Time varying harmonic analysis including determination of order components

• US 6,810,341 B2
• Filed: 06/26/2002
• Issued: 10/26/2004
• Est. Priority Date: 04/19/2000
• Status: Expired due to Term

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Shao, Hui, Zhang, Nanxiong, Qian, Shie
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): TSAI, CAROL S W
• Application Number:
  US10/180,765
• Publication Number:
  US 20020183948A1
• Time in Patent Office: 853 Days
• Field of Search: 702/54, 702/56, 702/66, 702/75-79, 702/103, 702/105, 702/106, 702/113-115, 702/12, 702/182-185, 702/188, 702/189, 702/FOR-107, 702/FOR.110, 702/FOR-123, 702/FOR-134, 702/FOR.168, 702/FOR-170, 702/33-36, 702/44, 700/279-280, 708/400, 708/401, 736/59, 736/60, 735/79, 735/83, 735/93, 736/09, 735/59, 736/00, 340/681, 340/682, 340/683, 324/207, 324/251, 324/226
• US Class Current: 702/75
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence

Abstract

A system and method for analyzing order components present in a physical signal X acquired from a physical system. Measurement information for the physical signal X may be received, where the measurement information includes information indicating a plurality of order components of the physical signal X. Time frequency plot information visually indicating order components of the physical signal X may be displayed. User input selecting one or more of the visually indicated order components may be received. A time domain signal may be created based on the one or more selected order components and may then be presented to a user on a presentation device. Presenting the time domain signal on the presentation device may enable the user to analyze the physical signal X or the physical system. Where the physical system includes one or more rotating elements, the method may enable order components of the signal to be analyzed even when no rotation speed information (e.g., tachometer information) for the rotating element is available.

Claims

1. A method for analyzing a physical system having one or more rotating elements, the method comprising:

receiving measurement information for a physical signal generated by the physical system, wherein the measurement information includes information indicating a plurality of order components of the physical signal, and wherein the measurement information does not include rotation speed information;

processing the measurement information to create time frequency plot information for the physical signal;

displaying the time frequency plot information on a display, wherein the time frequency plot information includes a plurality of points visually indicating the order components of the physical signal;

receiving user input selecting one or more of the visually indicated order components;

performing one of;

a) creating a time domain signal in which the one or more selected order components are suppressed;

or

b) creating a time domain signal consisting of the one or more selected order components; and

presenting the time domain signal to a user on a presentation device;

wherein the time domain signal is useable in analyzing the physical system having one or more rotating elements.

2. The method of claim 1,

wherein said plurality of points visually indicating the order components of the physical signal comprises the plurality of points visually indicating order curves corresponding to the order components;

wherein, for each selected order component, receiving user input selecting the order component comprises receiving user input selecting one or more points proximate to the corresponding order curve.

3. The method of claim 2, further comprising:

for each selected order component, determining a plurality of points comprising the order component based on the one or more selected points proximate to the corresponding order curve.

4. The method of claim 3,

wherein, for each selected order component, said determining the plurality of points comprising the order component comprises:

computing a curve fitted to the selected points proximate to the corresponding order curve; and

determining points having peak magnitudes proximate to the computed curve, wherein the points having peak magnitudes proximate to the computed curve comprise the order component.

5. The method of claim 4,

wherein said determining points having peak magnitudes proximate to the computed curve comprises:

determining a band of points including the computed curve; and

determining points having peak magnitudes within the band.

6. The method of claim 1,

wherein the presentation device comprises at least one speaker;

wherein said presenting the time domain signal to the user on the presentation device comprises audially presenting the time domain signal as sound output from the at least one speaker.

7. The method of claim 1,

wherein the presentation device comprises a display;

wherein said presenting the time domain signal to the user on the presentation device comprises visually displaying the time domain signal on the display.

8. A method for analyzing an input signal, the method comprising:

receiving samples of the input signal, wherein the input signal is sampled in time;

performing an invertible joint time-frequency transform on the samples of the input signal to produce a first array of coefficients which depend on time and frequency;

receiving user input selecting a plurality of points from the first array of coefficients, wherein the points are proximate to an order component present in the first array of coefficients;

determining a trajectory of the order component based on the selected points, wherein the trajectory comprises a subset of the points from the first array of coefficients;

generating a modified array of coefficients based on the trajectory;

generating a time domain signal from the modified array of coefficients; and

presenting the time domain signal to a user on a presentation device;

wherein the time domain signal is useable in analyzing information present in the signal.

9. The method of claim 8,

wherein the input signal is acquired from a physical system having a rotating element;

wherein the time domain signal is useable in analyzing the physical system having the rotating element.

10. The method of claim 9,

wherein said receiving samples of the input signal does not include receiving rotation speed information indicating rotation speed of the rotating element;

wherein the method is operable to analyze the input signal without utilizing rotation speed information.

11. The method of claim 8, wherein said determining the trajectory of the order component based on the selected points comprises:

estimating a trajectory of the order component based on the selected points, wherein the estimated trajectory comprises a curve fitted to the selected points; and

determining a more accurate trajectory of the order component based on the estimated trajectory of the order component.

12. The method of claim 11, wherein said determining the more accurate trajectory of the order component based on the estimated trajectory of the order component comprises:

determining a band of points from the first array of coefficients proximate to the estimated trajectory of the order component; and

determining coefficient positions having peak intensity values within the band, wherein the coefficient positions having peak values define the more accurate trajectory of the order component.

13. The method of claim 12,

wherein the width of the band is determined automatically based on the first array of coefficients.

14. The method of claim 12,

wherein the width of the band is determined based on user input specifying a desired width.

15. The method of claim 8,

wherein said generating the modified array of coefficients comprises setting coefficients of the modified array equal to zero at positions other than coefficient positions of the points in the trajectory.

16. The method of claim 15,

wherein said generating the modified array of coefficients further comprises setting coefficients of the modified array equal to coefficients of the first array at coefficient positions of the points in the trajectory.

17. The method of claim 8, further comprising:

displaying a visual representation of the first array of coefficients;

wherein said receiving user input selecting a plurality of points from the first array of coefficients comprises receiving user input to the visual representation of the first array of coefficients.

18. The method of claim 8,

wherein the presentation device comprises at least one speaker;

wherein said presenting the time domain signal to the user on the presentation device comprises audially presenting the time domain signal as sound output from the at least one speaker.

19. The method of claim 8,

wherein the presentation device comprises a display;

wherein said presenting the time domain signal to the user on the presentation device comprises visually displaying the time domain signal on the display.

20. The method of claim 8, wherein said generating the time domain signal from the modified array of coefficients comprises performing an inverse joint time-frequency transform on the modified array of coefficients.

21. The method of claim 8, wherein the joint time-frequency transform comprises the Gabor transform.

22. The method of claim 8,

wherein the input signal is acquired from a mechanical system;

wherein the method further comprises adjusting the mechanical system in response to analysis of the time domain signal.

23. The method of claim 22, wherein said adjusting the mechanical system comprises one or more of:

1) changing a design of the mechanical system;

     2) replacing one or more components of the mechanical system;

     3) predicting a failure of one or more components of the mechanical system; and

     4) adding a sound-absorbent material to one or more locations of the mechanical system.

24. The method of claim 8, wherein the input signal comprises a signal generated by a microphone proximate to a mechanical system.

25. The method of claim 8, further comprising:

constructing a scaling array in response to user input, wherein said generating the modified array of coefficients comprises scaling the first array with the scaling array.

26. The method of claim 25, wherein said scaling array is configured to emphasize one or more order components in the input signal.

27. The method of claim 25, wherein said scaling array is configured to de-emphasize one or more order components in the input signal.

28. A system for analyzing an input signal, the system comprising:

an input for receiving samples of an input signal, wherein the input signal is sampled in time;

a processor coupled to the input;

a memory medium coupled to the processor which stores analysis software;

wherein the processor is operable to execute the analysis software to;

perform an invertible joint time-frequency transform on the samples of the input signal to produce a first array of coefficients which depend on time and frequency;

receive user input selecting a plurality of points from the first array of coefficients, wherein the points are proximate to an order component present in the first array of coefficients;

determine a trajectory of the order component based on the selected points, wherein the trajectory comprises a subset of the points from the first array of coefficients;

generate a modified array of coefficients based on the trajectory;

generate a time domain signal from the modified array of coefficients; and

a presentation device coupled to the processor which is operable to present the time domain signal to a user;

wherein the time domain signal is useable in analyzing information present in the signal.

29. The system of claim 28,

wherein the system has a rotating element;

wherein the time domain signal is useable in analyzing operation of the rotating element.

30. The system of claim 29,

wherein said input receiving samples of the input signal does not include the input receiving rotation speed information indicating rotation speed of the rotating element;

wherein the processor is operable to execute the analysis software to present the time domain signal to the user without utilizing rotation speed information.

31. The system of claim 28, wherein, in determining the trajectory of the order component based on the selected points, the processor is operable to:

estimate a trajectory of the order component based on the selected points, wherein the estimated trajectory comprises one or more line segments connecting the selected points; and

determine the actual trajectory of the order component based on the estimated trajectory of the order component.

32. The system of claim 31, wherein, in determining the actual trajectory of the order component based on the estimated trajectory of the order component, the processor is operable to:

determine a band of points from the first array of coefficients proximate to the estimated trajectory of the order component; and

determine coefficient positions having peak values within the band, wherein the coefficient positions having peak values define the actual trajectory of the order component.

33. The system of claim 32,

wherein the processor is operable to determine the width of the band automatically based on the first array of coefficients.

34. The system of claim 32,

wherein the processor is operable to determine the width of the band based on user input specifying a desired width.

37. The system of claim 28, further comprising:

a display device coupled to the processor;

wherein the processor is further operable to execute the analysis software to display a visual representation of the first array of coefficients on the display device;

wherein said processor executing the analysis software to receive user input selecting the plurality of points from the first array of coefficients comprises receiving user input to the visual representation of the first array of coefficients.

38. The system of claim 28,

wherein the presentation device comprises at least one speaker;

wherein said presentation device presenting the time domain signal to the user comprises the at least one speaker audially presenting the time domain signal as sound output.

39. The system of claim 28,

wherein the presentation device comprises a display;

wherein said presentation device presenting the time domain signal to the user comprises the display visually displaying the time domain signal.

40. The system of claim 28,

wherein, in generating the time domain signal from the modified array of coefficients, the processor is operable to perform an inverse joint time-frequency transform on the modified array of coefficients.

41. The system of claim 28,

wherein, in performing the invertible joint time-frequency transform on the samples of the input signal, the processor is operable to perform a Gabor transform.

35. The system of system 28,

wherein, in generating the modified array of coefficients, the processor is operable to set coefficients of the modified array equal to zero at positions other than coefficient positions of the points in the trajectory.

36. The system of claim 35,

wherein, in generating the modified array of coefficients, the processor is further operable to set coefficients of the modified array equal to coefficients of the first array at coefficient positions of the points in the trajectory.

42. A memory medium for analyzing an input signal, the memory medium comprising program instructions executable to:

receive samples of the input signal, wherein the input signal is sampled in time;

perform an invertible joint time-frequency transform on the samples of the input signal to produce a first array of coefficients which depend on time and frequency;

receive user input selecting a plurality of points from the first array of coefficients, wherein the points are proximate to an order component present in the first array of coefficients;

determine a trajectory of the order component based on the selected points, wherein the trajectory comprises a subset of the points from the first array of coefficients;

generate a modified array of coefficients based on the trajectory;

generate a time domain signal from the modified array of coefficients; and

present the time domain signal to a user on a presentation device;

wherein the time domain signal is useable in analyzing information present in the signal.

43. The memory medium of claim 42,

wherein the input signal is acquired from a physical system having a rotating element;

wherein the time domain signal is useable in analyzing the physical system having the rotating element.

44. The method of claim 43,

wherein said receiving samples of the input signal does not include receiving rotation speed information indicating rotation speed of the rotating element;

wherein the memory medium comprises program instructions executable to analyze the input signal without rotation speed information.

45. The memory medium of claim 44, wherein said determining the trajectory of the order component based on the selected points comprises:

estimating a trajectory of the order component based on the selected points, wherein the estimated trajectory comprises one or more line segments connecting the selected points; and

determining the actual trajectory of the order component based on the estimated trajectory of the order component.

46. The memory medium of claim 45, wherein said determining the actual trajectory of the order component based on the estimated trajectory of the order component comprises:

determining a band of points from the first array of coefficients proximate to the estimated trajectory of the order component; and

determining coefficient positions having peak values within the band, wherein the coefficient positions having peak values define the actual trajectory of the order component.

47. The memory medium of claim 46,

wherein the width of the band is determined automatically based on the first array of coefficients.

48. The memory medium of claim 46,

wherein the width of the band is determined based on user input specifying a desired width.

49. The memory medium of claim 42,

wherein said generating the modified array of coefficients comprises setting coefficients of the modified array equal to zero at positions other than coefficient positions of the points in the trajectory.

50. The memory medium of claim 49,

wherein said generating the modified array of coefficients further comprises setting coefficients of the modified array equal to coefficients of the first array at coefficient positions of the points in the trajectory.

51. The memory medium of claim 42, further comprising program instructions executable to:

display a visual representation of the first array of coefficients;

wherein said receiving user input selecting a plurality of points from the first array of coefficients comprises receiving user input to the visual representation of the first array of coefficients.

52. The memory medium of claim 42,

wherein the presentation device comprises at least one speaker;

wherein said presenting the time domain signal to the user on the presentation device comprises audially presenting the time domain signal as sound output from the at least one speaker.

53. The memory medium of claim 42,

wherein the presentation device comprises a display;

wherein said presenting the time domain signal to the user on the presentation device comprises visually displaying the time domain signal on the display.

54. The memory medium of claim 42, wherein said generating the time domain signal from the modified array of coefficients comprises performing an inverse joint time-frequency transform on the modified array of coefficients.

55. The memory medium of claim 42, wherein the joint time-frequency transform comprises the Gabor transform.

56. The memory medium of claim 42, wherein the input signal comprises a signal generated by a microphone proximate to a mechanical system.