Navigation device, method, and program

• US 8,498,813 B2
• Filed: 02/19/2010
• Issued: 07/30/2013
• Est. Priority Date: 02/26/2009
• Status: Active Grant

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: Oohashi, Yusuke, Sakaki, Daisuke, Ando, Yohei
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): MOYER, DALE S
• Application Number:
  US12/656,943
• Publication Number:
  US 20100217524A1
• Time in Patent Office: 1,257 Days
• Field of Search: 701/216, 701445-447, 701/449, 701/454, 701/466, 701468-469, 701472-473, 701/475, 701/478.5, 701/495, 701/498, 701500-501, 701/505, 701/518, 701/521, 701/525, 701/527, 701/530, 701/534
• US Class Current: 701/447
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

Devices, methods, and programs identify a leading candidate point by calculating a cost for candidate points on a road, and match a vehicle position to the identified leading candidate point. The devices, methods, and programs acquire an estimated vehicle position based on dead reckoning navigation, acquire a GPS position of the vehicle, and set the candidate points for the vehicle position on nearby roads. The devices, methods, and programs calculate for each candidate point a normal cost of the candidate point with respect to the estimated position and a correction cost that corresponds to a value L1 (the value L1 being found by subtracting a width W of a road having the candidate point from a distance d between the GPS position and the candidate point), and identify the leading candidate point based on a total cost of the normal cost and the correction cost for each candidate point.

Claims

1. A navigation device that identifies a leading candidate point by calculating a cost for candidate points that are set on a road, and matches a vehicle position to the identified leading candidate point, the navigation device comprising:

a controller that;

acquires an estimated position of a vehicle based on dead reckoning navigation;

acquires a GPS position of the vehicle based on GPS;

sets the candidate points for the vehicle position on roads in the vicinity of the estimated position;

calculates for each candidate point a normal cost of the candidate point with respect to the estimated position;

calculates for each candidate point a correction cost that corresponds to a value L1, the value L1 being found by subtracting a width W of the road from a distance d between the GPS position and the candidate point; and

identifies the leading candidate point based on a total cost of the normal cost and the correction cost for each candidate point.

2. The navigation device according to claim 1, wherein the controller:

sets the correction cost to zero if the value L1 is negative.

3. The navigation device according to claim 1, wherein the controller:

acquires a speculative maximum error e that specifies a distance of an error range with respect to the GPS position;

calculates a value L2 by subtracting the speculative maximum error e from the value L1;

if the value L2 is negative, sets the correction cost as a value equal to the value L1 multiplied by a first proportionality constant; and

if the value L2 is positive, sets the correction cost as a value equal to the sum of;

the value L2 multiplied by a second proportionality constant larger than the first proportionality constant; and

the speculative maximum error e multiplied by the first proportionality constant.

4. The navigation device according to claim 3, wherein:

the speculative maximum error e is a radius of an error circle that is based on a dilution of precision of the GPS.

5. The navigation device according to claim 3, wherein:

the speculative maximum error e is a distance that corresponds to a reliability calculated from;

a dilution of precision;

a distance between the estimated position and the GPS position; and

a difference between a heading according to a trajectory of the estimated position and a heading according to a trajectory of the GPS position.

6. A navigation method that identifies a leading candidate point by calculating a cost for candidate points that are set on a road, and matches a vehicle position to the identified leading candidate point, the navigation method comprising:

acquiring, with a controller, an estimated position of a vehicle based on dead reckoning navigation;

acquiring, with the controller, a GPS position of the vehicle based on GPS;

setting, with the controller, the candidate points for the vehicle position on roads in the vicinity of the estimated position;

calculating, with the controller, for each candidate point a normal cost of the candidate point with respect to the estimated position;

calculating, with the controller, for each candidate point a correction cost that corresponds to a value L1, the value L1 being found by subtracting a width W of the road from a distance d between the GPS position and the candidate point; and

identifying, with the controller, the leading candidate point based on a total cost of the normal cost and the correction cost for each candidate point.

7. The navigation method according to claim 6, further comprising:

setting the correction cost to zero if the value L1 is negative.

8. The navigation device according to claim 6, further comprising:

acquiring, with the controller, a speculative maximum error e that specifies a distance of an error range with respect to the GPS position;

calculating, with the controller, a value L2 by subtracting the speculative maximum error e from the value L1;

if the value L2 is negative, setting the correction cost as a value equal to the value L1 multiplied by a first proportionality constant; and

if the value L2 is positive, setting the correction cost as a value equal to the sum of;

the value L2 multiplied by a second proportionality constant larger than the first proportionality constant; and

the speculative maximum error e multiplied by the first proportionality constant.

9. The navigation method according to claim 8, wherein:

the speculative maximum error e is a radius of an error circle that is based on a dilution of precision of the GPS.

10. The navigation method according to claim 8, wherein:

the speculative maximum error e is a distance that corresponds to a reliability calculated from;

a dilution of precision;

a distance between the estimated position and the GPS position; and

a difference between a heading according to a trajectory of the estimated position and a heading according to a trajectory of the GPS position.

11. A non-transitory computer-readable storage medium storing a computer-executable program usable to identify a leading candidate point by calculating a cost for candidate points that are set on a road, and matches a vehicle position to the identified leading candidate point, the program comprising:

instructions for acquiring an estimated position of a vehicle based on dead reckoning navigation;

instructions for acquiring a GPS position of the vehicle based on GPS;

instructions for setting the candidate points for the vehicle position on roads in the vicinity of the estimated position;

instructions for calculating for each candidate point a normal cost of the candidate point with respect to the estimated position;

instructions for calculating for each candidate point a correction cost that corresponds to a value L1, the value L1 being found by subtracting a width W of the road from a distance d between the GPS position and the candidate point; and

instructions for identifying the leading candidate point based on a total cost of the normal cost and the correction cost for each candidate point.

12. The non-transitory computer-readable storage medium according to claim 11, the program further comprising:

instructions for setting the correction cost to zero if the value L1 is negative.

13. The non-transitory computer-readable storage medium according to claim 11, the program further comprising:

instructions for acquiring a speculative maximum error e that specifies a distance of an error range with respect to the GPS position;

instructions for calculating a value L2 by subtracting the speculative maximum error e from the value L1;

instructions for, if the value L2 is negative, setting the correction cost as a value equal to the value L1 multiplied by a first proportionality constant; and

instructions for, if the value L2 is positive, setting the correction cost as a value equal to the sum of;

the value L2 multiplied by a second proportionality constant larger than the first proportionality constant; and

the speculative maximum error e multiplied by the first proportionality constant.

14. The non-transitory computer-readable storage medium according to claim 13, wherein:

the speculative maximum error e is a radius of an error circle that is based on a dilution of precision of the GPS.

15. The non-transitory computer-readable storage medium according to claim 13, wherein:

the speculative maximum error e is a distance that corresponds to a reliability calculated from;

a dilution of precision;

a distance between the estimated position and the GPS position; and

a difference between a heading according to a trajectory of the estimated position and a heading according to a trajectory of the GPS position.