基于VAE-GAN数据增强算法的小样本滚动轴承故障分类方法

VAE-GAN Data Enhancement Networks-based Model for Rolling Bearing Few-shot Fault Classification

  • 摘要: 近些年,数据增强算法被广泛应用于小样本故障分类中。然而,传统的数据增强模型在训练中经常出现梯度爆炸、梯度消失等问题,这在一定程度上限制了其在滚动轴承故障分类上的应用。为了解决上述问题,提出了一种新的模型框架。该模型首先将滚动轴承的原始一维振动数据通过连续小波变换(CWT)转换为二维图像,然后利用变分自动编码生成式对抗网络(VAE-GAN)对图像数据做样本增强,最后利用生成图片和原图片共同训练一个卷积神经网络(CNN)故障分类器。使用凯斯西储大学实验室的公开数据集对所提出的方法进行了验证。实验结果表明,与其他模型相比,所提出的模型具有更优越的性能。

     

    Abstract: At present, the rolling bearing fault diagnosis method in the nuclear power industry is mainly based on inspection and human analysis and judgment, and the effective sample data of bearing fault in the actual industrial process is relatively scarce, which limits the application of data-based intelligent models such as deep learning. Therefore, in the nuclear industry, the research on few-shot fault diagnosis is of great significance. In recent years, data augmentation algorithms have been widely used in small sample fault classification and achieved good results. However, the traditional data augmentation model often has problems such as gradient explosion and gradient disappearance during training, resulting in poor image quality and low fault diagnosis accuracy, which limits its application in rolling bearing fault classification to a certain extent. To address above issues, a new model framework was proposed. The model first converted the original onedimensional vibration data of the rolling bearing into a two-dimensional image through continuous wavelet transform (CWT). Then the variational autoencoder-generative adversarial network (VAE-GAN) was uesd to do sample enhancement. Finally, the generated image and the original image were used to jointly train a convolutional neural network (CNN) fault classifier. By introducing the CWT method, the one-dimensional time-frequency image is converted into a two-dimensional image, which can not only give full play to the powerful feature representation ability of convolutional neural networks, but also enable the classification network to better extract data features, and can also directly observe when the data is generated. The quality of generated images facilitates the improvement of network models. The introduction of VAE-GAN greatly improves the stability, diversity, and clarity of the images generated by the entire model compared with traditional data enhancement methods. And the using of the convolutional autoencoder makes it work better at image generation. The proposed method is validated using a publicly available dataset from the Laboratory of Case Western Reserve University. When using 80 original pictures to train the classifier, the classification accuracy rate of the classifier for 1 200 test samples after training is 81.2%. When using 800 generated pictures to train the classifier, the classification accuracy rate can reach 94.9%. When 80 original pictures and 800 generated pictures are mixed together to train the classifier, the classification accuracy of the classifier on 1 200 test samples can reach 99.0% after the training is completed. Experimental results show that the proposed model can effectively complete the rolling bearing fault diagnosis task in the case of few-shot problems. In addition, ablation experiments were carried out, and the results show that when any module in CWT, VAE-GAN, and CNN is removed, the performance of the model decreases to a certain extent, indicating that each proposed module is helpful to improve the fault diagnosis rate.

     

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