道路条件下车辆跟踪的多目标数据关联与决策

介绍一种根据证据理论和模糊数学实现航迹与量测之间数据关联的方法．利用模糊逻辑确定量测与航迹之间的mass函数，再用证据合成规则得到信度函数阵，最后根据最大信度原理确定量测与航迹的关联关系．蒙特卡洛仿真表明该方法具有较好的关联效果，与最近邻方法相比，可提高正确关联的概率。     

Automated reconstruction of 3D input data for noise simulation

Noise is one of the main problems in urban areas. To monitor and manage noise problems, governmental organisations at all levels are obliged to regularly carry out noise studies. The simulation of noise is an important part of these studies. Currently, different organisations collect their own 3D input data as required in noise simulation in a semi-automated way, even if areas overlap. This is not efficient, but also differences in input data may lead to differences in the results of noise simulation which has a negative impact on the reliability of noise studies. To address this problem, this paper presents a methodology to automatically generate 3D input data as required in noise simulations (i.e. buildings, terrain, land coverage, bridges and noise barriers) from current 2D topographic data and point clouds. The generated data can directly be used in existing noise simulation software. A test with the generated data shows that the results of noise simulation obtained from our generated data are comparable to results obtained in a current noise study from practice. Automatically generated input data for noise simulation, as achieved in this paper, can be considered as a major step in noise studies. It does not only significantly improve the efficiency of noise studies, thus reducing their costs, but also assures consistency between different studies and therefore it improves the reliability and reproducibility. In addition, the availability of countrywide, standardised input data can help to advance noise simulation methods since the calculation method can be adopted to improved ways of 3D data acquisition and reconstruction.     

异构数据源城市道路仿真模型接口

根据编译原理中的自动机理论,给出了异构数据源城市道路仿真模型的接口设计及接口实现算法,数据交换采用中性文件交换方式。以DXF格式源文件为例,建立图形实体自动机模型,通过状态转换图跟踪读取信息的轨迹;并给出了城市道路仿真模型在目标平台上重生成时的UML类图。结果表明,自动机理论为交通系统仿真建模提供了一条新的思路和方法,同时使异构数据源城市道路仿真模型接口实现具有一定的理论依据,有利于城市道路基础数据源的共享和重用。     

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.     

Methodology for rapid identification and collection of input data in the simulation of manufacturing systems

Computer simulation is a well-established decision support tool in the manufacturing industry. The rapid development and deployment of simulation models however, are inhibited by factors such as inefficient data collection, lengthy model documentation, and poorly planned experimentation. Typically, more than one third of project time is spent on identification, collection, validation, and analysis of input data. Whilst most research work has been focused on statistical techniques for data analysis, less attention has been paid to the development of systematic approaches to input data gathering. This paper presents a methodology for rapid identification and collection of input data in batch manufacturing environments. A functional module library and a reference data model, both developed using the IDEF (Integrated computer aided manufacturing DEFinition) family of constructs, are the core elements of the methodology. The paper also identifies the major causes behind the inefficient collection of data.     

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.     

输入有约束时的飞翼布局无人机姿态控制

针对大展弦比飞翼布局无人机的刚体运动与弹性运动耦合动力学模型,研究了输入有约束时的无人机姿态控制问题,提出了一种采用扩张状态观测器的反步滑模控制方法.首先,采用扩张状态观测器实时估计气动弹性模态和外界未知干扰的影响,并引入跟踪微分器避免了控制律中项数膨胀问题.然后,针对飞翼布局无人机多操纵面的配置和输入约束,给出了基于LMI的在线舵面分配算法.最后,针对指令滤波和输入约束情况下控制指令的滞后问题,设计了辅助补偿器对控制指令进行补偿.根据Lyapunov稳定性理论证明了该控制方法能够保证姿态跟踪误差收敛至有界,仿真表明存在复合干扰和输入约束时该方法具有良好的姿态跟踪性能.     

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.     

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.     

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.     

元模型输入参数筛选方法研究

针对传统的灵敏度分析方法应用于元模型输入参数筛选时存在的突出问题,基于信息熵理论提出了元模型输入参数筛选方法。以条件熵为基础,提出了用于元模型输入参数筛选的参数体系,包括不确定度、不确定度浮动、不确定度累积浮动,以及元模型输入参数筛选分析过程;采用贝叶斯网络技术研究了多个子模型构成的组合模型描述问题,以及相应的条件熵计算问题;针对航空兵轰炸对于装备的损伤仿真问题,对单一模型和组合模型的输入参数筛选问题开展了案例研究。     

Generating input data structures for automated program testing

Automatic test data generation usually concerns identifying input values that cause a selected path to execute. If a given path involves pointers, then input values may be represented in terms of two‐dimensional dynamic data structures such as lists or trees. Thus, it is very important to identify the shape of the input data structure describing how many nodes are required and how nodes are connected each other. The approach presented in this paper makes use of the points‐to information for each statement in the selected path for the shape generation. It also converts each statement into a static single assignment (SSA) form without pointer dereferences. The SSA form serves as a system of constraints to be solved to yield input values for non‐pointer types. An empirical evaluation shows that shape generation can be achieved in linear time in terms of the number of pointer dereference operations. Copyright © 2008 John Wiley & Sons, Ltd.     

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。     

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。     

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.