A protocol for Decentralized Synchronous Diagnosis with Coordination

Abstract

Recently, a new architecture for decentralized diagnosis of Discrete Event Systems, called Decentralized Synchronous Diagnosis, has been proposed in the literature. In this scheme, local diagnosers are computed based on the fault-free behavior of the system components, which, in comparison with the classical diagnosis approach, reduces the size of local diagnosers for implementation. Although this method has been successfully implemented, its main drawback is the emergence of an exceeding fault-free language of the system for diagnosis, which reduces the diagnosis efficiency. To circumvent this problem, in this paper, a protocol for Decentralized Synchronous Diagnosis with Coordination (DSDC), which refines the diagnosis status using cluster automata of the local component models, is proposed. The protocol is based on the implementation of local state estimators of the fault-free component models of the system which communicate cluster automata to a coordinator. The indication of the fault occurrence is carried out by the coordinator according to the observed behavior of the system. To do so, communication rules between local state estimators and the coordinator are proposed. The protocol prevents the emergence of an exceeding fault-free language for diagnosis, which guarantees the same diagnosis performance as the traditional monolithic approach. In addition, the implementation of the DSDC in a didactic manufacturing system is presented to illustrate the results.