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汽车防追尾碰撞数学模型研究 总被引:10,自引:2,他引:10
为了提高车辆在高速行驶状态下的主动安全性能,研究了处于追尾行驶状态的本车与前车的运动学特征;针对前车的不同运动状态分别推导出了跟车距离的计算模型并分析了模型中3个关键参数的随机性和动态性,对制动迟滞时间提出了基于模糊推理的确定方法,对本车制动减速度和前车的运动加速度提出了比较实用的动态测算公式;另外,研究了防追尾碰撞的控制与执行,建立了动态调整安全制动停车距离的神经网络模型,提出了基于危险裕度判别的安全控制方法。 相似文献
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License plate extraction method for identification of vehicle violations at a railway level crossing
B. K. Cho S. H. Ryu D. R. Shin J. I. Jung 《International Journal of Automotive Technology》2011,12(2):281-289
The primary cause of most railroad accidents is vehicle entry into railway level crossings despite warning messages. To identify
drivers who violate railway level crossing regulations, vehicle license plate recognition can be applied at railway level
crossings. The purpose of this paper is to present an effective method for extracting the license plate region from vehicle
images taken at railway level crossings. The method proposed in this paper uses the variation in the gray-level values across
the image of a license plate. For license plate region extraction, the character region is first recognized by identifying
the character width and the difference between the background region and the character region. The license plate region is
then extracted by finding the inter-character distance in the plate region. In addition, the license plate type is identified
by the difference in the gray-level value between the background region and the character region. The proposed method is effective
in solving the current challenges in extracting the license plate region from the damaged frames of license plates issued
for domestic use, including new types of license plates. According to the experimental results, the proposed method yields
a high extraction rate of 99.5% for vehicle license plates. 相似文献
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S. -J. Park S. -W. Chae E. -S. Kim 《International Journal of Automotive Technology》2010,11(3):441-445
Neck fracture is a major cause of death in traffic accidents. This pattern of injury normally occurs in a frontal collision
or overturn of a vehicle. This study investigates the case of a neck fracture from a low-speed collision. In the examined
case, the passenger in the front seat of the car fractured his neck and died. He did not have his seatbelt on when the vehicle
slipped on a frozen road surface on a downward slope of a hill and impacted into the shoulder of the road at low speed. In
this type of collision, an occupant’s body will be impacted by the windshield or other interior trim of the car. However,
in this case, rather unusually, neither body tissue nor fiber remained although the collision involved a broken windshield.
Thus, the reason for the passenger death was unidentified. This study applied the computer simulation package Madymo for analyzing
the accident. The result of the simulation was that the passenger, who did not wear a seatbelt, moved forward due to inertia.
The upper part of the passenger then rotated and lifted when the knee contacted with the dashboard. By evaluating the structural
deformation of the vehicle at the front, we deduced that the collision velocity was 30 km/h. Through a computational experiment
that was undertaken using Madymo 7.0, NIC was estimated to be 240 m2/s2. This result far exceeded the threshold for neck injuries. In particular, in comparison with whiplash injuries, when the
passenger’s head directly impacts the roof following a rear-end collision, the bending moment through hyperextension of the
neck is greatly increased. In this study, we concluded that the manner of death was the hyperextension of the neck, as the
passenger’s head contacted the roof from underneath. 相似文献
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为实现车辆自主避撞,改善道路交通安全状况,提出一种基于线性路径跟踪控制的换道避撞控制策略。为实时确定制动和换道时机,获取跟车状态下自车和前车车速、加速度、相对距离以及驾驶人制动反应时间计算制动安全距离和换道安全距离,并在此基础上分别引入制动危险系数B和换道危险系数S评估制动与换道风险,使得车辆发生追尾碰撞的危险程度和主动干预阈值更直观。根据车辆期望横向加速度和期望横向位移的变化特性,采用5次多项式法规划符合驾驶人换道避撞特性的避撞路径。为保证换道避撞过程中驾驶人的安全舒适,采用最大横向加速度约束换道避撞轨迹。为实现对换道避撞路径的线性跟踪控制,保证车辆的操纵稳定性和横摆稳定性,基于车辆稳态动力学模型建立前馈控制,结合线性反馈控制消除换道路径的位置和横摆角偏差,修正参考路径实现直车道场景追尾避撞控制。仿真和实车交叉验证试验表明:根据车辆期望横向加速度和期望横向位移建立的符合驾驶人换道避撞特性的五次多项式换道路径与驾驶人实际换道避撞路径基本吻合,结合碰撞时间和车间时距的制动避撞控制策略能够在保证车辆行驶安全舒适性的同时有效避免车辆追尾碰撞,减少交通事故的发生。 相似文献
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《国际交通安全学会研究报告》2022,46(1):138-146
Road safety is one of the major concerns in the ever-growing traffic network. In addressing this, surrogate safety measures play a critical role in identifying collision instincts. Besides the added advantage of quantifying collision instincts in advance, surrogate safety measures have their limitations. For example, in some instances, those measures tend to show erroneous results. In this paper, a new surrogate safety measure Instant Heeding Time (IHT), is presented based on follower vehicle attention in the traffic streams. This new measure is integrated with a distance gap and the vehicles' speeds to assess probable rear-end collisions. Further, along with other safety measures, the developed safety framework is tested over a study section, with the help of trajectory datasets at three traffic flow conditions (free flow, capacity, and congested) under prevailing heterogeneous (mixed) traffic conditions. Based on the safety framework, it is observed that, in the case of free flow and capacity conditions, 23 and 55 probable rear-end collisions points are detected. At the congested conditions, no rear-end collision points are observed. Further, smaller vehicles in the traffic stream are associated with a higher number of rear-end collision instincts than other vehicle categories. The conceptualized safety framework can be applied on a real-time basis for monitoring the safety measures for vehicles in a mixed traffic stream. 相似文献
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为改善常规驾驶车辆交通流追尾碰撞交通安全状况,提出智能网联车辆(Connected and Automated Vehicles,CAV)与常规车辆构成的混合交通流车队稳定性优化控制方法。基于全速度差模型,应用集成速度与加速度的多前车反馈构建CAV跟驰模型,考虑CAV混合交通流车辆空间分布的随机性,将各类型局部车队稳定性作为优化目标,以局部车队头车速度扰动为系统输入,以尾车速度扰动为系统输出,应用经典控制理论领域的传递函数法推导局部车队稳定性约束条件;分析关于平衡态速度与CAV反馈系数的车队稳定域,以各类型局部车队能够在任意平衡态速度下均稳定为控制目标,对CAV反馈系数输出进行优化控制;设计高速公路上匝道交通瓶颈数值仿真试验,在不同CAV比例等多种条件下,分析CAV混合交通流优化控制对交通流车辆追尾碰撞风险的影响。研究结果表明:CAV混合交通流优化控制可降低车辆追尾碰撞风险,在碰撞时间阈值小于2 s时,100%比例的CAV交通流可将交通流的车辆追尾碰撞风险降低85.81%以上;在碰撞时间阈值大于2 s时,追尾碰撞风险可降低48.22%~78.80%。所提优化控制方法可有效降低CAV车队优化控制的复杂性,为大规模CAV背景下的混合交通流优化控制以及车辆追尾碰撞交通安全提升策略提供直接理论参考。 相似文献
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为弥补传统风险评价指标对相对速度较小的跟车场景危险水平评价能力的不足,减少跟车场景中追尾事故的发生,提出了跟车场景潜在风险的概念。将假定前车以较大制动减速度减速条件下的风险称为潜在风险,并构建了代表驾驶人在潜在危险跟车场景下进行避撞操作需满足的最大反应时间的参数时间裕度(TM)。由于追尾危险工况中常见采取的避撞操作可分为制动和制动转向两大类,分别对典型制动避撞过程和制动转向避撞过程进行了分析,从而推导出分别针对2种跟车潜在危险场景的TM计算方式。通过自动筛选与人工筛选结合,获得了中国自然驾驶数据库(China-FOT)中具有中国驾驶人特点的制动避撞危险工况87个和转向制动避撞危险工况40个进行分级,并基于图像处理方法提取了前车制动开始时刻的TM值,从而得到跟车场景潜在风险两级危险域的划分。结果表明:制动避撞场景下,本车车速过低和过高时,TM值的变化均不明显;而在制动转向避撞场景中,只有速度较高时阈值才保持不变。通过对正常驾驶视频的分析,引入对比组共计正常跟车制动工况163例和正常跟车转向变道工况151例的车头时距(THW)值,其统计分析结果与支持向量机分类结果均难以清晰描述跟车场景危险水平与本车速度之间的关系。为研究跟车场景潜在风险评价在自动驾驶中的应用,对于制动避撞场景,在设定TM值不变和相对速度不变的条件下,分别对基于TM的最小相对距离和距离碰撞时间(TTC)值进行了仿真,仿真结果显示,相比于TTC而言,TM的评价稳定性受相对速度影响小,在自动驾驶跟车策略开发和避免其发生责任追尾事故中有重要应用价值。 相似文献
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《JSAE Review》1994,15(4):335-340
We have studied active safety technologies from the standpoint of “collision avoidance”. This paper describes a rear-end collision avoidance system with automatic brake control, which avoids a collision to the vehicle in front caused by inadvertent human errors using automatic emergency braking. The system is comprised of four key technological elements, headway distance measurement using scanning laser radar, path estimation algorithm with vehicle dynamics, collision prediction to the vehicle in front by a safe/danger decision algorithm, and longitudinal automatic brake control. 相似文献
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为研究十字路口发生的汽车与二轮车事故场景,基于NAIS事故数据库中发生在十字路口的汽车与二轮车事故数据开展研究。选择描述十字路口事故关键参数,依据事故发生时环境照明、十字路口信号灯、汽车所在道路车道数、道路限速、汽车种类、汽车速度、汽车运动方式、第一碰撞点、二轮车种类、二轮车运动方式等参数,对事故数据进行聚类分析,得到5类主要危险场景。基于发生频率最大和骑车人死亡风险最高的场景具有危险场景代表性,最终得到2类十字路口汽车与二轮车的典型事故场景。为十字路口汽车与二轮车的冲突消解、避撞策略研究提供参考。 相似文献
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按照我国乘用车追尾碰撞燃油系统安全法规,针对某款乘用车建立有限元模型,并进行追尾碰撞仿真研究,分析验证其燃油系统的安全性。仿真结果为今后的汽车追尾碰撞仿真及尾部耐撞性研究提供了借鉴。 相似文献
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长江三角洲地处长江和钱塘江与东海的入海口,水域环境复杂,气象条件恶劣。大型公路桥梁是长江三角洲区域道路交通网中的重要通道,对减少区域间行车时间、促进区域经济发展起着重要的作用。因此,长江三角洲区域大型公路桥梁的交通安全研究具有重要的现实意义。基于苏通大桥通车以来的交通事故资料,对事故的时空分布、事故形态、车辆类型、天气状况等多角度进行了分析。分析得出,交通高峰时段是交通事故高发时段,周五事故最多,2月、9月、10月是事故高发月,事故类型主要是撞物和追尾,事故车型以轿车为主,雨天事故率最高,事故原因与车流、天气、人的失误及车辆自身性能有关,并提出一些改善建议。研究结果为大桥管理部门制定行之有效的预防控制策略、减少交通事故提供了一定的理论依据。 相似文献
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市场上汽车和挂车后下部防护装置多为刚性连接,当发生车辆追尾碰撞时,不能有效保护乘坐人员的安全,屡屡发生小车钻进大货车尾部伤亡事故.本文目的是提供一种汽车和挂车后下部柔性防护装置,克服已有汽车和挂车后下部防护装置缺点和不足,使汽车发生追尾碰撞时避免发生伤亡事故.此后下部防护装置不仅仅是保护追尾的小车,同时也保护了货车自身... 相似文献
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高速公路的事故类型中追尾碰撞占了很大的比例,因而开发车辆防追尾碰撞安全系统是非常必要的。文章分析了影响行车安全的各种因素,建立了安全车距数学模型,利用现代技术,构造了一种车辆防追尾碰撞安全系统。指出此安全系统能减少由于驾驶员分心和疲劳等原因导致的交通事故,最大限度地提高车辆行驶的安全性。 相似文献