An automotive navigation 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.
History
Automotive navigation systems were the subject of extensive experimentation, including some efforts to reach mass markets, prior to the availability of commercial GPS.
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. Among 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, which arguably made car navigation systems practical for the first time. However, Japanese efforts on both digital and analog systems predate Etak’s founding;
Alpine claims to have created the first automotive navigation system in 1981. However, according to the company’s own historical timeline[2], 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”. See below for Honda’s history of the project.
Honda claims to have created the first navigation system starting in 1983, and culminating with general availability in the 1990 Acura Legend. The original analog Electro 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.
[...] progress in digital technology would not stop simply because Honda had turned its attention to analog. In 1985, for example, the U.S. company ETAK introduced its own digital map navigation system. Although the system’s effective range-the area of geographical coverage-was limited, the announcement was a dour one for Nakamura and his staff. Therefore, ultimately the development of a practical analog system was shelved. The staff experienced indescribable feelings of disappointment. The development of [Honda's] digital map navigation system resumed in 1987, following a three-year hiatus.
Both Mitsubishi Electric and Pioneer claim to be the first with a GPS-based auto navigation system, in 1990. Also in 1990, a draft patent application was filed within Digital Equipment Co. Ltd. for a multi-function device called PageLink that had real-time maps for use in a car listed as one of its functions.
Magellan, a GPS navigation system manufacturer, claims to have created the first GPS-based vehicle navigation system in the U.S. in 1995.
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)
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 (see map database management).
Points of interest (waypoints) will also be stored with their geographic coordinates. Point of interest specialties include speed cameras, fuel stations, public parking, and “parked here” (or “you parked here”).
Contents can be produced by the user base as their cars drive along existing streets (Wi-Fi) and communicating via the internet, yielding a free and up-to-date map.
Map Formats
Formats are almost uniformly proprietary; there is no industry standard for satellite navigation maps, although Navteq are currently trying to address this with S-Dal (see below).
The map data vendors such as Tele Atlas and NAVTEQ create the base map in a standard format GDF, but each electronics manufacturer compiles it in an optimized, usually proprietary format. GDF is not a CD standard for car navigation systems. GDF is used and converted onto the CD-ROM in the internal format of the navigation system.
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.
Real-time Data
Main article: Integration of traffic data with navigation systems
Some newer systems can not only give precise driving directions, they can also receive and display information on traffic congestion and suggest alternate routes. These may use either TMC, which delivers coded traffic information using radio RDS, or by GPRS/3G data transmission via mobile phones.
One key type of real-time data is Traffic information, which includes:
Real-time data about free/full parkings;
Nearest public transport lines and prices, to go to a destination, when there is a jam.
Other real-time data includes weather broadcasting, etc.
Integration and Other Functions
The color LCD screens on some automotive navigation systems can also be used to display television broadcasts or DVD movies.
A few systems integrate (or communicate) with mobile phones for hands-free talking and SMS messaging (i.e., using Bluetooth or Wi-Fi).
Automotive navigation systems can include personal information management for meetings, which can be combined with a traffic and public transport information system.
Controversy
Safety Features
Vehicles produced by Subaru and Lexus, as well as Lexus’ parent company, Toyota, lock out many of the features when the vehicle is in motion. The manufacturers claim this is a safety feature to avoid the driver being distracted. Many users have complained that passengers are not able to enter destinations while in motion, even though it is safe to do so. Additionally, drivers have complained that it is often more dangerous to pull off a highway and stop than it would be to enter a destination into the system.
Misdirection
A number of road accidents have been attributed to misdirection by satnav systems. On May 11, 2007, a driver followed satnav instructions in the dark and her car was hit by a train on a rail crossing that was not shown on the system.[6] In Exton, Hampshire, the County Council erected a sign warning drivers to ignore their “sat nav” system and to take another route, because the street was too narrow for vehicular traffic, and property damage resulted from vehicles getting stuck.[7]
GPS vs Speed Camera Accuracy
In July 2007, an Australian man successfully overturned a speeding conviction after evidence from a GPS navigational track proved that he did not exceed the speed limit.[
Other functions
Golf Carts may have integrated GPS units tailored to specific golf courses, providing interactive course maps and live readings of distance measurements to the green.
Many systems can give information on nearby points of interest (POIs), such as restaurants, cash machines and gas stations. Some navigation devices use this feature to store the location of known speed traps or speed cameras, and can alert the driver in much the same way as a radar detector. GPS may also be integrated into actual radar detection devices to enhance accuracy, and in some cases, implement a logic system where the system only alerts if the driver is traveling above the speed limit or in the direction to be ‘caught.’ Unlike radar detectors, GPS-based speed trap warnings are currently not illegal in very many countries.
The radio dispatching of taxicabs have been phased out in several countries in favor of GPS technology plus some form of mobile networking with on board computers. The central dispatch computer keeps track of all vehicles in its fleet, and automatically selects the nearest cab to respond to a passenger request.
Advanced car security vehicle tracking systems can relay the vehicle’s location via cellular phone services in case of loss or theft. The technology can also be used to manage fleet vehicles, in which case it’s known as automatic vehicle location.
A very basic form of GPS navigation is used on public buses in Taipei, where the location and sequence of bus stops for a particular route are programmed. The computer announces the approaching and upcoming bus stops and repeats the information on a dot-matrix display, all without intervention from the driver. This service was once provided based on tire revolutions and odometer mileage, which is not nearly as reliable as a GPS enabled system.
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