System and method for ratiometrically processing sensed speed and vibration signals for a non-uniformly rotating body

• US 5,412,985 A
• Filed: 09/18/1992
• Issued: 05/09/1995
• Est. Priority Date: 09/18/1992
• Status: Expired due to Fees

• Current Assignee: Ametek Incorporated
• Original Assignee: Ametek Aerospace Products, Inc. (Ametek Incorporated)
• Inventors: Garcia, David L., Hueston, Robert J., Bianchi, Robert G.
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): Oen, William L.
• Application Number:
  US07/947,425
• Time in Patent Office: 963 Days
• Field of Search: 73/460, 73/462, 73/660, 364/506, 364/508, 364/463
• US Class Current: 73/460
• CPC Class Codes: G01H 1/003 of rotating machines G01H1/10 takes precedence
• CPC Class Codes: G01M 1/22 and converting vibrations due to imbalance into electric variables
• CPC Class Codes: G01M 7/025 Measuring arrangements

Abstract

A digital ratiometric tracking filter provides superior measurement of the magnitude and phase of vibration of a rotating body, at uniform or non-uniform rotational speed. The sensed speed and vibration signals are concurrently processed and subsequently combined to produce the absolute magnitude and relative phase measurements. The concurrent processing of the sensed signals assures that any system-introduced errors are found in both signals and can be uniformly eliminated by the ratiometric processing thereof.

Claims

1. A method for characterizing the vibration of a rotating body comprising the steps of:

monitoring vibration signals during a measurement period;

asynchronously monitoring rotational speed signals during said measurement period, simultaneously with said monitoring of vibration signals;

concurrently processing said simultaneously monitored vibration and speed signals; and

ratiometrically combining said vibration and speed signals to yield the absolute magnitude and relative phase of vibration of said body.

2. The method of claim 1 wherein said processing comprises detecting the magnitude and phase of each of said vibration and speed signals and wherein said combining step comprises combining the magnitudes of said vibration and speed signals to yield the absolute magnitude of vibration of the body and combining the phase of said vibration and speed signals to yield the relative phases of vibration of said body.

3. The method of claim 2 wherein said detecting of the magnitude of the speed signal further comprises detecting the attenuation of said magnitude at at the fundamental frequency of rotation.

4. The method of claim 3 wherein said combining of magnitudes comprises dividing the magnitude of the vibration signal by the attenuation of the magnitude of said speed signal.

5. The method of claim 2 wherein said combining of phase angles comprises subtracting said phase of said speed signal from the phase of said vibration signal.

6. The method of claim 2 wherein said processing further comprises the step of converting said vibration and speed signals to digital signals.

7. The method of claim 2 wherein said processing further comprises the step of filtering said vibration and said speed signals prior to detecting said magnitudes.

8. The method of claim 2 wherein said processing further comprises conditioning said vibration signal by converting said vibration signals into analog voltage signals.

9. The method of claim 2 wherein said processing of said speed signal comprises converting said speed signal from a time-based signal to a frequency-based speed signal which corresponds to the rotational speed of the rotating body.

10. A method for characterizing the magnitude and relative phase of vibration of a rotating body comprising the steps of:

sensing vibration signals during a measurement period;

asynchronously sensing rotational speed signals during said measurement period simultaneously with said sensing vibration signal; and

concurrently processing said vibration signals and said rotational speed signals, wherein said concurrent processing comprises

converting said sensed vibration signals into analog vibration voltage signals;

converting said speed signals from time-based signals to frequency based speed signals;

effecting conversion of said analog vibration voltage signals and said frequency-based speed signals from analog to digital vibration and speed signals;

filtering said digital vibration and speed signals;

detecting the magnitudes of said digital vibration and speed signals;

detecting the phases of said digital vibration and speed signals;

combining said magnitudes of said digital vibration and speed signals to obtain the proportional magnitude of vibration of said rotating body; and

combining said phases of said digital vibration and speed signals to obtain the relative phase of vibration of said rotating body.

11. The method for claim 10 further comprising anti-aliasing filtering of said analog vibration voltage signals and said frequency-based speed signals.

12. The method of claim 10 further comprising selecting sets of said digital vibration and speed signals for a predetermined time period and wherein only said sets of said digital vibration and speed signals are subsequently filtered.

13. The method of claim 10 further comprising obtaining the speed attentuation by dividing the magnitude of the speed signal by the speed magnitude and wherein said combining of said magnitude comprises dividing the magnitude of said vibration signal by the speed attenuation to yield the absolute magnitude of vibration.

14. The method of claim 10 wherein said combining of phases comprises subtracting the phase of said speed signal from the phase of said vibration signal.

15. The method of claim 10 wherein said combining of phases comprises performing a cross-spectrum calculation.

16. A tracking filter system for providing the amplitude and phase of vibration of a rotating body, when the rotational rate is uniform or non-uniform comprising:

a first sensor for producing vibration signals;

a second sensor for producing first speed signals;

means for converting said vibration signals into vibration frequency signals;

means for converting said first speed signals into frequency-based second speed signals;

means responsive to said first speed signals for determining the magnitude of said vibration frequency signals and second speed signals;

means for determining the phases of said vibration frequency signals and said second speed signals;

means for combining said magnitudes to produce the magnitude of vibration of said rotating body; and

means for combining said phases to produce the phase of vibration of said rotating body.

17. The system of claim 16 further comprising means for converting said vibration frequency signals land said second speed signals into digital vibration and speed signals.

18. The system of claim 17 wherein said means for determining the magnitudes further comprises digital filter means.

19. The system of claim 18 wherein said means for determining the phases further comprises digital filter means.

20. The system of claim 16 wherein said first sensor is an accelerometer.

21. The system of claim 16 wherein said first sensor is a velometer.

22. The system of claim 16 wherein said first sensor is a displacement sensor.

23. The system of claim 16 wherein said second sensor means is a tachometer.

24. The system of claim 16 further comprising anti-aliasing filter means associated with each of said means for converting said vibration signals and means for converting said first speed signals.