Portable magnetic sensing system for real-time, point-by-point detection, localization and classification of magnetic objects

• US 7,688,072 B1
• Filed: 09/18/2007
• Issued: 03/30/2010
• Est. Priority Date: 09/18/2007
• Status: Active Grant

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Wiegert, Roy, Oeschger, John
• Primary Examiner(s): Patidar; Jay M
• Application Number:
  US11/974,004
• Time in Patent Office: 924 Days
• Field of Search: None
• US Class Current: 324/326
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A portable magnetic anomaly sensing system includes a non-magnetic support structure defined by a rigid beam and a rigid frame coupled thereto. Triaxial magnetometer (TM) sensors are rigidly coupled to the frame with one TM sensor being positioned at each vertex of a cubic space. Each TM sensor is positioned such that all respective X,Y,Z magnetic sensing axes are mutually parallel to one another. A data acquisition system is mechanically coupled to the beam such that any magnetic elements of the data acquisition system do not adversely affect accuracy of the TM sensors. The data acquisition system samples the sensed magnetic field data from all TM sensors synchronously with a timing signal. A processor is mechanically coupled to the beam such that any magnetic elements of the processor do not adversely affect accuracy of the TM sensors. The processor applies a magnetic scalar triangulation and ranging (STAR) processing scheme to the digitized magnetic field data in order to determine a position vector and a magnetic moment vector. One or more output generation devices are used to generate a human-discernable output to the position vector and the magnetic moment vector.

Claims

1. A portable magnetic anomaly sensing system, comprising:

a non-magnetic rigid beam having first and second ends;

a non-magnetic rigid frame coupled to said beam in proximity to said first end thereof, said frame encompassing a three-dimensional cubic space;

a plurality of triaxial magnetometer (TM) sensors rigidly coupled to said frame with one of said TM sensors positioned at each vertex of said cubic space, each of said TM sensors having X,Y,Z magnetic sensing axes, said TM sensors positioned such that respective ones of said X,Y,Z magnetic sensing axes are mutually parallel to one another, each of said TM sensors measuring a local magnetic field and generating magnetic field data indicative thereof;

a data acquisition system mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said data acquisition system do not adversely affect accuracy of said TM sensors, said data acquisition system electrically coupled to said TM sensors for sampling said magnetic field data synchronously with a timing signal wherein digitized magnetic field data is generated;

processing means mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said processing means do not adversely affect accuracy of said TM sensors, said processing means electrically coupled to said data acquisition system for processing said digitized magnetic field data in accordance with a magnetic scalar triangulation and ranging (STAR) processing scheme to determine a position vector and a magnetic moment vector from said digitized magnetic field data; and

output generation means coupled to said processing means for generating a human-discernable output of said position vector and said magnetic moment vector.

2. A portable magnetic anomaly sensing system as in claim 1 wherein said data acquisition system includes a Global Positioning System for generating said timing signal.

3. A portable magnetic anomaly sensing system as in claim 1 wherein said beam is aligned with the center of said cubic space.

4. A portable magnetic anomaly sensing system as in claim 3 further comprising sensing means mechanically coupled to said beam in proximity to said first end thereof, said sensing means sensing heading, pitch, roll and acceleration of said TM sensors, said sensing means further electrically coupled to said processing means wherein, prior to being processed in accordance with said STAR processing scheme, said digitized magnetic field data is adjusted using said heading, pitch, roll and acceleration of said TM sensors.

5. A portable magnetic anomaly sensing system as in claim 1 wherein said output generation means comprises at least one of a visual display and an audio generator.

6. A portable magnetic anomaly sensing system as in claim 5 wherein said visual display comprises a heads-up display.

7. A portable magnetic anomaly sensing system as in claim 1 further comprising temperature sensing means mechanically coupled to said frame for sensing temperature of an ambient environment in which said TM sensors reside, said temperature sensing means further electrically coupled to said processing means wherein, prior to being processed in accordance with said STAR processing scheme, said digitized magnetic field data is adjusted based on said temperature.

8. A portable magnetic anomaly sensing system, comprising:

a non-magnetic rigid beam having first and second ends;

a non-magnetic support structure rigidly coupled to said beam in proximity to said first end thereof, said support structure including four hollow tubes arranged parallel to one another along four edges of a cubic space;

four magnetic gradient sensors with each of said sensors rigidly mounted within one of said hollow tubes, each of said sensors measuring magnetic field data along each of three mutually orthogonal directions, said sensors positioned such that respective ones of said directions are mutually parallel to one another;

a data acquisition system mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said data acquisition system do not adversely affect accuracy of said sensors, said data acquisition system electrically coupled to said sensors for sampling said magnetic field data synchronously with a timing signal wherein digitized magnetic field data is generated;

processing means mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said processing means do not adversely affect accuracy of said sensors, said processing means electrically couple to said data acquisition system for processing said digitized magnetic field data in accordance with a magnetic scalar triangulation and ranging (STAR) processing scheme to determine a position vector and a magnetic moment vector from said digitized magnetic field data; and

output generation means coupled to said processing means for generating a human-discernable output of said position vector and said magnetic moment vector.

9. A portable magnetic anomaly sensing system as in claim 8 wherein said beam is coupled to a central portion of said support structure.

10. A portable magnetic anomaly sensing system as in claim 8 wherein said data acquisition system includes a Global Positioning System for generating said timing signal.

11. A portable magnetic anomaly sensing system as in claim 8 further comprising sensing means mechanically coupled to said beam in proximity to said first end thereof, said sensing means sensing heading, pitch, roll and acceleration of said sensors, said sensing means further electrically coupled to said processing means wherein, prior to being processed in accordance with said STAR processing scheme, said digitized magnetic field data is adjusted using said heading, pitch, roll and acceleration of said TM sensors.

12. A portable magnetic anomaly sensing system as in claim 8 wherein said output generation means comprises at least one of a visual display and an audio generator.

13. A portable magnetic anomaly sensing system as in claim 12 wherein said visual display comprises a heads-up display.

14. A portable magnetic anomaly sensing system as in claim 8 further comprising temperature sensing means mechanically coupled to said frame for sensing temperature of an ambient environment in which said sensors reside, said temperature sensing means further electrically coupled to said processing means wherein, prior to being processed in accordance with said STAR processing scheme, said digitized magnetic field data is adjusted based on said temperature.

15. A portable magnetic anomaly sensing system, comprising:

a non-magnetic rigid beam having first and second ends;

a non-magnetic rigid frame coupled to said beam in proximity to said first end thereof, said frame defining a three-dimensional cubic space;

a plurality of triaxial magnetometer (TM) sensors rigidly coupled to said frame with one of said TM sensors positioned at each vertex of said cubic space, each of said TM sensors having X,Y,Z magnetic sensing axes, said TM sensors positioned such that respective ones of said X,Y,Z magnetic sensing axes are mutually parallel to one another, each of said TM sensors measuring a local magnetic field and generating magnetic field data indicative thereof;

a data acquisition system mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said data acquisition system do not adversely affect accuracy of said TM sensors, said data acquisition system including a Global Positioning System for generating a timing signal, said data acquisition system electrically coupled to said TM sensors for sampling said magnetic field data synchronously with said timing signal wherein digitized magnetic field data is generated;

processing means mechanically coupled to said beam in proximity to said second end thereof such that any magnetic elements of said processing means do not adversely affect accuracy of said TM sensors;

sensing means mechanically coupled to at least one of said beam and said frame in proximity to said first end of said beam, said sensing means sensing heading, pitch, roll and acceleration of said TM sensors and sensing temperature of an ambient environment in which said TM sensors reside;

said processing means electrically coupled to said data acquisition means and said sensing means, said processing means adjusting said digitized magnetic field data using said heading, pitch, roll and acceleration of said TM sensors and based on said temperature of the ambient environment to generate compensated magnetic field data;

said processing means processing said compensated magnetic field data in accordance with a magnetic scalar triangulation and ranging (STAR) processing scheme to determine a position vector and a magnetic moment vector from said compensated magnetic field data; and

output generation means coupled to said processing means for generating a human-discernable output of said position vector and said magnetic moment vector.

16. A portable magnetic anomaly sensing system as in claim 15 wherein said beam is aligned with the center of said cubic space.

17. A portable magnetic anomaly sensing system as in claim 15 wherein said output generation means comprises at least one of a visual display and an audio generator.

18. A portable magnetic anomaly sensing system as in claim 17 wherein said visual display comprises a heads-up display.