Transforming GIS data into functional road models for large-scale traffic simulation

There exists a vast amount of geographic information system (GIS) data that model road networks around the world as polylines with attributes. In this form, the data are insufficient for applications such as simulation and 3D visualization-tools which will grow in power and demand as sensor data become more pervasive and as governments try to optimize their existing physical infrastructure. In this paper, we propose an efficient method for enhancing a road map from a GIS database to create a geometrically and topologically consistent 3D model to be used in real-time traffic simulation, interactive visualization of virtual worlds, and autonomous vehicle navigation. The resulting representation provides important road features for traffic simulations, including ramps, highways, overpasses, legal merge zones, and intersections with arbitrary states, and it is independent of the simulation methodologies. We test the 3D models of road networks generated by our algorithm on real-time traffic simulation using both macroscopic and microscopic techniques.     

Representation of occurrences for road vehicle traffic

Our 3D-model-based Computer Vision subsystem extracts vehicle trajectories from monocular digitized videos recording road vehicles in inner-city traffic. Steps are documented which import these quantitative geometrical results into a conceptual representation based on a Fuzzy Metric-Temporal Horn Logic (FMTHL, see [K.H. Schäfer, Unscharfe zeitlogische Modellierung von Situationen und Handlungen in Bildfolgenauswertung und Robotik, Dissertation, 1996]). The facts created by this import step can be understood as verb phrases which describe elementary actions of vehicles in image sequences of road traffic scenes. The current contribution suggests a complete conceptual representation of elementary vehicle actions and reports results obtained by an implementation of this approach from real-world traffic videos.     

Qualifying input test data for model transformations

Model transformation is a core mechanism for model-driven engineering (MDE). Writing complex model transformations is error-prone, and efficient testing techniques are required as for any complex program development. Testing a model transformation is typically performed by checking the results of the transformation applied to a set of input models. While it is fairly easy to provide some input models, it is difficult to qualify the relevance of these models for testing. In this paper, we propose a set of rules and a framework to assess the quality of given input models for testing a given transformation. Furthermore, the framework identifies missing model elements in input models and assists the user in improving these models.

Grid-based collaborative simulation system for vehicle crashworthiness

Globalization and increasing market competition are forcing the automotive industry to develop technology that will enable more efficient collaboration between carmakers and their suppliers. One of the options that can meet this demand is to adopt grid technology in the collaboration process. For the system to be successfully applied, the trust relationship among Virtual Organization (VO) members becomes a very important factor. Systems lacking in secure mechanisms require all the collaborating members to fully trust each other, and thus make their application quite limited. Based on grid technology, this paper proposes a collaborative simulation system for vehicle crash safety design, and discusses the trust relationship among VO members. The grid middleware VEGA and web services working for the collaboration also contribute to the simulation system. Also, a test bed is set up on the basis of the Local Area Network (LAN). At the end of this paper, a real case involving a carmaker and a door supplier is presented to demonstrate how the grid-based collaborative simulation system works.     

Robust tracking control for an air-breathing hypersonic vehicle with input constraints

The focus of this paper is on the design and simulation of robust tracking control for an air-breathing hypersonic vehicle (AHV), which is affected by high nonlinearity, uncertain parameters and input constraints. The linearisation method is employed for the longitudinal AHV model about a specific trim condition, and then considering the additive uncertainties of three parameters, the linearised model is just in the form of affine parameter dependence. From this point, the linear parameter-varying method is applied to design the desired controller. The poles for the closed-loop system of the linearised model are placed into a desired vertical strip, and the quadratic stability of the closed-loop system is guaranteed. Input constraints of the AHV are addressed by additional linear matrix inequalities. Finally, the designed controller is evaluated on the nonlinear AHV model and simulation results demonstrate excellent tracking performance with good robustness.     

A roadside simulation of road crossing for children

A simple and safe method is proposed for giving children practical experience similar to crossing the road and for assessing their performance. The method comprises a ‘pretend road’ laid out on the pavement, which the child crosses as if crossing the adjacent road in the face of oncoming vehicles. A comparison of adult performances in crossing through gaps in traffic on pretend and real roads indicates that the pretend task adequately simulates real road crossing. Similar experiments on pretend roads with 5-10 year olds crossing through gaps in traffic indicated that children are able to understand the simulation task and perform sensibly on it. Moreover, there were children of all ages who consistently performed at close to an adult level indicating that the visual timing required in the skill is not beyond young children. The results suggest that children should be trained in crossing in the presence of traffic at an early age. The pretend task could prove a valuable aid to training.     

Joint road geometry estimation and vehicle tracking

Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles.

Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.     

展示车辆平顺性的虚拟仿真技术

虚拟现实技术是车辆平顺性仿真展示的主要方法之一。为了能更直观地展示车辆平顺性,参考了1/2七自由度车辆模型,在分析三维模型车辆振动组成结构后构建了1/2二自由度车辆模型,并导出车辆垂向受力方程,实现了对车辆平顺性的模拟。为观测车辆平顺性仿真过程,提出"固定跟车"观测算法,通过平移和旋转变换,让摄像机视角与车辆位置相对固定并随车一起运动。实验表明,在车轮受到外力激励的情况下可以较真实地模拟模型车辆的振动状态,摄像机随车定点观测也更好地展现了仿真过程。     

Multirate numerical scheme for large-scale vehicle traffic simulation

In modeling vehicular traffic on large scales in large cities, the number of vehicles could reach tens of thousands, which, for the microscopic approach, corresponds to the solution of ordinary differential equations (ODEs) with large dimensions. The speed of changes in the size of the components of such systems usually lies in a wide range, as the dynamics and behavior of the vehicles can strongly differ. In this paper we introduce a multirate numerical scheme with a self-adjusting time stepping strategy. Instead of using a single step size for the whole system, the step size for each component is determined by estimating its own local variation. The stability analysis for the developed scheme is performed and the stability conditions are obtained. The presented multirate scheme provides a significant speed-up in the CPU times compared to the corresponding single-rate one. The use of multiple time steps allows parallel computing.     

低附着路面的弯道制动控制策略研究

为了解决车辆在低附着弯道路面制动中载荷转移造成的汽车失稳问题,建立7自由度整车模型。通过分析整车弯道制动过程的动态特性,推导出制动力与滑移率的关系,提出了纠正转向中车辆失稳的措施,设计了以滑移率为主的门限值控制方法。仿真验证了该方法能够有效提高制动稳定性。     

车辆视频导航中道路检测方法研究进展

视频导航以其获取信息丰富、对环境影响小、成本低廉等诸多优点成为了辅助车辆自动驾驶和陆地自主车(ALV)常用的一种自动导航方式,而从视频导航图像中检测出道路区域则是实现视频导航的基础和关键。对近年来车辆视频导航过程中道路检测的实现算法进行了回顾和分析,并对道路检测算法以后的研究方向进行了探讨。     

路面车辆的视觉检测方法

智能车辆是近年来的研究热点,基于视觉的车辆检测与识别技术是智能车辆技术研究的一个重要组成部分。介绍国内外路面车辆检测技术的研究方法和发展现状。根据检测的不同方法,以视觉传感器为主,从特征和运动的角度论述目标检测的方法;从模板、外观和分类的角度论述目标识别的方法。介绍立体视觉和多传感器融合的技术。对智能车辆障碍物检测和识别技术的发展进行了展望。     

A holistic approach to vehicle simulation

Vehicle simulators traditionally model a vehicle's components separately. This paper describes a “holistic” simulator that constructs a map of fuel consumption vs speed, acceleration, and gear for the vehicle as a whole, based on statistical analysis of road test data. A single computer routine can simulate any number of existing vehicles, once each is outfitted with instruments and a data logger and is tested 1 to 2 days on the road and perhaps on a chassis dynamometer. Results of simulating a 1979 Ford Fairmont station wagon are presented.     

带道路容量动态约束的关联运输调度问题

介绍了混沌遗传算法的基本原理,并对其进行改进,自适应地调整交叉概率和变异概率,引进了模拟退火机制,用聚类分析及改进的算法对多车场的关联运输调度问题进行求解,然后与遗传算法求解此模型的结果相比较。实例证明该算法求解关联运输调度问题是可行的,且优于传统的遗传算法。     

Codeword distribution for frequency sensitive competitive learningwith one-dimensional input data

We study the codeword distribution for a conscience-type competitive learning algorithm, frequency sensitive competitive learning (FSCL), using one-dimensional input data. We prove that the asymptotic codeword density in the limit of large number of codewords is given by a power law of the form Q(x)=C.P(x)(alpha), where P(x) is the input data density and alpha depends on the algorithm and the form of the distortion measure to be minimized. We further show that the algorithm can be adjusted to minimize any L(p) distortion measure with p ranging in (0,2].     

路政设施中时空数据模型的研究

对时空数据模型进行了研究,运用面向对象的方法分析路政设施中的时空数据,从时空对象的基本属性和行为出发,建立一个合适的时空数据模型,能够很好地封装对象的空间,专题,时间特征,表达时空对象的语义,满足一系列的查询要求.设计了标志标杆类的具体结构和存储方案,将时间作为独立的一维来处理,标记在对象属性上,减少了数据冗余,同时也为以后解决历史查询的问题提供了有效途径.     

小型无人地面车辆可视化仿真

以实验室中的小型无人地面车辆(SUGV)为背景,在MFC下利用OpenGL与3D Studio MAX进行该SUGV运动过程仿真,实现了三维可视化仿真场景系统中模型的建立、调入和视点的设置,在动力学分析基础上建立SUGV各种运动模型,实现了三维模型的交互控制.该仿真系统既可为操纵人员提供模拟操纵平台,也可为开发人员提供辅助设计和开发的平台.