Injury analysis of pedestrians in collisions using the pedestrian deformable model

Vehicle safety has become the most important issue in automobile design. However, all efforts to improve safety devices focus on enhancing safety features for occupants. Notably, pedestrians are the second largest category of motor vehicle deaths, after occupants, and account for about 13 percent of motor vehicle deaths. It is essential to design pedestrian-friendly vehicles and pedestrian protection systems to reduce pedestrian fatalities and injuries. To effectively assess pedestrian injuries resulting from vehicle impact, a deformable pedestrian model must be developed for vehicle-pedestrian collision analysis. This study constructs a pedestrian-collision numerical model based on LS-DYNA finite element code. To verify the accuracy of the proposed deformable pedestrian model, experimental data are used in the pedestrian model test. This study applies the proposed model to analyze the dynamic responses and injuries of pedestrians involved in collisions. The modeled results can help assess vehicle pedestrian friendliness and assist in the future development of pedestrian-friendly vehicle technologies.     

基于EEVC要求的行人碰撞试验台的研制和评估

基于EEVC/WG17制定的行人碰撞保护试验标准,开展了行人模块碰撞试验台的研制工作。文中介绍了该试验台的工作原理和各个功能模块的设计,并利用该试验台进行了行人头部模块和下肢模块碰撞试验,从能量、控制精度和试验可重复性等方面对其试验能力进行了初步评估。试验结果表明,该试验台满足EEVC制定的相关试验要求,可用于行人碰撞保护的研究和设计开发。     

国内乘用车对行人下腿碰撞保护现状

为研究我国国内乘用车对行人下腿型碰撞保护现状,文章以35款国内车型下腿型碰撞试验为基础,对试验结果数据进行了数据分段统计,并根据试验条件对结果数据进行了分析,从数据整体分布、车型特点及碰撞区域特征3个方面展开论述,提出了国内车型在改善行人下腿型碰撞保护性能方面亟需解决的问题和应当深入研究的方向。最后对行人下腿型碰撞保护试验的发展趋势进行了展望。     

行人保护小腿冲击器有限元模型开发

针对TRL公司开发的行人保护小腿冲击器,建立了有限元模型.通过EEVC WG17规定的静态、动态标定试验及台架试验,进一步证实了该模型在高速碰撞下的精度,可用于行人保护的开发设计.     

行人保护下腿碰撞器模块分析

行人保护项目是世界范围内的一个安全课题,已越来越多地受到人们的关注。下腿碰撞是行人保护评价的重要内容之一,而下腿碰撞器模块直接影响评价结果。文章介绍了当前世界上的3种下腿碰撞器模块,分析了各自的结构特点和应用,总结了3种下腿碰撞器模块对车辆行人保护评价的差异性,对我国刚刚起步的车辆行人保护项目的研究和开展提供了一定的借鉴。     

行人头部伤害与头部碰撞试验方法的相关性分析

本文通过对行人交通事故数据的统计分析,讨论造成行人头部伤害的原因与规律,并对现行的头部模块碰撞试验方法与行人交通事故的相关性进行了分析与讨论。结果表明,碰撞前行人的运动状态对碰撞结果有显著影响,目前EEVC头部模块试验方法中规定的碰撞方向与实际行人碰撞事故中行人头部的碰撞方向存在较大差异;行人头部与风档玻璃、A柱区域以及地面发生碰撞的可能性均比较大,所以有必要通过进一步的试验研究,分析头部与这些区域发生碰撞的规律,并将其纳入头部模块的碰撞试验中。     

行人保护法规现状及发展趋势

随着汽车保有量不断增加,交通事故中行人受到伤亡也在不断增多,因此各国都在加强汽车对行人碰撞保护的研究。文章在介绍各国行人保护法规现状的同时,对各国行人保护法规的试验条件及性能要求进行了比较,并对行人保护法规的发展进行了分析,指出我国应综合国外在行人保护方面取得的成果,逐步提出适合我国国情的行人保护要求,减少行人在交通事故中受到的伤害。     

行人-汽车碰撞试验腿部模块的可变形膝关节参数设计

根据行人-汽车碰撞中对行人腿部碰撞保护相关技术法规的要求,针对行人下肢的损伤机理,分析了腿部可变形膝关节部件的设计方法。通过力学模型的建立和分析,提出了确定膝关节部件结构类型、尺寸和材料的力学计算方法以及部件标定试验验证方案。经算例和部件的标定试验验证,该设计方法满足EEVCWG10的弯曲部分技术要求,可变形膝关节设计原理和分析方法可以为其他行人腿部模块技术规范中的部件设计提供参考。     

Optimizing the shape of a bumper beam section considering pedestrian protection

This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts. An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.     

Optimum SUV bumper system design considering pedestrian performance

Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees. Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed, which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method, the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis, which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced.     

Evaluation of a brake assistance system (BAS) using an injury severity prediction model for pedestrians

Through the years, traffic engineers and researchers have developed a variety of countermeasures to enhance pedestrian safety. Pedestrian-vehicle collisions are regarded as the most serious type of accident since they incur high fatality rates. A fundamental concept in developing effective countermeasures is to analyze pedestrian-vehicle collisions scientifically, which can identify the causes of accidents and accident severity. The objective of this study was to investigate the pedestrian safety benefit of the brake assistance system (BAS) and a functional requirement associated with BAS, namely the time needed to safely detect a pedestrian ahead. An injury severity prediction model for pedestrians was developed to systematically evaluate the BAS in this study. Ordered multinomial logistic regression analysis was used to establish a statistical model capable of predicting pedestrian injury severity. In addition to vehicle characteristics, collision speed and pedestrian characteristics were used as independent predictor variables. The outcomes of this study would be useful in directing the development of safety policies and technologies associated with pedestrian safety.     

Characteristics of collision damage mitigation braking system for pedestrian protection

The vehicle travel velocity at pedestrian contact is considered to be an important parameter that affects the crash outcome. To reduce vehicle/pedestrian impact velocity, a collision damage mitigation braking system (CDMBS) using a sensor for pedestrian protection could be an effective countermeasure. The first purpose of this study is to clarify the relation between vehicle travel velocity and pedestrian injury severity due to differences in pedestrians’ ages in actual traffic accidents. The accident analyses were performed using vehicle-pedestrian accident data in 2009 from the database of the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. The result revealed that the fatality risk became higher with the increase in vehicle travel velocity. The second purpose of this study is to determine the safety performance of production vehicles equipped with the CDMBS for pedestrian protection. It was found that the CDMBS was highly effective in reducing the impact velocity from 50 km/h (vehicle travel velocity) to below 17 km/h, that could result in a significant decrease in fatality risk to be 2% or less. Additionally, the authors investigated a detectable zone with respect to a pedestrian’s position in relation to the vehicle. It was shown that the detectable zones for production vehicles tested were limited to be inside the vehicle front width.     

无灯控行人过街元胞自动机交通模型研究

以无灯控行人过街对交通流影响为分析目标,在综合考虑行人穿越行为及车辆行为的基础上,建立了相应的行人及车辆元胞自动机模型规则,尤其是在模型中提出了行人等待区的概念及基于等待区内有无行人的车辆行为规则。以上述模型为基础,通过对不同行人产生概率及速度快的行人比例情况时路段交通流演化趋势进行了仿真。     

路段行人过街设施的合理间隔

通过对路段行人过街设施的合理间隔进行分析,发现如果路段行人过街设施间隔过大,会导致行人绕行距离过长,行人乱穿道路的现象加剧;如果过小,则车辆行驶时频繁启停,行车延误增大。以行人延误和机动车延误之和最小建立目标函数,求解得到行人过街设施的合理间隔。路段行人过街设施的合理间隔与行人交通量、机动车交通量、路段长度以及行人过街宽度有关,充分考虑行人过街设施设置的各种影响因素。路段行人过街设施依据合理间隔进行设置,可以有效降低行人和机动车延误。     

基于多特征融合的行人意图以及行人轨迹预测方法研究

行人作为重要的交通参与者,其行走意图和轨迹预测对智能驾驶汽车的决策规划具有重要意义。基于注意力机制增强的长短时记忆(Long Short-term Memory,LSTM)网络,设计一种多特征融合的行人意图以及行人轨迹预测方法。该方法通过融合行人骨架和头部方向特征,以加强行人运动特征的表达,并将融合特征作为意图预测网络输入,继而得到行人意图;由于行人运动具有不确定性,将行人意图预测类别和历史轨迹坐标的联合向量作为行人轨迹预测网络的输入,以期生成更为精确的轨迹预测结果。此外,在轨迹预测网络中引入注意力机制,以加强LSTM对各个时刻编码向量的有效利用,从而提高网络的行人轨迹预测性能,并基于Daimler数据集进行训练及验证。研究结果表明：所提出的多特征意图预测方法准确率可达96.0%,优于基于骨架单特征的意图预测网络;在预测时域为1 s的情况下,预测轨迹的位置均方根误差为347 mm,相较于恒速度(Constant Velocity,CV)模型、交互多模型(Interacting Multiple Model,IMM)、常规LSTM等基线方法均有明显的提升;在实际场景分析中,提出的方法可提前0.56 s识别行人的转弯意图,可为智能车辆的决策模块提供有益线索;提出的方法能够有效降低行人意图转变过程中的轨迹预测误差,对减小车辆与行人碰撞事故,提高智能车辆行驶安全性具有重要意义。     

发动机盖参数对行人头部伤害指标的影响

交通事故中行人的伤亡率较高,行人保护正日益受到重视。文章通过有限元分析的方法模拟GTR法规中的头部撞击试验,利用正交设计的方法总结各个参数对行人头部伤害的影响程度和影响趋势,表明发动机盖的弹性模量和厚度对行人头部伤害影响最大,通过改进车辆前端的设计,可以减轻碰撞中对行人的伤害。     

信号交叉口行人使用手机对其过街行为和安全的影响

针对信号交叉口处行人使用手机对其安全产生不利影响的问题,以武汉市9个信号交叉口的实测数据为基础,对行人使用与不使用手机情况下的过街行为与安全性差异进行统计分析.以往的研究中,评价行人安全多通过简单的对比分析,很少有量化的参数依据;针对行人使用手机对过街安全的影响,以人车冲突为评价指标,建立了基于有序概率(OP)的模型,可以更好地量化评价与预测信号交叉口处的行人安全.结果 表明,有11个因素与人车冲突显著相关,包括行人年龄、使用手机方式、过街速度、行人是否与他人结伴过街、嘹望次数、闯红灯与否、车道数、上游车道左转流量、上游车道右转流量、进口道右转流量和信号周期.其中,使用手机会增加人车冲突的概率:在双向2,4,5,6和7车道上,过街时打电话行人的人均冲突分别是不使用手机行人的3.56,3.42,3.33,3.29和3.00倍;看屏幕行人的人均冲突分别是不使用手机行人的4.78,4.17,3.80,3.59和3.30倍;而听音乐行人和不使用手机行人之间的人均冲突并没有明显差异.      

汽车碰撞行人交通伤害特点分析

旨在研究道路交通事故中行人损伤的发生特点、事故类型以及损伤机制,从而调查交通事故中行人、车辆以及环境三者之间的关系。事故分析对行人的年龄分布、性别、损伤部位以及严重程度、车辆类型进行了研究,对典型案例进行了详细分析,并进行了AIS、GCS分级。讨论了行人损伤的事故特点,提出了影响行人损伤的因素,讨论了车辆交通环境和道路使用者之间的关系。     

行人保护气囊设计与验证

在近几年我国实际交通事故中,超过70%的事故涉及弱势道路使用者,汽车对他们的保护需求日益凸显。本文中基于一款A级轿车,对能保护弱势道路使用者头部、并与弹起式发动机罩相配合的保护气囊(简称行人气囊)进行了设计和验证。首先,设计行人气囊的包型和布置,基于弹起式发动机罩仿真行人气囊头型冲击、联动展开等工况;其次,利用试验和理论推导对仿真结果进行验证,修正行人气囊和弹起式发动机罩的关键参数;最后,基于C-NCAP头型冲击试验,探究该行人气囊的保护效果。试验结果表明,基于该车开发的行人气囊对头部的保护效果良好,伤害降低60%以上,得分率高达93.1%。     

基于交通事故深度调查数据的行人头部损伤特征研究

基于未来出行交通事故场景研究 （Future Mobile Traffic Accident Scenario Study,FASS） 数据库中135例人车碰 撞事故深度调查数据,对造成行人头部损伤的来源及车速对头部损伤来源的影响进行了统计分析。采用Spearman相关系 数检验法,建立了车辆速度区间与头部平均 MAIS 的回归模型。结果表明,行人头部致伤物主要来源于车辆,占比约 58%,其次为地面,占比约40%。行人事故中,碰撞车速对行人头部损伤来源的分布情况有一定的影响,当车速低于30 km/h时,行人头部损伤主要来源为地面,当车速为 ［30,50］ km/h时,车辆和地面对行人头部造成的损伤风险相近,当 车速高于 50 km/h时,行人头部损伤主要致伤物来源为车辆。因此,在进行交通损伤流行病学研究、交通损伤事故数据 库构建时,特别是在中低速碰撞中,应重视地面对头部造成损伤的风险。