System and method for detecting the passage of an object in pipeline including shielded magnetometer and a microcontroller with adaptive thresholding detection means

• US 8,378,667 B2
• Filed: 05/22/2009
• Issued: 02/19/2013
• Est. Priority Date: 05/22/2009
• Status: Active Grant

• Current Assignee: TDW Delaware Incorporated
• Original Assignee: TDW Delaware Incorporated
• Inventors: Miska, Stephen J., Rankin, William J., Logan, Matthew W., Register, Mark G., Freeman, Eric N., Maltby, Philip M., Salsman, Lloyd N.
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US12/470,654
• Publication Number:
  US 20100295543A1
• Time in Patent Office: 1,369 Days
• Field of Search: 324220-221, 32420711-20726
• US Class Current: 324/207.26
• CPC Class Codes: F16L 55/48 Indicating the position of the pig or mole in the pipe or conduit
• CPC Class Codes: G01N 27/72 by investigating magnetic variables

Abstract

A pipeline pig signal made according to this invention houses one or more shielded magnetometer sensors and a microcontroller with adaptive thresholding detection means for reducing the likelihood of false alarms. The adaptive thresholding detection means removes outlier data from the magnetic flux data stream and then passes the outlier-free data stream through four low pass filters. A smoothed magnitude of the data stream is compared to detection limits and, if a passage event has occurred, a recent detection is indicated, a counter of a display unit is incremented, a time of passage is recorded, and both statistics are displayed on the display unit. Because a single object may produce multiple magnetic fields, the detector may be locked-out for a predetermined period of time after the passage event to prevent a second detection of the same object as it passes the detection device.

Claims

1. A system for detecting the passage of an object in a pipeline, the system comprising:

a detector configured for arrangement about and secured to an external surface of the pipeline and including at least one magnetometer sensor;

a shielding surrounding the at least one magnetometer sensor; and

a microcontroller in communication with the at least one magnetometer sensor and having an adaptive thresholding detection means for processing a magnetic flux data stream collected by the at least one magnetometer sensor and detecting a passage event;

the adaptive thresholding detection means calculating a baseline estimate and a noise estimate and using the baseline and noise estimates to determine an upper threshold and a lower threshold, the upper threshold being used to detect movement and the lower threshold being used to reset the detector.

2. A system according to claim 1 further comprising a second magnetometer sensor housed by the detector and being offset relative to said at least one magnetometer sensor.

3. A system according to claim 1 further comprising a display module in communication with said microcontroller.

4. A system according to claim 1 further comprising said adaptive thresholding detection means including a low pass filter.

5. A system according to claim 1 further comprising means for preventing detection by the detector of a passage of an object in a pipeline.

6. A system according to claim 5 wherein said preventing means is a reed switch.

7. A system according to claim 5 wherein said preventing means is a Bayesian lockout estimator.

8. A system according to claim 1 further comprising means for adjusting a position of the detector relative to the external surface of the pipeline.

9. A system according to claim 1 further comprising a detachably secured base receiving a portion of said detector.

10. A system according to claim 1 further comprising said shielding being a magnetic permeable shielding.

11. A system according to claim 1 further comprising said shielding being an electrical insulating shielding.

12. A system according to claim 1 further comprising a backup power source, said backup power source configured to break electrical contact prior to exposure to ambient environment.

13. A method for detecting the passage of an object in a pipeline, the method comprising the steps of:

securing a detector housing at least one magnetometer sensor on an exterior surface of the pipeline;

collecting a magnetic fax data stream from the at least one magnetometer sensor;

processing the magnetic flux data stream through an adaptive thresholding detection algorithm; and

using the processed magnetic flux data stream to detect a passage event;

wherein the adaptive thresholding detection algorithm calculates a baseline estimate and a noise estimate and uses the baseline and noise estimates to determine an upper threshold and a lower threshold, the upper threshold being used to detect movement and the lower threshold being used to reset the detector.

14. A method according to claim 13, said processing step further comprising the step of passing the magnetic flux data through at least one low pass filter.

15. A method according to claim 13, said processing step further comprising the step of removing outlier data from the magnetic flux data stream to provide an outlier-free magnetic flux data stream.

16. A method according to claim 15, said removing step including the steps of:

removing a baseline value from the magnetic flux data stream; and

limiting the magnetic flux data stream to a value no greater than an outlier limit.

17. A method according to claim 15 further comprising the step of passing the outlier-free magnetic flux data stream through a first low pass filter to estimate a baseline.

18. A method according to claim 15 further comprising the step of passing the outlier-free magnetic flux data stream through a low pass filter to produce a noise estimate.

19. A method according to claim 15 further comprising the step of passing the outlier-free magnetic flux data stream through a low pass filter to produce a smoothed magnitude of the outlier-free magnetic flux data stream.

20. A method according to claim 15 further comprising the step of comparing a smoothed magnitude of the outlier-free magnetic flux data stream to a set of detection limits.

21. A method according to claim 20 further comprising the step of passing the smoothed magnitude through a low pass filter to determine a length of a detection event.

22. A method according to claim 13 further comprising the step of counting a detection event.

23. A method according to claim 13 further comprising the step of displaying the detection event.

24. A method according to claim 13 further comprising signaling a remote device based upon the passage event.

25. A method according to claim 13, further comprising the step of preventing detection of a non-passage event.

26. A method according to claim 25 further comprising said preventing step including the sub-step of locking out the detector.

27. A method according to claim 25 further comprising said preventing step including the sub-step of locking out the detector for a predetermined time period after the passage event.

28. A method according to claim 13, said processing step further comprising the sub-step of estimating a noise estimate.

29. A method according to claim 13, said processing step further comprising the sub-step of smoothing a magnitude of the magnetic flux data stream.

30. A method according to claim 13, said processing step further comprising the sub-steps of:

determining an upper and a lower detection threshold value;

comparing a smoothed magnitude of the magnetic flux data stream to at least one of the upper and lower detection thresholds; and

updating a detector value based upon a result of the comparison.

31. A method according to claim 13 further comprising said processing step including the sub-step of determining a time length of the detection event.

32. A pipeline pig system comprising:

a detector configured for arrangement about an external surface of the pipeline and including a housing having at least one magnetometer sensor;

a shielding surrounding the at least one magnetometer sensor;

microcontroller in communication with the at least one magnetometer sensor and having an adaptive thresholding detection means and a first, a second, a third, and a fourth low pass filter;

the adaptive thresholding detection means removing outlier data from a magnetic flux data stream to provide an outlier-free magnetic flux data stream;

the first low pass filter processing the outlier-free magnetic flux data stream to estimate a baseline;

the second low pass filter processing the outlier-free magnetic flux data stream to produce a noise estimate;

the third low pass filter processing the outlier-free magnetic flux data stream to produce a smoothed magnitude of the outlier-free magnetic flux data stream;

the fourth low pass filter processing the smoothed magnitude of the outlier-free magnetic flux data stream to determine the length of a detection event.