Designs of Bisimilar Petri Net Controllers With Fault Tolerance Capabilities
Designs of Bisimilar Petri Net Controllers With Fault Tolerance Capabilities
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DOI：
10.1109/tsmca.2007.909559
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Lingxi Li;C. Hadjicostis;R. Sreenivas
中科院分区：
文献类型：
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作者：
Lingxi Li;C. Hadjicostis;R. Sreenivas
本文提出了一种容错的方法，这种容错可能会损害由Petri网建模的给定控制器的功能。该方法基于将给定的PETRI网控制器嵌入到一个更大的(冗余的)PETRI网控制器中，该控制器保留了原有的功能和属性，并使用附加的库所、连接和令牌来施加不变条件，从而允许通过线性奇偶校验来系统地检测和识别故障。具体地说，本文考虑了两种类型的冗余Petri网控制器：1)非独立冗余Petri网控制器具有与给定的Petri网控制器相同的功能，并允许故障检测和识别，但不一定保持给定的控制器不变；2)独立的冗余Petri网控制器是非分离的冗余控制器的特例，它保持给定的Petri网控制器不变，但增加了额外的位置以实现故障检测和识别。本文得到了这两类冗余控制器的完全刻画，以及它们与给定的原Petri网控制器互模拟等价的充要条件。此外，本文还讨论了如何将每种类型的冗余控制器设计成具有理想的故障检测和识别能力。当不直接实施互模拟等价要求时，非独立冗余控制器可能比单独的冗余控制器具有优势(例如，它们可以使用更少的连接来检测和识别相同数量的故障)。文中给出了一个生产单元的PETRI网控制器及其容错能力的例子，说明了该方法的可行性。
This paper proposes an approach for providing tolerance against faults that may compromise the functionality of a given controller modeled by a Petri net. The method is based on embedding the given Petri net controller into a larger (redundant) Petri net controller that retains the original functionality and properties, and uses additional places, connections, and tokens to impose invariant conditions that allow the systematic detection and identification of faults via linear parity checks. In particular, this paper considers two types of redundant Petri net controllers: 1) nonseparate redundant Petri net controllers have the same functionality as the given Petri net controller and allow for fault detection and identification, but do not necessarily retain the given controller intact; and 2) separate redundant Petri net controllers are a special case of the nonseparate redundant controllers that retain the given Petri net controller intact but enhance it with additional places to enable fault detection and identification. The work in this paper obtains complete characterizations of both types of redundant controllers along with necessary and sufficient conditions for them to be bisimulation equivalent to the given original Petri net controller. In addition, this paper discusses how each type of redundant controllers can be designed to have desirable fault detection and identification capabilities. When the bisimulation equivalence requirement is not directly enforced, nonseparate redundant controllers can potentially have advantages over separate ones (e.g., they can use fewer connections to detect and identify the same number of faults). An example of a Petri net controller for a production cell and its fault tolerance capabilities using separate and nonseparate embeddings is used to illustrate the approach.