基于多隐层小波卷积极限学习神经网络的滚动轴承故障识别

Fault identification of rolling bearing based on multi hidden layers wavelet convolution extreme learning neural network

  • 摘要: 煤矿旋转机械工作环境恶劣,实际采集到的滚动轴承振动信号呈现出明显的非线性和非平稳性,导致轴承故障特征提取较困难。传统的基于“人工特征提取+模式识别”的滚动轴承故障识别方法受主观影响大。针对上述问题,提出了一种基于多隐层小波卷积极限学习神经网络(MHLWCELNN)的滚动轴承故障识别方法。该方法综合了一维卷积神经网络、自动编码器、极限学习机和小波函数的优势:利用一维卷积神经网络的局部连接和权值共享机制,大大减少了需要学习的参数;通过自动编码器使算法适用于轴承振动信号无标签样本;通过极限学习机确定输出权重,避免陷入局部最优,提高训练速度;采用小波函数作为激活函数,提高对轴承时域和频域信号的分辨率,从而提高故障识别率。实验结果表明:与同类方法相比,MHLWCELNN具有更高的识别准确率和更小的标准差,能较为稳定地识别出滚动轴承的不同故障类型;MHLWCELNN的F1值高于同类方法,验证了其对不平衡数据集的有效性;高斯小波在时域、频域均有较高的分辨率,适合作为激活函数;训练集样本占比设置为80%较合适。

     

    Abstract: The working environment of coal mine rotating machinery is harsh, and the actual collected rolling bearing vibration signals show the characteristics of obvious nonlinearity and non-stationarity. Therefore, it is difficult to extract bearing fault characteristics. The traditional rolling bearing fault identification method based on ‘manual characteristic extraction+pattern identification’ is influenced subjectively. In order to solve the above problems, a rolling bearing fault identification method based on multi hidden layers wavelet convolution extreme learning neural network (MHLWCELNN) is proposed. The method combines the advantages of 1D convolution neural network, auto-encoder, extreme learning machine and wavelet function. The local connection and weight sharing mechanism of 1D convolution neural network is used to reduce the parameters to be learned greatly. The auto-encoder makes the algorithm applicable to the unlabeled samples of bearing vibration signals. The extreme learning machine is applied to determine the output weight so as to avoid falling into local optimum and improve the training speed. The wavelet function is used as the activation function to improve the resolution of the bearing time and frequency domain signals, thus improving the fault identification rate. The experimental results show that compared with similar methods, MHLWCELNN has higher identification accuracy and smaller standard deviation, and can identify different fault types of rolling bearings more stably. The F1 value of MHLWCELNN is higher than that of similar methods, which verifies its effectiveness on unbalanced data sets. Gaussian wavelet has higher resolution in both time and frequency domains, and is suitable to act as an activation function. And it is more appropriate to set the proportion of training set as 80%.

     

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