Coordinated decentralized protocols for failure diagnosis of discrete event systems

Abstract

Abstract. We address the problem of failure diagnosis in discrete event systems with decentralized information. We propose a coordinated decentralized architecture consisting of local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the system. We extend the notion of diagnosability, originally introduced in Sampath et al. (1995) for centralized systems, to the proposed coordinated decentralized architecture. We specify three protocols that realize the proposed architecture; each protocol is defined by the diagnostic information generated at the local sites, the communication rules used by the local sites, and the coordinator's decision rule. We analyze the diagnostic properties of each protocol. We also state and prove conditions for a language to be diagnosable under each protocol. These conditions are checkable off-line. The on-line diagnostic process is carried out using the diagnosers introduced in Sampath et al. (1995) or a slight variation of these diagnosers. The key features of the proposed protocols are: (i) they achieve, each under a set of assumptions, the same diagnostic performance as the centralized diagnoser; and (ii) they highlight the "performance vs. complexity" tradeoff that arises in coordinated decentralized architectures. The correctness of two of the protocols relies on some stringent global ordering assumptions on message reception at the coordinator's site, the relaxation of which is briefly discussed.

Fault detection for discrete event systems using Petri nets with unobservable transitions

“…They formulate the active diagnosis problem as a supervisory control problem. In [7] Debouk et al propose a coordinated decentralized architecture consisting of two local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the system. In [4] Boel and van Schuppen address the problem of synthesizing communication protocols and failure diagnosis algorithms for decentralized failure diagnosis of DES with costly communication between diagnosers.…”

Diagnosis of Plans and Agents

“…First, we wish to extend the model such that the agent might evolve through several abnormal states. The resulting model will be related to diagnosis in Discrete Event Systems [6,11]. Second, we intend to investigate plan repair in the context of the agent's current (abnormal) state.…”

“…6 2. O(π ) ∩ ran O (a) = ∅ for each a ∈ Q ∩ P t , since the result of executing an abnormal action cannot be predicted (even if such an action is enabled in π);…”

The Complexity of Codiagnosability for Discrete Event and Timed Systems

“…Such decentralized architectures have been introduced in [8] and later refined in [9,10]. In these architectures, local diagnosers (with their own partial view of the system) can send some information to a coordinator, summarizing their observations.…”

“…The goal is to obtain a coordinator that can detect the faults in the system. When local diagnosers do not communicate with each other nor with a coordinator (protocol 3 in [8]), the decentralized diagnosis problem is called codiagnosis [10,9]. In this case, codiagnosis means that each fault can be detected by at least one local diagnoser.…”