制下城市物流无人机自由飞行间隔研究

聚焦自由飞行场景,为确保城市物流无人机运行安全,需要为无人机配备安全间隔。借鉴气体模型和位置误差概率模型,提出考虑冲突探测与解脱机制的无人机自由飞行间隔综合评估模型。首先应用气体模型评估无人机冲突发生频率;接着综合考虑空中交通特性、冲突探测与解脱机制、航线结构、空中交通服务能力,计算冲突发生时碰撞概率,得到总体碰撞概率。最后,对标安全目标水平,计算城市物流无人机自由飞行所需间隔。应用该模型,针对某运行空间无人机自由飞行场景,制定所需间隔。研究结果为城市物流无人机间隔标准制定提供可行方法,同时可用于指导冲突探测与解脱机制,降低突破间隔后碰撞概率。

融合空域下基于ADS-B IN的无人机防撞研究

基于无人机未来融入国家空域系统的发展趋势,针对无人机数量增多导致与有人机之间碰撞风险增大的问题,根据ADS-B IN的优势和特点,提出了一种融合空域下,无人机利用ADS B IN进行冲突探测和解脱的模型。模型中依据飞行器的具体参数划设了有人机的安全区和保护区,并利用几何法设置潜在碰撞风险判定标准和解脱完成标准,根据最小机动和最快解脱原则,无人机在空域内进行实时探测并对可能产生冲突的有人机主动避让,在避让过程中分别考虑了速度解脱、航向解脱、速度和航向混合解脱三种解脱策略。在实际运行场景中,同时考虑了风对航空器速度和航向的影响,进行了风速修正。设置三种运行场景进行了仿真试验,仿真结果满足最低安全间隔的要求。为进一步验证模型的优势,另与传统的人工势场方法进行了仿真对比。以上两种结果均证实了模型的可靠性和优越性,未来可用于降低管制员工作负荷,提高空域整体安全性。

基于Ordered Probit模型的人车冲突安全影响因素研究

为探究和定量分析人车冲突严重程度的影响因素,通过采集3个信号交叉口的人车冲突视频数据,利用T-Analyst标定人车轨迹并计算冲突指标(PET),采用85%位累计频率曲线法划分人车冲突等级;从人、车、路及环境特征中选取10个因素作为变量,构建Ordered Probit模型,以确立人车冲突严重程度的显著影响因素,并通过边际效应定量分析不同显著因素的影响程度。研究结果表明:行人闯红灯情况、年龄、行人交通量、人行道占用情况、人行道起点终点、车辆速度变化及车流量是人车冲突严重程度的显著因素,相较于各自参考量,行人闯红灯、车辆加速通过冲突点、人行道起点及老年人造成严重冲突的概率分别增加8.2%,5.9%,5.1%,4.4%;相较于低流量的交通流,较高流量的车流和行人交通流使得严重冲突的概率分别增加3.7%,2.5%,但人行道占用使得严重冲突的概率下降6.8%。研究结果可为信号交叉口行人过街交通安全设施的设计和实施提供理论依据。

车辆轨迹数据驱动的急弯路段追尾冲突风险时空演化规律

为有效揭示急弯路段上车辆间追尾冲突风险的形成与变化态势,选取典型事故多发急弯路段使用无人机航拍等方式采集交通流数据,利用Tracker软件提取车辆轨迹信息,构建急弯路段追尾冲突后侵入时间PET判别指标,结合冲突先导车LV与跟随车FV的速度、加速度变化划分追尾冲突模式,进而界定临界冲突点、冲突风险范围及PET变化率指标DPET,运用回归分析量化LV与FV的速度、加速度、速度差及加速度差对DPET的影响,阐明临界冲突点及主要追尾冲突模式的微观变化特性及时空演化规律。结果表明:车辆追尾冲突存在空间集聚性,主要集中在入弯缓和曲线上游、曲中标志断面下游及出弯缓和曲线下游;在潜在追尾冲突的九大类别中发生频率最高的四大类冲突数量占比高达83.24%;PET在冲突临界点和冲突风险范围内均下降,导致DPET均为负值,在冲突临界点PET快速下降,其下降程度显著大于冲突风险范围;FV速度、加速度及LV、FV间速度差、加速度差四个指标显著影响追尾冲突临界点的DPET变化;T10模式(LV减速、FV加速)冲突过程中的DPET均值最小,PET序列下降最为剧烈,危险性显著高于其他冲突模式。

V2X环境下基于圆风险域的交通冲突识别模型

为提高快速路匝道区域合流冲突的识别精度,并缓解合流冲突提供决策依据,提出一种V2X(vehicle to everything)环境下基于圆风险域的交通冲突识别模型.通过V2X技术实时获取车辆位置和速度,以冲突风险时间为关键参数,分析主线车辆和匝道车辆的不同运动状态特性;引入风险域概念,结合车辆运动学,构建基于圆风险域冲突识别模型,进而通过两圆的位置关系表征两车之间的运动关系,实现交通冲突的识别;为细化冲突风险程度,采用累计频率曲线法判定冲突风险程度等级.仿真结果表明,采用冲突识别模型的识别率相比未采用时提高25.81%,说明该模型能有效识别匝道合流冲突,提高通行效率,并可为V2X环境下匝道合流车辆提供安全预警.

苜蓿叶立交交织区冲突特征及严重程度影响因素分析

为明确城市快速路苜蓿叶立交交织区的冲突特征及冲突严重程度的关键影响因素,以重庆市北环立交为研究对象,使用无人机拍摄交织区车辆自然驾驶视频。搭建基于YOLOX和Deep-SORT的车辆目标检测和追踪框架,从航拍视频中获取10483条车辆轨迹数据,根据交互车辆的相对位置提取纵向和侧向冲突样本,并基于二维拓展碰撞时间指标将冲突事件划分为轻微、一般和严重;考虑包括宏观交通流参数和车辆微观运动参数等17个解释变量,计算多元Logistic回归模型、随机森林模型和CatBoost模型的评估指标,并分别选择对纵向冲突和侧向冲突识别性能更优的模型,进一步分析影响交织区内冲突严重程度的关键影响因素。结果表明,侧向冲突是苜蓿叶立交交织区的主要冲突类型,冲突持续时间较纵向冲突更长,碰撞风险更高;一般冲突在交织区内分布范围最广,严重冲突其次,轻微冲突分布最集中,主要分布于合流三角区附近;不同解释变量对冲突严重程度的影响程度存在一定差异,纵向严重冲突与相对速度差和目标车长度等6种指标显著相关,对于侧向冲突,重要性前5的变量分别是相对速度差、平均车头间距、目标车速度、目标车横向位置及目标车纵向位置,且当相对速度超过20 km·h^(-1),车速超过60 km·h^(-1)及平均车头间距低于12 m时,侧向碰撞风险将大幅增加。研究成果可对苜蓿叶立交交织区危险驾驶行为预警系统的设计和主动交通安全管理提供依据。

城市道路中间路段人车冲突中网联预警信息对驾驶行为的影响

本文旨在研究网联预警信息对城市道路人车冲突中驾驶人行为的影响。利用驾驶模拟器设计城市道路驾驶场景与网联预警信息系统,考虑不同类型的视觉盲区,构建了6个典型的行人与机动车冲突场景。将招募的70名驾驶人划分为实验组和对照组,进行驾驶模拟器实验,采集实验过程中的驾驶人行为和车辆轨迹数据。利用生存分析法研究了不同因素对冲突过程中驾驶人避让反应时间与制动持续时间的影响,并建立面向冲突过程的人车事故风险预测模型,评估网联预警信息对驾驶行为的影响。结果表明:由公交车、路侧停车及树木与车辆等导致的视觉盲区会降低驾驶绩效,增加冲突过程中驾驶人的避让反应时间,降低制动持续时间;人行横道的存在使平均避让反应时间减少0.90 s,使平均制动持续时间增加0.41 s,并降低人车事故风险;网联预警信息可使驾驶人的平均避让反应时间减少0.52 s,平均制动持续时间增加0.40 s,使制动过程更加平稳,显著降低冲突过程中的事故风险,保障行人安全。

Conflict resolution for connected automated vehicles at unsignalized roundabouts considering personalized driving behaviours

To address the driving conflicts of connected automated vehicles(CAVs)at unsignalized roundabouts,a cooperative decision-making framework is proposed.The personalized driving preferences of CAVs are considered in the decision-making algorithm,which are reflected by different driving styles.A motion prediction algorithm is used to improve the decision-making performance.The effect of the motion prediction algorithm on the decisionmaking performance is evaluated,including the advancement of driving safety and the computational load for the hardware.The cooperative game theoretic approach is applied to the interaction modelling and collaborative decision making of CAVs.Finally,hardware-in-the-loop(HIL)tests are carried out to evaluate the feasibility and real-time performance of the proposed algorithm.

不确定情景下AGV系统调度算法的仿真平台

不确定情境下的完整自动引导车(automated guided vehicle,AGV)系统调度算法,除了要包含常见的任务指派策略和路径规划算法之外,还需要包含冲突应对策略。由于存在随机性,这样的调度算法难以从理论上分析其特性,相关研究也较少。基于离散事件仿真技术,设计并开发了一个AGV系统仿真平台,可以灵活地设置调度问题,并选择调度算法中的任务指派策略、路径规划算法和路径冲突应对策略进行仿真。该平台具有可视化的界面,可以直观地观察AGV的运行状态和调度算法的表现,也可以输出最终的仿真实验统计数据。实验表明:该平台可以准确有效地对不确定情景下的调度算法进行评估与比较。

Multi-UAVs Collaborative Path Planning in the Cramped Environment

Due to its flexibility and complementarity, the multiUAVs system is well adapted to complex and cramped workspaces, with great application potential in the search and rescue(SAR) and indoor goods delivery fields. However, safe and effective path planning of multiple unmanned aerial vehicles(UAVs)in the cramped environment is always challenging: conflicts with each other are frequent because of high-density flight paths, collision probability increases because of space constraints, and the search space increases significantly, including time scale, 3D scale and model scale. Thus, this paper proposes a hierarchical collaborative planning framework with a conflict avoidance module at the high level and a path generation module at the low level. The enhanced conflict-base search(ECBS) in our framework is improved to handle the conflicts in the global path planning and avoid the occurrence of local deadlock. And both the collision and kinematic models of UAVs are considered to improve path smoothness and flight safety. Moreover, we specifically designed and published the cramped environment test set containing various unique obstacles to evaluating our framework performance thoroughly. Experiments are carried out relying on Rviz, with multiple flight missions: random, opposite, and staggered, which showed that the proposed method can generate smooth cooperative paths without conflict for at least 60 UAVs in a few minutes.The benchmark and source code are released in https://github.com/inin-xingtian/multi-UAVs-path-planner.

考虑道路限制的建设场地内车辆调度问题研究

针对大型设备运输车辆进入建设场地后,在场内道路上的车辆调度和路径规划问题进行了研究。受场内道路宽度限制,车辆难以在同一道路上相向行驶;同时,由于不同车辆所运输的货物及运输任务的紧急程度不同,车辆的通行具有不同优先级。针对上述特性,利用时空网络技术构建整数规划模型,在考虑道路限制和不同车辆优先级情况下,对建设场地内的车辆进行调度和会车规避。模型的目标为最小化所有车辆在场内的总时间,包括行驶时间和会车等待时间;模型包含两类约束,即车辆流平衡约束和车辆会车避让约束。为快速有效地求解模型,设计基于时空网络的启发式算法得到各车辆的时空路径,为车辆的路径规划和会车避让提供指导。结合一个实际的大型风电场路网,构建多个算例,对模型和算法的有效性进行验证。结果表明,提出的算法能迅速对不同规模的问题进行求解;另外,算法可以在消除车辆时空冲突的同时,保证车辆在会车时不等待过长时间,最终的方案具有较高的车辆运输效率。