Method And Apparatus For Generating And Using A Regional-Terrain Model

• US 20100235094A1
• Filed: 05/28/2010
• Published: 09/16/2010
• Est. Priority Date: 03/21/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Van Diggelen, Frank
• Granted Patent: US 8,301,370 B2
• Time in Patent Office: Days
• US Class Current: 701/208
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks

Abstract

A method and apparatus for computing position using a regional-terrain model is provided. The method includes obtaining from at least three satellites pseudorange measurements, computing a transitional position by using a default altitude with a large uncertainty, using this transitional position to obtain from a terrain model altitude information associated with a region, and computing an accurate three-dimensional position as a function of the pseudorange measurements and the altitude information. The region defines a boundary, and the boundary includes the transitional position.

Claims

1. A method for computing position comprising:

obtaining pseudorange measurements at a location;

obtaining from a regional-terrain model altitude information associated with a modeled region, wherein the location is in a vicinity of the modeled region, and

computing a position as a function of the pseudorange measurements and the altitude information.

2. The method of claim 1, wherein obtaining from a regional-terrain model altitude information comprises obtaining from the regional-terrain model an altitude and an altitude uncertainty.

3. The method of claim 2, wherein the altitude comprises a first altitude from a given reference point associated with the earth, and the altitude uncertainty comprises a given deviation from the first altitude.

4. The method of claim 1, wherein the altitude information is used when a speed of a receiver that is computing the position is less than a threshold value.

5. The method of claim 1, wherein the boundary is defined by an interconnection of a number of coordinate-system points that together delineate the modeled region.

6. The method of claim 5, wherein the boundary comprises a shape selected from a group of shapes consisting of a circle, ellipse and polygon.

7. The method of claim 1, wherein the boundary is defined by a coordinate-system point and a line segment.

8. The method of claim 1, further comprising:

determining a transitional position of the location as a function of fixed altitude information and the pseudorange measurements.

9. A method for forming a regional terrain model, the method comprising:

defining at least one modeled region as a function of an altitude and altitude uncertainty; and

storing the modeled region in the regional terrain model in a memory.

10. The method of claim 9, wherein the altitude and altitude uncertainty define a range of altitudes, wherein defining at least one model region comprises:

defining a boundary that delineates an amount of terrain, wherein the boundary is formed as a function of a first altitude at a first location and at least one second altitude at a second location, and wherein the first altitude and the at least one second altitude are within the range of altitudes.

11. The method of claim 10, wherein defining a boundary of the modeled region comprises:

obtaining from a point-based-terrain model the first altitude for the first location;

locating in the point-based terrain model the at least one additional location;

obtaining from the point-based-terrain model an additional altitude associated with the at least one additional location, wherein the at least one additional location is spaced apart from the first location;

excluding from the boundary the at least one additional location when the additional altitude is not within the range of altitudes; and

including in the boundary as the at least one second location when the additional altitude is on a limit of the range of altitudes.

12. The apparatus of claim 10, wherein the boundary comprises a shape selected from a group of shapes consisting of a circle, ellipse and polygon.

13. A method for computing position comprising:

computing a transitional position as a function of a first altitude and a first altitude uncartainty;

obtaining from a regional-terrain model altitude information associated with a modeled region, wherein the transitional position is in a vacinity of the modeled region; and

computing a position as a function of the altitude information.

14. The method of claim 13, wherein the first altitude is fixed to a default value and the first altitude uncertainty is fixed to a large value.

15. A method for forming a regional-terrain model, the method comprising:

collecting, at a mobile receiver, a plurality of altitudes associated with a respective plurality of positions of the mobile receiver;

defining at least one modeled region as a function of an altitude and altitude uncertainty associated with the plurality of altitudes; and

storing the modeled region in the regional-terrain model.

16. The method of claim 15, wherein the altitude comprises a mean altitude of the plurality of altitudes, and the altitude uncertainty comprises a given deviation from the mean altitude.