共查询到16条相似文献,搜索用时 171 毫秒
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为研究在车辆碰撞过程中主动弹起式发动机罩对行人头部的保护作用,考查行人头部损伤指标HIC值,比较接触式和非接触式发动机罩抬升传感器的动作时序,仿真BUCK标准车模型撞击6岁儿童假人的冲击过程,得到传感器的最小反应时间,据此判断主动弹起式发动机罩的作用效果。采用LS DYNA显式分析算法对某型轿车以45 km/h的初始速度撞击6岁儿童假人进行仿真分析,对比主动弹起式和非主动弹起式发动机罩的行人保护性能及其星级评定结果,由行人头部保护得分占比可知主动弹起式发动机罩可大幅提高行人头部碰撞保护性能。 相似文献
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研究行人体型在人车碰撞事故中对关键部位损伤程度的影响规律,针对保护行人安全,建立碰撞力学模型,以多刚体接触动力学为基础,提出进行受撞变形研究,采用ADAMS软件对轿车分别与中国5、50、95百分位三种不同体型男性成年行人的碰撞过程进行仿真.仿真结果表明,随着行人体型的增大,对头部、胸部和下肢的损伤风险都依次增大,而且头部与轿车前端碰撞的位置和时间压间都依次往后推移.从结论中可以看出,应对轿车外置安全气囊,根据不同型体在轿车前端安装合理位置,可有效地起到保护行人的安全作用. 相似文献
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针对行人与车辆碰撞中行人小腿的保护问题,建立基于MCKF模型和简单梁理论的新型小腿冲击器二维多体动力学模型.用柔性体模拟韧带以满足小腿冲击器对膝关节建模的较高精度要求;将不同阻尼系数和刚度系数引入多体模型以满足某些连接部位的阻尼和刚性要求.参考ECRNo.631/2009中的小腿冲击器动态试验并改进原始的刚性冲击锤的材... 相似文献
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基于计算机视觉的人流量双向统计 总被引:1,自引:0,他引:1
提出了一种采用视频监控系统对人行通道口进行双向人流量计数的方法。首先建立发色模型与头部形状模型,采用形态学运算提取人的头部目标,然后跟踪目标建立人头目标移动链,依据目标链位置信息判别行人的进出方向,最后设置感兴趣的检测区域,并对通过该检测区域的行人计数。实验结果表明,该方法能实时有效地统计通道口处双向人流量。 相似文献
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为了降低儿童乘员在碰撞过程中胸部和头部的损伤率,对增高座椅儿童约束系统进行参数化分析。本文采用多体动力学软件MADYMO建立儿童乘员碰撞仿真模型,并按照FMVSS213法规验证模型的有效性。在此基础上,以头部质心合成加速度、头部损伤准则HIC36、胸部合成加速度为损伤指标,分析增高座椅与台车座椅之间的摩擦系数、汽车座椅安全带刚度、增高座椅在高度方向上变化对儿童损伤的影响,仿真结果表明:在增高座椅底面涂以摩擦材料以提高摩擦系数,适当提高安全带刚度及维持现有座椅高度可以显著减少儿童在碰撞过程中的头部和胸部损伤。 相似文献
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基于元胞自动机的行人模型仿真研究 总被引:1,自引:1,他引:1
为了直观地显示行人行走的特性以及与车流之问的相互作用,在分析行人交通特性后,以元胞自动机(CA)和规则描述为理论基础,提出基于CA的行人仿真模型,利用VC建立相对于其他交通对象的行人避让模型,最后用OpenGL对模型进行可视化渲染.方法以模型与现实世界的高相似性有效克服了精确数学模型在仿真行人交通时的难题.结合行人cA模型和行人避让模型开发了混合交通流仿真试验原形系统.仿真结果表明,方法有效地模拟了现实交通状况,在城市交通规划、交通需求管理和交通控制等领域有广泛的应用前景. 相似文献
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对作大范围运动柔性机械臂系统,进行斜碰撞动力学分析.基于柔性多体系统刚柔耦合动力学理论,计入耦合变形项,全面考虑大范围刚体运动与弹性小变形运动的耦合,建立系统连续动力学方程.引入斜碰撞力学模型,将法向和切向碰撞力以广义力的形式加入动力学方程中,对系统进行斜碰撞动力学建模分析.法向碰撞模型选取基于连续接触力法的非线性弹簧阻尼模型,切向碰撞模型选取一种修正Coulomb摩擦模型,对切向摩擦力进行统一描述.给出接触、分离判据,实现不同状态的动力学模型转换与求解.对斜碰撞全局动力学进行了仿真验证,分析了柔性机械臂全局过程的动力学特性变化以及碰撞对大范围运动和小变形运动的作用,并对比了不同碰撞方向对大范围运动、变形、机械能、碰撞力等动力学参数的影响. 相似文献
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Marhefka D.W. Orin D.E. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》1999,29(6):566-572
Contact modeling is an important aspect of simulation of many robotic tasks. In the paper, a compliant contact model with nonlinear damping is investigated, and many previously unknown characteristics of the model are developed. Compliance is used to eliminate many of the problems associated with using rigid body models with Coulomb friction, while the use of nonlinear damping eliminates the discontinuous impact forces and most sticky tensile forces which arise in Kelvin-Voigt linear models. Two of the most important characteristics of the model are the dependence of the coefficient of restitution on velocity and damping in a physically meaningful manner, and its computational simplicity. A full mathematical development for an impact response is given, along with the effects of the system and model parameters on energy loss. A quasistatic analysis gives results which are consistent with energy loss characteristics of a more complex distributed foundation model under sustained contact conditions. A foot contact example for a walking machine is given which demonstrates the applicability of the model for impact on foot placement, sustained contact during the support phase, and the breaking of the contact upon liftoff of the foot 相似文献
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Multiple human tracking in high-density crowds 总被引:1,自引:0,他引:1
In this paper, we introduce a fully automatic algorithm to detect and track multiple humans in high-density crowds in the presence of extreme occlusion. Typical approaches such as background modeling and body part-based pedestrian detection fail when most of the scene is in motion and most body parts of most of the pedestrians are occluded. To overcome this problem, we integrate human detection and tracking into a single framework and introduce a confirmation-by-classification method for tracking that associates detections with tracks, tracks humans through occlusions, and eliminates false positive tracks. We use a Viola and Jones AdaBoost detection cascade, a particle filter for tracking, and color histograms for appearance modeling. To further reduce false detections due to dense features and shadows, we introduce a method for estimation and utilization of a 3D head plane that reduces false positives while preserving high detection rates. The algorithm learns the head plane from observations of human heads incrementally, without any a priori extrinsic camera calibration information, and only begins to utilize the head plane once confidence in the parameter estimates is sufficiently high. In an experimental evaluation, we show that confirmation-by-classification and head plane estimation together enable the construction of an excellent pedestrian tracker for dense crowds. 相似文献
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A non-penetration approach of frictional contact analysis is presented for modeling revolute clearance joints of planar rigid multibody systems. In the revolute clearance joint, the motion modes of the journal are divided into three categories, namely, the free motion, collision, and permanent contact modes. The switch between different contact modes is identified by the state of the journal and bearing, including the gap and the normal relative velocity. When impact in the revolute clearance joint is detected, the collision process is simulated by the impulse-based differential approach, where Stronge’s improved model for restitution is employed to determine the relative velocity after impact. Instead of algebraic equations, the impact process is described by a set of ordinary differential equations (ODEs), which avoids solving complementarity problems. Moreover, in the permanent contact mode, the constraint-based approach and modified Coulomb’s friction law are adopted. The permanent contact mode maintains for most of the time and the governing ODEs are non-stiff. There is general agreement that the constraint-based approach is more efficient than the force-based method. A slider–crank mechanism with a revolute clearance joint is considered as a demonstrative application example where the comparison with the continuous contact force model is investigated. 相似文献
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人群聚集场所往往存在着较大的安全隐患,当紧急事件发生时,公共场所出口处易发生踩踏事故。针对该现象,设计了一种行人踩踏模型:将行人在踩踏过程中的跌倒情况分为三种,昏迷倒地、推挤倒地、被行人绊倒;在此基础上,设置了行人跌倒的判定规则和行人跌倒后重新站立的条件。行人跌倒的判定规则融合了改进后的社会力模型。改进的社会力模型考虑了跌倒行人对站立行人的影响。仿真过程中对影响人群踩踏的若干因素进行了分析,包括出口宽度、行人平均运动速率、操场塑胶跑道的摩擦系数、心理作用系数,撞击阻碍角度等。仿真结果显示,出口宽度越小,行人平均速率越快,操场塑胶跑道的摩擦力系数越小,越容易发生踩踏事件。心理作用系数和撞击阻碍角度超过一定阈值后,踩踏现象会显著减弱。 相似文献
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汽车与行人碰撞的动力学响应仿真研究 总被引:7,自引:0,他引:7
行人保护是汽车安全研究领域的重要问题之一。该文旨在研究真实事故中汽车前碰撞行人的动态响应。基于这一点,使用了一个经过验证的行人数学模型,模拟真实碰撞事故中行人的动态响应。文中对行人模型的运动学响应以及真实事故记录进行了比较,并且计算了头、胸、骨盆、下肢等人体各部分与损伤相关的参数。基于模拟研究的结果,提出了减少行人损伤风险的城区限行时速和通过改进汽车前部结构减少行人碰撞损伤严重程度的可行措施。 相似文献