METHOD AND APPARATUS FOR AUTOMATICALLY TRACKING THE LOCATION OF VEHICLES

A system for automatically tracking the location of a vehicle includes a visual image detector mounted on the vehicle for producing as the vehicle moves along a route digitized strips of image data representing successive panoramic views of scenery about the vehicle at respective locations along the route. A sparse tracking subsystem processes and stores only selected ones of the image data strips representing substantially spaced apart successive locations along the route, for use as a sparse database. A dense tracking subsystem processes and stores as a dense database every successive one of the image data strips representing location along the route, whereby the dense tracking subsystem provides more accurate location of the vehicle when it retraces some portion of the route than the sparse tracking subsystem. After the sparse and dense databases are established, the location of the vehicle in real time as it retraces the route is performed by the dense tracking subsystem matching current image data strips from the visual image detector with the dense database strips to determine the location of the vehicle, as long as the vehicle stays on the pre-established route. If the vehicles strays from the route, the system senses the deviation and switches to the sparse tracking system to search a broader area in less time than the dense tracking system to attempt to relocate the vehicle along the route, after which the system switches back to the dense tracking subsystem.