An Improved Multi-Ridge Extraction Method Based on Differential Synchro-Squeezing Wavelet Transform

Yanfeng Li,Tiansheng Zhao,Zhijian Wang,Wanqing Song

doi:10.1109/access.2021.3095054

Abstract

It is very important to accurately extract the instantaneous frequency (IF) of complex non-stationary signals, so the signal processing methods based on IF are widely used in engineering. However, in non-stationary complex vibration signals, it is difficult to extract the instantaneous frequency under strong noise because the frequency changes rapidly. This paper proposes an improved multi-ridge extraction method based on differential synchro-squeezing wavelet transform (DSWT). First, an improved method DSWT is proposed to reduce the computation time and image noise of synchro-squeezing wavelet transform (SWT). The running time of the algorithm can be further reduced by segmenting the signal and compressing the time-frequency matrix. The image noise can be significantly reduced by differentiating SWT time-frequency matrix. It lays a good foundation for the extraction of the time-frequency ridge line. Secondly, an improved multi-ridge extraction method is proposed. The ridge jump due to end effect can be eliminated adaptively in segmented extraction. It further improves the time-frequency aggregation and extraction effect of the wavelet ridgeline image. Finally, the improved multi-ridge extraction method based on DSWT (DSWT-IMRE) is verified by the simulation data and experimental data under different conditions. Compared with the method proposed in previous study, the results show that DSWT-IMRE has higher extraction accuracy.

Highlights

The instantaneous frequency (IF) estimation of signals is an important method in the analysis and processing of rotating machinery non-stationary signals[1]
It can be found that analysis of (a) .It can be found that Empirical Mode Decomposition (EMD) can extract the differential synchro-squeezing wavelet transform (DSWT) can significantly improve the time-frequency instantaneous frequency for different components of the aggregation compared to continuous wavelet transform (CWT), and provides a more accurate signal
This paper proposes an improved multi-ridge extraction method based on DSWT, and is verified by the simulation data and experimental data under different conditions

Summary

I.INTRODUCTION

The instantaneous frequency (IF) estimation of signals is an important method in the analysis and processing of rotating machinery non-stationary signals[1]. Because the time-frequency aggregation of wavelet transform is not high, it cannot be used as the basis for accurate extraction of time-frequency ridge lines, and the traditional peaks detection methods cannot be used for adaptive multi-ridge extraction, so the CWT Peaks Detection method is not suitable for complex production environment. Pham [25] combined STFT with the Synchro-squeezing Transform This method realized the high concentration time-frequency representation of multi-component signals with various amplitude-frequency modulations. In the reference [26], the ridge line of the current signal of motor was extracted by peaks detection based on SST. It worked well, but only for single-component signals. Aiming at problems of SWT-AMRE, this paper proposes an improved adaptive multi-ridge extraction method based on differential Synchro-squeezing Wavelet Transform (DSWT). The improved method lays a foundation for the following research work

Methodology

Simulation

Conclusion and Recommendations