In this paper, we present a method for discrete event system identification with the aim of fault detection. The method is based on a new model called Deterministic Automaton with Outputs and Conditional Transitions (DAOCT), which is computed from observed fault-free paths, and represents the fault-free system behavior. In practice, a trade-off between size and accuracy of the identified automaton has to be found. In order to obtain compact models, loops are introduced in the model, which implies that sequences that are not observed can be generated by the model leading to an exceeding language. This exceeding language is associated with possible non-detectable faults, and must be reduced in order to use the model for fault detection. We show, in this paper, that the exceeding language generated by the DAOCT is smaller than the exceeding language generated by another model proposed in the literature, reducing, therefore, the number of possible non-detectable faults. We also show that if the identified DAOCT does not have cyclic paths, then the exceeding language is empty, and the model represents all and only all observed fault-free sequences generated by the system. In order to illustrate the results of the paper, a physical system is simulated by using a 3D simulation software controlled by a Programmable Logic Controller (PLC). The main idea is to use a virtual digital system to simulate the fault-free behavior of a physical system, captured by the sequences of input and output signals of the PLC, and then use the method proposed in the paper to obtain the DAOCT model of the plant.

中文翻译：

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以故障检测为目的的离散事件系统识别

在本文中，我们提出了一种以故障检测为目的的离散事件系统识别方法。该方法基于称为具有输出和条件转换的确定性自动机 (DAOCT) 的新模型，该模型根据观察到的无故障路径计算得出，并表示无故障系统行为。在实践中，必须找到已识别自动机的大小和准确性之间的权衡。为了获得紧凑的模型，在模型中引入了循环，这意味着模型可以生成未观察到的序列，从而导致超出语言。这种超出范围的语言与可能的不可检测的故障相关联，必须减少以使用该模型进行故障检测。我们在本文中表明，由 DAOCT 生成的超出语言小于由文献中提出的另一个模型生成的超出语言，因此减少了可能的不可检测故障的数量。我们还表明，如果识别出的 DAOCT 没有循环路径，则超出的语言是空的，并且模型表示所有且仅所有观察到的系统生成的无故障序列。为了说明论文的结果，使用可编程逻辑控制器 (PLC) 控制的 3D 仿真软件对物理系统进行了仿真。其主要思想是利用虚拟数字系统来模拟物理系统的无故障行为，通过PLC的输入输出信号序列捕获，然后利用论文中提出的方法得到DAOCT模型植物。