NAVIGATION APPARATUS, NAVIGATION METHOD AND NAVIGATION PROGRAM

PROBLEM TO BE SOLVED: To accurately calculate a vehicle position, in comparison with a conventional apparatus, even if a branch has a small branch angle. SOLUTION: The navigation apparatus is provided with a current position information calculating section 21, and a Y-shape branch determining section 22. The current position information calculating section 21 obtains a current position P, based on a wireless signal from a GPS satellite and identifies the vehicle position Q on map data, based on the predetermined map data and the current position P. The Y-shape branch determining section 22 determines whether there is the branch having a branch point, at which a branch road candidate is branched from a branch source road candidate within a predetermined range in the travelling direction, based on the obtained current position P, calculates a distance D2 between the current position P and a road link of the branch source road candidate, at which the vehicle position Q corresponding to the current position P exists, and a distance D3 between the current position P and a road link of the branch road candidate, at which a virtual vehicle position R corresponding to the current position P exists, if there is the branch, and determines whether a vehicle enters into the branch road candidate by comparing the distances D2, D3. COPYRIGHT: (C)2009,JPO&INPIT