轴承智能故障诊断

Bearing intelligent fault diagnosis

轴承振动信号作为一种时间序列数据,其时间维度特征在分类中起着关键作用,单独使用卷积神经网络(CNN)进行轴承故障诊断会造成时间维度信息的丢失,导致诊断精度下降。针对上述问题,提出了一种结合一维CNN、双向门控循环单元(Bi GRU)和注意力机制的轴承故障诊断模型。首先利用CNN自适应提取一维振动信号局部空间特征;然后将该特征信息作为Bi GRU的输入,利用Bi GRU将提取的特征信息进行时间维度的融合,并引入注意力机制对多个时刻的特征信息进行加权,提取出更关键的故障特征;最后将故障特征输入全连接层得到分类结果,实现轴承智能故障诊断。实验结果表明:①在测试集混淆矩阵上,轴承运行状态基本分类正确,只有部分标记类型没有被完全分类正确,但是召回率达到了95%以上,总的故障识别准确率为99.3%。②利用t-SNE技术对降维处理后的数据进行可视化,轴承各运行状态的数据很好地聚集在各自的空间内,只有少量数据被混杂到其他区域,说明该模型具有较强的特征提取能力。③在恒定负载情况下,该模型故障诊断准确率较一维CNN、Bi GRU和注意力CNN等模型的平均准确率分别提高了0.8%、0.6%和0.3%。④在变负载情况下,与SVM(支持向量机)、一维CNN、Bi GRU和注意力CNN等模型相比,该模型具有更好的稳定性,当负载为2.25 kW时,准确率达85%以上。该模型既具有一维CNN局部特征提取能力,又具有Bi GRU时间依赖信息的建模能力,能够在获取轴承信号局部复杂特征后进一步融入特征之间的时间维度信息,同时注意力机制能进一步关注与故障更相关特征,因此具有较好的精度。

Bearing vibration signal is a kind of time series data, and its time dimension characteristic plays a key role in classification. Using convolutional neural network(CNN) alone to diagnose bearing fault will cause the loss of time dimension information. This results in the decline of diagnosis accuracy. To solve the above problems, a bearing fault diagnosis model combining one-dimensional CNN, bidirectional gated recurrent unit(BiGRU) and attention mechanism is proposed.Firstly,CNN is used to adaptively extract the local space characteristic of one-dimensional vibration signals.Secondly,the characteristic information is taken as the input of the Bi GRU.Bi GRU is used to perform time dimension fusion on the extracted characteristic information.The attention mechanism is introduced to weigh the characteristic information of a plurality of moments so as to extract a more critical fault characteristic.Finally,the fault characteristic is input into a full connection layer to obtain a classification result,so as to realize intelligent fault diagnosis of the bearing.The experimental result shows the following points.① On the confusion matrix of the test set,the classification of the bear running state is basically correct.Only some mark types are not completely classified correctly.But the recall rate is more than95%,and the total fault recognition accuracy rate is 99.3%.② The t-SNE technology is used to visualize the data after dimensionality reduction processing.The data of each running state of the bearing are well gathered in their own space.Only a small amount of data are mixed into other areas,which shows that the model has strong characteristic extraction capability.③ Under the condition of constant load,the average accuracy of fault diagnosis of this model is 0.8%,0.6%and 0.3%higher than that of one-dimensional CNN,Bi GRU and attention CNN models respectively.④ Under the condition of variable load,this model has better stability than SVM,onedimensional CNN,Bi GRU,attention CNN and other models.When the load is 2.25 k W,the accuracy rate is more than 85%.The model has the capability to extract one-dimensional CNN local characteristics and the capability to model Bi GRU time-dependent information.The model can further fuse time dimension information among the characteristics after acquiring the bear signal local complex characteristics.And the attention mechanism can further pay attention to the characteristics more relevant to faults.Therefore,the model has better precision.