Decentralized prognosis of failures in discrete event systems
Decentralized prognosis of failures in discrete event systems
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DOI：
10.1109/wodes.2008.4605975
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发表时间：
2008-05
期刊：
影响因子：
--
通讯作者：
R. Kumar;S. Takai
中科院分区：
文献类型：
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作者：
R. Kumar;S. Takai
我们研究失败的预后，即，它们的预测发生之前，在分散设置的离散事件系统中，多个预测器使用它们的本地观察来发布本地预测决策。我们定义的概念的正确性的一个分散的一组的observers在ldquono错过的detectionsrdquo（每一个故障是observed之前，它的发生）和ldquono假alarmsrdquo（一个不正确的预后决定是从来没有发出），并引入概念的coobservability作为一个存在条件。当专用于集中式情况时（即，在一个单一的条件下），这个条件比在（S。Gene和Sl Lafortune，2006年），因为不需要在其中将发生故障的步骤的数量上的统一界限。为了比较，我们还引入了更强的概念ldquuniformly有界coquilabilityrdquo，并确定子类的分散的callersers，它作为一个存在条件。我们表明，这两个概念相吻合时，底层系统和其非故障规范具有有限状态表示，并提出了一个验证算法。我们还介绍了反应界的概念，coprojective-as最早的时间超出了预测的决定时，可能发生故障，并提出了一个算法来计算它。我们发现，概念的cobensability和它的一致有界的版本是在一般情况下无法比拟的概念的cobidiosability（保证一个统一的有界延迟检测故障的本地诊断）。当系统不能执行一个无界序列的不可观测事件时，一致有界可协性意味着可协诊断性，而可协性和可协诊断性仍然是不可比较的。
We study the prognosis of failures, i.e., their prediction prior to their occurrence, in discrete event systems in a decentralized setting where multiple prognosers use their local observations to issue local prognosis decisions. We define the notion of correctness of a decentralized set of prognosers in terms of ldquono missed detectionsrdquo (each failure is prognosed prior to its occurrence) and ldquono false alarmsrdquo (an incorrect prognostic decision is never issued), and introduce the notion of coprognosability as an existence condition. When specialized to the centralized case (i.e., the case of a single prognoser), this condition turns out to be weaker than the one introduced in (S. Gene and Sl Lafortune, 2006) since a uniform bound on the number of steps within which a failure will occur is not required. For comparison we also introduce the stronger notion of ldquouniformly bounded coprognosabilityrdquo and identify the subclass of decentralized prognosers for which it serves as an existence condition. We show that the two notions coincide when the underlying system and its nonfailure specification possess finite-state representations, and present a verification algorithm. We also introduce the notion of reaction bound for coprognosis as the earliest time beyond a prognostic decision when a failure can occur, and present an algorithm for computing it. An algorithm is also presented for an online prognosis of failures. We show that the notions of coprognosability and its uniformly bounded version are in general incomparable with the notion of codiagnosability (that guarantees a uniformly bounded delay detection of a failure by a local diagnoser). When the system cannot execute an unbounded sequence of unobservable events, uniformly bounded coprognosability implies codiagnosability, whereas coprognosability and codiagnosability remain incomparable.