A new l0-norm embedded MED method for roller element bearing fault diagnosis at early stage of damage

Deconvolution methods have been extensively applied for enhancing the impulsive feature of those bearing signals, which promotes the accuracy of the bearing fault diagnosis. However, these methods are sensitive to the inverse filter length, which leads to poor effect. To overcome the existing problems, a new adaptive sparse representation-based minimum entropy deconvolution (AdaSRMED) is proposed on basis of the impulsive feature extraction of sparse representation, which promotes the robustness for inverse filter length and its effectiveness of impulse enhancement. In AdaSRMED, a new adaptive sparse representation (SR) is proposed based on the features of fault impulsive signals for solving these existing problems of previous SR methods. Moreover, the new adaptive SR is integrated with the minimum entropy deconvolution (MED) for improving the performance of MED, which avoids the shortcomings of MED and MED-related methods. A series of simulation signal and real fault signal experiments are performed to illustrate the superiority of AdaSRMED in fault detection. The comparison analysis with the conventional MED and improved MEDs shows that AdaSRMED can effectively enhance the impulsive features and show good bearing fault detection performance.

Adaptive Sparse Representation-Based Minimum Entropy Deconvolution for Bearing Fault Detection

On the basis of empirical mode decomposition and teager energy operator, the new approach for rolling bearing fault diagnosis based on phase difference correction method is presented. It focuses on...

Application of the phase difference correct method in rolling bearing fault diagnosis

Aimed at the limitation of two current kinds of Phase Difference Correction on discrete spectrum,a new global method is presented.That is to construct a new sequence by shifting the former N/2 points of original time-domain sequence at the scale of N/4 points,set both the former and latter N/4 points to zero,and then perform FFT analysis on the original sequence and new one.The spectrum can be corrected by taking advantage of the phase difference of two corresponding peak lines.Compared with the original two kinds of Phase-Difference Correction,only one sequence of time-domain signal is sampled and FFT analysis of same points is performed twice in this method.Simulated result demonstrates that this method is easily carried out with high precision,suits for all kinds of symmetrical window function and has high ability of anti-noise.

A Phase Difference Correcting Method on Discrete Spectrum Adapting to Any Window Function

This paper presented the problem of wrong choice of spectral bins in the energy-based frequency estimation method under intensive noise, and studied its impact on the frequency estimation. Based on the theory of energy-based method, the causes for wrong location of spectral bins in the traditional estimation method were analyzed. In order to reduce wrong choice rate of spectral bins, two optimizational location strategies of spectral bins were introduced, and the effects of them were confirmed by computer simulation. A numerical test under intensive noise was carried out, in which estimation errors returned by optimizational spectral location strategies were compared. It was demonstrated that the estimation accuracy under intensive noise can be remarkably improved by using optimizational spectral location strategies. In particular, Macleod’s optimizational strategy is strongly suggested because of its prominent advantage in reducing occurrences of wrong location as well as its best performance in frequenc...

Research on choices of spectral bins in energy-based frequency estimators under intensive noise:

Classic windows have constant time delay and linear phase because of the symmetry and the time shift causality-imposed in the time domain. And thus, all such windows have the same spectral phase response. Removal of the symmetry constraint on a classic window can result in a variable phase response and in an alterable time delay. In essence the time delay becomes shorter will bring about a lot of benefits in speech coding. Some asymmetric windows with better magnitude response also can lead to a better recognition performance if the result is relatively insensitive to phase distortion. However, it is surprising that so little attention has been paid to the asymmetric windows in past literature; and never in past history has this issue been systematically or comprehensively studied. As a result, several methods to obtain the asymmetric windows are being presented in this paper. The asymmetric windows are displayed and compared with the classic windows, concerning both in time and frequency domains. Some ne...

Asymmetric Windows and their Application in Frequency Estimation

The study of harmonics signal analysis in electric power system is a classic and important research subject. The signal by using traditional Fourier transform methods are nearly truncated by constant coefficient symmetry window or asymmetric window. This paper propose the improved continuously adjustable asymmetric window for precise harmonic parameters measurement and the uniform formulas for calculating the parameters of harmonics and interharmonic is obtained by the asymmetric window-based phase difference correction method. The major advantages of this method is easy to implement and independent of window spectrum. The simulation analysis results proves that there is obvious high precision, effectiveness and universal applicability of this method.

Xinyi Li

Papers

Asymmetric Windows and their Application in Frequency Estimation

Application of the phase difference correct method in rolling bearing fault diagnosis

Power Harmonic Analysis Based on Continuously Adjustable Asymmetric Window