我国风险投资发展现状:基于嵌入式LINUX的GPS导航系统的研究与实现

硕士研究生毕业论文 作者：周念东 指导教师：胡晨 毕业时间：2005年4月
摘    要
随着GPS系统在包括道路测控、汽车导航、交通管理、石油勘探、海上作业和紧急救援等军事和民用的众多领域中的应用和发展，GPS系统的影响也越来越广泛。另一方面，不断发展的嵌入式操作系统促使移动计算技术在手持设备中也得到广泛的应用，以掌上电脑(PDA)为代表的移动式计算系统日益普及，在手持式设备中实现GPS移动导航功能具有良好的市场前景。
本课题选择Linux为嵌入式操作系统，并采用Trolltech公司Qt/Embedded为应用程序开发平台，研究应用于手持终端设备的GPS导航系统的实现方案，开发具有自主知识产权的导航系统。
坐标系统转换和地图投影是GPS导航系统中的核心技术。本文首先分析GPS系统中地理坐标系统的定义和坐标转换基本原理，从大地坐标系、空间直角坐标系以及国家当地坐标系的概念入手，研究大地地心坐标系与空间直角坐标系以及当地国家坐标系的关系，并研究从大地地心坐标系转换为国家当地坐标系的转换算法，研究地心坐标系到平面直角坐标系的转换方法，并推导了相应的转换公式。
在我国导航系统中应用上述转换算法，实现WGS-84坐标系到北京54坐标系或西安80坐标系的转换，利用高斯正形投影算法实现地图投影，减小投影变形。研究横轴墨卡托投影、兰勃特投影以及线性投影等其它坐标投影方式，实现地理经纬度坐标到平面直角坐标的转换，支持多比例尺地图。通过GPS数据接收装置，检测卫星状态并获取地理信息，研究如何快速有效的获取可用于定位的坐标信息的数据处理方法。
根据设备体积小、功耗低、人机界面简单易用以及运行稳定、操作简单、处理速度快的系统要求，选择Intel Xscale系列应用处理器PXA255作为处理器平台，构建系统硬件平台。选择Open Source的Arm Linux作为嵌入式操作系统以及选择Qt/Embedded 为GUI平台，搭建了软件开发环境，完成了Arm Linux的系统移植，并实现了TIMB-E010-2 GPS模块的设备驱动，设计和实现了GPSD数据通信模块，改善了GPS数据接收与GPS导航应用之间的数据通信接口。根据坐标系转换以及地图投影算法的研究成果，使用C和C++语言采用面向对象编程技术进行了程序编码，实现了定位、导航、轨迹显示/地图下载和设置等功能。
本文最后给出了目标系统的实验结果，并分析了系统设计中的一些不足，提出了在以后工作中改进系统性能的设想。
ABSTRACT
By perpetual development of embedded operating system, mobile computer technique is applied abroad in handheld device. Mobile computer system represented by PDA being incresingly popularization makes it good market outlook of handheld device with GPS navigation function. This paper mainly introduces a scheme applying the GPS navigation system of intellectual property rights in handheld terminal, which adopts Linux as embeded operating system and Qt/Embeded from Trolltech Company as application program platform.
The coordinate system conversion and the map projection are the key technique in GPS navigation system. This paper analyses the definition and the basic principle of geographical coordinate system conversion firstly. Then it researchs the relationship of world geodetic system with local geodetic systems and the transformations from world geodetic system to local geodetic system and figures out the corresponding conversion formula.
This paper also researches transfer algorithm from world geodetic system to right angle coordinate system utilizing gauss projection to reduce the shape of projection. Using these algorithms in Chinese navigation system, it achieves the transformation from world geodetic system 1984(WGS-84) to Beijing 54 or Xi'an 80 coordinate system. And this paper researches projection ways of coordinate such as the Mercator projection, Lambert projection and linear projection to achieve the conversion of level rectangular coordinate by latitude coordinate and geography. By the data received through GPS receiver device and the state of satellites with geographical information, it shows how to process the coordinate information data effectively.
According to the requirement of small equipment, low power dissipation, simple man-machine interface, stabilization and easy operation, this project chooses Intel Xscale series processor琍XA255 to design the systematic hardware platform. Using Arm Linux of open source as the embedded operating system and Qt/Embedded as GUI platform, it is easy to set up the development environment of the application software. The project has finished porting Arm Linux, the drivers of TIM B-E010-2 GPS module, implementation of GPSD data communication module, and has optimized the data communication interface between GPS navigation application and GPS receiver module. According to the coordinates system conversion research results and algorithm of map projection, the project uses C and C ++ language to carry on the procedure code under Object-Oriented Design technology and has implemented the functions of object orientation, navigation, tracks, maps download.
This paper provides the experimental result of the target system and summarizes insufficient of the system design in this project and also gives some imaginations of working in the future at last.