基于改进VMD的岩石声发射信号去噪方法

Denoising method of rock acoustic emission signal based on improved VMD

针对岩石声发射(AE)信号中包含的噪声分量难以有效滤除的问题,提出了一种变分模态分解(VMD)与样本熵(SE)相结合的AE信号去噪方法。首先,将含噪声的岩石声发射信号进行VMD分解,并获得一系列具有不同中心频率的固有模态函数(IMF);其次,计算各个IMF分量的样本熵,将其大于设定阈值的IMF分量视为噪声分量剔除并保留最优分量;最后,对最优IMF分量进行重构,进而获得降噪后的AE信号。利用改进VMD去噪与EMD去噪、小波阈值去噪方法对含噪声的岩石声发射信号进行去噪对比分析,结果表明:EMD去噪方法对噪声的滤除效果并不理想;小波阈值去噪方法虽然可以滤除信号中的噪声分量,但去噪后的信号波形出现畸变;改进的VMD去噪方法能够更好地滤除岩石声发射信号中的噪声分量,该方法有助于提取信号的时频特征及信号识别。

Aiming at the problem that the noise components contained in rock acoustic emission( AE) signals are difficult to be filtered effectively,a denoising method based on variational mode decomposition( VMD) and sample entropy( SE)is proposed. Firstly,the acoustic emission signal of rock with noise is decomposed by VMD,and a series of intrinsic mode functions( IMF) with different center frequencies are obtained. Then,the sample entropy of each IMF component is calculated,and the IMF component is removed whose sample entropy is greater than the set threshold is regarded as the noise component,and the optimal component is retained. Finally,the optimal IMF component is reconstructed to obtain the denoising AE signal. The improved VMD denoising,EMD denoising and wavelet threshold denoising methods were used to analyze the denoising of rock acoustic emission signal with noise.The experimental results showed that the effect of EMD denoising was not ideal. Although the wavelet threshold denoising method could filter out the noise component in the signal,the signal waveform after denoising showed distortion. In contrast,the improved VMD denoising method proposed in this paper can better filter the noise components in the rock acoustic emission signal,which is helpful to extract the time-frequency characteristics of the signal and signal recognition.