Time window specification and validation with Petri Nets

The existence of maximal durations drastically modifies the performance evaluation of discrete event systems (DES). For instance, the classical formulas used for a cycle time computing can not be used. Nevertheless, there are a lot of these constraints in food and chemical industries. Therefore, using P-time PN in order to compute performance evaluation and to prove functioning margin existence is depicted in this paper. Then, the HLPN are shortly described. Based upon HLPN definition, the Hypernets are introduced. It is shown that the behaviour of a system considering time window constraints specification can be performed by the same way using P-time PN or Hypernets. Moreover, handling P-time PN as a sub-class of Hypernets allows integrating them in a global approach. It is obvious that time is not the only parameter to take into account in a plant scheduling. Hypernets allows integrating the parameter that P-time PN are not able to model. The paper ends with a proposition for an integrated approach based upon the two kinds of net. A global scheduling is made with Hypernets and a local analysis with P-time PN. This approach is illustrated on electroplating lines.