“…In signal-based methods, there are many kinds of signals such as vibration and acoustic signals (Liu et al, 2016), electric current (Boudinar et al, 2016), temperature (Yuan et al, 2018), and wear debris. Among these, the vibration signal is the most widely used approach (Lin & Ye, 2019;Sohaib et al, 2017). The signal processing methods generally include Fourier Transform (FT), Short-Time Fourier Transform (STFT), Wavelet Transform (WT), Wavelet Package Transform (WPT), Empirical Wavelet Transform (EWT), Hilbert-Huang Transform CONTACT Jungan Chen friendcen21@hotmail.com (HHT), Empirical Mode Decomposition (EMD), Variation Mode Decomposition (VMD), and Ensemble Empirical Mode Decomposition (EEMD).…”