PATH CURVE CONFIDENCE FACTORS

• US 20140236482A1
• Filed: 02/19/2013
• Published: 08/21/2014
• Est. Priority Date: 02/19/2013
• Status: Active Grant

• Current Assignee: HERE Global B.V. (HERE Holding Corporation)
• Original Assignee: Navteq B.V. (HERE Holding Corporation)
• Inventors: Dorum, Ole Henry, Lynch, James D.
• Granted Patent: US 9,423,261 B2
• Time in Patent Office: Days
• US Class Current: 701/533
• CPC Class Codes: G01C 21/34 Route searching; Route guidance
• CPC Class Codes: G01C 21/3819 Road shape data, e.g. outline of a route
• CPC Class Codes: G01C 21/3841 Data obtained from two or more sources, e.g. probe vehicles
• CPC Class Codes: G01C 21/3844 Data obtained from position sensors only, e.g. from inertial navigation

Abstract

In one embodiment, navigational features of a navigation device are activated or deactivated according to the accuracy of the geographic data. The navigation features may be predictive features related to upcoming portions of a path curve. The path curve is compared to measured data. For example, a first curve is accessed from a map database and a second curve is based on measured position data collected while traversing the path. The first curve and the second curve correspond to the same geographic area. A difference of an attribute between a section of the first curve and a section of the second curve is used to assign a confidence factor to the section of the first polycurve based on the difference. The attribute may be heading, position, curvature, or another aspect of the path curves.

Claims

1. A method comprising:

obtaining a first polycurve representing a path from a map database;

generating a second polycurve based on measured position data collected while traversing the path;

calculating, with a processor, a relative difference between a section of the first polycurve and a section of the second polycurve, wherein the section of the first polycurve corresponds geographically to the section of the second polycurve; and

assigning a confidence factor to the section of the first polycurve based on the relative difference.

2. The method of claim 1, further comprising:

enabling at least one feature of a navigation device based on the confidence factor.

3. The method of claim 1, further comprising:

comparing the confidence factor to a threshold confidence level;

activating a first mode for a navigation feature if the confidence factor exceeds the threshold confidence level; and

activating a second mode for the navigation feature if the confidence factor is less than the threshold confidence level.

4. The method of claim 1, wherein the relative difference between the section of the first polycurve and the section of the second polycurve is a relative difference in position.

5. The method of claim 1, wherein the relative difference between the section of the first polycurve and the section of the second polycurve is a relative difference in heading.

6. The method of claim 1, wherein the relative difference between the section of the first polycurve and the section of the second polycurve is a relative difference in curvature.

7. The method of claim 6, further comprising:

excluding a subsequent section of the first polycurve when a curvature of the subsequent section is below a minimum curvature threshold.

8. The method of claim 1, further comprising:

calculating a correlation value for a plurality of sections of the first polycurve by comparing a plurality of sections of the second polycurve, wherein the first polycurve corresponds to link geometry in the map database.

9. The method of claim 8, further comprising:

excluding at least one of the plurality of sections of the first polycurve when the correlation value is less than a correlation threshold.

10. The method of claim 8, wherein the correlation value is based on shape.

11. An apparatus comprising:

a memory configured to store a first curve representing a path; and

a controller configured to receive position data and to calculate a confidence factor based on a difference between a section of the first curve and a section of a second curve based on measured data collected while traversing the path, wherein at least one navigation feature is provided based on the confidence factor.

12. The apparatus of claim 11, wherein the controller is configured to generate an enablement message for a navigation device based on a comparison of the confidence factor to a threshold level.

13. The apparatus of claim 12, wherein the enablement message is configured to enable or disable a driving assistance feature.

14. The apparatus of claim 12, wherein the enablement message is configured to instruct the navigation device to change modes.

15. The apparatus of claim 11, wherein the confidence factor is based on curvatures of the first curve and the second curve.

16. The apparatus of claim 11, wherein the confidence factor is based on headings of the first curve and the second curve.

17. A non-transitory computer readable medium including instructions that when executed by a processor are operable to:

access a first curve representing a path in a map database;

generate a second curve based on measured data collected while traversing the path;

calculate a difference between a section of the first curve and a section of the second curve, wherein the section of the first curve corresponds geographically to the section of the second curve; and

assign a confidence factor to the section of the first curve based on the difference.

18. The non-transitory computer readable medium of claim 17, wherein the difference between the section of the first curve and the section of the second curve is a relative difference in position.

19. The non-transitory computer readable medium of claim 18, wherein the difference between the section of the first curve and the section of the second curve is a relative difference in heading.

20. The non-transitory computer readable medium of claim 17, wherein the difference between the section of the first curve and the section of the second curve is a relative difference in curvature.