Patent ID: 8396659

Claim:
A navigation device for a vehicle, comprising: a controller that: recalls a previous vehicle position; uses the previous vehicle position as a reference and calculates an estimated vehicle position as a result of subsequent movement; uses the estimated vehicle position in a map matching process to select a best candidate position from candidate positions that are set on roads around the estimated vehicle position; calculates a vehicle heading corresponding to the estimated vehicle position; calculates a heading reliability at the estimated vehicle position; acquires a speculative heading error that corresponds to the calculated heading reliability; calculates a candidate heading as a heading when the estimated vehicle position is corrected to the best candidate position; calculates a heading difference between the vehicle heading and the candidate heading; determines whether the calculated heading difference is within the acquired speculative heading error; sets the best candidate position as a current vehicle position if the calculated heading difference is within the acquired speculative heading error; and sets the estimated position as the current vehicle position if the calculated heading difference is not within the acquired speculative heading error.