Vehicle navigation with vehicle position correction feature

A vehicle navigation method in which a position of a vehicle is dead-reckoned when a predetermined distance is traveled by the vehicle, a most probable candidate road satisfying a predetermined condition is obtained from the dead-reckoned vehicle position and by map matching processing, the vehicle position is corrected to be a position on the most probable candidate road, and the map matching processing is thereafter continued by dead-reckoning the vehicle position, said method comprising:

• monitoring whether a point from which two or more branch roads extend has been passed;
• obtaining a most probable candidate road and a second candidate road satisfying said predetermined condition by map matching processing after passing the point;
• correcting the dead-reckoned vehicle position to a position on the most probable candidate road to regard the corrected position as an actual vehicle position;
• correcting the dead-reckoned vehicle position to a position on the second candidate road to set the corrected position as a temporary vehicle position;
• thereafter executing first map matching processing based on the actual vehicle position and second map matching processing based on the temporary vehicle position when the predetermined distance is traveled;
• and
• continuing the first map matching processing by setting the temporary vehicle position as the actual vehicle position when the map matching processing based on the actual vehicle position finds no road satisfying said predetermined condition.

A vehicle navigation apparatus, having a self-contained navigation sensor, where a most probable candidate road satisfying a predetermined condition is obtained from a dead-reckoned vehicle position and by map matching processing and the vehicle position is corrected to a position on a most probable candidate road, and the map matching processing is thereafter continued by dead-reckoning the vehicle position, said apparatus comprising:

• means for monitoring whether a point from which two or more branch roads extend has been passed;
• means for obtaining a most probable candidate road and a candidate road different from the most probable candidate road and satisfying said predetermined condition by map matching processing after passing the point, correcting the dead-reckoned vehicle position to be a position on the most probable candidate road, to regard the corrected position as an actual vehicle position, and correcting the dead-reckoned vehicle position to be a position on the other candidate road, to set the corrected position as a temporary vehicle position;
• means for executing map matching processing based on the actual vehicle position and map matching processing based on the temporary vehicle position each other time the predetermined distance is traveled;
• and
• means for continuing map matching processing by setting the temporary vehicle position as the actual vehicle position when the map matching processing based on the actual vehicle position finds no road satisfying said predetermined condition.

A vehicle navigation apparatus, having a self-contained navigation sensor, where a most probable candidate road satisfying a predetermined condition is obtained from a dead-reckoned vehicle position and by map matching processing, and the vehicle position is corrected to a position on the most probable candidate road, and the map matching processing is thereafter continued by dead-reckoning the vehicle position, said apparatus comprising:

• means for monitoring whether a point from which two or more branch roads extend has been passed;
• means for obtaining a most probable candidate road and a second candidate road satisfying said predetermined condition by map matching processing after passing the point, correcting the dead-reckoned vehicle position to be a position on the most probable candidate road to regard the corrected position as an actual vehicle position, and correcting the dead-reckoned vehicle position to a position on the second candidate road to set the corrected position as a temporary vehicle position;
• means for executing first map matching processing based on the actual vehicle position and second map matching processing based on the temporary vehicle position each time the predetermined distance is traveled;
• and
• means for continuing the first map matching processing by setting the temporary vehicle position as the actual vehicle position when the map matching processing based on the actual vehicle position finds no road satisfying said predetermined condition.