行人运动建模技术综述*

随着计算机数值模拟技术的迅速发展,行人运动仿真技术开始成为人群疏散仿真、城市规划和计算机疏散软件开发方面的研究热点。介绍了对行人建模仿真的初步研究,重点介绍了基于行人行为的微观行人运动建模方法,并对各个模型进行了比较分析和研究展望。     

考虑个体行为的改进CA模型人员疏散研究

为更好模拟行人疏散过程中微观个体行为,考虑行人身材半径及在疏散过程中行人步行速度随运动状态变化,将社会力模型运行规则引入元胞自动机模型,建立了一种社会力模型计算步行速度、空间离散化程度和步行速度较高的疏散模型,用于模拟紧急情况下的行人疏散过程。在该模型中空间划分为更小网格,每个行人占用一到多个单元格,行人的身材半径不再不变,每个行人移动的距离由其速度决定,根据基于速度的出口选择方法和行人运动规律,通过数值模拟分析,研究了疏散过程中的动态性。研究表明基于速度的网格移动数量、行人数量、期望速度、行人身材半径、松弛时间等参数影响疏散效率,结合连续模型的优点能够更加客观真实刻画疏散过程,有助于离散模型描述行人疏散微观行为特征。     

A Hybrid Model for Simulating Crowd Evacuation

Macroscopic and microscopic models are typical approaches for simulating crowd behaviour and movement to simulate crowd and pedestrian movement, respectively. However, the two models are unlikely to address the issues beyond their modelling targets (i.e., pedestrian movement for microscopic models and crowd movement for macroscopic models). In order to solve such problem, we propose a hybrid model integrating macroscopic model into microscopic model, which is capable of taking into account issues both from crowd movement tendency and individual diversity to simulate crowd evacuation. In each simulation time step, the macroscopic model is executed first and generates a course-grain simulation result depicting the crowd movement, which directs microscopic model for goal selection and path planning to generate a fine-grain simulation result. In the mean time, different level-of-detail simulation results can also be obtained due to the proposed model containing two complete models. A synchronization mechanism is proposed to convey simulation results from one model to the other one. The simulation results via case study indicate the proposed model can simulate the crowd and agent behaviour in dynamic environments, and the simulation cost is proved to be efficient.     

贪心选择在地铁站内行人疏散中的应用

大型室内场所空间布局较为复杂(如地铁站), 人群的高密度聚集往往存在一些潜在的风险. 本文在分析国内外人群快速疏散研究现状的基础上, 提出了一种基于贪心选择的行人疏散方法. 该方法以地铁站内复杂场景作为研究背景: 首先, 针对地铁站内的行人的行动轨迹难以获取问题, 本文利用地铁站内行人真实出站数据, 基于元胞自动机, 构建了行人疏散轨迹半仿真模型, 并利用实际流量数据优化该半仿真模型; 其次, 基于该轨迹模型, 为了满足高动态场景中的实时性, 采用复杂度较低的贪心选择策略分配最优疏散出口; 最后, 以杭州武林广场地铁站为例, 使用真实出站数据设计对比实验, 验证行人轨迹模型的有效性以及出口分配方法的性能. 结果表明, 本文所提出的行人轨迹模型能够较好的模拟行人的轨迹, 仿真中各出口疏散人数同真实出站数据拟合程度的可决系数R2达到了0.67. 相较于最短路径和最短时间出口分配方法, 本文所提出的方法在整体疏散效率上分别提高了27.2%和16.5%.     

一种考虑Wardrop均衡的行人流疏散模型

针对室内空间行人流的疏散问题,基于元胞自动机和Wardrop均衡原理提出了一种新的疏散模型。该模型首先基于位置吸引力、出口拥挤度、行人之间作用力和团队效应定义了行人移动概率的计算公式,并根据Wardrop均衡原理建立了疏散优化模型,同时对该优化模型进行求解。最后,利用实验平台进行仿真分析,深入研究了系统疏散时间、系统平均速度和行人流密度之间的关系。结果发现适当提高系统平均速度可以提高系统疏散效率,同时在不同行人流密度下,需要采取不同的疏散策略。     

基于突发事件影响力传播的双向人流疏散仿真

当突发事件发生时,行人行走行为会因为突发事件本身以及突发事件在人群中的传播而改变。对于突发事件影响下的行人行走特征的研究能够提高人流疏散的效率。针对现有研究中数据获取方式的不足,对真实行人场景视频进行图像处理,提取相关数据后分析了无突发事件时行人一般行走特性。针对突发事件下的行人流,利用k-邻近算法和合力的思想描述了突发事件的影响传播和突发事件下行人流的自组织现象,并由此提出一种新的元胞自动机模型,该模型中的行人元胞会受到正常行走、突发事件、安全标识这三个因素所抽象产生的三个作用力的影响。利用模型对突发情况下的双向人流疏散进行仿真,实验结果表明,当安全标识的距离为0、10、20个元胞时,在小范围行人通道中安全标识分布的距离对人群疏散作用不明显;通过对人群间是否存在影响力的研究发现,疏散的效果主要受到附近行人对突发事件传播的影响;突发事件的影响程度太大或影响范围过小都会引发拥堵,不利于人群的疏散。仿真结果与真实世界中的双向行人流疏散情况基本吻合。     

A conflict–congestion model for pedestrian–vehicle mixed evacuation based on discrete particle swarm optimization algorithm

A simulation model based on temporal–spatial conflict and congestion for pedestrian–vehicle mixed evacuation has been investigated. Assuming certain spatial behaviors of individuals during emergency evacuation, a discrete particle swarm optimization with neighborhood learning factor algorithm has been proposed to solve this problem. The proposed algorithm introduces a neighborhood learning factor to simulate the sub-group phenomenon among evacuees and to accelerate the evacuation process. The approach proposed here is compared with methods from the literatures, and simulation results indicate that the proposed algorithm achieves better evacuation efficiency while maintaining lower pedestrian–vehicle conflict levels.     

Modeling pedestrian flow accounting for collision avoidance during evacuation

Collision avoidance behavior has become an open challenging problem since it is one of critical factors that influence the pedestrian flow dynamics. In this paper, a cellular automaton (CA) model is developed to depict the pedestrian movements when collision avoidance behaviors exist during evacuation. Then, we utilize the proposed model to simulate the influences of the collision avoidance on the pedestrian movements during the evacuation in a classroom with two exits. The numerical results indicate that more collision avoidance behaviors have negative influences on the evacuation efficiency, and that more competition behaviors generate more collisions while have no prominent positive impacts on the evacuation efficiency. Moreover, the evacuation time increases with the decreasing number of aisles in the classroom and the number of collisions increases with the increasing number of parts in the classroom divided by aisles. The above results are helpful to develop effective evacuation strategies and design the internal layouts of buildings.     

Calibrating a social force based model for simulating personal mobility vehicles and pedestrian mixed traffic

Personal mobility vehicles (PMVs), such as the Segway, have recently gained remarkable popularity as an alternative transport mode for short-distance trips in indoor and outdoor settings. Before allowing them on shared sidewalks, where the pedestrian and cyclist demand is high, interactions between PMV riders and other shared space users should be properly understood. Further, the designs of shared sidewalks and implementation policies should also be evaluated. Calibrated microscopic simulation tools could facilitate such purposes. This study aims to explore the applicability of a social force based microscopic simulation model, which was originally used to simulate pedestrian movements and interactions, for Segway and pedestrian mixed traffic. The parameters of the model are calibrated with data collected through controlled experiments under different Segway–pedestrian interaction scenarios. Lateral and longitudinal avoidance distances measured from trajectory data collected in a different controlled experiment was used to validate the model for a Segway rider avoiding a pedestrian. The findings of this study suggest that, with proper calibration, the social force model can potentially be used to simulate Segway-like PMVs and pedestrian mixed traffic.     

复杂条件下多层建筑人员协作疏散仿真

研究具有复杂多层协作过程条件下的人员疏散控制系统,就能够比较准确地模拟突发情况下人员的疏散情况。本文对元胞自动机进行了改进,综合人员个体特征和从众心理等各种复杂因素,对具有复杂障碍物的多层建筑中人员疏散过程进行了计算机仿真分析,并给出了人员疏散效率与人员的从众系数、障碍物及出口位置等因素的关系。该仿真能够很好地模拟大型公共场所发生突发事件时人员疏散的情况,对在复杂地理环境及人员特性条件下的多层建筑突发事件疏散策略制定具有一定的实际参考意义。     

初始分布非均匀的行人流疏散仿真研究

为了有效模拟研究初始分布非均匀的行人流疏散问题,通过定义行人方向模糊可视域,改进了场域元胞自动机模型。模型中,行人的目标位置选择受到方向模糊可视域内行人之间的排斥力和吸引力、出口处行人分布、距可选位置相对距离三种因素共同作用。研究表明,改进模型能够有效地实现初始分布非均匀的行人流在疏散过程中的动态平衡;改进模型不依赖于各因素的影响系数,从而避免了影响系数量化过程的主观性和疏散系统的限制性;在疏散过程中,如果行人保持一个较大的视野半径,疏散系统能够实时提供出口处行人分布状态,就可以有效地提高行人流疏散效率。该研究有助于相关行人流疏散策略和方案的制定。     

Experiment and analysis on microscopic characteristics of pedestrian movement in building bottleneck

In this paper, evacuation experiments are carried out to study pedestrian movement behaviors in building bottleneck. An image processing method based on mean-shift algorithm is used to extract pedestrian movement trajectory. Based on the extracted trajectory, we analyze the microscopic movement characteristics of pedestrians such as lane formation, change of velocity and distance between two sequential pedestrians. A pedestrian lane is a group of pedestrians moving in a column. The lane formation is verifie...     

基于Agent的应急疏散模型研究

根据突发事件出现的等级,选择安全区域,并采用适当的疏散方式,选择受灾区域的周边安全区域作为避难所;通过分析影响应急情况下人员选择目的地的因素,对人员疏散行为直观分析并结合人机功效评估,对疏散行为规范,建立基于Agent的应急疏散人员避难所选择模型。通过设定可能影响人员疏散的多种可能因素,该模型能够比较真实地模拟紧急情况下的人员疏散状态。仿真过程与实际情况相似,方法可广泛用于人员应急疏散过程分析研究。     

Environment optimization for crowd evacuation

The layout of a building, real or virtual, affects the flow patterns of its intended users. It is well established, for example, that the placement of pillars at proper locations can often facilitate pedestrian flow during the evacuation of a building. Such considerations are therefore important for architects, game level developers, and others whose domains involve agents navigating through buildings. In this paper, we take the first steps towards developing a simulation framework that can be used to study the optimal placement of architectural elements, such as pillars or doors, for the purposes of facilitating dense pedestrian flow during the evacuation of a building. In particular, we show that the steering algorithms used to model the local navigation abilities of the agents significantly affect the results, which motivates the need for a statistically valid approach and further study. Copyright © 2015 John Wiley & Sons, Ltd.     

Risk of fire emergency evacuation in complex construction sites: Integration of 4D-BIM,social force modeling,and fire quantitative risk assessment

Construction industry is claimed to be the fourth most dangerous sector by number of fatalities. In complex construction sites, emergency evacuation risk assessment is a challenging task due to their ever-changing nature. This study developed a model to analyze the risk of fire emergency occurrence, and risks which are associated with evacuation performance (in response to that emergency) through an integrated approach in complex construction sites. To analyze the evacuation scenarios more realistically, we utilized Social Force Model (SFM) simulation engine. Using SFM for simulating the evacuation of complex construction sites has not been adequately addressed in the literature. Microscopically simulating the evacuation scenarios for all workdays of the studied complex project required high computation efforts. To tackle this computation challenge, a parallel computing technique was coupled with SFM simulation engine. More importantly, in this paper site’s evacuation performance was evaluated multi-objectively considering evacuation time and evacuation safety. The construction site’s emergency scenarios were modeled by 4D-BIM, potential for trigger fire emergency was determined by a fire ignition Quantitative Risk Assessment (QRA) module, and site evacuation was simulated by SFM simulation engine. The proposed framework handled the collaboration of 4D-BIM, fire QRA module, and SFM engine. This research study benefited from data driven from a real mega project. The findings demonstrated that analyzing the risk of evacuation through an integrated approach by the proposed model could render more realistic results. The results also provided the project managers with a reliable safety decision-making support.     

Extended route choice model based on available evacuation route set and its application in crowd evacuation simulation

In this study, we propose an extended route choice model based on an available evacuation route set to simulate the selection of pedestrians in selecting an appropriate route during evacuation in emergency situations. In this model, four parameters (i.e., distance to available route, length of available route, level of congestion in available route, and capacity of available exit) affect the route choice of the pedestrian and the evacuation route set. In this study, the evacuation route set is created and optimized by a modified social force model and a route learning method. Experimental results show that the extended model can effectively reproduce crowd behavior in an emergency situation, which can assist in analyzing emergency evacuation scenarios. Moreover, two important conclusions regarding increasing evacuation efficiency show that the proposed model is in line with real-world situations.     

一种基于SPH方法的人员疏散混合模型及模拟

为减少室内火灾环境下人员伤亡,研究了人员疏散计算机模拟问题.将人员运动视为一种流体运动,利用流体力学原理,构建一种新的人员疏散混合模型,并在其中引入了一种从众模式.同时,采用光滑粒子流体动力学方法对模型离散化,从而减少了计算量.不同工况下进行的疏散模拟实验表明,所提出的模型及算法能够较准确地模拟出实际疏散的现象.     

基于FDS和元胞自动机动态耦合的火灾疏散模型

为研究火灾场景下温度、烟气和CO浓度等灾害因子对疏散的影响,建立基于FDS和元胞自动机动态耦合的火灾疏散模型。将FDS的网格和元胞自动机的元胞一一对应,将由FDS运行得到的灾害数据通过Python等技术手段实时加载到元胞中,使灾害数据持续影响行人转移概率,从而实现灾害和疏散的动态耦合;以单层教学楼作为仿真场景进行模拟分析,对火源位置和热释放速率等因素进行讨论,得出这些因素对行人疏散进程的影响规律;将模型与传统软件和同类方案进行对比。研究表明,火灾导致的高温和烟气会影响行人对疏散路径和安全出口的选择;热释放速率越大,行人越早处于危险状态,同时处于危险状态的行人也越多;该模型相比传统疏散软件不仅能考虑火灾产生的致灾因子对行人疏散的动态影响,还能确定行人最早处于危险状态的位置和时间,并用可视化的方式表现出来。     

A social force evacuation model driven by video data

This paper proposes a video data-driven social force model for simulating crowd evacuation. The initialization of pedestrian position, path navigation, and goal selection in the improved social force model was guided by real video data. To initialize pedestrian position and determine path navigation, the distribution of the pedestrians is set according to the real video. We also extracted the trajectories of pedestrian movement from the videos, and these trajectories were stored into a path set to guide the evacuation of pedestrians. Moreover, a fitness function was defined to model the behavior of a pedestrian goal selection. The fitness function could process the evacuation parameters, which were extracted from the video, and consider the degree and distance of exit congestion. Furthermore, we quantified the relationship values among pedestrians, and a new force called “group force” was added to the primary social force model. Pedestrians with close relationship gathered into one group and walked together. To validate the effectiveness of the proposed method, the video data-driven model was applied to simulate campus halls and roads. Simulation results show that the proposed approach is consistent with real-world situations and can assist in analyzing emergency evacuation scenarios.     

虚拟结点法在多出口疏散方案中的适用性分析

城市化进程的迅速推进促使城市规模日益扩大、人口密度不断提高,制定一个有效的应急疏散方案,使得人员在存在危险时快速且有序地撤离到安全场所,已经成为迫切需要解决的问题。目前已有一些研究成果,而虚拟结点法在网络流中已有较多应用。结合基于道路网络的单出口分阶段疏散算法,将虚拟结点法应用在多出口疏散方案中,旨在对虚拟结点法的适用性进行分析。模拟结果显示,该方法能够有序、快速地组织大规模人群到安全场所。