In this paper, we present two different methods for the synthesis of a simplified controller using Petri Nets. The supervisory control theory presented by Ramadge and Wonham is adapted to Petri nets modeling. Uncontrollable transitions in discrete event systems are the cause of forbidden states in supervisory control. This paper concerns the problem of forbidden states in safe Petri Net. We present different methods to reduce the number of constraints that prevent from forbidden states. Using these methods, we can construct a maximally permissive controller. The implementation of these approaches is considered using the SFC model.
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[*]Semnan University, IRAN (Tel: (+98)231-3354123
[**]GIPSA lab, 38402 St Martin d'Heres Cedex FRANCE