基于建康管理技术的机载计算机智能故障诊断方法

为了满足飞机机载电子设备以状态监控为基础的视情维修保障策略,提升设备可维护性,提出了一种基于在线检测、故障预测、辅助决策的健康监控管理故障诊断方法,支持对机载电子设备的健康状态进行预测和评估。通过划分机载电子设备子功能的敏感威胁区域,对这些区域设计专门的威胁预警监控电路,进行功能危害监控,建立推理监控模型对监控电路故障进行预警监控,结合辅助决策的方式对预警到的故障进行定位,实现对电子设备的智能故障诊断。通过FMEA的分析与故障注入测试验证,该预警电路、推理模型和辅助决策能有效的预测故障及定位,具有较高的故障预测覆盖率,可提高机载计算机的维修性、降低维修时间,在电子设备视情维修策略上具备工程应用价值。     

New trends in machine tool monitoring and diagnostics

The line of evolution of manufacturing systems indicates rapidly increasing complexity at every system level, which necessitates enhanced requirements for the monitoring and diagnostic sybsystems applied in these manufacturing complexes. This means they must correspond—in performance, complexity and intelligence—to the entire material and data-processing system. This paper summarizes the fundamental requirements for a new family of monitoring and diagnostic equipment and describes two multipurpose, flexible machine tool monitoring systems, which can be regarded as first attempts in this direction. Special emphasis is placed on the generation of reference data for such complex monitoring equipment. Process modelling and teaching approaches are discussed. Pattern recognition methods during learning and decision-making are suggested. Among the most important research and development trends, the use of AI techniques in monitoring and diagnostics is also investigated.     

A predictive maintenance system for multi-granularity faults based on AdaBelief-BP neural network and fuzzy decision making

Predictive maintenance of production equipment is a prerequisite to ensure safe and reliable manufacturing operations. To avoid unexpected shutdown and even casualties caused by faults during production, it is paramount to design an effective predictive maintenance decision system for production equipment. Most of the related research works concentrate on early warn of specific faults but neglect the differentiations of the fault severity. To address the issue, this paper presents an intelligent predictive maintenance system for multi-granularity faults of production equipment based on the AdaBelief-BP (back propagation) neural network and the fuzzy decision making. The characteristics of the system presented in this paper include: (1) The proposed system implements a two-stage framework, integrating the functions of fault type prediction and fault degree prediction, which can provide comprehensive fault information throughout production lifecycles; (2) On the maintenance solution identification stage, fuzzy logic-based decision making is carried out to determine appropriate maintenance solutions based on the practical vague boundary of fault severity. In the system, the design of the AdaBelief-BP neural network can achieve a higher convergence rate and a better generalization capability as well. Meanwhile, to the best of our knowledge, in this research, it is the first time to use the migration of the fuzzy membership degree as the indicator of the changing condition of fault severity to facilitate more accurate maintenance solution identification. To verify the effectiveness of the system, comparison experiments with some popular algorithms are conducted. Benchmarking results show that the developed system can achieve higher prediction accuracy as well as higher efficiency than the comparative methods.     

柔性制造系统中CNC机床故障诊断机理研究

为了及时发现处理柔性制造系统数控机床的故障或异常现象,设计了CNC在线故障诊断测试系统。该系统不仅便于查找数控机床故障的一个或多个症结,可以快捷、准确地对CNC故障定位,而且解决了诊断处理与知识应用中的相关问题。为了对CNC设备终端提供可靠的故障排除建议,对伺服控制组件与后台服务关联关系进行深入剖析,并对故障数据库进行描述与测试程序设计,解决了系统维护、扩展与升级操作等问题。     

A novel diagnostic and prognostic framework for incipient fault detection and remaining service life prediction with application to industrial rotating machines

Data-driven machine health monitoring systems (MHMS) have been widely investigated and applied in the field of machine diagnostics and prognostics with the aim of realizing predictive maintenance. It involves using data to identify early warnings that indicate potential system malfunctioning, predict when system failure might occur, and pre-emptively service equipment to avoid unscheduled downtime. One of the most critical aspects of data-driven MHMS is the provision of incipient fault diagnosis and prognosis regarding the system’s future working conditions. In this work, a novel diagnostic and prognostic framework is proposed to detect incipient faults and estimate remaining service life (RSL) of rotating machinery. In the proposed framework, a novel canonical variate analysis (CVA)-based monitoring index, which takes into account the distinctions between past and future canonical variables, is employed for carrying out incipient fault diagnosis. By incorporating the exponentially weighted moving average (EWMA) technique, a novel fault identification approach based on Pearson correlation analysis is presented and utilized to identify the influential variables that are most likely associated with the fault. Moreover, an enhanced metabolism grey forecasting model (MGFM) approach is developed for RSL prediction. Particle filter (PF) is employed to modify the traditional grey forecasting model for improving its prediction performance. The enhanced MGFM approach is designed to address two generic issues namely dealing with scarce data and quantifying the uncertainty of RSL in a probabilistic form, which are often encountered in the prognostics of safety-critical and complex assets. The proposed CVA-based index is validated on slowly evolving faults in a continuous stirred tank reactor (CSTR) system, and the effectiveness of the proposed integrated diagnostic and prognostic method for the monitoring of rotating machinery is demonstrated for slow involving faults in two case studies of an operational industrial centrifugal pump and one case study of an operational centrifugal compressor.     

Condition monitoring and fault diagnostics for hydropower plants

This paper presents a condition monitoring and fault diagnostics (CMFD) system for hydropower plants (HPP). CMFD is based on the concept of industrial product-service systems (IPS2), in which the customer, turbine supplier, and maintenance service provider are the IPS2 stakeholders. The proposed CMFD consists of signal acquisition, data transfer to the virtual diagnostics center (VDC) and fault diagnostics. A support vector machine (SVM) classifier has been used for fault diagnostics. CMFD has been implemented on an HPP with three Kaplan units. A signal acquisition system for CMFD consists of data acquisition from a unit control system and a supplementary system for high-frequency data acquisition. The implemented SVM method exhibits high training accuracy and thus enables adequate fault diagnostics. The data are analyzed in the VDC, which allows all stakeholders access to diagnostic information from anywhere at any time. Based on this information, the service providers can establish condition-based maintenance and offer operational support. Furthermore, through the VDC, cooperation between the stakeholders can be achieved; thus, better maintenance scheduling is possible, which will be reflected in higher system availability.     

一起500千伏变压器多维状态监测与故障诊断

为了提升变压器故障诊断水平并有效实现状态检修,本文针对一起500千伏主变压器内部潜伏性故障案例介绍了利用多种在线监测、离线检测等手段与故障诊断方法快速准确查找出变压器故障原因及位置。它通过采用油色谱检测、变压器振动及声音检测、容性设备在线监测、变压器局部放电检测、带电测试等多维状态监测技术开展变压器状态评价及故障诊断,并帮助实现对主变压器内部故障的准确定位和制定状态检修策略。该主变在通过状态监测及故障诊断后实现隐患故障快速准确定位,并通过紧急处理重新恢复正常运行状态,从而避免一起重大设备事故发生。结果表明,应用变压器油溶解气体色谱分析检测技术,可通过排除法准确地判断变压器故障性质和严重程度,它是早期发现变压器潜伏性故障特别有效的方法。同时,采用基于交叉小波的变压器振动信号特征量提取方法分析评价结果表明,变压器铁芯发生接地故障后其振动信号存在大量50赫兹谐波分量。借助振动及声音检测技术,能够有助于变压器故障诊断及准确定位,提高设备状态检修效率。     

Predictive maintenance decision-making for variable faults with non-equivalent costs of fault severities

Predictive Maintenance is crucial for production systems as it helps maintaining the reliability and availability of components/equipment as well as preventing unexpected shutdowns during production. Traditional maintenance strategies mostly focus on the predictive diagnosis of fault types and identical maintenance decisions would be delivered for the equipment with the same fault type. It often results in “over-maintenance” as the variable fault severities may require non-equivalent costs of maintenance resources. To tackle this problem, this paper aims at developing a fault prediction model firstly predicting fault severity and fault type simultaneously and subsequently providing distinguished maintenance strategy for variable faults accordingly, through which the abnormal faults of equipment can be effectively prevented, and machines can be efficiently and economically maintained based on the model suggested decisions. The main works in this study are 1) The fault features based on monitored vibration signals are extracted from multi-domains, and most significant features are selected by L1-Support Vector Machine (L1-SVM) together with variance filtering method; 2) A parallel fault prediction model based on Back propagation Neural Network and Long Short Term Memory Neural Network (BP-LSTM) is proposed, which is used to predict the fault type and fault degree simultaneously; 3) A Deep Q-Network (DQN)-based maintenance decision-making model is established for different fault types with various fault severities.     

Measurement of machine performance degradation using a neural network model

Machines degrade as a result of aging and wear, which decreases performance reliability and increases the potential for faults and failures. The impact of machine faults and failures on factory productivity is an important concern for manufacturing industries. Economic impacts relating to machine availability and reliability, as well as corrective (reactive) maintenance costs, have prompted facilities and factories to improve their maintenance techniques and operations to monitor machine degradation and detect faults. This paper presents an innovative methodology that can change maintenance practice from that of reacting to breakdowns, to one of preventing breakdowns, thereby reducing maintenance costs and improving productivity. To analyze the machine behavior quantitatively, a pattern discrimination model (PDM) based on a cerebellar model articulation controller (CMAC) neural network was developed. A stepping motor and a PUMA 560 robot were used to study the feasibility of the developed technique. Experimental results have shown that the developed technique can analyze machine degradation quantitatively. This methodology could help operators set up machines for a given criterion, determine whether the machine is running correctly, and predict problems before they occur. As a result, maintenance hours could be used more effectively and productively.     

基于大数据平台的水轮发电机组故障诊断系统

水轮发电机组是水电站的关键设备,它的运行状况直接关系到水电站的安全生产。目前对水轮发电机组运行状况的掌握大都通过装设的状态监测系统运行数据的分析比对和计划检修相结合的方式,但往往都是故障已经发生后才能予以发现,不能提前对设备运行工况进行预判。本文详细介绍了一种基于大数据平台的水轮发电机组故障诊断系统,该系统主要由数据处理平台、模型算法平台、可视化展示平台三部分组成,是一种基于大数据平台和互联网技术的典型应用。其主要通过挖掘水电厂现有计算机监控系统、状态监测系统等信息系统的实时及历史数据,再经过一系列关联算法提取这些数据中蕴含的丰富的价值信息来实现对机组的运行状况监视、健康评价、趋势预警、故障诊断、检修指导等。     

基于人机共融的包装机故障诊断系统的设计与实现

随着工业4.0和物联网时代的来临,基于经验和手册的设备维修方式已不能满足复杂设备维修的要求。而传统的设备诊断系统往往只注重从物理传感器采集数据,缺少引入人的经验,难以拥有自学习能力。本文以ZB45烟草包装机为例,提出一种具有自学习能力的人机共融新型故障诊断系统。系统采用贝叶斯网络,实现对传感器数据的自动推理。通过自然语言处理模块与用户交互,学习用户的维修经验,并用来改进诊断效果。提出了基于凸优化的标签选择方法,根据观察到的现象推荐合适的标签,以快速确定最可能的故障,实现快速找到报警号码对应的故障源。生产现场的实测数据表明,本系统可以有效降低万箱故障次数,有效提高故障诊断精度,降低故障排查时间。     

A hybrid feature selection scheme for unsupervised learning and its application in bearing fault diagnosis

With the development of the condition-based maintenance techniques and the consequent requirement for good machine learning methods, new challenges arise in unsupervised learning. In the real-world situations, due to the relevant features that could exhibit the real machine condition are often unknown as priori, condition monitoring systems based on unimportant features, e.g. noise, might suffer high false-alarm rates, especially when the characteristics of failures are costly or difficult to learn. Therefore, it is important to select the most representative features for unsupervised learning in fault diagnostics. In this paper, a hybrid feature selection scheme (HFS) for unsupervised learning is proposed to improve the robustness and the accuracy of fault diagnostics. It provides a general framework of the feature selection based on significance evaluation and similarity measurement with respect to the multiple clustering solutions. The effectiveness of the proposed HFS method is demonstrated by a bearing fault diagnostics application and comparison with other features selection methods.     

A spiking neural network-based approach to bearing fault diagnosis

Fault diagnosis, with the aim of accurately identifying the presence of various faults as early as possible so at to provide effective information for maintenance planning, has been extensively concerned in advanced manufacturing systems. With the increase of the amount of condition monitoring data, fault diagnosis methods have gradually shifted from the model-based paradigm to data-driven paradigm. Intelligent fault diagnosis approaches which can automatically mine useful information from a huge amount of raw data are becoming promising ways to identify faults of manufacturing systems in the context of massive data. In this paper, the Spiking Neural Network (SNN), as the third generation neural network, is tailored as an intelligent fault diagnosis tool for bearings in rotating machinery. Compared to the perceptron and the back propagation neural network (BPNN) which are respectively the first and second generations of neural networks. SNN, which introduces the concept of time into its operating model can more closely mimic natural neural networks and possesses high bionic characteristics. In the proposed SNN-based approach to bearing fault diagnosis, features extracted from raw vibration signals through the local mean decomposition (LMD) are encoded into spikes to train an SNN with the improved tempotron learning rule. The performance of the proposed method is examined by the CWRU and MFPT datasets, and the experimental results show that the method can achieve a promising accuracy in bearing fault diagnosis.     

复杂系统的智能故障诊断技术现状及其发展趋势

智能故障诊断技术为保障工程技术系统的可靠性和安全性开辟了新的途径，随着系统设备和功能的日益复杂化，发生故障的机率以及由此带来的损失越来越大，现有单一、固定的故障诊断方法却难以满足复杂系统诊断的全部要求。该文针对复杂系统故障现象的特点，分析了现有基于规则、基于结构和行为、案例、模糊逻辑、神经网络及其集成知识诊断技术的各自特点和局限性，指出了机器学习对于当前复杂系统智能故障诊断发展的重要性，有利于改变现有单一、固定的故障诊断思维，并对未来的主要发展方向进行了一些探讨。     

Modeling and analysis of fault-tolerant systems for machining operations based on Petri nets

This paper introduces a methodology for modeling and analyzing fault-tolerant manufacturing systems that not only optimizes normal productive processes, but also performs detection and treatment of faults. This approach is based on the hierarchical and modular integration of Petri nets. The modularity provides the integration of three types of processes: those representing the productive process, fault detection, and fault treatment. The hierarchical aspect of the approach allows us to consider processes on different levels of detail (i.e., factory, manufacturing cell, or machine). Case studies considering detection and treatment of faults are presented, and a simulation tool is applied to verify the models.     

Remote,condition-based maintenance for web-enabled robotic system

The current trends in industry include an integration of information and knowledge-base network with a manufacturing system, which coined a new term, e-manufacturing. From the perspective of e-manufacturing any production equipment and its control functions do not exist alone, instead becoming a part of the holistic operation system with distant monitoring, remote quality control, and fault diagnostic capabilities. The key to this new paradigm is the accessibility to a remotely located system and having the means of responding to a changing environment, which is better suited for today's rapidly changing environment. Within the framework of the web-enabled robotic system, this paper focuses on the remote maintenance schemes with an emphasis on condition-based maintenance strategies. Real-time monitoring of robot harmonic drive systems and operational status have been attained over the Web. A mathematical modeling of system availability has been derived in order to account for other failures that might occur in the subsystems of the robot. Compared to the schedule-based maintenance strategies, the proposed approach shows great potential for improving overall production efficiency, while reducing the cost of maintenance.     

Neural clouds for monitoring of complex systems

Condition monitoring is an important and challenging task actual for many areas of industry, medicine and economics. Nowadays it is necessary to provide on-line monitoring of the complex systems status, e.g. the steel production, in order to avoid faults, breakdowns or wrong diagnostics. In the present paper a novel machine learning method for the automated condition monitoring is presented. Neural Clouds (NC) is a novel data encapsulation method, which provides a confidence measure regarding classification of the complex system conditions. The presented adaptive algorithm requires only the data which corresponds to the normal system conditions, which is typically available. At the same time the fault related data acquisition is expensive and fault modeling is not always possible, especially in case one is dealing with steel production, power stations operation, human health condition or critical phenomena in financial markets. These real word applications are also presented in the paper.     

A data-driven two-stage maintenance framework for degradation prediction in semiconductor manufacturing industries

To reduce the production costs and breakdown risks in industrial manufacturing systems, condition-based maintenance has been actively pursued for prediction of equipment degradation and optimization of maintenance schedules. In this paper, a two-stage maintenance framework using data-driven techniques under two training types will be developed to predict the degradation status in industrial applications. The proposed framework consists of three main blocks, namely, Primary Maintenance Block (PMB), Secondary Maintenance Block (SMB), and degradation status determination block. As the popular methods with deterministic training, back-propagation Neural Network (NN) and evolvable NN are employed in PMB for the degradation prediction. Another two data-driven methods with probabilistic training, namely, restricted Boltzmann machine and deep belief network are applied in SMB as the backup of PMB to model non-stationary processes with the complicated underlying characteristics. Finally, the multiple regression forecasting is adopted in both blocks to check prediction accuracies. The effectiveness of our proposed two-stage maintenance framework is testified with extensive computation and experimental studies on an industrial case of the wafer fabrication plant in semiconductor manufactories, achieving up to 74.1% in testing accuracies for equipment degradation prediction.     

微服务系统服务依赖发现技术综述

微服务架构得到了广泛的部署与应用, 提升了软件系统开发的效率, 降低了系统更新与维护的成本, 提高了系统的可扩展性. 但微服务变更频繁、异构融合等特点使得微服务故障频发、其故障传播快且影响大, 同时微服务间复杂的调用依赖关系或逻辑依赖关系又使得其故障难以被及时、准确地定位与诊断, 对微服务架构系统的智能运维提出了挑战. 服务依赖发现技术从系统运行时数据中识别并推断服务之间的调用依赖关系或逻辑依赖关系, 构建服务依赖关系图, 有助于在系统运行时及时、精准地发现与定位故障并诊断根因, 也有利于如资源调度、变更管理等智能运维需求. 首先就微服务系统中服务依赖发现问题进行分析, 其次, 从基于监控数据、系统日志数据、追踪数据等3类运行时数据的角度总结分析了服务依赖发现技术的技术现状; 然后, 以基于服务依赖关系图的故障根因定位、资源调度与变更管理等为例, 讨论了服务依赖发现技术应用于智能运维的相关研究. 最后, 对服务依赖发现技术如何准确地发现调用依赖关系和逻辑依赖关系, 如何利用服务依赖关系图进行变更治理进行了探讨并对未来的研究方向进行了展望.     

Monitoring of complex systems of interacting dynamic systems

Increases in functionality, power and intelligence of modern engineered systems led to complex systems with a large number of interconnected dynamic subsystems. In such machines, faults in one subsystem can cascade and affect the behavior of numerous other subsystems. This complicates the traditional fault monitoring procedures because of the need to train models of the faults that the monitoring system needs to detect and recognize. Unavoidable design defects, quality variations and different usage patterns make it infeasible to foresee all possible faults, resulting in limited diagnostic coverage that can only deal with previously anticipated and modeled failures. This leads to missed detections and costly blind swapping of acceptable components because of one??s inability to accurately isolate the source of previously unseen anomalies. To circumvent these difficulties, a new paradigm for diagnostic systems is proposed and discussed in this paper. Its feasibility is demonstrated through application examples in automotive engine diagnostics.