Fault diagnosis resilient to observation delays in Networked Discrete-Event Systems using sequence numbers

Abstract

In order to reduce the costs of implementation and maintenance, communication networks are used in networked Discrete-Event Systems (NDES), providing an efficient way to establish communication between several devices in the plant. In many cases, multi-hop mesh networks are used, as on wireless sensor networks, with re-transmissions due to degradation, leading to delays in communication and, consequently, the observation of events in a different order from their occurrence in the system. In this paper, we address the problem of fault diagnosis of NDES, resilient to observation delays in the communication network. We consider that each event is communicated together with its sequence number, and we show how the sequence number can be used to improve the fault diagnosis capability in the presence of observation delays, without the need to reorder the sequence of events according to the sequence number.