Automotive navigation system

A taxi equipped with GPS navigation device

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.

Increasingly, these systems are integrated with the car's controls. 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 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.[1]

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.

[...] 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.

However it was not until 2000 that the United States made a more accurate GPS signal available for civilian use.[13]

Technology

Visualization

Navigation systems may (or may not) use a combination of any of the following:

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

Navigation with Gosmore, an open source routing software, on a personal navigation assistant with free map data from OpenStreetMap.

Formats are almost uniformly proprietary; there is no industry standard for satellite navigation maps, although some companies are currently trying to address this with SDAL and NDS (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.

CARiN

CARiN Database Format (CDF) is a proprietary navigation map format created by Philips Car Systems (this branch was sold to Mannesman VDO, which became VDO/Dayton in 1998, then Siemens VDO in 2002, then Continental in 2007) and is used in a number of navigation-equipped vehicles. The 'CARiN' portmanteau is derived from Car Information and Navigation.

SDAL

This is a proprietary map format published by Navteq, who released it royalty free in the hope that it would become an industry standard for digital navigation maps. Vendors who used this format include:

The format has not been very widely adopted by the industry.

Navigation Data Standard (NDS)

The Navigation Data Standard (NDS) 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. The NDS effort began in 2004 and became a registered association in 2009.[14] Standardization would improve interoperability, specifically by allowing the same navigation maps to be used in navigation systems from 20 manufacturers.[15] Companies involved include BMW, Volkswagen, Daimler, Renault, ADIT, Aisin AW, Alpine Electronics, Navigon, Navis-AMS, Bosch, DENSO, Mitsubishi, Harman International Industries, Panasonic, PTV, Continental AG, Clarion, Navteq, Navinfo, 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.

Real-time data

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:

Other real-time data includes weather broadcasting, etc.

Integration and other functions

Controversy

Safety features

Vehicles produced by Cadillac, Cadillac's parent company General Motors, Subaru, Lexus, and 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.

Misdirection

A number of road accidents in the UK have been attributed to misdirection by satellite navigation systems. On May 11, 2007, a driver followed satellite navigation instructions in the dark and her car was hit by a train on a rail crossing that was not shown on the system.[16] In Beacon Hill Lane, 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.[17]

A homemade 'No Sat Nav' sign, near Petersfield, UK

On March 25, 2009, a man drove down a steep mountain path and almost off a cliff after he was allegedly directed by his portable GPS system. He was finally stopped by a wire fence.[18]

In Australia, tourists using a satellite navigation system became bogged in Moreton Bay when the system indicated it was possible to drive to North Stradbroke Island.[19]

Misdirection can also occur when a road is altered either permanently or temporarily, such as during road re-construction.

Issues arising from heavy goods vehicles using satellite navigation systems are often caused by the driver using a device designed for cars, therefore a route suitable for a car sized vehicle will always be chosen if they are a legal right of way. This can often lead to lorries getting stuck on narrow country lanes, tight bends, and hitting low bridges. However, software packages and navigation devices that adapt the routing based on vehicle dimensions and legal restrictions are becoming more commonplace. The software allows drivers to enter the weight, height, length, width and cargo details.

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.[20]

Other functions

Retrofitting of GPS

A vehicle can be retrofitted with a GPS navigation device unit if it did not originally have one. There are three approaches that can be taken here:

Portable GPS

This type of GPS navigation device is not permanently integrated into the vehicle, having only a simple bracket to mount the device on the surface of the dashboard and powered via the car cigarette lighter. This class of GPS unit does not require professional installation and can typically be used as handheld device, too.

Benefits of this type of GPS unit include low cost as well as the ability to move them easily to other vehicles. Their portability means they are easily stolen if left inside the vehicle. Furthermore, not having a compass, accelerometer or inputs from the vehicle's speed sensors, means that they cannot navigate as accurately by dead reckoning as some built-in devices when there's no GPS signal. More modern portable devices (such as the TomTom 920) have an inbuilt accelerometer to try to address this.

A portable automotive navigation system kit generally includes:

Early Factory Navigation System (as fitted to 1997 UK Specification Ford Mondeo)

Original factory equipment

Many vehicle manufacturers offer a GPS navigation device as an option in their vehicles. Customers whose vehicles did not ship with GPS can therefore purchase and retrofit the original factory-supplied GPS unit. In some cases this can be a straightforward "plug-and-play" installation if the required wiring harness is already present in the vehicle. However, with some manufacturers, new wiring is required, making the installation more complex.

Modern Factory Navigation System (as fitted to a 2009 U.S. Honda Accord)

The primary benefit of this approach an integrated and factory-standard installation. Many original systems also contain a gyrocompass or accelerometer and may accept input from the vehicle's speed sensors, thereby allowing them to navigate via dead reckoning when a GPS signal is temporarily unavailable.[21] However, the costs can be considerably higher than other options.

Aftermarket

A number of manufacturers supply aftermarket GPS navigation devices that can be integrated permanently into the vehicle. A typical location for such an installation is the DIN slot for the radio/tape/CD. However, in extreme cases, the dashboard may also be remodeled to accommodate the unit.

This approach can be considered a trade off between the previous two options. Benefits include a more secure and better cosmetic finish than a portable device, and lower cost compared to the installation of an original factory-supplied GPS.

Alternatives

Smartphones with GPS, and other navigation devices, may also be used without installing in a car.

Further information: GPS navigation device

SMS

Establishing points of interest in real-time and transmitting them via GSM cellular telephone networks using the Short Message Service (SMS) is referred to as Gps2sms. Some vehicles and vessels are equipped with hardware that is able to automatically send an SMS text message when a particular event happens, such as theft, anchor drift or breakdown. The receiving party (e.g., a tow truck) can store the waypoint in a computer system, draw a map indicating the location, or see it in an automotive navigation system.

Example systems

Navigon

See also

References

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  18. "BMW left teetering on 100ft cliff edge after sat-nav directs driver up steep footpath". MailOnline. 2009-03-25. Retrieved 2010-01-25.
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