Bearing Defect and Misalignment Diagnostics using Local Regularity and Sparse Frequency Analysis


  • Juhani Nissilä
  • Jouni Laurila
  • Keijo Ruotsalainen
  • Toni Liedes



Hölder regularity, continuous wavelet transform, sparse signals, Lomb-Scargle periodogram, compressed sensing, envelope analysis


A local regularity signal can be estimated from a vibration measurement with the help of the continuous wavelet transform (CWT). The resulting local regularity signal contains a lot of diagnostic information about different faults states of a machine. It is also typically a sparse signal and thus not well suited for frequency analysis using the discrete Fourier transform (DFT). In this paper, the frequency analysis of the local regularity signal is performed using the Lomb-Scargle periodogram. Another possibility is to use the methods of compressed sensing. Vibration measurements from different fault states from test rigs are utilized in validating the proposed method and comparing it with other methods. The induced fault conditions include a bearing inner ring defect and misalignment of a claw clutch. The results are compared to more traditional spectra calculated directly from the vibration measurement, such as the spectrum of the squared envelope.


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