基于FFT-SDAE的地铁牵引电机轴承故障智能诊断

针对地铁牵引电机轴承故障诊断中因工况复杂影响人工提取特征效果的问题,提出了一种基于快速傅里叶变换(Fast Fourier Transform,FFT)和堆叠降噪自编码器(Stacked Denoising Auto Encoder,SDAE) (FFT-SDAE)的地铁牵引电机轴承故障智能诊断方法.首先,使用大量无标签数据预训练深度自编码器的特征提取能力,自适应提取轴承故障特征;然后,通过小样本有标签数据微调网络学习分类性能,搭建地铁牵引电机轴承的FFT-SDAE网络模型;最后,通过试验研究FFT-SDAE网络结构对轴承故障诊断准确率的影响,选取最佳网络参数.试验结果表明,在变转速和变载荷的情况下,所提方法可以很好地提取故障的深层特征,在使用工况较复杂的数据集时,所提方法的诊断准确率优于传统的故障诊断方法.     

基于小波卷积自编码器和LSTM网络的轴承故障诊断研究

针对传统滚动轴承故障诊断方法过度依赖专家经验和故障特征提取困难的问题,结合深层神经网络处理高维、非线性数据的优势,提出了一种基于深层小波卷积自编码器(DWCAE)和长短时记忆网络(LSTM)的轴承故障诊断方法。首先构造了小波卷积自编码器(WCAE),改进了其损失函数,并加入了收缩项限制防止网络过拟合;其次将多个WCAE堆叠构成DWCAE,利用大量无标签样本对DWCAE进行了无监督预训练,挖掘出更有利于故障诊断的深层特征;最后利用深层特征训练LSTM网络,从而建立了诊断模型。仿真信号和实验数据分析结果表明:该方法能有效地对轴承进行多种故障类型和多种故障程度的识别,特征提取能力和识别能力优于人工神经网络、支持向量机等传统方法及深度信念网络、深层自编码器等深度学习方法。     

基于深度一维残差卷积自编码网络的齿轮箱故障诊断

一维振动信号常常被用于齿轮箱的监测与故障诊断中,使得能及时地对齿轮箱维护以减少损失。因此,从一维振动信号中提取出关键故障特征决定了故障诊断模型的准确性与可靠性。典型的深度神经网络(deep neural network, DNN),如卷积神经网络已经在故障诊断中表现出良好的性能并得到了广泛的应用,但其监督式训练方式往往需要大量的标签数据而限制了其可应用性。因此,提出一种新的深度神经网络模型,一维残差卷积自编码器(1-dimension residual convolutional auto-encoder,1DRCAE),成功应用于振动信号的无监督学习及故障特征提取,显著提高了齿轮箱的故障诊断率。首先,提出了一维卷积层与自编码器的有效集成方法,形成了深度一维卷积自编码器;其次,引入残差学习机制训练一维卷积自编码器,实现对一维振动信号有效地特征提取;最后,基于编码器提取的特征,使用少量标签数据进行分类微调实现齿轮箱故障模式识别。通过齿轮箱试验台采集的传感器数据进行实验验证表明,这种无监督学习方法具有良好的去噪能力和故障特征提取能力,其特征提取效果好于典型的深度神经网络,如深度置信网络(Deepbeliefnetwork,DBN)和堆叠自编码网络(Stackedauto-encoders,SAE),同时故障诊断效果也优于一维卷积神经网络(1-dimension convolutional neural network, 1DCNN)。     

基于SSDAE深度神经网络的钛板电涡流检测图像分类研究

钛板电涡流成像检测易受工业现场中的噪声影响,包含噪声的检测图像往往难以提取较好的特征,从而影响分类识别精度。针对以上问题,提出了一种基于栈式稀疏降噪自编码(SSDAE)深度神经网络的钛板缺陷电涡流检测图像分类方法。将稀疏性限制引入降噪自编码器并进行逐层无监督自学习,然后将自编码器栈式组合后添加逻辑识别(LR)层,构建出SSDAE深度神经网络,网络在有监督微调后可实现钛板缺陷电涡流图像特征自动提取与分类识别。稀疏性限制的引入提高了特征学习能力,降噪自编码器的栈式组合提高了深度网络的鲁棒性。实验结果表明,相比其他常规方法,所提出方法不仅在理想环境下有更高的分类准确率,且该方法能有效抵抗噪声,在复杂工况下能更有效地对钛板缺陷进行分类识别。     

基于深度强化学习的旋转机械故障诊断策略

由于传统深度学习方法无法挖掘原始振动数据与旋转机械状态之间的非线性映射关系,提出了一种基于堆叠式自动编码器与深度Q网络相结合的深度强化学习旋转机械故障诊断方法.首先建立故障诊断"博弈"模型,该博弈模型可以为故障诊断代理提供观察、行动和获得奖励的交互式环境.然后,堆叠式自动编码器采用完全连接模型进行逐级的内在特征学习从而构建了故障诊断代理,然后通过引入记忆回放和迭代更新策略以及奖励反馈机制,使得深度Q网络实现了原始振动信号与故障模式之间的非线性映射关系.最后通过实验证明了提出方法的有效性与可行性.     

压缩感知和改进深层小波网络在轴承故障诊断中的应用

针对传统滚动轴承故障诊断方法过度依赖专家经验和故障特征提取困难的问题,提出一种基于压缩感知(Compressive Sensing,CS)和改进深层小波神经网络(Deep Wavelet Neural Network,DWNN)方法。首先对采集到的轴承振动信号进行CS降噪并压缩采样;其次设计改进小波自编码器(Wavelet Auto-Encoder,WAE)进而构造DWNN,并引入"跨层"连接缓解网络的梯度消失现象;最后利用大量无标签轴承压缩数据对DWNN进行无监督预训练并利用少量带标签数据对网络有监督微调,进而实现故障判别。实验结果表明提出方法能够有效地对轴承进行多种故障类型和多种故障程度的识别,受先验知识和主观影响较小,避免了复杂的人工特征提取过程,特征提取能力和识别能力优于人工神经网络、深度信念网络、深度稀疏自编码器等模型。     

基于改进堆叠稀疏降噪自编码器的轴承故障诊断

为提高堆叠稀疏降噪自编码器的性能,解决其计算复杂度高、收敛速度慢等问题,提出了一种基于堆叠边缘化稀疏降噪自编码器的滚动轴承故障诊断方法。首先,对稀疏降噪自编码器的损失函数进行边缘化处理,并结合逐层贪婪训练策略构建出SMSDAE网络;然后,将SMSDAE网络与Softmax分类器结合,得到SMSDAE-Softmax特征提取模型;最后,将提取到的特征输入到SVM多分类器中完成对滚动轴承的智能故障诊断。QPZZ-Ⅱ旋转机械故障模拟试验平台所得故障信号的处理结果表明,该方法的平均故障诊断率达到了99.9%,相对于其他方法具备更快的收敛速度,更好的诊断效果,以及更强的鲁棒性。另外,采用美国西储大学轴承数据中心10种轴承故障信号进行分析,结果证明了该方法在面对不同类型轴承以及多种故障信号时具备良好的诊断性能,有一定的普适性。     

基于深度自编码网络的航空发动机故障诊断

为有效解决航空发动机的故障诊断难题,提出了基于深度自编码网络的航空发动机故障诊断方法,对发动机进行故障诊断技术研究。首先,对监测数据进行预处理,根据数据特征构建深度自编码网络的基本结构,采用无标签数据样本集对深度自编码网络进行预先训练,得到网络参数的初始值;其次,利用有标签的数据样本集对该网络进行训练,对网络参数进行微量调整,创建基于深度自编码神经网络的航空发动机故障诊断模型;最后,采用含有标签的测试样本集对创建的故障诊断模型进行诊断测试。为了表明所提出方法的优越性,将本研究方法与其他几种常用故障诊断方法的故障诊断结果进行了对比。结果表明,与反向传播神经网络、径向基神经网络等常用的故障诊断方法相比,所提出方法的诊断正确率更高,诊断效果更好。     

基于拉普拉斯小波滤波和SA-DS-CNN的滚动轴承故障诊断

针对基于深度学习模型的滚动轴承故障诊断方法易受环境噪声干扰的问题,提出了一种基于拉普拉斯小波滤波(LWF)和自注意力机制-动态选择-卷积神经网络(SA-DS-CNN)的滚动轴承故障诊断模型。首先,提出一种拉普拉斯小波阻尼参数自适应选取策略,使用拉普拉斯小波对采集的滚动轴承振动信号进行相关滤波并进行功率谱变换;其次,基于卷积神经网络框架,引入自注意力机制和动态选择机制,构造SA-DS-CNN;最后,利用SA-DS-CNN提取功率谱特征,根据轴承的不同故障状态定位相关特征信息,实现故障特征的提取和诊断。对N205EM圆柱滚子轴承的故障诊断试验表明：LWF降噪效果较好,能为SA-DS-CNN模型提供优秀的训练样本;SA-DS-CNN模型能抑制无用通道信息,增强网络特征学习能力;LWF和SA-DS-CNN组合模型的故障诊断准确率达到99.65%,优于其他组合模型。     

基于改进集成多隐层小波极限学习神经网络的滚动轴承故障识别研究

由于强噪声和非线性、非平稳性等特性,导致滚动轴承振动信号存在难以提取和其工况状态难以辨识的问题,对此提出了一种基于改进集成多隐层小波极限学习神经网络的滚动轴承故障识别模型。首先,使用了谱分割小波变换,将采集到的滚动轴承振动信号分解为若干本征模态分量;然后,选择了较能反映轴承运行工况特征的模态分量,并加以了重构;最后,利用了不同小波函数设计了不同的多隐层小波极限学习神经网络,并加入了卷积机制,将重构后的信号输入不同的深层网络,进行了特征学习与故障识别,利用集成方法得到了最后的滚动轴承故障识别结果。研究结果表明:提出方法的平均故障识别准确率达到99.42%,标准差仅为0.11;该方法自动特征提取能力和工况识别能力优于深度稀疏自动编码器、深度降噪自动编码器和深度信念网络等深度学习方法,适用于滚动轴承故障的自动识别。     

An Intelligent Fault Diagnosis Method of Multi-Scale Deep Feature Fusion Based on Information Entropy

For a single-structure deep learning fault diagnosis model,its disadvantages are an insufficient feature extraction and weak fault classification capability.This paper proposes a multi-scale deep feature fusion intelligent fault diagnosis method based on information entropy.First,a normal autoencoder,denoising autoencoder,sparse autoencoder,and contractive autoencoder are used in parallel to construct a multi-scale deep neural network feature extrac-tion structure.A deep feature fusion strategy based on information entropy is proposed to obtain low-dimensional features and ensure the robustness of the model and the quality of deep features.Finally,the advantage of the deep belief network probability model is used as the fault classifier to identify the faults.The effectiveness of the proposed method was verified by a gearbox test-bed.Experimental results show that,compared with traditional and existing intelligent fault diagnosis methods,the proposed method can obtain representative information and features from the raw data with higher classification accuracy.     

A fault diagnosis scheme for rotating machinery using hierarchical symbolic analysis and convolutional neural network

Fault diagnosis of rotating machinery is crucial to improve safety, enhance reliability and reduce maintenance cost. The manual feature extraction and selection of traditional fault diagnosis methods depend on signal processing skills and expert experience, which is labor-intensive and time-consuming. As a typical intelligent fault diagnosis method, the convolutional neural network automatically learns features from original data, but it is extremely difficult to design and train a deep network architecture. This paper proposes a fault diagnosis scheme combined of hierarchical symbolic analysis (HSA) and convolutional neural network (CNN), which achieves laborsaving and timesaving preliminary feature extraction and accomplishes automatically feature learning with simplified network architecture. Firstly, hierarchical symbolic analysis is employed to extract features from original signals. The extracted features are able to identify different health conditions under various operating conditions. Then, convolutional neural network instead of human labor is used to learn the complex non-linear relationship between features and health conditions automatically. The architecture of CNN diagnosis model is simple and convenient to implement. Finally, a centrifugal pump dataset and a motor bearing dataset are adopted to validate the effectiveness of the proposed method. The diagnosis results show that the proposed method exhibits superior performance compared with shallow methods and deep learning methods.     

A Deep Learning Approach for Fault Diagnosis of Induction Motors in Manufacturing

Extracting features from original signals is a key procedure for traditional fault diagnosis of induction motors, as it directly influences the performance of fault recognition. However, high quality features need expert knowledge and human intervention. In this paper, a deep learning approach based on deep belief networks (DBN) is developed to learn features from frequency distribution of vibration signals with the purpose of characterizing working status of induction motors. It combines feature extraction procedure with classification task together to achieve automated and intelligent fault diagnosis. The DBN model is built by stacking multiple-units of restricted Boltzmann machine (RBM), and is trained using layer-by-layer pre-training algorithm. Compared with traditional diagnostic approaches where feature extraction is needed, the presented approach has the ability of learning hierarchical representations, which are suitable for fault classification, directly from frequency distribution of the measurement data. The structure of the DBN model is investigated as the scale and depth of the DBN architecture directly affect its classification performance. Experimental study conducted on a machine fault simulator verifies the effectiveness of the deep learning approach for fault diagnosis of induction motors. This research proposes an intelligent diagnosis method for induction motor which utilizes deep learning model to automatically learn features from sensor data and realize working status recognition.     

一种面向旋转机械的基于 Transformer 特征提取的域自适应故障诊断

针对基于深度学习的旋转机械故障诊断方法在新工作条件下缺乏标注数据、跨域诊断精度较低的问题,提出了一种基 于 Transformer 的域自适应故障诊断方法。 采用 Transformer 的变体 VOLO 构造特征提取器以获取细粒度更佳的故障特征表示。 利用源域数据进行监督学习对源域和目标域数据的特征提取器进行预训练,并且冻结源域提取器参数以获取固定的源域特征。 利用域对抗自适应策略和局部最大平均差异结合目标域未标注数据训练目标域特征提取器,实现源域特征与目标域特征的边 缘分布、条件分布对齐。 通过两个多工况实验对所提出的故障诊断算法进行了验证,结果表明提出的基于 Transformer 特征提 取的域自适应故障诊断方法相比 5 种传统域自适应方法,在齿轮和轴承数据集上分别平均提升了 22. 15% 和 11. 67% 的诊断精 度,证明所提出方法对于跨域诊断精度具有提升作用。     

A multi-step progressive fault diagnosis method for rolling element bearing based on energy entropy theory and hybrid ensemble auto-encoder

It is meaningful to efficiently identify the health status of bearing and automatically learn the effective features from the original vibration signals. In this paper, a multi-step progressive method based on energy entropy (EE) theory and hybrid ensemble auto-encoder (HEAE), systematically blending the statistical analysis approach with the deep learning technology, is proposed for rolling element bearing (REB) fault diagnosis. Firstly, a preliminary detection about the REB health status is performed by the statistical analysis technique integrated with the EE theory. Secondly, if fault exists in REB, a new HEAE is constructed based on denoising auto-encoder and contractive auto-encoder to strengthen the feature learning ability and automatically extract the deep state features from the raw data. Subsequently, a modified t-distributed stochastic neighbor embedding (M-tSNE) algorithm is developed to achieve the features reduction to further improve the diagnosis efficiency. Finally, the low-dimensional representations after features reduction are as the inputs of softmax classifier to recognize the fault conditions. The proposed method is applied to the fault diagnosis of REB. The results confirm the effectiveness and superiority of the proposed method, and it is more suitable for the actual engineering applications compared with other existing methods.     

基于随机投影和NB网络的模拟电路故障诊断

针对模拟电路故障诊断中故障类型复杂多样、典型故障信息难以获取以及易受噪声、温度等环境影响的难题,提出一种基于随机投影和朴素贝叶斯网络的模拟电路故障诊断方法。该方法首先提取模拟电路故障信息,并利用随机投影算法降维后获取模拟电路故障特征向量,然后通过朴素贝叶斯分类器诊断模型识别模拟电路各个故障。通过对CSTV滤波器电路、四运放双二次高通滤波器电路和实际Sallen-Key带通滤波器电路的实验结果分析表明,相对于传统的模拟电路故障诊断方法,该方法表现出更优的故障诊断性能,并具有更强的抗干扰能力。     

Connected Components-based Colour Image Representations of Vibrations for a Two-stage Fault Diagnosis of Roller Bearings Using Convolutional Neural Networks

Roller bearing failure is one of the most common faults in rotating machines.Various techniques for bearing fault diagnosis based on faults feature extraction have been proposed.But feature extraction from fault signals requires expert prior information and human labour.Recently,deep learning algorithms have been applied extensively in the condition monitoring of rotating machines to learn features automatically from the input data.Given its robust per-formance in image recognition,the convolutional neural network(CNN)architecture has been widely used to learn automatically discriminative features from vibration images and classify health conditions.This paper proposes and evaluates a two-stage method RGBVI-CNN for roller bearings fault diagnosis.The first stage in the proposed method is to generate the RGB vibration images(RGBVIs)from the input vibration signals.To begin this process,first,the 1-D vibration signals were converted to 2-D grayscale vibration Images.Once the conversion was completed,the regions of interest(ROI)were found in the converted 2-D grayscale vibration images.Finally,to produce vibration images with more discriminative characteristics,an algorithm was applied to the 2-D grayscale vibration images to produce connected components-based RGB vibration images(RGBVIs)with sets of colours and texture features.In the second stage,with these RGBVIs a CNN-based architecture was employed to learn automatically features from the RGBVIs and to classify bearing health conditions.Two cases of fault classification of rolling element bearings are used to validate the proposed method.Experimental results of this investigation demonstrate that RGBVI-CNN can generate advan-tageous health condition features from bearing vibration signals and classify the health conditions under different working loads with high accuracy.Moreover,several classification models trained using RGBVI-CNN offered high performance in the testing results of the overall classification accuracy,precision,recall,and F-score.     

时频分析和深度学习相结合的滚动轴承故障诊断

滚动轴承大量使用在旋转机械中,轴承的工况严重影响着机械设备的正常运行。为了提高轴承故障的诊断精度,本文提出了一种时频分析和深度学习相结合的滚动轴承诊断方法。首先,分析了十种不同时频分析方法;其次,建立了深度学习的滚动轴承故障诊断模型,并利用迁移学习克服训练样本数量少的问题,通过对比分析,常数Q变换(Constant Q transform, CQT)的准确率可达100%;最后,利用实验数据对所提方法的有效性和可靠性进行验证,分别评估了在不同负载和噪声情况下的识别精度,并与文献中的方法对比,证明所提方法在不同工作环境条件下都有较好的鲁棒性和较高的识别精度。     

基于深度学习理论的机械装备大数据健康监测方法

机械装备正在朝着高速、高精、高效方向发展,为了确保这些装备的健康运行,健康监测系统采集了海量数据来反映机械的健康状况,促使机械健康监测领域进入了“大数据”时代。机械大数据具有大容量、多样性与高速率的特点,研究和利用先进的理论与方法,从机械装备大数据中挖掘信息,高效、准确地识别装备的健康状况,成为机械装备健康监测领域面临的新问题。深度学习理论作为模式识别和机器学习领域最新的研究成果,以强大的建模和表征能力在图像和语音处理等领域的大数据处理方面取得了丰硕的成果。结合机械大数据的特点与深度学习的优势,提出了一种新的机械装备健康监测方法。该方法通过深度学习利用机械频域信号训练深度神经网络,其优势在于能够摆脱对大量信号处理技术与诊断经验的依赖,完成故障特征的自适应提取与健康状况的智能诊断,因此克服了传统智能诊断方法的两大缺陷：需要掌握大量的信号处理技术结合丰富的工程实践经验来提取故障特征;使用浅层模型难以表征大数据情况下信号与健康状况之间复杂的映射关系。试验结果表明,该方法实现了多种工况、大量样本下多级齿轮传动系统不同故障位置不同故障类型的故障特征自适应提取与健康状况准确识别。     

Weighted sparsity-based denoising for extracting incipient fault in rolling bearing

Given that the incipient fault is too weak for extraction, a novel approach that is based on sparse optimization is proposed for incipient fault diagnosis. The proposed optimization method consists of three steps: First, autocorrelation analysis is utilized to filter broadband random noise. Then, the weighted sparsity-based denoising method is proposed to extract periodic impulses. The prior knowledge that periodic impulses are sparse is used to constitute a penalty term; thus a novel weighted sparse optimization model is established. The majorization-minimization method is used to solve the optimization model. The high-pass filter in quadratic fidelity term is constructed by a Butterworth filter based on banded matrices, thus effectively improving computational efficiency. Lastly, the interval of periodic impulses, which corresponds to the fault frequency of rolling bearing, is obtained. Moreover, simulation and experimental results show that the proposed approach can successfully extract fault features from the signals of low signal to noise ratio.