Automobile navigation systems are essentially tools that aid the drivers in locating their destination. Modern automobile navigation systems are based technologies such as dead-reckoning, map matching, satellite positioning, proximity beacon and so forth. The map intelligent systems achieve high relative accuracy by matching dead-reckoned paths with road geometry encoded in a computerized map. This is also used to perform other functions like vehicle routing and geocoding. Satellite-based navigation systems attain high absolute accuracy with the support of dead-reckoning augmentation.
The capabilities and functions of automobile navigation systems depend on:
- Selecting the required technology.
- Integrating the overall system.
- Resolving the driver interface.
- Providing the map data basis.
- Coordinating mobile communications.
Stored digital maps combined with effective communications provided through mobile data communications enhances the automobile navigation systems. The effectiveness of a navigation system is related to the accuracy in position determination. There are various technologies as aforementioned that are employed with varying accuracy; we will look at them briefly as follows:
Dead-Reckoning
Dead-reckoning is the process of determining the vehicle location relative to an initial position by integrating the measured increments and directions of travel. The devices used include the odometer, the differential odometer, and a magnetic compass. Even though, dead-reckoning systems suffer from error accumulation, they are widely used inertial navigation systems, particularly in robotics and vehicular applications.
Map Matching
AI concepts are applied to match dead-reckoned vehicle paths, which are stored in computers. In map matching, sensed mathematical features of the vehicle paths are continuously associated with those encoded in a map database. As a result, a vehicle’s dead-reckoned location can be initialized automatically at every turn to prevent accumulation of dead-reckoning errors.
In a map matching system, provided that the streets and road connections are accurately defined, the process identifies position relative to the road network as visually perceived by the vehicle driver.
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Proximity Beacon
This technique utilizes strategically located short-range transmitters and reception of their location coded signal infers the receiving vehicle’s instantaneous location. One version of proximity technique involves two-way communications with the equipped vehicle. Usually, the driver enters the destination code on the vehicle panel, for automatic transmission to the roadside unit, as the vehicle approaches an instrumented intersection. The roadside unit, which can be networked with a traffic management system, analyzes the destination code and transmits route instructions to the display on the vehicle panel.
Radiolocation
In radiolocation, the global positioning system (GPS) is used extensively. However LORAN is gaining popularity as means of tracking land vehicle location from a central location. Nonetheless, its modest accuracy limits its global application in automotive navigation.
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