How in-car navigation grew from dead-reckoning computers and cassette routes into GPS, live traffic and the map data that self-driving cars depend on.
Automotive navigation uses satellite positioning, often backed by dead reckoning, to locate a car on a digital road map. Its first commercial system was Honda's Electro Gyrocator in 1981. GPS reached production cars in 1990, and live traffic now feeds routing.
An automotive navigation system is part of a car's controls, or a third-party add-on, that helps the driver find the way. It usually takes its position from a satellite navigation receiver and matches that position to a road. When a destination is set, the system calculates a route, and live traffic information such as closures and congestion can change the route on the move. Navigation has also become central to the development of self-driving cars.
How does a navigation system know where the car is?
Satellite positioning is the main source, but it can fail in urban canyons or tunnels, and signals bouncing off buildings can throw it off. To stay reliable, many systems add dead reckoning. It estimates movement from distance data taken from the drivetrain, along with an accelerometer, a gyroscope and a magnetometer, and so keeps tracking the car while the satellite signal is lost.
Once the position is known, the route is worked out mathematically. Automotive navigation rests on the shortest path problem in graph theory, which asks how to find the path that best meets a criterion between two points in a large network. The criterion might be shortest, cheapest or fastest, and the road network is treated as a graph of connected junctions.
The first car navigation systems had to steer by their own wheels, long before satellites were available to help.
Where did car navigation begin?
Car navigation brought together many technologies, several of which had existed for years but were too costly or inaccessible. Batteries, displays and processing power all had to improve before a product could sell. The earliest work was primitive. In 1961 Hidetsugu Yagi designed a wireless navigation system aimed at the military. In 1966 General Motors Research worked on DAIR, short for Driver Aid, Information and Routing, a non-satellite system. GM found it was not scalable, but the idea came back decades later as OnStar, founded in 1996.
Japan was more active. In 1973 the Ministry of International Trade and Industry (MITI) and Fuji Heavy Industries sponsored CATC, a research project on automobile navigation. Its work led to the first generation of systems from Honda, Nissan and Toyota in 1981, which used dead reckoning. Honda's Electro Gyrocator was the first commercially available car navigation system, and the first to include a map display. It used inertial navigation to track the distance travelled, the starting point and the heading.
| Year | Milestone |
|---|---|
| 1971 | Compact Cassette systems follow predetermined routes using tones |
| 1981 | Honda Electro Gyrocator, the first commercially available system |
| 1983 | Etak introduces map-matching on standard cassette tapes |
| 1987 | Toyota Crown offers the first CD-ROM-based navigation system |
| 1990 | Mazda Eunos Cosmo becomes the first production car with built-in GPS |
| 1994 | BMW 7 Series E38 becomes the first European model with GPS navigation |
| 1995 | Oldsmobile GuideStar becomes the first GPS navigation in a US production car |
| 2007 | Toyota Map on Demand distributes map updates to car systems |
Etak followed in 1983 with a system that used map-matching to improve on dead reckoning, storing its digital map on standard cassette tapes. Toyota introduced the first CD-ROM-based system on the Crown in 1987, and in 1989 a concept car called the Magna Torrero carried a navigation computer costing $40,000. That machine was first built to locate fire hydrants, and it combined satellite signals with dead reckoning to make up for the limits of civilian GPS at the time.
When did GPS reach ordinary cars?
Mazda's Eunos Cosmo of 1990 was the first production car with built-in GPS navigation. In 1991 General Motors worked with the American Automobile Association, the Florida Department of Transportation and the city of Orlando on TravTek, a computerised in-car navigation trial. A fleet of 100 Oldsmobile Toronados was fitted with the system, 75 of them rented through Avis at Orlando International Airport and 25 test-driven by local drivers. TravTek covered an area of 12,000 square miles around Orlando, with listings for restaurants, approved hotels and attractions.
Toyota and Mitsubishi also brought GPS navigation to their cars in 1991, and Toyota added voice-assisted guidance on the Celsior in 1992. BMW's 7 Series E38 became the first European model with GPS navigation in 1994, developed with Philips and its CARIN system. The following year Oldsmobile introduced GuideStar, the first GPS navigation in a United States production car, developed with Zexel. Zexel also partnered with Avis Car Rental to make the system widely available in rental cars, which gave many Americans their first taste of in-car navigation. In 2000 the United States made a more accurate GPS signal available for civilian use.
How are the maps stored and shared?
The road database is a vector map. Street names, house numbers and points of interest are encoded as geographic coordinates, so a driver can search by address or by coordinates. Map formats are almost uniformly proprietary. The Navteq format SDAL was released royalty free in the hope of becoming an industry standard, and a number of companies adopted it, including Microsoft, Magellan, Pioneer, Panasonic, Clarion and InfoGation. It has not been widely taken up across the industry.
The Navigation Data Standard (NDS) is an industry grouping of car makers, navigation suppliers and map data companies. It began in 2004, became a registered association in 2009, and aims to let the same map run on systems from 20 manufacturers. Members include BMW, Volkswagen, Daimler, Renault, Bosch and TomTom. Map vendors such as Tele Atlas and Navteq create base maps in the GDF format, but each electronics maker compiles them into its own optimised format.
The database can sit in read-only memory, on a CD or DVD, in flash memory or on a hard disk. A common scheme keeps a base map permanently in ROM and adds detailed regional data as the driver needs it. Some makers offer free map updates, which are downloaded from the vendor's website by connecting the device to a computer.
How is traffic information delivered?
Some systems receive and display traffic congestion through TMC or RDS broadcasts, or through GPRS or 3G data over a mobile phone. Real-time data is growing in importance. In 2014 Google updated Google Maps for Android and iOS to alert users when a faster route appeared, which brings live data into the parts of a route that lie further away.
What else can a navigation system do?
Colour LCD screens on some systems also show television broadcasts or DVD movies. A few systems link to phones for hands-free calls and text messages, using Bluetooth or Wi-Fi. Some can combine personal information for meetings with traffic and public transport data.
Points of interest can also be sent between devices. Gps2sms transmits waypoints by SMS over GSM networks. Some vehicles and boats send an automatic text when a particular event happens, such as theft, anchor drift or a breakdown. A tow truck can then store the waypoint and plot it on its own navigation system.
Are factory and aftermarket systems different?
Many manufacturers offer satellite navigation as an option. Owners whose cars lack it can buy and fit the factory unit later. Sometimes that is a plug-and-play job if the wiring harness is already in place, but with some makers new wiring is needed. The main advantage is an integrated, factory-standard installation. Factory units often include a gyrocompass or accelerometer and can take input from the speed sensors and the reverse gear signal, so they can keep navigating by dead reckoning when GPS drops out. Their cost can be much higher than other options.
