Navigation system.

摘要

The navigation system matches the vehicle's position, determined either by dead reckoning (Pslf) or by using GPS (Pgps), to the nearest road (RD) in its map database. If the smallest perpendicular distance (L) to any road in the database is larger than a predetermined value (Lref), or if it is not but the angle ( theta ) subtended by the vehicle's position is larger than a predetermined value ( theta ref), then the navigation system assumes that the vehicle is moving on a road which is not in the database. It then omits the step of matching the position to the roads in the database, and displays the dead-reckoned position (Pslf) or the GPS position (Pgps). <IMAGE>