Systems and methods for locating buried or hidden objects using sheet current flow models

• US 9,599,449 B2
• Filed: 09/06/2012
• Issued: 03/21/2017
• Est. Priority Date: 09/06/2011
• Status: Active Grant

• Current Assignee: Seescan, Inc.
• Original Assignee: Seescan, Inc.
• Inventors: Merewether, Ray
• Primary Examiner(s): BHAT, ADITYA S
• Application Number:
  US13/605,960
• Publication Number:
  US 20130245990A1
• Time in Patent Office: 1,657 Days
• Field of Search: None
• US Class Current: 1/1
• 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 buried object locator, a first magnetic field measurement at a first position;

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

generating, in the buried object 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 non-transitory 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, Db, of the buried object below a ground surface,

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 in the form;

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

3. The method of claim 2, wherein the line is along a vertical centerline extending upward from the buried object and ground surface.

4. The method of claim 2, 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.

5. 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.

6. 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.

7. The method of claim 6, wherein the measurements at the first, second, and third positions are generated approximately simultaneously by the first, second, and third magnetic field antenna sensors.

8. 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.

9. 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.

10. 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.

11. 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.

12. The method of claim 11, 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.

13. 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.

14. The method of claim 13, wherein the notification includes providing an operator alarm if the estimated depth is less than the specification.

15. The method of claim 13, wherein the notification includes storing a database entry indicative of the difference between the estimated depth and the specification.

16. The method of claim 1, wherein the estimate of the depth is provided on a visual display of the locator.

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

A housing;

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 non-transitory memory module; and

a processor module disposed in the housing and operatively coupled to the non-transitory memory module, wherein the processor is programmed to;

receive the first, second, and third magnetic field measurement information from the magnetic field sensor(s);

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, 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 in the form;

18. The locator of claim 17, 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.

19. The locator of claim 17, 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.