Machine fault diagnosis using a cluster-based wavelet feature extraction and probabilistic neural networks

In this paper, a cluster-based feature extraction from the coefficients of a discrete wavelet transform and probabilistic neural networks are proposed for machine fault diagnosis. The proposed approach first divides the matrix of wavelet coefficients into clusters, which are centered around the discriminative coefficient positions identified by an unsupervised procedure, based on the entropy value of coefficients from a set of representative signals. The features that contain the informative attributes of the signals are computed from the energy content of the obtained clusters. Then, machine faults are diagnosed based on these feature vectors using a probabilistic neural network. The experimental results from the application on bearing fault diagnosis have shown that the proposed approach is able to effectively extract important intrinsic information content of the test signals and increase the overall fault diagnostic accuracy, as compared to conventional methods.     

Rolling element bearing fault diagnosis for rotating machinery using vibration spectrum imaging and convolutional neural networks

The International Journal of Advanced Manufacturing Technology - In this paper, we propose a novel method for the classification of bearing faults using a convolutional neural network (CNN) and...     

Intelligent fault diagnosis and prognosis approach for rotating machinery integrating wavelet transform, principal component analysis, and artificial neural networks

This paper proposes a new approach for rotating machinery which integrates wavelet transform (WT), principal component analysis (PCA), and artificial neural networks (ANN) to classify the fault and predict the conditions of components, equipment, and machines. The standard deviation of wavelet coefficients are extracted from processed historical signals of manufacturing equipment as features. Then, the features are analyzed by PCA and several new principal features obtained from original features can be used as inputs to train ANN. After training, the conditions and degradations of components and machines can be predicted, and the fault of them can be classified if it exists, by the trained ANN using the same kinds of principal features extracted from real time signals. A case study is used to evaluate the proposed method and the result indicates its higher efficiency and effectiveness comparing to traditional methods.     

基于小波神经网络的滚动轴承故障诊断

根据滚动轴承振动信号的频域变化特征,利用小波分析对其建立频域特征向量,准确地提取了故障的特征信息,结合RBF神经网络训练速度快的优点,将RBF神经网络应用于轴承故障特征的选择,并利用所确定的特征及RBF分类器进行故障诊断。实验结果表明,该方法可实现滚动轴承故障的可靠诊断。     

基于切片谱免疫系统的旋转机械故障诊断

根据旋转机械故障振动信号的特点,本文基于免疫学机制,提出了切片谱免疫故障诊断方法,建立了基于该方法的诊断模型,介绍了该诊断方法的实现过程.切片谱免疫故障诊断方法利用双谱对先验故障样本进行分析,获得与旋转机械故障类型一一对应的特征样本,将特征样本归一化作为人工免疫系统(AIS)模式识别的特征向量,利用AIS中的阴性选择算法(NSA)进行自己-非己匹配运算得到检测器集,然后将建立(训练)好的检测器集应用于实时故障诊断.通过轴承故障诊断的实验,结果表明,本方法是可行和有效的.     

Multiscale slope feature extraction for rotating machinery fault diagnosis using wavelet analysis

This paper proposes a multiscale slope feature extraction method using wavelet-based multiresolution analysis for rotating machinery fault diagnosis. The new method mainly includes three following steps: the discrete wavelet transform (DWT) is first performed on vibration signals gathered by accelerometer from rotating machinery to achieve a series of detailed signals at different scales; the variances of multiscale detailed signals are then calculated; finally, the wavelet-based multiscale slope features are estimated from the slope of logarithmic variances. The presented features reveal an inherent structure within the power spectra of vibration signals. The effectiveness of the proposed feature was verified by two experiments on bearing defect identification and gear wear diagnosis. Experimental results show that the wavelet-based multiscale slope features have the merits of high accuracy and stability in classifying different conditions of both bearings and gearbox, and thus are valuable for machinery fault diagnosis.     

基于全矢谱和径向基概率神经网络的旋转机械故障诊断方法研究

结合全矢谱和径向基概率神经网络的优点,提出一种故障诊断的新方法,该方法是以提取全矢幅值谱的特征输入到径向基概率神经网络分类器进行故障识别.试验结果表明,该方法与传统单通道相比故障正确识别率很高,把它应用于旋转机械故障诊断是有效的.     

基于等距映射与加权KNN的旋转机械故障诊断

针对旋转机械高维复杂故障特征数据难以快速准确辨识的问题,提出一种基于等距映射非线性流形学习与加权KNN(K-nearest neighbor)分类器相结合的旋转机械故障诊断方法.在由时域统计指标和内禀模态分量能量构造的原始特征空间中,首先利用等距映射非线性流形学习算法提取旋转机械故障状态变化的本质特征,随后将提取的低维本质特征输入给加权KNN进行旋转机械的故障模式辨识.通过对齿轮箱的实验数据分析表明,该方法不仅对高维复杂的非线性故障特征具有良好的降维性能,而且故障识别率较之传统方法也明显提高,能够有效识别出高维特征空间的非线性故障特征.     

基于数学形态学和模糊聚类的旋转机械故障诊断

提出了一种数学形态学与GG (Gath-Geva)模糊聚类相结合的旋转机械故障诊断方法,通过对滚动轴承信号的多尺度形态运算得到信号的形态谱,定量反映了信号在不同尺度下的形态变化特征.为进一步对滚动轴承信号进行故障识别,提取出基于形态学操作的分形维数和描述不同信号形态特征的指标即形态谱墒,并把这2个参数作为GG聚类的故障特征向量,进行聚类分析,同时对GG聚类与FCM(fuzzy center means)聚类和GK (Gustafaon-Kessel)聚类进行了比较.实验证明了基于数学形态学与GG聚类相结合的机械故障诊断方法的有效性,且证明了GG聚类更适合对不同形状、大小和密度的空间故障数据模糊聚类,聚类效果更好.     

基于粒子群优化LS-WSVM的旋转机械故障诊断

为了更好地进行旋转机械故障诊断,提出一种粒子群优化(particle swarm optimization,PSO)最小二乘小波支持向量机(least square wavelet support vector machine,LS-WSVM)的故障诊断模型.先将故障信号经验模式分解(empirical mode decomposition,EMD)为多个内禀模态分量(intrinsic mode function,IMF)之和,再提取表征故障特征的IMF分量能量构造特征向量输入到PSO优化的LS-WSVM进行故障模式识别.EMD分解可自适应提取故障特征信号,PSO参数优化可快速准确得到LS-WSVM的全局最优参数,提高LS-WSVM的故障诊断精度和自适应诊断能力.通过滚动轴承的故障模拟实验验证了该方法的有效性.     

小波算法在旋转机械故障诊断系统中的应用

目前旋转机械在社会各个方面均有着广泛的应用,同时旋转机械的故障也十分普遍。一旦发生故障就会造成巨大的经济损失。该文基于小波算法对旋转机械故障特征进行提取,在时域和频域中对提取数据进行分析处理,在上位中对故障诊断结果进行显示。以Visual Studio 2010为开发平台,C#为开发语言,运用小波算法,最终完成了故障诊断系统的开发。验证结果表明,该诊断系统具有诊断精度高、速度快等优点。     

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.     

基于神经网络技术的数字信号处理飞控系统设计

针对无人机性能指标和体积限制,设计一种基于TMS320C5402型数字信号处理器的新型飞控系统.详细阐述系统的设计思想以及软、硬件结构和控制策略,给出相应的飞控流程图与神经网络动态逆控制原理图.通过在环回路仿真验证,所设计的系统具有计算速度快、可靠性好等优点,能够赋予无人机更大的机动性和更广泛的适用性.     

Weak feature enhancement in machinery fault diagnosis using empirical wavelet transform and an improved adaptive bistable stochastic resonance

Machinery vibration signal is a typical multi-component signal and fault features are often submerged by some interference components. To accurately extract fault features, a weak feature enhancement method based on empirical wavelet transform (EWT) and an improved adaptive bistable stochastic resonance (IABSR) is proposed. This method makes full use of the signal decomposition performance of EWT and the signal enhancement of the IABSR to achieve the purpose of fault feature enhancement in low frequency band of FFT spectrum. Firstly, EWT is used as the preprocessing program of bistable stochastic resonance (BSR) to decompose the machinery vibration signal into a set of sub-components. Then, the sensitive component that contains main fault information is further input into BSR system to enhance fault features with the assistance of residual noises. Finally, the fault features are identified from fast Fourier transform (FFT) spectrum of the BSR output. To achieve the optimal BSR output, the IABSR method based on salp swarm algorithm (SSA) is presented. Compared with the tradition adaptive BSR (ABSR), the IABSR optimizes not only the BSR system parameters but also the calculation step size. Two case studies on machinery fault diagnosis demonstrate the effectiveness and superiority of the proposed method. In addition, the proposed method is easy to implement and is robust to noise to some extent.     

全信息小波分析及其在旋转机械故障诊断中的应用

传统旋转机械故障诊断用单通道信号进行诊断,信息量不完整,容易导致误诊.在介绍全信息技术的基础上,结合小波分析的频带分离和刻画信号局部特征的能力,提出了一种全新的信号处理方法--全信息小波分析.用小波分析把信号分解到不同的频带,然后把双通道的对应频带的信号用全矢谱技术进行融合,根据融合后的数据进行故障诊断.用全信息小波分析技术对转子的摩擦故障进行诊断,取得了满意的效果.     

Vibration analysis of rotating machinery using time-frequency analysis and wavelet techniques

Time-frequency analysis, including the wavelet transform, is one of the new and powerful tools in the important field of structural health monitoring, using vibration analysis. Commonly-used signal analysis techniques, based on spectral approaches such as the fast Fourier transform, are powerful in diagnosing a variety of vibration-related problems in rotating machinery. Although these techniques provide powerful diagnostic tools in stationary conditions, they fail to do so in several practical cases involving non-stationary data, which could result either from fast operational conditions, such as the fast start-up of an electrical motor, or from the presence of a fault causing a discontinuity in the vibration signal being monitored. Although the short-time Fourier transform compensates well for the loss of time information incurred by the fast Fourier transform, it fails to successfully resolve fast-changing signals (such as transient signals) resulting from non-stationary environments. To mitigate this situation, wavelet transform tools are considered in this paper as they are superior to both the fast and short-time Fourier transforms in effectively analyzing non-stationary signals. These wavelet tools are applied here, with a suitable choice of a mother wavelet function, to a vibration monitoring system to accurately detect and localize faults occurring in this system. Two cases producing non-stationary signals are considered: stator-to-blade rubbing, and fast start-up and coast-down of a rotor. Two powerful wavelet techniques, namely the continuous wavelet and wavelet packet transforms, are used for the analysis of the monitored vibration signals. In addition, a novel algorithm is proposed and implemented here, which combines these two techniques and the idea of windowing a signal into a number of shaft revolutions to localize faults.     

基于多元经验模态分解的旋转机械早期故障诊断方法*

针对旋转机械早期微弱故障诊断问题,提出了基于多元经验模态分解的旋转机械早期故障诊断新方法。首先将多个加速度传感器合理布置在轴承座的关键位置,同步采集多通道振动信息;再利用多元经验模态分解同时对多通道振动信号进行自适应分解,得到一系列多元IMF分量;最后,依据峭度准则和相关系数从中选取包含故障主要信息的IMF分量进行信号重构,提取故障特征。多元经验模态分解方法克服了EMD等方法在进行多通道数据融合时缺乏理论依据的局限性。仿真信号和旋转机械故障信号的实验结果表明,该方法明显优于EEMD方法,对齿轮和滚动轴承故障的检测精度更高,可以在强背景噪声情况下更好地提取出故障冲击特征。     

Fractional cell formation in group technology using modified ART1 neural networks

Group technology (GT) is a manufacturing philosophy that attempts to reduce production cost by reducing the material handling and transportation cost. The GT cell formation by any known algorithm/heuristics results in much intercell movement known as exceptional elements. In such cases, fractional cell formation using reminder cells can be adopted successfully to minimize the number of exceptional elements. The fractional cell formation problem is solved using modified adaptive resonance theory1 network (ART1). The input to the modified ART1 is machine-part incidence matrix comprising of the binary digits 0 and 1. This method is applied to the known benchmarked problems found in the literature and it is found to be equal or superior to other algorithms in terms of minimizing the number of the exceptional elements. The relative merits of using this method with respect to other known algorithms/heuristics in terms of computational speed and consistency are presented.     

基于小波包分析和BP神经网络的字符识别方法

利用小波包分析具有提取图像时、频两域细节和局部特征的能力,提出了将字符图像的小波包分析和BP神经网络相结合以达到识别字符的新方法。该方法首先对字符图像进行小波包分解,然后对分解系数进行重构,求得重构图像的能量;然后提取了不同字符图像的能量构造成能量特征向量,作为神经网络的输入;然后通过选取初始权值、隐层节点数和权值学习算法,创建BP神经网络;最后通过神经网络模型进行训练。实验证实该方法具有识别正确率高、速度快等优点。