Position determination method and navigation device

• US 20030069688A1
• Filed: 11/02/2002
• Published: 04/10/2003
• Est. Priority Date: 05/02/2000
• Status: Active Grant

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Mosis, Torsten
• Granted Patent: US 6,766,247 B2
• Time in Patent Office: Days
• US Class Current: 701/207
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

In the case of a position determination method, during traversal of a curve (K) the centroid (C_d) of the latter is determined from measured values of a direction sensor. The centroid (C_m) of the curve (K) of a digitized road (511) is determined from the alignment of road segments (S) of the digitized road which correspond to positions (P_d) determined by dead reckoning. The positions determined by dead reckoning are corrected on the basis of the difference between the determined curve centroids (C_d; C_m).

Claims

1. A position determination method operating by means of adjustment of a position determined by dead reckoning with the aid of a digital road map, comprising the following steps:

a succession of positions determined by dead reckoning is tracked on digitized roads of the digital road map and assigned to road segments of the digital road map,

during traversal of a curve the centroid of the curve is determined from measured values of a direction sensor,

the centroid of the curve of a digitized road is determined from the alignment of road segments of the digitized road which corresponds to the determined positions, and

the position determined by dead reckoning is corrected on the basis of the difference between the determined curve centroids.

2. The method as claimed in claim 1, wherein the centroid of the curve recorded in the digital road map is calculated by weighting differences in the angles of consecutive road segments in their succession and adding them, and dividing the sum thus determined by the sum of the differences in the angles of the consecutive road segments.

3. The method as claimed in claim 1, wherein the differences in the angles are determined from shape points that define the road segments of the curve, and in that the differences in the angles are weighted with the time interval that has elapsed during tracking of the road segments on the digital road map.

4. The method as claimed in claim 1, wherein the average speed during traversal of the curve is determined, and in that the time interval between the traversal of the curve centroids is multiplied by the average speed in order to correct the position, determined by dead reckoning, with the distance thus obtained.

5. A position determination method operating for a navigation system comprising the steps:

tracking a plurality of positions by dead reckoning on digitized roads of a digital road map and assigning the positions to road segments of the digital road map,

determining the centroid of a curve from measured values of a direction sensor while traveling along the curve,

determining a digital centroid of the curve of a digitized road from the alignment of road segments of the digitized road which corresponds to the determined positions, and

correcting the position determined by dead reckoning on the basis of the difference between the determined curve centroid and digital curve centroid.

6. The method as claimed in claim 5, wherein the centroid of the curve recorded in the digital road map is calculated by weighting differences in the angles of consecutive road segments in their succession and adding them, and dividing the sum thus determined by the sum of the differences in the angles of the consecutive road segments.

7. The method as claimed in claim 5, wherein the differences in the angles are determined from shape points that define the road segments of the curve, and in that the differences in the angles are weighted with the time interval that has elapsed during tracking of the road segments on the digital road map.

8. The method as claimed in claim 5, wherein the average speed during traversal of the curve is determined, and in that the time interval between the traversal of the curve centroids is multiplied by the average speed in order to correct the position, determined by dead reckoning, with the distance thus obtained.

9. The method as claimed in claim 5, wherein a curve is defined in the digitized road by shape points.

10. The method as claimed in claim 5, wherein the centroid of the curve is determined by obtaining the individual changes in direction from consecutive direction measurements and by weighting and adding the changes with the elapsed time and by dividing the weighted and added changes by the sum of the measured changes in direction.

11. The method as claimed in claim 5, wherein the digital centroid of the curve recorded in the digital road map is determined by weighting and adding the differences in the angles of consecutive road segments in their succession with the respectively elapsed time which has elapsed during tracking of the road segments on the digital road map and by dividing the sum by the sum of the differences in the angles of the consecutive road segments.

12. A navigation device comprising:

a distance sensor,

a direction sensor,

a map memory for a digital road map, and

at least one processor for dead reckoning, which is connected to the distance sensor, the direction sensor and the map memory,

which during traversal of a curve determines the centroid of the latter from measured values of the direction sensor,

which determines the centroid of the curve of the digitized road from the alignment of road segments of a digitized road which corresponds to the determined positions and which corrects the position determined by dead reckoning on the basis of the difference between the determined curve centroids.

13. The navigation device as in claim 12, wherein the direction sensor is a gyroscope.

14. The navigation device as in claim 12, further comprising a satellite receiver for operating as a distance and direction sensor.

15. The navigation device as in claim 12, further comprising a display for displaying the determined position on the digitized map.