首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6篇
  完全免费   7篇
  自动化技术   13篇
  2018年   1篇
  2017年   4篇
  2016年   2篇
  2014年   1篇
  2013年   1篇
  2010年   2篇
  2009年   1篇
  2004年   1篇
排序方式: 共有13条查询结果,搜索用时 61 毫秒
1.
Diagnosis of Intermittent Faults   总被引:1,自引:0,他引:1  
The diagnosis of intermittent faults in dynamic systems modeled as discrete event systems is considered. In many systems, faulty behavior often occurs intermittently, with fault events followed by corresponding reset events for these faults, followed by new occurrences of fault events, and so forth. Since these events are usually unobservable, it is necessary to develop diagnostic methodologies for intermittent faults. Prior methodologies for detection and isolation of permanent faults are no longer adequate in the context of intermittent faults, since they do not account explicitly for the dynamic behavior of these faults. This paper addresses this issue by: (i) proposing a modeling methodology for discrete event systems with intermittent faults; (ii) introducing new notions of diagnosability associated with fault and reset events; and (iii) developing necessary and sufficient conditions, in terms of the system model and the set of observable events, for these notions of diagnosability. The definitions of diagnosability are complementary and capture desired objectives regarding the detection and identification of faults, resets, and the current system status (namely, is the fault present or absent). The associated necessary and sufficient conditions are based upon the technique of diagnosers introduced in earlier work, albeit the structure of the diagnosers needs to be enhanced to capture the dynamic nature of faults in the system model. The diagnosability conditions are verifiable in polynomial time in the number of states of the diagnosers.  相似文献
2.
We present an approach dealing with repeated fault events in the framework of model-based monitoring of discrete-event systems (DES). Various notions of diagnosability reported in the literature deal with uniformly bounded finite detection of counting delays over all faulty behaviors (uniform delays for brevity). The situation where the diagnosability notion of interest fails to hold under a given observation configuration leads typically to the deployment of more observational devices (e.g., sensors), which may be costly or infeasible. As an alternative to the additional deployment of observational devices, one might want to relax the uniformity of delays, while delays remain finite. To this end, we introduce a notion of diagnosability characterized with nonuniformly bounded finite counting delays (nonuniform counting delays for brevity), where finite delay bounds can vary on faulty behaviors. To evaluate the introduced notion of diagnosability with nonuniform counting delays, a polynomial-time verification algorithm is developed. Notably, the developed verification technique can readily be modified to construct a computationally superior verification algorithm for diagnosability under uniformly bounded finite counting delays (uniform counting delays for brevity) as compared to an algorithm previously reported in the literature. We also develop a novel on-line event counting algorithm that improves the time and space complexities of the currently available algorithms for the counting of special events.
Humberto E. Garcia (Corresponding author)Email:

Tae-Sic Yoo   received the B. Eng degree from Korea University, Seoul, Korea, in 1994, the M. Eng. and the Ph.D. degree from the University of Michigan, Ann Arbor, in 1999 and 2002, respectively, all in electrical engineering. Since 2002, he has been with Argonne National Laboratory-West and Idaho National Laboratory as a researcher. He was a recipient of the distinguished graduate student awards from the University of Michigan in 2003. His general research interests are in systems and control: theory and applications. His research experience includes discrete-event systems, sensor networks, empirical data-driven systems, stochastic systems, and modeling and analysis of nuclear engineering systems. Humberto E. Garcia   Humberto E. Garcia received an Ingeniero Electricista degree from the Universidad de Carabobo, Venezuela, and MS and Ph.D. degrees in Electrical and Computer Engineering (with a minor in Mechanical Engineering) from the Pennsylvania State University, USA. He is currently with Idaho National Laboratory, being previously with Argonne National Laboratory. Dr. Garcia has over sixteen years of work experience in modeling, monitoring, control, and optimization of complex dynamical systems gained from numerous research, development, and demonstration efforts. His interests include sensor networks/systems, online condition monitoring, diagnostics, and prognostics, process monitoring and event detection, supervisory control, life-extended control, anomaly tolerant/reconfigurable systems, advanced safeguards/nonproliferation, proliferation detection, and counter-proliferation, process-infrastructure analysis, computational intelligence, and decision theory applications. His current duties include group lead, Sensor and Decision Systems, and principal investigator in several projects for advanced energy systems and national security applications. Developed technologies have been successfully demonstrated not only on simulated, hardware-in-the-loop, and lab-scale experimental test beds, but also on actual engineering-scale systems. Dr. Garcia has served as chair, panel member, and technical lead in numerous technical meetings, including being an expert member to International Atomic Energy Agency (IAEA) consultancy meetings on the subject of online condition monitoring. He has over 60 technical publications and two U.S. patents.   相似文献
3.
沈霆  李明禄  翁楚良 《计算机工程》2010,36(20):244-246
Xen虚拟化环境没有考虑CPU的间歇性故障带来的影响。基于此,建立模拟CPU间歇性故障的时间模型,在该模型下未修改的Xen系统中的虚拟机会立刻崩溃。提出一种自适应的策略来改进Xen的CPU调度,该策略主动跟踪CPU的状态变化,将发生故障的CPU上的虚拟处理器迁移到可用的其他CPU上。实验结果表明,当CPU间歇性故障频繁发生时,应用该策略可以使虚拟机继续稳定地工作,性能平滑地降低。  相似文献
4.
基于分段连续监测的思想,提出一种在MANET中采用累计信任度判断节点间断性故障的监测方法,在单次监测中利用信息熵记录节点响应频率,通过共享信息熵,并根据伪空间距离联合诊断节点的间断性可知,该单次监测方法的效率高于已有方法,为进一步提高节点高速运动的监测准确性,通过分段连续监测,把单次监测结果作为分类器,计算节点的累计信任度,并通过累计信任度衡量节点的间断性。仿真实验结果表明,该方法是有效可行的。  相似文献
5.
Intermittent faults (IFs) have the properties of unpredictability, non-determinacy, inconsistency and repeatability, switching systems between faulty and healthy status. In this paper, the fault detection and isolation (FDI) problem of IFs in a class of linear stochastic systems is investigated. For the detection and isolation of IFs, it includes: (1) to detect all the appearing time and the disappearing time of an IF; (2) to detect each appearing (disappearing) time of the IF before the subsequent disappearing (appearing) time; (3) to determine where the IFs happen. Based on the outputs of the observers we designed, a novel set of residuals is constructed by using the sliding-time window technique, and two hypothesis tests are proposed to detect all the appearing time and disappearing time of IFs. The isolation problem of IFs is also considered. Furthermore, within a statistical framework, the definition of the diagnosability of IFs is proposed, and a sufficient condition is brought forward for the diagnosability of IFs. Quantitative performance analysis results for the false alarm rate and missing detection rate are discussed, and the influences of some key parameters of the proposed scheme on performance indices such as the false alarm rate and missing detection rate are analysed rigorously. The effectiveness of the proposed scheme is illustrated via a simulation example of an unmanned helicopter longitudinal control system.  相似文献
6.
This study proposes a fault-tolerant control method for stochastic systems with multiple intermittent faults (IFs) and nonlinear disturbances, and both sensor and actuator faults are considered. The occurrence and disappearance of IFs are governed by Markov chain, and its transition probabilities are partly known. Hence, the faulty system can be described by a Markovian jump system (MJS). In order to ensure that the MJS is stochastically stable and satisfies H performance index, mode-dependent output feedback controllers are modelled using linear matrix inequalities. Numerous sufficient conditions for stochastic stability are obtained on the basis of Lyapunov stability theory. Finally, the effectiveness of the developed method is evaluated on the three-tank system.  相似文献
7.
A passive fault-tolerant control strategy is proposed for systems subject to a novel kind of intermittent fault, which is described by a Bernoulli distributed random variable. Three cases of fault location are considered, namely, sensor fault, actuator fault, and both sensor and actuator faults. The dynamic feedback controllers are designed not only to stabilise the fault-free system, but also to guarantee an acceptable performance of the faulty system. The robust H performance index is used to evaluate the effectiveness of the proposed control scheme. In terms of linear matrix inequality, the sufficient conditions of the existence of controllers are given. An illustrative example indicates the effectiveness of the proposed fault-tolerant control method.  相似文献
8.
鄢镕易  何潇  周东华 《自动化学报》2016,42(7):1004-1013
间歇故障(Intermittent faults, IFs)具有随机性,其检测要求在本次间歇故障消失之前检测出间歇故障的发生,在下一次间歇故障发生之前检测出间歇故障的消失.本文针对一类存在未知时变参数摄动的离散线性随机动态系统,研究了其鲁棒间歇故障检测与分离问题.基于降维未知输入观测器,通过引入滑动时间窗口,本文设计了一组与未知时变摄动解耦的结构化截断残差,并提出其存在的一个充分条件.与传统残差相比,截断残差信号更为显著地反映了间歇故障的发生和消失.为满足间歇故障的检测要求,本文提出两个假设检验分别用于检测间歇故障的发生时刻和消失时刻,并给出了一个详细算法.最后,在沿参考轨道运行的卫星模型上对所述方法进行了仿真实验,结果表明该方法能够有效检测出间歇故障的所有发生时刻和消失时刻,并准确实现故障分离.  相似文献
9.
介绍了间歇故障的概念,对间歇故障的背景和产生原因以及间歇故障诊断问题的研究意义进行了分析,以间歇故障的成因、幅值特性和不同时刻发生故障之间的相关性等为依据,对间歇故障进行了 分类. 然后对间歇故障诊断的研究现状进行了概述,把目前间歇故障诊断的方法大体分为定性分析和定量分析两大类,并对每一类现有 的方法进行细分,对每种方法的基本思想、优劣特点和适用条件进行了概述 和讨论. 最后探讨了间歇故障诊断研究中亟待解决的问题.  相似文献
10.
针对带有未知扰动和噪声的导弹间歇故障诊断问题,设计了一种基于未知输入观测器的导弹问题故障诊断方法,系统的输入部分或全部未知情况下也能获取系统状态的称为未知输入观测器.首先,为实现对外部扰动的解耦,设计降维未知输入观测器,并通过滑动时间窗口得到对间歇故障敏感而对未知扰动解耦的残差信号;然后,在满足误报率和漏报率的条件下,通过假设检验,确定了间歇故障发生时刻和消失时刻的可检测阈值;最后,对所提出的方法进行了仿真验证.仿真结果表明,在误差允许的范围内,设计的方法能够实现对间歇故障检测,满足实时性和准确性的要求.  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号