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June 07, 2003
GPS in cars @04:13 PM
regarding the research project:
How Do In-Car Navigation Systems Work?
In-car navigation systems utilize GPS with a combination of the following computer hardware and software components:
Map Database: A highly detailed database, including an electronic map of the road structure, is stored on CD-ROM. This database includes a directory of potential travel destinations and businesses in the region.
GPS Receiver: This instrument picks up Global Positioning System (GPS) signals that locate the car's position as it travels.
Monitor: A screen displays electronic maps, system menus, and other information useful to the driver.
CD-ROM Drive: This device reads the database and electronic map features that are stored on CD-ROM.
Central Processing Unit (CPU): The computer's CPU works with information received from each component of the navigation system to determine a driver's location, calculate routes, display the car's position on the monitor, and more.
So the maps are just kept on a CD-ROM. And since a CD can only hold a certain amount of maps, different discs are used for different regions. For example, I'm pretty sure that the CD included with US manuf. cars is the US + major cities in Canada. So if you're travelling in the yukon or something, you'd have to buy another disc. I guess the switch that's happening is that DVDs are replacing the CDs so that a single disc can be more comprehensive. So it seems for the purposes of this project, the way they feed the maps is pretty uninteresting. Although, on a significantly cooler note, I learned that pre-GPS cars used to use systems called autonomous navigation systems (ANS), which used a internal gyroscope and the calculations of a car's rate of travel to track it's position relative to a given starting point. Turns out these systems were quite accurate, except when the car was travelling on dirt, gravel, etc., which would cause the tires to spin more frequently relative to the total distance travelled. But this system is apparently still used in some GPS-ANS hybrids, which use the ANS to make up for a loss of GPS information when, for example, the car goes underneth a tunnel. When the car emerges, then the GPS info is reestablished.
For the most popular GPS mapping device, the Garmin V GPS, comes with a series of base-maps loaded into it's firmware - in the U.S. this would include parts of major cities and the interstate system. The local CDs are loaded on top of these, and if you venture outside the local maps, then the system reverts to it's base-map.
These maps can be purchased at the Garmin subsidiary Map Source: http://www.garmin.com/cartography/ or at a site called Route 66: http://www.66.com/route66/index.php.
posted by will | comments (2) | 
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Man, these things are just begging to be toyed with. A web browser in your car...could be worse than cell-phone drivers.
Posted by: Todd at June 12, 2003 05:17 AM
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Posted by: Tommo Constaphopilous at August 24, 2003 10:24 PM