【作者】 陶代琴；

【导师】 尹志勇；

【作者基本信息】 第三军医大学 ， 生物医学工程学， 2011， 博士

【摘要】 道路交通事故已成为世界第一公害,全世界在道路交通事故中每年约有130万人死亡,200～500万人受伤。对发展中国家而言,每年的经济损失高达六千多亿元。在交通事故中,车辆碰撞速度是非常重要的指标,直接影响交通伤害与财产损失的严重度。因此,在交通伤害机理研究、道路交通法律规范、交通事故的责任认定等方面,车辆碰撞速度都扮演十分重要的角色。交通事故中的车辆速度鉴定方法一直以来都是研究热点与难点。传统的速度鉴定多基于路面上轮胎制动痕迹、事故车辆的变形量、散落物以及车体或轮胎擦痕、行人的抛距、人体损伤的特点等。随着ABS和柏油路面的逐步普及,各种不确定因素增多,刹车痕迹勘察难度越来越大,速度鉴定工作面临极大的挑战,因此急需引入新的车辆速度鉴定方法。本课题是作者导师团队在开展交通事故司法鉴定中,偶然观察到事故车辆的车速表指针存在卡位现象,由此提出指针痕迹假设。因速度表指针为一悬臂梁,如果车辆碰撞时的减速度足够大,则车速表指针在盘面上会留下相应的印迹。若能将这类痕迹有效显现并提取作为证据固定,则可利用此痕迹快速鉴定车辆的碰撞速度。基于此,本研究通过车速表撞击实验研究验证上述假设,并对其造痕机理进行探讨。鉴于多数情况下指针印迹十分微弱,肉眼识别难度很大,为提高显现率以扩大提取范围,本研究还采用了多光谱检测技术、特定的图像增强技术和水分子覆膜增强显现技术,建立了能有效提高指针印迹检出率的方法。最后从真实交通事故中选择多起典型案例进行分析,就其适用范围进行深入探讨,并建立指针痕迹形态学图谱,以供碰撞速度鉴定应用。全文分为三个部分。(一)第一部分,指针痕迹假设的实验研究与力学模型分析。首先,为了验证指针痕迹存在的假设,本研究从冲击与振动原理着手,以常见的机械式车速表指针悬臂梁结构作为研究主体,通过高速摄像实时观测不同碰撞速度或减速度下指针运动和盘面振动,对碰撞瞬间指针与盘面受力关系与造痕位置进行了分析。由减速度波形可知,减速度影响指针与盘面的撞击接触。指针做扭转悬臂梁振动。垂直于盘面方向的悬臂梁振动幅度明显大于水平方向的扭转幅度。在撞击瞬间,车速表盘面隆起,作类似鼓面膜状振动。实验中观察到的指针与盘面的实际接触部位为指针尖部。只要转轴高度不超过指针和盘面的振幅叠加范围,指针将与盘面发生接触,并留下撞击痕迹。并由此提出假设二(可能存在独立于针尖痕迹之外的针杆中部印痕)。车速仪指针撞击痕迹的形成机理涉及到指针振动和车速表盘面振动的相互作用,其理论实质在于振幅的叠加效应。因振幅的叠加位在现实中的不可超越性,导致物体之间发生“接触-碰撞-挤压-印痕-分离”。这一作用过程亦可推广到痕迹学领域中有关印压痕迹的形成机制。通常认为悬臂梁远端(即针尖部位)振幅大,容易发生接触,形成痕迹。但实验中观察到,在中高速撞击下悬臂梁的运动是一复杂的往复运动,盘面也在作往复运动,且振动幅度和频率也不尽相同,从而使悬臂梁中段与盘面也发生接触或碰撞而在悬臂梁中段位置的盘面上留下痕迹。本实验研究除了纠正前人在这一问题上的不完整看法,还据此提出新的假设(将通过第三部分实案分析进行验证)。(二)第二部分,指针痕迹光学显现与图像提取的关键技术研究。为了对实案样本数据进行有效分析,必须对指针痕迹显现与提取的关键技术进行研发。首先采用多波段光谱与特定的图像处理技术,对疑似痕迹的部位进行全方位多光谱分析,筛选出适合指针痕迹图像采集的最佳方案。尤其对紫外荧光痕迹进行了深入探讨,并建立了激光与其它多光谱光源(例如多波长LED光源等)的技术替代方法,解决体积和功耗等问题,使之满足本课题图像采集与处理的需要。本技术是作为第三部分实案样本数据采集中第一实验组与第三实验组不可或缺的关键技术。其次,对于使用多光谱技术也难以检测到的痕迹,则进行了特殊的水分子覆膜法增强痕迹显现,并及时采集图像进行固定。本技术同样适用于路面潜在轮胎痕迹的增强显现。本技术是作为第三部分实案样本数据采集中第一实验组与第二实验组的补充技术。此外,在三维几何光学测量技术方面,对事故现场的三维摄影测量与重建技术进行了宏观与微距的深入探索。宏观上,以本技术替代传统现场勘查中的卷尺测量与手工绘制(作为第三部分实案样本数据采集中第二实验组的补充技术)。研制了十字标与锥形标,并与传统点标进行了误差分析和精度比较。不仅有效提高了误差率,且精度远高于同类研究。本技术同样适用于微距测量,作为第三部分指针同一认定测量中的补充技术,其结果在指针测量上,比普通毫米级直尺测量更精确更便捷。上述三种技术还有各自具备独立的应用价值,不仅适用于指针痕迹,还能用于其它痕迹类型的显现与提取,或用于其它工程实践。(三)第三部分,实案样本分析与指针痕迹形态学图谱。首先,对从真实案例中采集到的59个随机样本进行痕迹有效性研究。为了保证结果的准确性,将课题组分为相互独立的三个组。第一组利用多光谱技术与水分子覆膜增强技术对指针痕迹进行读取,并将其速度值结果记录在特定的标签下。第二组负责从现场采集案件信息,采用传统方法对车速进行计算,并将其速度值结果记录在同一个特定的标签下。第三组负责管理标签下记录的两组数据值,汇总分析。结果表明,正面碰撞中获得的指针痕迹速度值明显比传统算法精确,可作为真实车速进行鉴定。侧面碰撞的痕迹结果与传统结果有一部分交叉,需结合其它信息认定车速。追尾或其它碰撞情况,实案中暂未发现指针痕迹的存在,因此无法得出结论。在实案获取的阳性结果中,最低车速为42 km/h,这一结论将本研究的应用范围从高速撞击延伸到常速交通事故范畴。其次,在确证实案样本结果有效的基础上,对阳性结果进行了不同标准的形态学分类,并有效解决了本课题第一部分研究中所遗留的新假设验证问题。指针痕迹可分为针尖痕迹与针杆印痕;单一痕迹与多重痕迹;擦划痕迹与印压痕迹;可见光痕迹与荧光痕迹。它们各自具备形态学上的独立属性,对观测者而言,能够有效识别。最后,作为物证痕迹研究不可或缺的一部分,必须对实案采集到的指针痕迹进行同一认定与真伪辨识。不是所有的指针痕迹都能进行同一认定,但对于部分清晰的针杆痕迹,能够通过微距测量与痕迹比对进行针杆与印痕的同一认定。真实的针尖痕迹是不规则的短曲线,与伪造的点状痕迹有明显不同。除非卸下车速表,否则无法伪造针杆印痕。而针尖擦划痕迹的真伪辨别则较为困难。在连续撞击下,存在多重指针痕迹,可通过能量耗损前后的不同表现形态,对撞击的先后次序进行判别。鉴于指针的轴高、盘面材料与撞击类型都会对痕迹形态造成一定影响,实践中需要结合其它信息对痕迹真伪进行判定。综上所述,通过对指针痕迹进行实验研究与实案分析,本课题首先建立了一种可靠、实用的车辆碰撞速度鉴定的新方法。其次,纠正了前人在造痕部位与力学关系上的错误理解,并提供了一种将振动方式与痕迹图谱相关联的途径,丰富了振动力学与痕迹形态学的理论研究。再次,率先对指针痕迹进行了详细的图谱绘制与真伪鉴识。另外,多光谱技术、水分子覆膜技术与平面图像的三维测量等关键技术的引入,大大提高了指针痕迹的检出率和鉴定结果的准确性。虽在本课题以上方面有所创新,但仍有一定的不足之处。由于同类研究文献较少,实案样本随机分布较散且难以控制,而实车碰撞实验验证难度亦较大。因此,对于本课题研究过程中发现的部分疑难问题,例如指针的卡位与碰撞速度的量效关系,某种盘面材质与特定光谱的反射关系,以及撞击速度与痕迹形态的具体关联,还需进行更深入的研究。本课题所建立的方法,仅用于中高车速正面碰撞事故车辆的车速鉴定,而对侧碰、追尾和低速正面碰撞的车速鉴定暂不适用。更多还原

【Abstract】 As a major cause of death and disability, traffic accidents have become the world’s largest public nuisance. Currently, there are about 1,300,000 people died and about 2,000,000 ~ 5,000,000 people injured in traffic accidents worldwide each year. The economic cost to developing countries is at least $100 billion a year. The United Nations General Assembly in 2010 has proclaimed the period 2011-2020 as the Decade of Action for Road Safety. The collision speed as a very important indicator for traffic accidents directly affects the severity of traffic casualties and economic loss, because the impact energy is proportional to the square of velocity. Therefore, it plays a very important role in the mechanism of traffic injuries, the road traffic laws and regulations and the responsibility in accidents. The speed identification techniques have always been hot and difficult.The traditional methods for traffic accident speed analysis are by the brake marks of tyres, the deformation of vehicles, the fallouts from the vehicles, the scratches on the vehicle body or tyres, to calculate the braking speeds and the collision speeds. With the gradual popularization of ABS and the asphalt surface, and with more and more uncertainties, fewer and fewer brake traces have been found on the road, that the traditional speed identification methods can not meet the new difficult situations. It needs to improve techniques for collision speed determination.The topic in this thesis is from the scene observation by the team of the mentor. Blocked needles have been found in a sudden that experts have imagined there might be needle impressions like fingerprints left on the gauge plates. If the decelerations were high enough to make the needle cantilever impact with the gauge plate and leave marks on it, experts could take use of them to determine the collision speed quickly. Based on this assumption, it established an experimental platform of deceleration impact to verify the assumption and to discuss its inner mechanism. Since the needle marks are usually so weak for detection by naked eyes that it takes the multiple spectrum techniques and special visualization enhancement processings to improve the detection ratio. Finally, real cases were randomly gathered to do data analysis and typical morphological maps were illustrated to do further study for their applications.This thesis is divided into three parts.Part I - Experimental study on needle marks hypotheses and mechanical model analysisIn order to verify the initial trace hypothesis, based on the physical principles in mechanical shock and vibration, the structure of cantilever with perpendicular and torsional vibration of a common mechanical speedometer has been chosen as a theoretical subject, and the mechanics between the needle and the gauge plate as well as the instant contact structures have been chosen as the research objects.The deceleration waveforms have shown that it influences the contact between the needle and the gauge plate. The needle moves as a cantilever beam during the collision. The direction perpendicular to the bottom of the cantilever vibration amplitude is significantly greater than the horizontal direction to reverse range. In the moment of impact, the gauge plate uplifts, similar to the drum membrane vibration.The contact is observed as the tip location. As long as the shaft height does not exceed the amplitude stack of the gauge plate and the needle, the needle should be in contact with the gauge plate, and left traces of collision. According to this, it brings forward Hypothesis II (the existence of middle marks independent of the tip marks).The formation of needle marks is from the amplitude of the superposition effects, which leads to the process of "contact - collision - squeeze - prints - separation" between them. This role can also be extended to the whole formation mechanism process in the field of indentation marks.It is generally considered that the farther the distal cantilever (i.e. the needle tip), the more the vibration energy is, therefore, it is more prone to contact. However, by observation in experiments, the needle cantilever beam is reciprocating complexly with gauge plate including such low-level vibrations and high vibrations with various amplitudes and frequencies which may cause the middle position (i.e. the needle bar) to leave marks on the gauge plate, for the reason that it should be more likely to leave middle marks on gauge plates than single tip marks. It eliminates the previous incompletely misconceptions about this issue, and a new hypothesis is generated which will be verified by real marks analysis in Part III.Part II - Special techniques on visualization of needle marks and image processingFor effective analysis on real sample data, critical techniques on visualization and extraction about needle marks must be developed.Firstly, it has developed multi-band waves and special image processings to do multi-spectral analysis on the suspected locations. Depth discussions are taken especially for UV fluorescence traces, and alternatives have been established for multi-spectral laser with other light sources (such as multi-wavelength LED light source) which have solved issues such as size and power consumption to meet the project needs of image acquisition and processing. This technology is essential for Group 1 and 3 (in Part III) on the sample data collection.Secondly, vapour-coating techniques have been developed to get latent needle marks which are difficult detected by the multiple spectrum technique. Vapour-coating techniques are also applicable for latent tyre marks on road surfaces. They are assistants for Group 1 and 2 in Part III.Thirdly, it has developed a quick and high accurate method for 3D measurements from 2D images. In macro, on reconstruction of the scene by teleprocessing to replace the traditional manual operations based on tape measure (for Group 2 in Part III), three types of feature marks in the matrix array have been projected. The calibrations of the camera with fixed focal length have been calculated and compared before and after revision. The cross-shaped feature is the most accurate mark. And the cone barrel with sharp apex is also more accurate than the traditional round dot. The real case practices have been engaged in to verify the practicability and efficiency of the projects which are very accurate and highly active. And for mini size measurements, as a supplementary technique (accuracy less than 0.01 mm) in measurement of needle marks identification, it is more accurate and convenient than common rulers (accuracy in 0.1 mm).These three techniques are of their independent values in applications. They are suitable not only for needle marks but also for other engineering practices.Part III - Real samples analysis and morphological maps on needle marks First, validity studies on 59 random samples collected from real cases have been down and 10 positive results have been obtained. Based on the experimental techniques developed in Part II, there are three individual groups which are Group 1 (to visualize the needle marks by optical techniques), Group 2 (to calculate the speed by traditional methods and 2D-3D measurements) and Group 3 (to do statistics and morphological categories by image processings). Different speed results are obtained isolated from Group 1 and 2, and results under same labels are then submitted to Group 3 to do morphological analysis is carried out on the final positive data, such as the typical forms of classification, the identification and the authenticity discrimination. Results have shown that, frontal collision results are significantly more accurate and reliable than traditional algorithms that they can be identified as the real speed values. There are cross sections between side impact results and traditional results, therefore, it needs to determine the speed value in combination with other information. No needle marks have been found in rear collision or other situations, so it can not draw valid conclusions. In real positive results, the lowest speed is 42 km/h, which can extend the application range from high-speed impact to general traffic areas.Second, on the basis of the case sample validity, the morphological classifications have been down on positive results under various criteria, and the left issue about the new hypothesis (in Part I) has also been effectively solved. Needle marks include tip and middle marks, single and multiple marks, scratches and impressions and visible and fluorescent marks. Each of them has independent morphological properties that experts can detect them effectively.Last but not the least, as an integral part of physical evidence researches, it must make identifications and discriminations on the authenticity of needle marks gathered from real cases. Not all needle marks can be identified, but for some clear middle marks, it can take identification between the needle bar and the impressions through mini size measurements and traces comparisons. Real tip marks are irregular short curves, which are significantly different from the forgeries. Middle marks can not be forged unless the speedometers are disassembled. It is difficult to discriminate tip scratch marks from forgeries. For multiple marks from consecutive impacts, the time order can be determined by the definition of impressions based on the energy theorem. For the needle shaft heights, gauge plate materials and collision types would influence the formation of needle marks, so it requires determining the authenticity of needle marks by combining other information in practice.In summary, by the experimental study and real case analysis of needle marks, first, it has established a reliable and practical new method for identification of vehicle collision speed. Second, it has corrected the previous misunderstanding about the relationship between impression positions and mechanism. It has provided an association with vibration mode and traces patterns, which enriches the theory of mechanical vibration and traces morphology. Third, it is the first time to draw detailed morphological maps and to do authenticity discriminations on needle marks. What is more, critical technologies, such as the multi-spectrum technology, the vapour-coating technology and the three-dimensional measurement technology, have greatly improved the detection rate of needle marks and accuracy for identifications.Although there are such innovative aspects, it is still of some deficiencies. Since similar literatures are less and real car crashes are difficult to operate for verification, for some difficult problems found during the research process, such as the quantity-effects relationship between blocked needles and collision speeds, the reflection relation between gauge plate materials and specific spectra and the association between impact velocities and traces morphological patterns, need to be in-depth studied. The method established in this study is only suitable for the determination of the medium- or high-speed frontal collision speeds, but temporarily not for the side, the rear or the low-speed frontal collision speeds.更多还原