Vibration signal analysis for determining rotational speed

Patent metadata

Field	Value
Publication number	US-10895495-B2
Application number	US-201815926512-A
Country	US
Kind code	B2
Filing date	Mar 20, 2018
Priority date	Mar 20, 2018
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

Rotational speed of a rotating component is determined using frequency domain vibrational data. A time sequence of vibrational data of the rotating component is sensed and converted to the frequency domain vibrational data. A portion of the frequency domain vibrational data corresponding to an expected rotational speed of the rotating component is identified. A frequency bin index of the frequency domain vibrational data corresponding to a maximum vibration within the portion of the frequency domain vibrational data is identified. The maximum vibration at the identified frequency bin index and vibrations associated with adjacent frequency bin indices are fitted to a model curve. A floating point frequency bin index corresponding to a maximum of the model curve is identified, and the rotational speed of the rotating component is determined based on the frequency bin index corresponding to the maximum of the model curve.

First claim

The invention claimed is:

1. A method for determining rotational speed of a rotating component, the method comprising:
sensing a time sequence of vibrational data of the rotating component using one or more sensors;
converting the time sequence of vibrational data to frequency domain vibrational data;
identifying a portion of the frequency domain vibrational data corresponding to an expected rotational speed of the rotating component;
identifying a frequency bin index of the frequency domain vibrational data corresponding to a maximum vibration within the portion of the frequency domain vibrational data;
fitting the maximum vibration at the identified frequency bin index and vibrations associated with adjacent frequency bin indices to a model curve;
identifying a floating point frequency bin index corresponding to a maximum of the model curve;
determining the rotational speed of the rotating component based on the frequency bin index corresponding to the maximum of the model curve;
providing the rotational speed of the rotating component to a prognostics health management system of an aircraft; and
identifying, by the prognostics health management system using the rotational speed, a fault condition of the rotating component;
wherein identifying the portion of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component comprises:
identifying a frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component; and
identifying the portion of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component as a portion of the frequency domain vibrational data centered around the frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component.

2. The method of claim 1 ,
wherein sensing the time sequence of the vibrational data of the rotating component comprises sensing the time sequence of the vibrational data of the rotating component using one or more accelerometers.

3. The method of claim 1 ,
wherein converting the time sequence of vibrational data to the frequency domain vibrational data comprises converting the time sequence of vibrational data to the frequency domain vibrational data using one of a discrete Fourier transform and a power spectral density transformation.

4. The method of claim 1 ,
wherein identifying the frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component comprises identifying the frequency bin index of the frequency domain vibrational data according to the following equation:

i
estimate

=

round
⁢

⁢

(

S
·
H
·
B

f
max

)

wherein i estimate is the frequency bin index of the frequency domain vibrational data corresponding to the expected rotational speed of the rotating component;
wherein S is the expected rotational speed of the rotating component;
wherein H is a defined multiple of the expected rotational speed of the rotating component;
wherein B is a number of frequency bin indices of the frequency domain vibrational data;
wherein f max is half of a time-based sampling rate of the time sequence of vibrational data; and
wherein round is a rounding function that outputs a nearest integer.

5. The method of claim 1 ,
wherein the model curve comprises a parabola.

6. The method of claim 5 ,
wherein fitting the maximum vibration at the identified frequency bin index and vibrations associated with adjacent frequency bin indices to the model curve comprises fitting the maximum vibration at the identified frequency bin index, a vibration at a frequency bin index that is sequentially-previous the identified frequency bin index, and a vibration at a frequency bin index that is sequentially-next the identified frequency bin index to the parabola using second order parabolic interpolation.

7. The method of claim 1 ,
wherein identifying the frequency bin index corresponding to the maximum of the model curve comprises identifying the frequency bin index corresponding to the maximum of the model curve according to the following equation:

j
true

=

ln
⁡

(

Q

m
-
1

)

-

ln
⁡

(

Q

m
+
1

)

2
·

(

ln
⁡

(

Q

m
-
1

)

-

2
·

ln
⁡

(

Q
m

)

+

ln
⁡

(

Q

m
+
1

)

Assignees

• Simmonds Precision Products

Inventors

• Duke Alan M

Classifications

• G01P3/48 Primary

  by measuring frequency of generated current or voltage {(in general G01R23/00)} · CPC title

• G01M13/045

  Acoustic or vibration analysis · CPC title

• G06F17/17

  Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method ({G06F17/18 takes precedence } ; interpolation for numerical control G05B19/18) · CPC title

• G01M1/16

  by oscillating or rotating the body to be tested · CPC title

• G01P3/44

  for measuring angular speed (G01P3/56 takes precedence) · CPC title