Method and apparatus for locating objects using parametric inversion

• US 6,700,381 B2
• Filed: 04/08/2002
• Issued: 03/02/2004
• Est. Priority Date: 04/08/2002
• Status: Expired due to Fees

• Current Assignee: Underground Imaging Technologies LLC, Witten Technologies Incorporated
• Original Assignee: Witten Technologies Incorporated
• Inventors: Hansen, Thorkild, Miller, Douglas E., Oristaglio, Michael L.
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): KINDER, DARRELL D
• Application Number:
  US10/117,093
• Publication Number:
  US 20030189427A1
• Time in Patent Office: 694 Days
• Field of Search: 324/326, 324/67, 324/339, 324/345, 324/529, 324/232, 342/459, 702/11, 702/150
• US Class Current: 324/326
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

An apparatus for locating a target object using parametric inversion employs a signal injector capable of injecting a signal into the target object, wherein at least a portion of the target object is buried, a magnetic field receiver, a matching processor for matching to a magnetic field received by the magnetic field receiver a parametric magnetic field distribution model corresponding to the target object and at least one other object, and a locating processor for locating the target object using parameters from the parametric magnetic field distribution model. A method for locating a target object using parametric inversion injects a signal into the target object, at least a portion of which is buried, receives a magnetic field radiated from the target object, matches to the received magnetic field a parametric magnetic field distribution model corresponding to the target object and at least one other object, and locates the target object using parameters from the parametric magnetic field distribution model.

Claims

1. A method for locating a target object, at least a portion of which is buried, comprising:

injecting a signal into the target object;

receiving a magnetic field radiated from the target object;

determining parameters in a parametric magnetic field distribution model corresponding to the target object and at least one other object so that the difference between the model and the received magnetic field minimizes a preselected cost function; and

locating the target object using parameters from said parametric magnetic field distribution model.

2. The method of claim 1, wherein the determining step comprises the substep of:

selecting a parametric magnetic field distribution model corresponding to at least two substantially linear objects.

3. The method of claim 1, wherein the determining step comprises the substep of:

selecting a parametric magnetic field distribution model that models a substantially curved region in said target object as at least two linear objects.

4. The method of claim 1, further comprising the step of:

injecting at least one additional signal into an object other than the target object to create the magnetic field,

and wherein the determining step further comprises the substep of using the injected at least one additional signal to generate a match.

5. The method of claim 1, where the determining step includes the substep of using a parametric magnetic field distribution model at a receiver location {overscore (r)}, the model including at least a term corresponding to {overscore (B)}({overscore (r)}, {overscore (r)}_z, {overscore (r)}_b, {overscore (I)}_ab) having the form:

$k<br><br>{\stackrel{\_}{I}}_{\mathrm{ab}}\otimes <br><br>{\int <br><br>}_{{\stackrel{\_}{r}}_a}^{{\stackrel{\_}{r}}_b}<br><br>\frac{\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}}{{<br><br>\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}<br><br>}^3}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>r^{\mathrm{\prime <br><br>}}$

where;

{overscore (B)} is the modeled magnetic field;

{overscore (I)}_ab is points and b the target object;

k is a multiplier;

{overscore (r)}_a is a first point on the target object; and

{overscore (r)}_b is a second point on the target object.

6. The method of claim 1, further comprising:

displaying the target object location.

7. The method of claim 1, wherein the step of receiving a magnetic field radiated from the target comprises the substep of:

receiving the magnetic field at at least two elevations above the target object.

8. An apparatus for locating a target object, at least a portion of which is buried, comprising:

a signal injector capable of injecting a signal into the target object;

a magnetic field receiver;

a processor for determining parameters in a parametric magnetic field distribution model corresponding to the target object and at least one other object so that the difference between the model and a magnetic field received by said magnetic field receiver minimizes a preselected cost function; and

a locating processor for locating the target object using parameters from said parametric magnetic field distribution model.

9. The apparatus of claim 8, wherein the processor comprises:

a parametric magnetic field distribution model corresponding to at least two substantially linear objects.

10. The apparatus of claim 8, wherein the processor comprises:

a parametric magnetic field distribution model that models a substantially curved region in said target object as at least two linear objects.

11. The apparatus of claim 8, further comprising:

an injector for injecting at least one additional signal into an object other than the target object to create the magnetic field;

and wherein the processor further comprises a processor for using the injected at least one additional signal to generate a match.

12. The apparatus of claim 8, wherein the processor further comprises a parametric magnetic field distribution model at a receiver location {overscore (r)}, the model including at least a term corresponding to {overscore (B)}({overscore (r)}, {overscore (r)}_a, {overscore (r)}_b, {overscore (I)}_ab) having the form:

$k<br><br>{\stackrel{\_}{I}}_{\mathrm{ab}}\otimes <br><br>{\int <br><br>}_{{\stackrel{\_}{r}}_a}^{{\stackrel{\_}{r}}_b}<br><br>\frac{\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}}{{<br><br>\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}<br><br>}^3}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>r^{\mathrm{\prime <br><br>}}$

where;

{overscore (B)} is the modeled magnetic field;

{overscore (I)}_ab is a line current between points a and b on the target object;

k is a multiplier;

{overscore (r)}_a is a first point on the target object; and

{overscore (r)}_b is a second point on the target object.

13. The apparatus of claim 8 further comprising:

a target object display.

14. The apparatus of claim 8, wherein at least one of said signal injector, magnetic field receiver, matching processor, and locating processor is mounted in a mobile platform.

15. The apparatus of claim 8, wherein at least one of said signal injector, magnetic field receiver, matching processor, and locating processor is mounted in a portable platform.

16. A computer program product for use in a computer adapted for locating a target object, at least a portion of which is buried, the computer program product comprising a computer readable medium for storing computer readable code means, which when executed by the computer, enables the computer to locate the target object, and wherein the computer readable code means includes computer readable instructions for causing the computer to execute a method comprising:

injecting a signal into the target object;

receiving a magnetic field radiated from the target object;

determining parameters in a parametric magnetic field distribution model corresponding to the target object and at least one other object so that the difference between the model and the received magnetic field minimizes a preselected cost function; and

locating the target object using parameters from said parametric magnetic field distribution model.

17. The computer program product of claim 16, wherein the computer readable code means further includes computer readable instructions for causing the computer to compute parameters of a parametric magnetic field distribution model at a receiver location 7, the model including at least a term corresponding to {overscore (B)}({overscore (r)}, {overscore (r)}_a, {overscore (r)}_b, {overscore (I)}_ab) having the form:

$k<br><br>{\stackrel{\_}{I}}_{\mathrm{ab}}\otimes <br><br>{\int <br><br>}_{{\stackrel{\_}{r}}_a}^{{\stackrel{\_}{r}}_b}<br><br>\frac{\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}}{{<br><br>\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}<br><br>}^3}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>r^{\mathrm{\prime <br><br>}}$

where;

{overscore (B)} is the modeled magnetic field;

{overscore (I)}_ab is a line current between points a and b on the target object;

k is a multiplier;

{overscore (r)}_a is a first point on the target object; and

{overscore (r)}_b is a second point on the target object.

18. An apparatus for locating a target object, at least a portion of which is buried, comprising:

means for injecting a signal into the target object;

means for receiving a magnetic field radiated from the target object;

means for determining parameters in a parametric magnetic field distribution model corresponding to the target object and at least one other object so that the difference between the model and the received magnetic field minimizes a preselected cost function; and

means for locating the target object using parameters from said parametric magnetic field distribution model.

19. The apparatus of claim 18, wherein the means for determining further comprises:

means for selecting a parametric magnetic field distribution model corresponding to at least two substantially linear objects.

20. The apparatus of claim 18, wherein the means for determining further comprises:

means for selecting a parametric magnetic field distribution model that models a substantially curved region in said target object as at least two linear objects.

21. The apparatus of claim 18, further comprising:

means for injecting at least one additional signal into an object other than the target object to create the magnetic field;

and wherein the means for determining further comprises means for using the injected at least one additional signal to generate a match.

22. The apparatus of claim 18, where the means for matching determining further comprises means for using a parametric magnetic field distribution model at a receiver location 7, the model including at least a term corresponding to {overscore (B)}({overscore (r)},{overscore (r)}_a, {overscore (r)}_b, {overscore (I)}_ab) having the form:

$k<br><br>{\stackrel{\_}{I}}_{\mathrm{ab}}\otimes <br><br>{\int <br><br>}_{{\stackrel{\_}{r}}_a}^{{\stackrel{\_}{r}}_b}<br><br>\frac{\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}}{{<br><br>\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}<br><br>}^3}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>r^{\mathrm{\prime <br><br>}}$

where;

{overscore (B)} is the modeled magnetic field;

{overscore (I)}_ab is a line current between points a and b on the target object;

k is a multiplier;

{overscore (r)}_a is a first point on the target object; and

{overscore (r)}_b is a second point on the target object.

23. The apparatus of claim 18, wherein at least one of said means for injecting, means for receiving, means for determining, and means for locating is mounted in a mobile platform.

24. The apparatus of claim 18, wherein at least one of said means for injecting, means for receiving, means for determining, and means for locating is mounted in a portable platform.

25. A method for locating a target object, at least a portion of which is buried, comprising:

injecting a first signal into the target object;

injecting a second signal into a secondary object, at least a portion of which is buried;

receiving a magnetic field at a first frequency attributable to the target object;

receiving a second magnetic field at a secondary frequency attributable to the secondary object;

determining parameters in a parametric magnetic field distribution model corresponding to at least two objects so that the difference between the model and the first and second magnetic fields minimizes a preselected cost function; and

locating the target object and the secondary object using parameters from said parametric magnetic field distribution model.

26. The method of claim 25, where the determining step includes the substep of using a parametric magnetic field distribution model at a receiver location {overscore (r)}, the model including at least a term corresponding to {overscore (B)}({overscore (r)}, {overscore (r)}_a, {overscore (r)}_b, {overscore (I)}_ab) having the form:

$k<br><br>{\stackrel{\_}{I}}_{\mathrm{ab}}\otimes <br><br>{\int <br><br>}_{{\stackrel{\_}{r}}_a}^{{\stackrel{\_}{r}}_b}<br><br>\frac{\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}}{{<br><br>\stackrel{\_}{r}-{\stackrel{\_}{r}}^{\mathrm{\prime <br><br>}}<br><br>}^3}<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>r^{\mathrm{\prime <br><br>}}$

where;

{overscore (B)} is the modeled magnetic field;

{overscore (I)}_ab a line current between points and b the target object;

k is a multiplier;

{overscore (r)}_a is a first point on the target object; and

{overscore (r)}_b is a second point on the target object.