摘 要

随着国民经济和科技的不断发展，电子商务已经成了国民经济的一个重要组成部分。伴随着电子商务的高速发展，社会对物流服务的需求也变得越来越强烈。与此同时，由于人们对于物流服务的要求越来越高，物流运输行业在运输过程中存在的问题急需解决。目前，在物流系统中主要存在运输效率低下、运输成本高的问题。为了实现物流运输的优化，这就要求在定位和运输路径安排方面能够合理提升。通过准确定位来合理控制物流运输车队，优化整合资源。传统物流运输车队的定位主要依赖于GPS全球定位系统，车辆定位的精度关系到物流运输的实用价值和整体效率。但是，由于目前的GPS定位系统存在技术瓶颈，可靠性低，无法在复杂环境中准确定位，需要新的定位技术来满足物流运输车队的定位需求。

车联网是物联网在汽车领域其中的一个应用，作为集合通信技术、智能驾驶、安全节能等等的融合性汽车技术，是移动互联网与物联网技术深度研究、纵向发展出的一个成果。近年来，移动车辆的定位技术已成为智能交通系统中的一个关键问题。无线传感网是一种新的数据采集与信息处理方式，其核心节点定位技术为无线传感器网络各种功能的实现提供了强有力的支持。这就使得传感器时钟之间的同步协议被寄予了很高的期待。在车辆定位技术中，无线传感器被广泛的应用于观察和实时监控等方面。它们所组成的大范围无线网络就叫做无线传感网络。节点定位技术作为它的核心部分，使得无线传感网络各种功能的实现成为了可能。本文基于ATS时钟同步算法，做了如下工作：

首先，对分析了国内外车辆定位以及定位算法的现状，确定了本研究的目的和意义。接着，根据国内外定位算法的现状，确定了本文的研究内容，为下文的研究奠定了基础；

其次，分析了目前主流的无线定位技术。也对全球四大定位导航系统的理论进行了相关补充，比较了这四个导航系统的应用领域以及优势和面临的难题，为物流运输车队协同定位的研究提供了理论依据；

然后，研究了基于车联网的时间同步，进一步分析了车联传感网络的时间同步机制。同时分析了车联传感网络同步机制的性能指标，指出了时间同步方法对于物流运输车队协同定位的发散性内容进行研究的基本方法；

接下来，对物流运输车队协同定位进行了时钟同步的研究。介绍了ATS算法，并通过数学模型的方式对物流运输车队协同定位系统进行了建模，接着得出了文章的主要结论并对该结论进行了证明，结论指出时间不同步，即随着时间的推移，ATS算法在物流运输车队协同定位系统CAN网络中无法达到收敛效果；

最后，对MATLAB仿真软件做了环境介绍，并且根据上一章节的结论，在MATLAB仿真软件上，对系统中节点的误差进行比较，验证了ATS算法在物流运输车队协同定位系统中的性能。

本文以复杂环境下的车辆准确定位为目标，对无线传感网络中有时延的ATS算法进行了研究，并对ATS算法在有时延的情况下是否保持有界一致性进行了讨论。从而验证了含时延的ATS算法在参数有界的情况下是发散的。

关键词：物流运输车队；车辆定位；无线传感器网络；时钟同步；发散性

Logistics transport fleet co-location divergent problem in the process of research

ABSTRACT

With the continuous development of national economy and science and technology, electronic commerce has become an important part of the national economy. With the rapid development of e-commerce, the demand for logistics services has become increasingly strong. At the same time, due to people's increasingly high demand for logistics services, logistics and transportation industry in the transport process of the existing problems need to be solved urgently. At present, there are some problems in logistics system, such as low transportation efficiency and high transportation cost. In order to achieve the optimization of logistics transportation, this requires that the location and transportation path arrangement can be reasonably improved. Through accurate positioning, we can reasonably control the logistics fleet and optimize the integration of resources. The positioning of traditional logistics transportation fleet mainly depends on GPS global positioning system. The accuracy of vehicle positioning is related to the practical value and overall efficiency of logistics transportation. However, due to the technical bottleneck and low reliability of the current GPS positioning system, it is impossible to accurately locate in complex environment. New positioning technology is needed to meet the positioning needs of logistics fleet.

Vehicle Internet is one of the applications of Internet of Things in the automotive field. As an integrated automotive technology, such as integrated communication technology, intelligent driving, safety and energy saving, it is a result of in-depth research and vertical development of mobile Internet and Internet of Things technology. In recent years, the location technology of mobile vehicles has become a key issue in ITS. Wireless sensor network is a new way of data acquisition and information processing. Its core node location technology provides strong support for the realization of various functions of wireless sensor network. This makes the synchronization protocol between sensor clocks highly expected. In vehicle location technology, wireless sensor is widely used in observation and real-time monitoring. The large-scale wireless network composed of them is called wireless sensor network. As the core part of wireless sensor networks, node location technology makes it possible to implement various functions of wireless sensor networks. This paper does the following work based on ATS clock synchronization algorithm:

Firstly, the status quo of vehicle location and location algorithm at home and abroad is analyzed, and the purpose and significance of this study are determined. Secondly, based on the analysis of the current research situation, the contents and methods of this study are determined, and the specific research is carried out.

Secondly, the current mainstream wireless positioning technology is analyzed, and the positioning methods about signal strength, signal arrival time, signal arrival angle and signal arrival time difference are explained. The theory of the four global positioning and navigation systems is supplemented. The application fields, advantages and difficulties of the four navigation systems are compared, which provides a theoretical basis for the research of coordinated positioning of logistics fleet.

Then, the time synchronization based on Vehicle Networking is studied, and the time synchronization mechanism of Vehicle Networking Sensor Network is further analyzed. At the same time, the performance indicators of synchronization mechanism of vehicle-link sensor network are analyzed, and the basic method of time synchronization method to study the divergence content of collaborative positioning of logistics fleet is pointed out.

Next, the clock synchronization of logistics fleet cooperative positioning is studied. This paper introduces ATS algorithm, and builds a model of logistics fleet cooperative positioning system by means of mathematical model. Then it draws the main conclusion of the paper and proves the conclusion. The conclusion points out that the time is not synchronous, that is, with the passage of time, ATS algorithm can not achieve convergence effect in the CAN network of logistics fleet cooperative positioning system.