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US-12620977-B2 - Device and method for processing a digital signal

US12620977B2US 12620977 B2US12620977 B2US 12620977B2US-12620977-B2

Abstract

A device for processing a digital signal includes a Farrow structure ( 14 ) that applies to the digital signal a time-varying sample rate conversion from the fixed sample rate to a time varying sampling. The digital signal sampled at the time varying sampling is a resulting signal. The Farrow structure ( 14 ) is controlled from a control variable. A spectral analysis means ( 15 ) performs a spectral analysis of the resulting signal to determine the frequency values of the resulting signal. A determining means ( 16 ) determines a sparseness parameter of the frequency values of the resulting signal. A controlling means ( 17 ) modifies the control variable according to the value of the sparseness parameter.

Inventors

  • James P. LeBlanc
  • Patrik Pääjärvi

Assignees

  • AKTIEBOLAGET SKF

Dates

Publication Date
20260505
Application Date
20231009
Priority Date
20221017

Claims (14)

  1. 1 . A method for processing a digital signal comprising samples of a continuous signal sampled at a fixed sample rate, the continuous signal being representative of vibrations of a bearing undergoing rotational speed changes, the method comprising: applying to the digital signal a time-varying sample rate conversion by a Farrow structure from the fixed sample rate to a time varying sampling, the digital signal sampled at the time varying sampling being a resulting signal, the Farrow structure being controlled from a control variable; performing a spectral analysis of the resulting signal to determine frequency values of the resulting signal; determining a sparseness parameter of the frequency values of the resulting signal; and modifying the control variable according to the value of the sparseness parameter.
  2. 2 . The method according to claim 1 , wherein performing a spectral analysis of the resulting signal comprises performing a fast Fourier transform of the resulting signal.
  3. 3 . The method according to claim 1 , wherein a statistical parameter of the frequency values is a skewness of the frequency values.
  4. 4 . The method according to claim 1 , further comprising modifying an intermediate sampling including implementing a line search algorithm to modify the control variable.
  5. 5 . The method according to claim 2 , wherein a statistical parameter of the frequency values is a skewness of the frequency values.
  6. 6 . The method according to claim 5 , further comprising modifying an intermediate sampling including implementing a line search algorithm to modify the control variable.
  7. 7 . A device for processing a digital signal comprising samples of a continuous signal sampled at a fixed sample rate, the continuous signal being representative of vibrations of a bearing undergoing rotational speed changes, the device comprising: a Farrow structure configured to apply to the digital signal a time-varying sample rate conversion from the fixed sample rate to a time varying sampling, the digital signal sampled at the time varying sampling being a resulting signal, and the Farrow structure being configured to be controlled from a control variable; spectral analysis means configured to perform a spectral analysis of the resulting signal to determine frequency values of the resulting signal; determining means configured to determine a sparseness parameter of the frequency values of the resulting signal; and controlling means configured to modify the control variable according to the value of the sparseness parameter.
  8. 8 . The device according to claim 7 , wherein the spectral analysis means are configured to implement a fast Fourier transform algorithm.
  9. 9 . The device according to claim 7 , wherein a statistical parameter of the frequency values is a skewness of the frequency values.
  10. 10 . The device according to claim 7 , wherein the controlling means are configured to implement a line search algorithm to modify the control variable.
  11. 11 . A bearing device comprising: a bearing provided with an inner ring and with an outer ring capable of rotating concentrically relative to one another; a sensor configured to measure the vibrations of the said inner or outer ring and configured to deliver a continuous signal; a sampler configured to sample the continuous signal at a fixed sample rate and configured to deliver the digital signal comprising the samples; and a device according to claim 7 configured to process the digital signal.
  12. 12 . The device according to claim 8 , wherein a statistical parameter of the frequency values is a skewness of the frequency values.
  13. 13 . The device according to claim 12 , wherein the controlling means are configured to implement a line search algorithm to modify the control variable.
  14. 14 . A bearing device comprising: a bearing provided with an inner ring and with an outer ring capable of rotating concentrically relative to one another; a sensor configured to measure the vibrations of the said inner or outer ring and configured to deliver a continuous signal; a sampler configured to sample the continuous signal at a fixed sample rate and configured to deliver the digital signal comprising the samples; and a device according to claim 13 configured to process the digital signal.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to German Application No. 102022210929.5, filed Oct. 17, 2022, the entirety of which is hereby incorporated by reference. FIELD The present disclosure is directed to devices for processing a digital signal and methods for processing a digital signal. BACKGROUND Condition monitoring algorithms, for example to detect a fault of a bearing such as a fault of an inner raceway of the bearing, require a constant rotational speed of the bearing to work properly. Generally, condition monitoring algorithms perform spectral analysis of the rotating bearing to detect faults from specific tones and harmonics. Rotational speed changes of the bearing during signal measurement smears out the spectral tones reducing the ability to identify the frequencies and harmonics that may be associated with faults, for example faults of an inner raceway of the bearing or faults of the outer raceway of the bearing. Consequently, the present disclosure intends to correct deleterious effects of rotational speed changes to perform a spectral analysis. SUMMARY According to an aspect, a method for processing a digital signal comprising samples of a continuous signal sampled at a fixed sample rate, the continuous signal being representative of vibrations of a bearing undergoing rotational speed changes is proposed. The method comprises: applying to the digital signal a time-varying sample rate conversion by a Farrow structure from the fixed sample rate to a time varying sampling, the digital signal sampled at the time varying sampling being a resulting signal, the Farrow structure being controlled from a control variable;performing a spectral analysis of the resulting signal to determine the frequency values of the resulting signal;determining a sparseness parameter of the frequency values of the resulting signal; andmodifying the control variable according to the value of the sparseness parameter. The method permits the use of existing constant rotation speed algorithms in conditions of varying rotational speed so that repetitive attempts to obtain constant-speed data acquisition are not necessary. The suppression of repetitive attempts at data acquisition permit to save supply power of a device implementing the method for example a wireless power comprising a supply source such as a battery. Advantageously, performing a spectral analysis of the resulting signal comprises performing a fast Fourier transform of the resulting signal. Preferably, the statistical parameter of the frequency values is the skewness of the frequency values. Advantageously, modifying the intermediate sampling comprises implementing a line search algorithm to modify the control variable. According to an aspect, a device for processing a digital signal comprising samples of a continuous signal sampled at a fixed sample rate, the continuous signal being representative of vibrations of a bearing undergoing rotational speed changes is proposed. The device comprises: a Farrow structure configured to apply to the digital signal a time-varying sample rate conversion from the fixed sample rate to a time varying sampling, the digital signal sampled at the time-varying sampling being a resulting signal, and the Farrow structure being configured to be controlled from a control variable;spectral analysis means configured to perform a spectral analysis of the resulting signal to determine the frequency values of the resulting signal;determining means configured to determine a sparseness parameter of the frequency values of the resulting signal; andcontrolling means configured to modify the control variable according to the value of the sparseness parameter. Preferably, the spectral analysis means are configured to implement a fast Fourier transform algorithm. Advantageously, the statistical parameter of the frequency values is the skewness of the frequency values. Preferably, the controlling means are configured to implement a line search algorithm to modify the control variable. According to an aspect, a bearing device is proposed. The bearing device comprises: a bearing provided with an inner ring and with an outer ring capable of rotating concentrically relative to one another;a sensor configured to measure the vibrations of the said inner or outer ring and configured to deliver a continuous signal;a sampler configured to sample the continuous signal at a fixed sample rate and configured to deliver the digital signal comprising the samples; anda device as defined above configured to process the digital signal. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features of the present disclosure will appear on examination of the detailed description of embodiments, in no way restrictive, and the appended drawings in which: FIG. 1 illustrates schematically a rotating machine according to the present disclosure; FIG. 2 illustrates schematically an example of a device for processing a digital signal accord