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

Patent metadata

Field	Value
Publication number	US-9599449-B2
Application number	US-201213605960-A
Country	US
Kind code	B2
Filing date	Sep 6, 2012
Priority date	Sep 6, 2011
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

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.

First claim

I claim:

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:

D
b

=

(

-

B
m

+

B
t

)

*

sep
1

*

sep
2

-

(

B
t

*

sep
1

)

+

B
b

*

(

sep
1

-

sep
2

)

+

B
m

*

sep
2

-
H

;

and
storing the estimate of the depth in the non-transitory memory of the locator for either providing an estimate of the depth to a user of the buried object locator, post-processing of the estimated depth, or both.

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 i

Assignees

• Merewether Ray
• Seescan Inc

Inventors

• Merewether Ray

Classifications

• G01B7/14 Primary

  for measuring distance or clearance between spaced objects or spaced apertures (G01B7/30 takes precedence) · CPC title

• G01V3/08 Primary

  operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices (with electromagnetic waves G01V3/12) · CPC title

• G01V3/15

  specially adapted for use during transport, e.g. by a person, vehicle or boat · CPC title

• G01B7/26

  for measuring depth · CPC title