SYSTEMS AND METHODS FOR LOCATING BURIED OR HIDDEN OBJECTS USING SHEET CURRENT FLOW MODELS

• US 20130245990A1
• Filed: 09/06/2012
• Published: 09/19/2013
• Est. Priority Date: 09/06/2011
• Status: Active Grant

• Current Assignee: Seescan, Inc.
• Original Assignee: Seektech Inc.
• Inventors: Merewether, Ray
• Granted Patent: US 9,599,449 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G01B 7/14 for measuring distance or clearance between spaced objects or spaced apertures G01B7/30 takes precedence
• CPC Class Codes: G01B 7/26 for measuring depth
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

Systems, methods, and apparatus for determining an estimated depth of a buried object using sheet current flow models are disclosed. In one embodiment a buried object locator may process magnetic signals emitted from the buried object using a closed form sheet current flow model taken from three or more sensor positions to determine, store, and/or display estimated depth information of the buried object.

Claims

1. A method for locating a buried object with a buried object locator, comprising:

generating, in the locator, a first magnetic field measurement at a first position;

generating, in the locator, a second magnetic field measurement at a second position different from the first position;

generating, in the locator, a third magnetic field measurement at a third position different from the first and second positions;

storing the first, second, and third magnetic field measurements and associated position information in a memory of the locator;

processing the first, second, and third magnetic field measurements and associated position information in accordance with a closed-form sheet current flow model to generate an estimate of the depth, D_b, of the buried object below a ground surface; and

storing the estimated depth in the memory.

2. The method of claim 1, further comprising providing a visual display of the estimated depth on a display of the locator.

3. The method of claim 1, wherein the first, second, and third positions are substantially co-linear on a line intersecting the buried object.

4. The method of claim 3, wherein the line is along a vertical centerline extending upward from the buried object and ground surface.

5. The method of claim 3, wherein the line is offset at an angle of approximately ten degrees or less from a vertical centerline extending upward from the buried object and ground surface.

6. The method of claim 1, wherein the first, second, and third positions are co-linear on a line translated horizontally from a vertical centerline extending upward from the buried object and ground surface.

7. The method of claim 1, wherein the measurements at the first, second, and third positions are generated by corresponding first, second, and third magnetic field antenna sensors.

8. The method of claim 7, wherein the measurements at the first, second, and third positions are generated substantially simultaneously by the first, second, and third magnetic field antenna sensors.

9. The method of claim 1, wherein the measurements at the first, second, and third positions are generated sequentially by a single magnetic field antenna sensor moved between the first, second, and third positions.

10. The method of claim 1, wherein the measurements at the first, second, and third positions are generated by two magnetic field antenna sensors moved between two or more of the positions.

11. The method of claim 1, wherein the sheet current flow model includes a magnetic field component modeled as being generated by an infinite sheet current and another magnetic field component modeled as being generated by a current flowing in a buried conductor.

12. The method of claim 11, wherein the estimate of the buried object depth, D_b, is determined using a closed-form sheet current flow model of the form:

13. The method of claim 1, wherein the sheet current flow model includes a magnetic field component modeled as being generated by a finite sheet current.

14. The method of claim 1, wherein the first and second positions are at a first distance relative to each other and the second and third positions are at a second distance relative to each other, wherein the first distance is different than the second distance.

15. The method of claim 1, wherein the sheet current flow model includes a model of a sheet current flowing in a ground material in proximity to a ground surface and a model of a conductor current flowing in a conductor disposed at a distance below the ground surface.

16. The method of claim 1, wherein the sheet current flow model is represented by an open-form equation solution rather than a closed-form solution, the method further comprising solving the open-form equation.

18. The method of claim 1, further comprising:

automatically determining an optimal measurement position above the ground to the buried object;

generating and processing the magnetic field measurements responsive to the automatically determining an optimal measurement position.

19. The method of claim 18, wherein the automatically determining an optimal measurement position above the ground includes determining a centerline using one or more horizontally oriented magnetic field sensors to provide information to position the locator over the buried object.

20. The method of claim 1, further comprising:

storing a specification of a buried object depth in the locator;

comparing the estimated depth to the specification depth; and

providing, responsive to the comparing, a notification.

21. The method of claim 20, wherein the notification includes providing an operator alarm if the estimated depth is less than the specification.

22. The method of claim 20, wherein the notification includes storing a database entry indicative of the difference between the estimated depth and the specification.

17. The method of claim 17, wherein the open-form equation is iteratively solved in the locator.

23. A locator for determining the location of a buried object, comprising:

A magnetic field sensor assembly including;

one or more magnetic field sensors configured to generate first, second, and third magnetic field measurement information at corresponding first, second, and third positions;

a memory module; and

a processor module coupled to the memory, wherein the processor is configured to;

receive the first, second, and third magnetic field measurement information;

process the received first, second, and third magnetic field measurement information in accordance with a closed-form sheet current flow model to generate an estimated distance to the buried object;

store the estimated depth in the memory; and

provide a visual display of the estimated depth on the locator.

24. The locator of claim 23, wherein the magnetic field sensor assembly includes:

a first magnetic field sensor module configured to generate the first magnetic field measurement information;

a second magnetic field sensor module configured to generate the second magnetic field measurement information; and

a third magnetic field sensor module configured to generate the third magnetic field measurement information.

25. The locator of claim 23, wherein the magnetic field sensor assembly includes:

a location determination module; and

A magnetic field sensor module configured to generate the first magnetic field measurement information, the second magnetic field measurement information, and the third magnetic field measurement information based at least in part on information provided from the location determination module.

26. The locator of claim 23, wherein the estimated depth, D_b, is determined in the processor module using a closed-form sheet current flow model of the form:

27. A non-transitory machine-readable medium containing processor-executable instructions for causing a computer to:

receive first, second, and third magnetic field measurement information; and

process the received first, second, and third magnetic field measurement information in accordance with a sheet current flow model to generate an estimated depth of a buried object below a ground surface.

28. A method for locating a buried object with a buried object locator, comprising:

generating, in the locator, a lower magnetic field measurement at a first locator position;

generating, in the locator, an upper magnetic field measurement at the first locator position;

generating, in the locator, a lower magnetic field measurement at a second locator position different from the first position;

generating, in the locator, an upper magnetic field measurement at the second locator position;

storing the first and second locator position lower and upper magnetic field measurements in a memory of the locator;

processing the first and second position lower and upper magnetic field measurements in accordance with a closed-form sheet current flow model to generate an estimate of the depth, D_b, of the buried object below a ground surface; and

storing the estimated depth in the memory.

29. The method of claim 28, wherein the estimate of the buried object depth, D_b, is determined using a closed-form sheet current flow model of the form:

30. A locator for determining the location of a buried object, comprising:

A magnetic field sensor assembly including;

A plurality of magnetic field sensors configured to generate lower and upper magnetic field measurement information at first and a second locator positions;

a memory module; and

a processor module coupled to the memory, wherein the processor is configured to;

process the first and second position lower and upper magnetic field measurements in accordance with a closed-form sheet current flow model to generate an estimate of the depth, D_b, of the buried object below a ground surface;

store the estimated depth in the memory; and

provide a visual display of the estimated depth on the locator.

31. The locator of claim 30, wherein the estimated depth, D_b, is determined in the processor module using a closed-form sheet current flow model of the form: