Patent ID: 7548813

Claim:
A navigation apparatus for displaying a map covering a position of a vehicle and surroundings thereof, the apparatus comprising: a storage section operable to store map information including data for specifying a gradient of a road link; an acceleration sensor operable to detect acceleration of the vehicle; an inclination calculator operable to determine an angle of inclination of a currently traveled road link based on a detected acceleration of the vehicle, or to determine a value corresponding to the angle of inclination based on the detected acceleration of the vehicle; a vertical-deviation accumulator operable to determine a vertical distance traveled on the currently traveled road link based on at least two angles of inclination determined based on the currently traveled road link or at least two values corresponding to angles of inclination determined based on the currently traveled road link that were determined by the inclination calculator based on accelerations of the vehicle detected along the currently traveled road link, and to output an accumulated value of vertical deviations; a gradient determination section operable to determine if the currently traveled road link is an upgrade link or a downgrade link when the accumulated value of the vertical deviations is larger than a set value; and a map matching processor operable to perform map matching processing using data from the gradient determination section.