基于EMD自适应阈值的铡草机振动信号去噪  

Denoising of vibration signal of chaff cutters based on EMD adaptive threshold

作　　者：王晓蓉[1] 王海超 王春光[1] WANG Xiaorong;WANG Haichao;WANG Chunguang(College of Mechanical and Electrical Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China;College of Energy and Transportation Engineering.Inner Mongolia Agricultural University,Hohhot 010018,China)

机构地区：[1]内蒙古农业大学机电工程学院,呼和浩特010018 [2]内蒙古农业大学能源与交通工程学院,呼和浩特010018

出　　处：《中国农业大学学报》2021年第1期99-106,共8页Journal of China Agricultural University

基　　金：国家自然科学基金项目(50865005);国家重点研发计划重点专项(2016YFD0701704)。

摘　　要：针对铡草机振动信号噪声污染的问题,采用EMD(Empirical mode decomposition)与基于SURE(Stein’s unbiased risk estimate)的自适应阈值算法,并利用自相关函数性质与二阶可导阈值函数,对铡草机振动信号进行研究。结果表明:(1)模拟信号经EMD自适应阈值去噪后,信噪比SNR(Signal to-noise ratio)提高了15~19dB;经小波阈值去噪后,SNR提高了9~13dB;经EMD低通去噪后,SNR提高了5~11dB;经EMD阈值去噪后,SNR提高了12~15dB。(2)铡草机振动信号经EMD自适应阈值算法去噪后,>200 Hz的高频信号均消除,并且保留了≤200Hz低频信号的幅值;经小波阈值去噪后,振动信号>200Hz的高频信号未能消除;经EMD低通与EMD阈值去噪后,振动信号≤200Hz低频信号幅值降低,导致部分信号失真。本研究提出的EMD自适应阈值算法可一定程度上降低铡草机振动信号噪声。Aiming at the problem of noise pollution from the vibration signal of the chaff cutter,the vibration signals of chaff cutter was analyzed by using EMD(Empirical mode decomposition)and adaptive threshold algorithm based on SURE(Stein’sunbiased risk estimate).The nature of the auto correlation function and the second-order derivative threshold function were also adopted.The results showed that:(1)The analog signal was denoised by the EMD adaptive threshold,the SNR(Signal to-noise ratio)was increased by 15-19 dB;After denoising through the wavelet threshold,The SNR was increased by 9-13 dB;After denoising BY the EMD,the SNR was increased 5-11 dB;After denoising with the EMD threshold,the SNR was increased by 12-15 dB.(2)After denoising the vibration signal of the chaff cutters by the EMD adaptive threshold algorithm,the high-frequency signal>200 Hz was eliminated,and the amplitude of the low-frequency signal≤200 Hz was retained;After the denoising by the wavelet threshold,the vibration signal with >200 Hz was not eliminated;After denoising with EMD low-pass and EMD threshold,the amplitude of the low-frequency signal of vibration signal≤200 Hz was reduced,resulting in partial signal distortion.In summary,the EMD adaptive threshold algorithm proposed in this study is not only versatile,but also can achieve noise reduction function on the vibration signal of the hay machine.

关 键 词：铡草机 振动信号 信号去噪 EMD 自适应阈值 

分 类 号：S229.1[农业科学—农业机械化工程]