Patent ID: 7603233
Filing Date: 2009-10-13
Classification: G01C

Abstract:
1. A map matching method for a navigation system, comprising the following steps of: recording a pair of locations where a GPS signal was lost and recovered as previous locations in a memory when a user of a navigation system newly encounters GPS signal loss and its recovery; comparing a current location of the user with the previous locations recorded in the memory and retrieving the pair of previous locations when the user is approaching the location where the GPS signal was previously lost; selecting one or more candidate routes between the pair of previous locations retrieved from the memory when the user experiences the GPS signal loss in a second time by extrapolating between the pair of previous locations; estimating a route out of the candidate routes which is most likely that the user is taking based on measured data through a dead reckoning process in addition to predetermined factors; and map matching a current location of the user with a road segment on the estimated route derived from a map database of the navigation system; wherein the predetermined factors include, in addition to proximity with a road, at least a road class which indicates a type of road.