Commande supervisée d'un système à événements discrets. Une approche par l'outil Grafcet

Abstract

In the supervised control of the systems with discrete events, the uncontrollable transitions are the source of prohibited states. The majority of the studies developed to solve this problem are based on the RDP. we presents here an approach for the checking of the properties of Grafcet command (presenting transitions of synchronization), the removal of the prohibited states, then the validation compared to the schedule of conditions. The technique of “precedence”, developed in order to synthesize the supervisor, rests on the extraction of the automat equivalent of the Grafcet (graph of accessible states). It allows obtaining the optimal supervisor: minimal number of stages and arcs. The Grafcet is used from beginning to end: to the modelling at the implementation on API. The results obtained were tested on an industrial system of dieing and evacuation of pieces, then implemented on a TSX 17-20 programmed in PL7-2.