Position correction method for vehicle navigation system

Abstract

A vehicle navigation system is used to determine the absolute position of a vehicle with improved accuracy on freeways or rural highways. First, the system stores a known vehicle position in its memory. As the vehicle moves away from the known position, the system uses a variety of means to sense external signals. These means include satellite transmission receivers and magnetic compasses. When a change in the external signals occurs, the system recognizes the presence of a landmark which can then be used to set the vehicle's position. To accomplish this, the system's data processor searches a map data base, attempting to fix the position of the sensed landmark with respect to the initially stored known position. When the system identifies the most likely landmark, the position of the vehicle is then reset to that position.

Dependencies are inferred from the claim text.