METHOD AND APPARATUS FOR GEOGRAPHICALLY AIDING NAVIGATION SATELLITE SYSTEM SOLUTION

• US 20110257885A1
• Filed: 04/16/2010
• Published: 10/20/2011
• Est. Priority Date: 04/16/2010
• Status: Active Grant

• Current Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Original Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Inventors: Tuck, David Allan, Heshmati, Ardalan, Chansarkar, Mangesh
• Granted Patent: US 8,442,763 B2
• Time in Patent Office: Days
• US Class Current: 701/214
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

The present invention is related to position calculation and navigation systems, and more particularly, to a method and apparatus for making accuracy improvements to a GPS receiver'"'"'s navigation solutions. According to a first aspect, selective cartography information from a map database accessed by a GPS receiver from a location-aiding device is integrated into the position calculations performed by the GPS receiver. According to another aspect, selective cartography information includes indices representing associated attributes of geographical objects, such as, a width-indicator index for a road segment.

Claims

1. A method for improving positional accuracy of a GPS receiver, the method comprising:

deriving an initial location from a navigation satellite system (NSS) data received at a GPS receiver, wherein the initial location is determined to be within an area of interest;

receiving navigation state information of the GPS receiver;

receiving selective cartography information from a location-aiding device coupled to the GPS receiver, wherein the selective cartography information includes attributes of one or more geographic objects within the area of interest;

overlaying the initial location onto the selective cartography information;

deriving positional correction from the NSS data, the navigation state information, the selective cartography information;

applying the derived positional correction to the initial location to determine a corrected location of the GPS receiver; and

outputting the corrected location of the GPS receiver.

2. The method of claim 1, wherein the location-aiding device is one or more of a remote server, and, an on-board computer external to a navigation device containing the GPS receiver but located within a moving object that includes the navigation device.

3. The method of claim 1, wherein the navigation state information comprises one or more parameters of the GPS receiver including a position, a heading direction, a velocity, and an altitude.

4. The method of claim 1, wherein the attributes of the geographic objects comprises one or more attributes including:

line segments along roads, intersection points where two roads cross each other;

connection points where a multi-lane road meets with another single or multi-lane road;

end points where a road or a lane terminates;

width of roads;

number of lanes on a road;

designated traffic direction of a road;

width of each lane on a road;

radial dimension of a traffic circle with connection points where corresponding roads connect with the traffic circle; and

center-to-peripheral or corner-to-corner distance of a polygonal traffic plaza with connection points where corresponding roads connect with the traffic plaza.

5. The method of claim 1, wherein the positional correction to be applied is based on one or more metrics including:

the initial location;

uncertainty in the initial location;

perpendicular distance between the initial location and a selected line segment;

radial distance between the initial location and a selected intersection point;

radial distance between the initial location and a selected connection point;

heading direction;

uncertainty in heading direction;

velocity;

uncertainty in velocity;

width of lanes;

uncertainty in the width of lanes;

width of roads; and

uncertainty in the width of roads.

6. The method of claim 1, wherein a width-indicator index is assigned to intersection points, connection points, or end points of two or more roads or lanes and is stored as an attribute of the corresponding intersection point, connection point, or end point.

7. The method of claim 6, wherein a variance associated with the positional correction to be applied to the initial location is based on the width-indicator index.

8. The method of claim 1, wherein a width-indicator index is assigned to line segments along different roads and lanes, and is stored as an attribute of the corresponding road or lane.

9. The method of claim 8, wherein a variance associated with the positional correction to be applied to the initial location is based on the width-indicator index.

10. The method of claim 1, wherein the width-indicator index depends on a number of lanes on a road.

11. The method of claim 1, wherein the area of interest includes geographic regions where acquiring NSS signal is difficult due to one or more obstructions in an environment surrounding the GPS receiver.

12. The method of claim 1, wherein the step of receiving selective cartography information comprises:

pre-storing cartography information about one or more areas of interests in a database at the location-aiding device, wherein each area of interest include geographic objects;

assigning attributes to the geographic objects within each area of interest;

partitioning each area of interest into units of cartography information including corresponding attributes of one or more of the geographic objects;

using a map-matching algorithm to associate one or more units of cartography information with the determined initial location;

retrieving the one or more associated units of cartography information from the location-aiding device; and

extracting selective cartography information from the associated units of cartography information.

13. The method of claim 12, where the map-matching algorithm further uses the navigation state information to select the associated units containing selective cartography information.

14. The method of claim 12, wherein the map-matching algorithm uses predetermined thresholds, including one or more of a perpendicular distance threshold, and a road segment azimuth threshold to select the associated units containing selective cartography information.

15. The method of claim 1, wherein the method further comprises:

using a navigational routine to correlate selective cartography information with the initial location derived from the NSS data while deriving positional correction.

16. The method of claim 15, wherein the navigational routine uses one or more of the following techniques:

least-squares combiner, Kalman filter, maximum likelihood estimator, particle filter, neural networks, and Bayesian estimator.

17. The method of claim 1, wherein the step of deriving the positional correction comprises:

determining whether the initial location is closest to an intersection point, a connection point, or an end point, or closest to a line segment along a road.

18. The method of claim 17, wherein if it is determined that the initial location is closest to an intersection point, connection point, or end point, the method further comprises:

applying a positional correction based on a radial distance of the initial location from the intersection point, the connection point, or the end point, and a variance assigned for the intersection point, connection point, or the end point.

19. The method of claim 17, wherein if it is determined that the initial location is closest to a line segment along a road, the method further comprises:

applying a positional correction based on a perpendicular distance of the initial location from the line segment, and a variance assigned for the line segment.

20. The method of claim 17, wherein if it is uncertain whether the initial location is closest to an intersection point, a connection point, or an end point, or, closest to a line segment along a road, the method further comprises:

calculating respective radial positional corrections based on corresponding radial distances of the initial location from one or more of the closest intersection points, connection points, and end points, and, respective variances assigned to the closest intersection points, the connection points, and the end points;

calculating respective perpendicular positional corrections based on corresponding perpendicular distances of the initial location from one or more of the closest line segments along roads, and respective variances assigned to the line segments; and

calculating a final positional correction combining the respective radial positional corrections and the respective perpendicular positional corrections.

21. A system for improving positional accuracy of a GPS receiver, wherein the system comprises:

a navigation device containing the GPS receiver; and

a location-aiding device, wherein the location-aiding device is one or more of a remote server, and, an on-board computer external to the navigation device but located within a moving object that includes the navigation device;

wherein the system performs the method of claim 1.