Automotive navigation system
An automotive avigation system is    a satellite navigation system designed for use in automobiles. It typically uses a GPS navigation device to acquire position data to locate the user on a road in the unit's map database. Using the road database, the unit can give directions to other locations along roads also in its database. Dead reckoning using distance data from sensors attached to the drivetrain, a gyroscope and an accelerometer can be used for greater reliability, as GPS signal loss and/or multipath can occur due to urban canyons or tunnels. Some sorts can be taken out of the car and used hand-held while walking.
History
Automotive navigation systems were the subject of extensive experimentation, including some efforts to reach mass markets, prior to the availability of commercialGPS.
Most major technologies required for modern automobile navigation were already established when the microprocessor emerged in the 1970s to support their integration and enhancement by computer software. These technologies subsequently underwent extensive refinement, and a variety of system architectures had been explored by the time practical systems reached the market in the late 1980s. Am
ong the other enhancements of the 1980s was the development of color displays for digital maps and of CD-ROMs for digital map storage.
However, there is some question about who made the first commercially available automotive navigation system. There seems to be little room for doubt that Etak was first to make available a digital system that used map-matching to improve on dead
reckoning instrumentation. Etak's systems, which accessed digital map information stored on standard cassette tapes, arguably made car navigation systems practical for the first
time.[2] However, Japanese efforts on both digital and analog systems predate Etak's founding. Steven Lobbezoo developed the first commercially available satellite navigation system for cars. It was produced in Berlin from start 1984 to January 1986. Publicly presented first at the Hannover fair in 1985 in Germany, the system was shown in operation on the evening news from the first German television channel in that year. It used a modified IBM PC, a large disc for map data and a flat screen, built into the glove compartment. It was called Homer
Alpine claims to have created the first automotive navigation system in 1981. However, according to the company's own historical timeline,[3] the company claims to
have co-developed an analog automotive navigation product called the Electro Gyrocator, working with Honda. This engineering effort was abandoned in 1985. Although there are reports of the Electro Gyrocator being offered as a dealer option on the Honda Accord in 1981, it's not clear whether an actual product was released, whether any customers took delivery of an Electro Gyrocator-equipped Accord, or even whether the unit appeared in any dealer showrooms; Honda's own official history appears to pronounce the Electro Gyrocator as not practical.
Honda claims[4] to have created the first navigation system starting in 1983, and culminating with general availability in the 1990 Acura Legend. The original analogElectro Gyrocator system used an accelerometer to navigate using inertial navigation, as the GPS system was not yet generally available. However, it appears from Honda's concessions in their own account of the Electro Gyrocator project that Etak actually trumped Honda's analog effort with a truly practical digital system, albeit one whose effective range of operation was limited by the availability of appropriately digitized street map data.
Technology
Visualization
Navigation systems may (or may not) use a combination of any of the following:
▪top view for the map
▪top view for the map with the map rotating with the automobile (so that "up" on the map always corresponds to "forward" in the vehicle)
extensive翻译▪bird's-eye view for the map or the next curve
▪linear gauge for distance, which is redundant if a rotating map is used
▪numbers for distance
▪schematic pictograms
▪voice prompts
Road database
Contents
The road database is a vector map of some area of interest. Street names or numbers and house numbers are encoded as geographic coordinates so that the user can find some desired destination by street address .
Points of interest will also be stored with their geographic coordinates. Point of interest specialties include speed cameras, fuel stations, publicparking, and "parked here". Contents can be produced by the user base as their cars drive along existing streets and communicating via the internet, yielding a free and up-to-date map.
Physical Storage Format
The Physical Storage Format (PSF) initiative is an industry grouping of car manufacturers, navigation system suppliers and map data suppliers whose objective is the standardization of the data format used in car navigation systems, as well as allow a map update capability. Standardization would improve interoperability, specifically by allowing the same navigation maps to be used in navigation systems from 19 manufacturers. Companies involved
include BMW, Volkswagen, Daimler,Renault, ADIT, Aisin AW, Alpine
Electronics, Navigon, Bosch, DENSO, Mitsubishi, Harman Becker, Panasonic,
PTV, Continental AG, Clarion, Navteq, Tele Atlas and Zenrin.
Media
The road database may be stored in solid state read-only memory (ROM), optical media (CD or DVD), solid state flash memory, magnetic media (hard disk), or a combination. A common scheme is to have a base map permanently stored in ROM that can be augmented with detailed information for a region the user is interested in. A ROM is always programmed at the factory; the other media may be preprogrammed, downloaded from a CD or DVD via a computer or wireless connection (bluetooth, Wi-Fi), or directly used utilizing a card reader. Some navigation device makers provide free map updates for their customers. These updates are often obtained from the vendor's website, which is accessed by connecting the navigation device to a PC.
汽车导航系统
汽车导航系统是一个设计供汽车使用的卫星导航系统。它通常使用一个GPS导航设备获取定位数据在单位的地图数据库来到道路上的用户。使用道路数据库，系统也可以使用这个数据库给沿公路的其他地点指点方向。在其数据库中。因为城市峡谷或隧道可能会导致GPS信号丢失和/或多重路径，这时使用来自连接到传动系统的传感器发出远程信号的航位推算和一个陀螺仪、加速计可以提高可靠性。
一些种类可以从汽车上拿下来，走路时拿在手中使用。
.历史
汽车导航系统是广泛的实验的产物，包括一些达到大众市场的努力，以前商用GPS的可用性。
当二十世纪七十年代通过电脑软件支持他们的集成和增强的微处理器出现时，运用到现代汽车导航的大多数主要技术已经建立了。这些技术随后进行了广泛的细化，并在20世纪80年代末通过时间探索多种系统产生的许多建筑系统到达了市场。在20世纪80年代的其他增强的数字地图是彩显示器和CD-ROM的数字地图存储的发展。
然而，到底是谁发明了第一个商用汽车导航系统仍存在一些质疑。Etak通过地图匹配来提高航位推算精确度数字系统首次做成了可用的数字系统，似乎没有怀疑的余地。Etak的系统，就是存储在标准盒式磁带的数字地图信息系统，可以说是使汽车导航系统第一次成为现实。然而，日本对数字和模拟系统努力都高于Etak的经费。
Steven Lobbezoo研制出第一台商品化卫星导航系统车辆。它产生于1984年柏林开始到1986年1月。第一次公开展出是在在1985年德国汉诺威博览会上，这个系统的操作是在同年德国第一频道晚间新闻上播出的。它使用一个改进的IBM个人计算机，一个大的地图数据和一个平坦的荧屏建成了仪表板，它被称
为荷马。在1981年Alpine声称已经创造了第一个汽车导航系统。不过，根据公司自身的历史时间表，该公司声称和本田汽车合作已经取得一种模拟汽车导航产品称为Electro
Gyrocator。在1985年这个工程的影响消除了。虽然有报道声称在1981年Electro Gyrocator已经被经销商选用到本田雅阁，但是还不清楚是否实际的产品已经公布了，是否有顾客提到了装备Electrio Gyrcator的雅阁车，甚至是否出现在任何单位经销商陈列室，本田的官方历史似乎没有声明Electrio Gyrocator已经被实用。
从1983年开始本田声称已经创造了第一个导航系统，并在二十世纪九十年代的Acura Legend上通过商业运转达到鼎盛。因为GPS系统尚未普遍使用，原模拟电子系统使用一个加速度计为惯性导航领航。然而，起于本田的在他们自己的帐户Gyrocator电子工程上的让步,Etak实际上夸大本田analog 与一个真正实用的数字系统模拟的作用，尽管其有效范围的操作被适当的数字化地图数据所限制。
.技术
.可视化
导航系统可能使用（或没有）下列任意组合:
.地图的俯视图
.随着汽车旋转的地图俯视图
.对地图或是下个转弯像鸟一样的视觉
.如果使用的是旋转地图，那么直线测量就是多余的
.里程数
.象形原理图
.语音提示
.道路数据库
.内容
道路数据库是某一关注区域的矢量地图。街道名称或编号和房屋编号作为地理坐标编码，使用户通过街道地址发现目的地。
兴趣点也通过他们的地理坐标储存起来。这些兴趣点包括：速度摄像头，加油站，公共停车场,“停在这里”.
这些内容可以由用户根据他们的车现有街道开车和通过因特网的交流，还有免费和持续更新的地图为依据产生的。
.物理存储格式
物理存储格式(PSF)倡议是一个工业集团的汽车制造商，供应商和地图导航系统供应商，其目标是那些数据标准化的数据格式用于汽车导航系统，以及允许地图更新的能力。标准化将改善互用性，特别是通过允许相同的导航地图用于导航系统。参与公司包括宝马、大众、戴姆勒、雷诺、硐,Aisin亚历山大-伍尔兹,Alpine Electronics、Navigon、博世、电装、三菱、贝克‧哈尔曼、松下、PTV，大陆航空公司, Clarion,Navteq、Tele Atlas 和Zenrin。
.媒体
道路数据库可能是储存在固态只读存储器(ROM)、光学媒体(CD或DVD)、固态快闪记忆体、磁性媒体(硬盘)，或者两者兼有。一个共同的计划是有一个基地图永久储存在ROM中，这样可以为用户感兴趣的地区增强详细的信息。ROM是在工厂中编程的；其他媒体可能是预编程序，通过电脑或无线连接(蓝牙技术、无线网络)从CD或DVD下载，或者直接利用一个读卡器。
一些导航设备制造商为他们的客户提供免费地图更新。这些更新往往从供应商的网站得到，这个网站是通过导航设备连接到个人电脑上的。

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