Adaptive high frequency energy detection

• US 6,868,348 B1
• Filed: 10/29/1999
• Issued: 03/15/2005
• Est. Priority Date: 10/29/1999
• Status: Expired due to Fees

• Current Assignee: Rockwell Automation, Inc.
• Original Assignee: Entek IRD International Corp. (Rockwell Automation, Inc.)
• Inventors: Xu, Ming, Stoutenburg, Donn V.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): PRETLOW, DEMETRIUS R
• Application Number:
  US09/430,077
• Time in Patent Office: 1,964 Days
• Field of Search: 702/34, 702/56, 702/182, 702/183, 340/679, 340/680, 340/683, 340/17, 700/174, 700/175, 735/79, 736/09, 736/60
• US Class Current: 702/56
• CPC Class Codes: G01M 7/025 Measuring arrangements
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects

Abstract

A data collector having a digital signal processing circuit that receives a digitized vibration signal, and performs processing steps to isolate high frequency pulses in the digitized vibration signal and quantify energy content of those pulses by detecting a peak negative value of the digitized peak-to-peak amplitude of the received vibration signal, and then using this peak negative value to compute a maximum peak-to-peak value of the received vibration signal. Periodically, the maximum peak-to-peak value and peak negative value are reduced in magnitude by a decay factor, such that the peak negative value and maximum peak-to-peak value decay over time. The decay factors used in computing the maximum peak-to-peak value and peak negative value are determined by the digital signal processing circuit and may be readily changed. As a consequence, high frequency processing performed by the digital signal processing circuit may be readily adapted to the particular frequency characteristics of the machine being analyzed for predictive maintenance, without modification of the analog circuitry of the data collector. The resulting maximum peak-to-peak value comprises a peak-detected digital output signal that may be stored and/or displayed to a user as a reflection of the high frequency content of the vibration signal, or frequency transformed for storage and/or display to a user.

Claims

1. A data collector for detecting and quantifying high frequency energy in a received signal, comprising

an analog to digital converter converting said received signal to a digitized signal at a sampling rate that is sufficient to reproduce a highest frequency of interest in said received signal, and

a digital signal processing circuit that receives said digitized signal and performs processing steps to isolate high frequency pulses in the digitized signal from lower frequency components of the digitized signal, and process said high frequency pulses by forming a time-varying peak-detected signal from said high frequency pulses, the time variation of the peak-detected signal corresponding to time variation of peak amplitudes of the high frequency pulses, to quantify energy content of the isolated pulses.

3. The data collector of claim 1 said digital signal processing circuit detects a peak-to-peak amplitude of said digitized signal by comparing a current sample of said digitized signal to a peak value and when the excursion of said current sample from zero exceeds said peak value then said digital signal processing circuit updates said peak value to be equal to said current sample.

4. The data collector of claim 3 wherein said peak value is a peak negative value and said digital signal processing circuit detects a peak-to-peak amplitude of said digitized signal by comparing a maximum peak-to-peak value to a difference between said current sample and said peak negative value, and if the difference is larger, updating said maximum peak-to-peak value.

5. The data collector of claim 3 wherein said digital signal processing circuit periodically reduces said peak value of said digitized signal by a factor such that said peak value decays over time.

6. The data collector of claim 5 wherein said digital signal processing circuit is responsive to user input to alter said factor, whereby quantification of high frequency energy content by said digital signal processing circuit can be adapted to frequency characteristics of said signal.

7. The data collector of claim 6 wherein said digital signal processing circuit comprises a software programmable processor performing a software-defined signal processing procedure, said software-defined procedure adapted to obtain said factor from a storage location, and to permit a user to define said factor and store said factor in said storage location.

8. The data collector of claim 1 wherein said digital signal processing circuit detects a peak-to-peak amplitude of said digitized signal and periodically reduces said peak-to-peak amplitude of said digitized signal by a factor such that said maximum peak-to-peak amplitude decays over time.

9. The data collector of claim 8 wherein said digital signal processing circuit is responsive to user input to alter said factor, whereby quantification of high frequency energy content by said digital signal processor can be adapted to frequency characteristics of said signal.

10. The data collector of claim 9 wherein said digital signal processing circuit comprises a software programmable processor performing a software-defined signal processing procedure, said software-defined procedure adapted to obtain said factor from a storage location, and to permit a user to define said factor and store said factor in said storage location.

11. The data collector of claim 3 further comprising a storage device, said digital signal processing circuit storing said maximum peak-to-peak value in said storage device.

12. The data collector of claim 3 further comprising a display, said digital signal processing circuit displaying said maximum peak-to-peak value on said display.

13. The data collector of claim 3 wherein said digital signal processing circuit further performs a frequency transformation upon the maximum peak-to-peak value to derive a spectrum for the maximum peak-to-peak value.

14. The data collector of claim 13 wherein said frequency transformation is a Fast Fourier Transform.

15. The data collector of claim 1 wherein said digital signal processing circuit comprises a software programmable processor performing a software-defined signal processing procedure.

30. The data collector of claim 5 wherein said digital signal processing circuit automatically computes said factor so that quantification of high frequency energy content by said digital signal processing circuit is adapted to frequency characteristics of said digitized signal.

2. A data collector for detecting and quantifying high frequency energy in a received vibration signal from a rotating machine, comprising

an analog to digital converter converting said received vibration signal to a digitized vibration signal at a sampling rate that is sufficient to reproduce a highest frequency of interest in said received vibration signal, and

a digital signal processing circuit that receives said digitized vibration signal and performs processing steps to isolate high frequency pulses in the digitized vibration signal from lower frequency components of the digitized signal, and process said high frequency pulses to quantify energy content of the isolated pulses and evaluate the potential for mechanical faults in the rotating machine.

16. A method of detecting and quantifying high frequency energy in a received signal, comprising

converting said received signal to a digitized signal at a sampling rate that is sufficient to reproduce a highest frequency of interest in said received signal, and

receiving said digitized signal,

isolating high frequency pulses in the digitized signal from lower frequency components of the digitized signal, and

processing said high frequency pulses by forming a time-varying peak-detected signal from said high frequency pulses, the time variation of the peak-detected signal corresponding to time variation of peak amplitudes of the high frequency pulses, to quantify energy content of the isolated pulses.

18. The method of claim 16 further comprising detecting a peak-to-peak amplitude of said digitized signal by comparing a current sample of said digitized signal to a peak value, and when the excursion of said current sample from zero exceeds said peak value, updating said peak value to be equal to said current sample.

19. The method of claim 18 wherein said peak value is a peak negative value and a peak-to-peak amplitude of said digitized signal is detected by comparing a maximum peak-to-peak value to a difference between said current sample and said peak negative value, and if the difference is larger, updating said maximum peak-to-peak value.

20. The method of claim 18 further comprising periodically reducing said peak value of said digitized signal by a factor such that said peak value decays over time.

21. The method of claim 20 further comprising responding to user input to alter said factor, whereby quantification of high frequency energy content can be adapted to frequency characteristics of said received signal.

22. The method of claim 21 further comprising

obtaining said factor from a storage location, and

permitting a user to define said factor and store said factor in said storage location.

23. The method of claim 16 further comprising detecting a maximum peak-to-peak amplitude of said digitized signal, and periodically reducing said maximum peak-to-peak amplitude of said digitized signal by a factor such that said maximum peak-to-peak amplitude decays over time.

24. The method of claim 23 further comprising responding to user input to alter said factor, whereby quantification of high frequency energy content can be adapted to frequency characteristics of said digitized signal.

25. The method of claim 24 further comprising

obtaining said factor from a storage location, and

permitting a user to define said factor and store said factor in said storage location.

26. The method of claim 16 further comprising storing said a maximum peak-to-peak value in a storage device.

27. The method of claim 16 further comprising displaying a maximum peak-to-peak value on a display.

28. The method of claim 16 further comprising performing a frequency transformation upon the peak-detected signal to derive a spectrum for the peak-detected signal.

29. The method of claim 28 wherein said frequency transformation is a Fast Fourier Transform.

31. The method of claim 20 further comprising automatically computing said factor so that quantification of high frequency energy content is adapted to frequency characteristics of said digitized signal.

17. A method for detecting and quantifying high frequency energy in a received vibration signal from a rotating machine, comprising

converting said received vibration signal to a digitized vibration signal at a sampling rate that is sufficient to reproduce a highest frequency of interest in said received vibration signal, and

receiving said digitized vibration signal,

isolating high frequency pulses in the digitized vibration signal from lower frequency components of the digitized signal, and

processing said high frequency pulses to quantify energy content of the isolated pulses and evaluate the potential for mechanical faults in the rotating machine.