基于EEMD-Treelet和高斯过程的起重机齿轮故障诊断

齿轮故障诊断对于起重机安全运行至关重要;提出了一种基于集成经验模态分解(ensemble empirical mode decomposition, EEMD)-Treelet变换和高斯过程(gaussian process, GP)的起重机齿轮振动故障诊断新方法;设计一种细菌觅食算法(bacterial foraging optimization, BFO)优化高斯过程模型超参数;建立基于集成经验模态分解-希尔伯特变换的齿轮振动参数信号特征提取方法,利用Treelet变换实现这些特征的降维学习;建立基于细菌觅食算法优化高斯过程的齿轮故障模型;实验结果表明,EEMD-Treelet-GP诊断方法不仅可以识别最佳特征向量,而且可以识别故障位置。     

基于PGAT模型的氧气顶吹转炉小样本故障诊断

针对现有的深度学习方法对小样本情况下的故障诊断精度不佳和图神经网络构造图的方式依赖其他算法的问题,提出一种图的构造方法,并基于该方法提出一种基于图注意力机制与先验知识库的PGAT(prior knowledge-graph attention network)模型.将有标签样本和无标签样本按照固定的方式连接在一起,通过引入图注意力机制计算出样本之间的相似程度,使得新加入的样本不依赖于图的拓扑结构,解决图卷积神经网络不易于扩展的问题.在基准数据集和氧气顶吹转炉数据集上的实验表明,在只有少量有效数据的条件下,所提模型相较于其他模型具有更好的故障诊断精度.     

基于TE-DS的半监督化工过程故障诊断方法

针对现有基于深度学习的化工过程故障诊断方法通常需要完备的标签数据才能构建故障诊断模型等局限,提出一种基于时间集成—双重学生模型(temporal ensembling-dual student, TE-DS)的半监督化工过程故障诊断方法。该方法首先以双重学生模型为基础,通过分类项约束、稳定性约束和一致性约束条件指导相互训练,有效地缓解了误差累积情况的发生;然后利用时间集成(temporal ensembling)将多个先前网络评估的预测集成作为一致性正则化对象,达到缓解预测值噪声、降低模型训练时间的目的,以提高分类性能,实现故障诊断;最后通过田纳西—伊斯曼(Tennessee-Eastman)化工过程基准数据进行故障诊断实验,验证提出方法的有效性和可行性,并与BNLSTM、DCNN和MCLSTM等有监督方法进行比较,证明了TE-DS算法对故障诊断的优越性。     

EEMD-GSSA-SVM滚动轴承故障诊断方法研究

针对现有滚动轴承故障诊断算法诊断准确度不高的问题,提出了一种基于集合经验模态分解(EEMD)以及全局麻雀群搜索算法(GSSA)优化支持向量机(SVM)的滚动轴承故障诊断方法.所提方法利用EMMD以及能量矩对原始信号进行模态分解与特征提取.为提高诊断精度,提出一种GSSA-SVM算法.首先提出一种对原始麻雀搜索算法(SS...     

小样本轴承故障诊断研究综述

随着数据时代的来临,基于数据驱动的轴承故障诊断方法表现出了优越的性能,但是此类方法依赖大量标记数据,而在实际生产过程中很难收集到大量的数据,因此小样本的轴承故障诊断具有很高的研究价值。对小样本条件下的轴承故障诊断方法进行了回顾,并将其分为两类：基于数据的方法和基于模型的方法。其中基于数据的方法是从数据角度对原始样本进行扩充;基于模型的方法是指利用模型优化特征提取或者提高分类精度等。总结了当前小样本条件下故障诊断方法的不足,并展望了小样本轴承故障诊断的未来。     

多模态引导的局部特征选择小样本学习方法

深度学习模型取得了令人瞩目的成绩,但其训练依赖于大量的标注样本,在标注样本匮乏的场景下模型表现不尽人意.针对这一问题,近年来以研究如何从少量样本快速学习的小样本学习被提了出来,方法主要采用元学习方式对模型进行训练,取得了不错的学习效果.但现有方法:1)通常仅基于样本的视觉特征来识别新类别,信息源较为单一; 2)元学习的使用使得模型从大量相似的小样本任务中学习通用的、可迁移的知识,不可避免地导致模型特征空间趋于一般化,存在样本特征表达不充分、不准确的问题.为解决上述问题,将预训练技术和多模态学习技术引入小样本学习过程,提出基于多模态引导的局部特征选择小样本学习方法.所提方法首先在包含大量样本的已知类别上进行模型预训练,旨在提升模型的特征表达能力;而后在元学习阶段,方法利用元学习对模型进行进一步优化,旨在提升模型的迁移能力或对小样本环境的适应能力,所提方法同时基于样本的视觉特征和文本特征进行局部特征选择来提升样本特征的表达能力,以避免元学习过程中模型特征表达能力的大幅下降;最后所提方法利用选择后的样本特征进行小样本学习.在MiniImageNet、CIFAR-FS和FC-100这3个基准数...     

半监督在线增量自学习异常检测方法研究

在深入分析现有基于监督学习和非监督学习方法的缺点后,提出了一个新颖的基于K-means与Markov模型相结合的半监督异常检测方法.半监督方法的学习样本包括已标示类别的样本和未标示样本,并且通过对已标示样本的学习来指导对未标示样本的学习来提高识别率.方法首先将经过标示的(正常的)系统调用序列投影到高维空间进行有监督聚类后,利用Markov模型来学习聚类间的时序关系,建立起正常行为的初始模型.由Markov模型产生的状态序列计算状态概率,根据状态序列概率来评价进程行为的异常情况.正常行为模型由2种关系确定:①空间分布关系(聚类);②空间的时序关系(Markov模型).在初始模型的导引下对未标示的序列进行学习,利用迭代过程对模型进行改进.实验表明,该算法能够在已标示样本较少的情况下通过对未标示样本的学习来改善模型的检测性能,达到在线增量学习的目的.     

基于内禀模态奇异值分解和支持向量机的故障诊断方法

提出了一种基于内禀模态(Intrinsic mode functions,简称IMFs)奇异值分解和支持向量机(Support vector machine,简称SVM)的故障诊断方法.采用经验模态分解(Empirical mode decomposition,简称EMD)方法对旋转机械故障振动信号进行分解,将得到的若干个内禀模态分量自动形成初始特征向量矩阵,然后对该矩阵进行奇异值分解,提取其奇异值作为故障特征向量,并进一步根据支持向量机分类器的输出结果来判断旋转机械的工作状态和故障类型.对齿轮振动信号的分析结果表明,即使在小样本情况下,基于内禀模态奇异值分解和支持向量机的故障诊断方法仍能有效地识别齿轮的工作状态和故障类型.     

运用模态融合的半监督广义零样本学习

映射域漂移和偏见性预测问题使得现有的方案无法很好地应对广义零样本学习挑战.在CADA-VAE模型的基础上,提出了基于模态融合的半监督学习方案,就如何利用未标注样本及语义辅助模型进行模态内自学习提供了一种思路.该方案使用潜层向量空间作为视觉和语义模态融合的桥梁,提出了视觉质心和异类语义潜层向量概念,用以指导模态间互学习;...     

基于深度迁移自编码器的变工况下滚动轴承故障诊断方法

在实际工业场景下的轴承故障诊断,存在轴承故障样本不足,训练样本与实际信号样本存在分布差异的问题;文章提出一种新的基于深度迁移自编码器的故障诊断方法FS-DTAE,应用于不同工况下的轴承故障诊断;该方法首先采用小波包变换进行信号处理与特征提取;其次,采用提出的基于朴素贝叶斯与域间差异的特征选取(FSBD)方法对统计特征进行评估,选取更有利于跨域故障诊断和迁移学习的特征;然后,利用源域特征数据训练深度自编码器,将训练得到的模型参数迁移至目标域,再利用目标域正常状态样本对深度迁移自编码器模型进行微调,微调后的模型用于目标域无标签特征数据的故障分类;最后,基于CWRU轴承故障数据开展不同工况下故障诊断实验,结果表明,所提出的FS-DTAE方法能够有效提高不同工况下的故障诊断准确率。     

基于网络结构搜索的工业过程自动故障诊断方法

针对现有基于深度神经网络的工业过程故障诊断方法存在网络结构设计烦琐及参数寻优耗时等问题,提出了一种基于网络结构搜索的工业过程自动故障诊断方法(automatic fault diagnosis, AutoFD),该方法采用AutoFD网络结构搜索算法,来自动完成卷积神经网络的网络结构设计和网络参数寻优。在此基础上,首先通过在原始数据上施加操作生成新通道;接着利用表现预测加速获取通道适应性排序的过程;然后依据通道适应性排序,通过表现预测来快速选取最优卷积通道数;最终根据最优卷积通道来搜索表现最优的多通道卷积神经网络模型用于工业过程自动故障诊断。采用田纳西—伊斯曼(Tennessee Eastman, TE)工业过程和数值系统对提出方法进行验证,结果表明该方法可以实现网络结构自动设计及网络参数的自动寻优,并且具有优良的故障诊断性能。     

面向旋转机械故障诊断的深度流形迁移学习

深度学习因强大的特征提取能力已逐渐成为旋转机械故障诊断的主要方法。但深层模型缺乏领域适应能力,工况变化时性能衰退严重。迁移学习为解决变工况诊断问题提供新的途径。然而现有深度迁移学习方法大多仅对齐不同领域分布的均值中心,未考虑特征分布的流形结构,其适配性能仍难以应对不同工况复杂的机械故障信号。针对该问题,提出一种深度流形迁移学习方法,以堆叠自编码器为框架,在无监督预训练阶段同时利用源域和目标域样本训练,充分挖掘数据本质特征;针对模型微调,提出流行迁移框架,在适配分布差异同时还保持领域间特征分布结构的一致性。将新方法与现有迁移学习方法在旋转机械故障诊断案例进行充分的比较实验,结果表明,新方法优于现有方法,能显著提高变工况故障诊断精度。通过有效性分析在机理上进一步证明了融合目标域数据的无监督预训练策略和流形迁移微调策略对提高变工况故障诊断的有效性。     

A novel fault diagnosis method based on CNN and LSTM and its application in fault diagnosis for complex systems

Fault diagnosis plays an important role in actual production activities. As large amounts of data can be collected efficiently and economically, data-driven methods based on deep learning have achieved remarkable results of fault diagnosis of complex systems due to their superiority in feature extraction. However, existing techniques rarely consider time delay of occurrence of faults, which affects the performance of fault diagnosis. In this paper, by synthetically considering feature extraction and time delay of occurrence of faults, we propose a novel fault diagnosis method that consists of two parts, namely, sliding window processing and CNN-LSTM model based on a combination of Convolutional Neural Network (CNN) and Long Short-Term Memory Network (LSTM). Firstly, samples obtained from multivariate time series by the sliding window processing integrates feature information and time delay information. Then, the obtained samples are fed into the proposed CNN-LSTM model including CNN layers and LSTM layers. The CNN layers perform feature learning without relying on prior knowledge. Time delay information is captured with the use of the LSTM layers. The fault diagnosis of the Tennessee Eastman chemical process is addressed, and it is verified that the predictive accuracy and noise sensitivity of fault diagnosis can be greatly improved when the proposed method is applied. Comparisons with five existing fault diagnosis methods show the superiority of the proposed method.

     

支持向量机在模拟电路故障诊断中的应用

故障诊断发展的瓶颈之一是故障样本的缺乏，而不仅在于诊断方法本身。支持向量机是建立在结构风险最小原则基础上，专门针对小样本情况的，其目标是得到现在信息下的最优值而不仅仅是样本数趋于无穷大时的最优值。它能在训练样本很少的情况下达到很好的分类效果，从而为故障诊断技术向智能化发展提供了新的途径。介绍了支持向量机的二值分类算法，以支持向量机二值分类为基础，构建了基于支持向量机的多值分类器并应用于模拟电路故障诊断。以两管视频放大器的多种故障分类为例，进行了实际应用验证。结果表明，该诊断方法具有算法简单、可对故障在线分类，有很好的分类能力和较高的计算效率，不需要对原始数据进行预处理就可达到满意的效果。     

A gray correlation based Bayesian network model for fault source diagnosis of multistage process – Small sample manufacturing system

Fault source diagnosis methodology is one of the key technologies of quality control and assurance for multi-source & multi-stage manufacturing processes, especially in small sample manufacturing systems. By analyzing the existing research on fault source diagnosis methods, a Bayesian network-based methodology is proposed. Gray correlation theory and mechanism analysis method are used in the process of Bayesian network model construction to reduce the dependence of sample data size for structure learning in the process of small sample manufacturing of complex products. In addition, two fault source diagnosis methods based on manufacturing principle analysis and reverse Bayesian network respectively are proposed. The strategy of the combined use of the two methods in the actual manufacturing scenes is given to cope with the fault source diagnosis scenario in the real manufacturing process. In the end, an example from an actual factory is provided to validate the effectiveness and efficiency of the proposed model and methodologies.     

Intelligent fault diagnosis for rotating machinery using deep Q-network based health state classification: A deep reinforcement learning approach

Fault diagnosis methods for rotating machinery have always been a hot research topic, and artificial intelligence-based approaches have attracted increasing attention from both researchers and engineers. Among those related studies and methods, artificial neural networks, especially deep learning-based methods, are widely used to extract fault features or classify fault features obtained by other signal processing techniques. Although such methods could solve the fault diagnosis problems of rotating machinery, there are still two deficiencies. (1) Unable to establish direct linear or non-linear mapping between raw data and the corresponding fault modes, the performance of such fault diagnosis methods highly depends on the quality of the extracted features. (2) The optimization of neural network architecture and parameters, especially for deep neural networks, requires considerable manual modification and expert experience, which limits the applicability and generalization of such methods. As a remarkable breakthrough in artificial intelligence, AlphaGo, a representative achievement of deep reinforcement learning, provides inspiration and direction for the aforementioned shortcomings. Combining the advantages of deep learning and reinforcement learning, deep reinforcement learning is able to build an end-to-end fault diagnosis architecture that can directly map raw fault data to the corresponding fault modes. Thus, based on deep reinforcement learning, a novel intelligent diagnosis method is proposed that is able to overcome the shortcomings of the aforementioned diagnosis methods. Validation tests of the proposed method are carried out using datasets of two types of rotating machinery, rolling bearings and hydraulic pumps, which contain a large number of measured raw vibration signals under different health states and working conditions. The diagnosis results show that the proposed method is able to obtain intelligent fault diagnosis agents that can mine the relationships between the raw vibration signals and fault modes autonomously and effectively. Considering that the learning process of the proposed method depends only on the replayed memories of the agent and the overall rewards, which represent much weaker feedback than that obtained by the supervised learning-based method, the proposed method is promising in establishing a general fault diagnosis architecture for rotating machinery.     

数据失衡下基于WGAN和GAPCNN的轴承故障诊断研究

针对轴承故障数据严重失衡导致所训练的模型诊断能力和泛化能力较差等问题,提出基于Wasserstein距离的生成对抗网络来平衡数据集的方法。该方法首先将少量故障样本进行对抗训练,待网络达到纳什均衡时,再将生成的故障样本添加到原始少量故障样本中起到平衡数据集的作用;提出基于全局平均池化卷积神经网络的诊断模型,将平衡后的数据集输入到诊断模型中进行训练,通过模型自适应地逐层提取特征,实现故障的精确分类诊断。实验结果表明,所提诊断方法优于其他算法和模型,同时拥有较强的泛化能力和鲁棒性。     

One-dimensional convolutional auto-encoder-based feature learning for fault diagnosis of multivariate processes

Noise and high-dimension of process signals decrease effectiveness of those regular fault detection and diagnosis models in multivariate processes. Deep learning technique shows very excellent performance in high-level feature learning from image and visual data. However, the large labeled data are required for deep neural networks (DNNs) with supervised learning like convolutional neural network (CNN), which increases the time cost of model construction significantly. A new DNN model, one-dimensional convolutional auto-encoder (1D-CAE) is proposed for fault detection and diagnosis of multivariate processes in this paper. 1D-CAE is utilized to learn hierarchical feature representations through noise reduction of high-dimensional process signals. Auto-encoder integrated with convolutional kernels and pooling units allows feature extraction to be particularly effective, which is of great importance for fault detection and diagnosis in multivariate processes. The comparison between 1D-CAE and other typical DNNs illustrates effectiveness of 1D-CAE for fault detection and diagnosis on Tennessee Eastman Process and Fed-batch fermentation penicillin process. The proposed method provides an effective platform for deep-learning-based process fault detection and diagnosis of multivariate processes.