Network codiagnosability of Discrete-Event Systems subject to event communication delays

Failure diagnosis is a crucial task in modern industrial systems, and several works in the literature address this problem by modeling the system as a Discrete-Event System. Most of them assumes perfect communication between sensors and diagnosers, i:e:, no loss of observation of events, or event communication delays between the measurement sites and the diagnosers. However, industrial systems can be large and physically distributed. In these cases, communication networks can be used to provide an efficient way to establish communication between devices with a view to diagnosing failure occurrence. The use of networks can introduce delays in the communication of event occurrences to local diagnosers, leading to an incorrect observation of the order of occurrence of events generated by the system and, consequently, an incorrect diagnosis decision by the local diagnoser. In this paper, we address the problem of decentralized diagnosis of networked Discrete-Event Systems subject to event communication delays, and we introduce the definition of network codiagnosability of the language of a system subject to event communication delays. We also propose an algorithm to verify this property.