Synthèse structurelle d'un contrôleur basée sur le Grafcet
Bassam Kattan · HAL (Le Centre pour la Communication Scientifique Directe) · 2004
In this thesis, we have presented two contributions for the problem of synthesis of a discrete event systems controller using the Grafcet Model. The supervisory control theory of discrete event systems (DES) introduced by Ramadge and Wonham, is not directly implemented under the form of an operational control. We can find in the literature various extensions of the approach RW in which the supervisor can force events, among those there exist the supervised control suggested by François Charbonnier in his thesis (1996). We have made an extension of this approach, in the case where the language of the specifications is not controllable compared to the language of the extended process. To implement the supervisor's automat obtained, we have proposed a systematic method of passage of the automaton of the supervisor to the Grafcet of the supervisor in a structural way. However in this approach, the final Grafcet of the supervisor obtained contains a significant number of steps that is identical to the synthesized automat. Thus the complexity of the supervisors always remains prohibitive. This is why we have proposed an approach of structural synthesis, in which the size of Grafcet obtained is reduced and directly implemented in the PLC. This method is based on the place invariants which allow determining a certain number of steps to be added to the initial model to make respect the specifications of control. We have established general properties that made it possible to find the set of the linear constraints starting from the set of the forbidden states. The solution obtained gives an optimal controller. This optimality comes from the equivalence between the set of authorized states and the set of linear constraints. It was proven thanks to the Boolean character of the marking of Grafcet.