Using Interval Constrained Petri Nets for Regulation of Quality: The Case of Weight in Tobacco Factory

The existence of maximal durations drastically modifies the performance evaluation in Discrete Event Systems (DES). The same particularity may be found on systems where the associated constraints do not concern the time. For example weight measures, in chemical industry, are used in order to control the quantity of consumed raw materials. This parameter also takes a fundamental part in the product quality as the correct transformation process is based upon a given percentage of each essence. Weight regulation therefore increases the global productivity of the system by decreasing the quantity of rejected products. The main contribution of this paper is to describe the behaviour of the Interval Constrained Petri Nets (ICPN). Their basic evolution rules are presented and the extension of the P- time PN structural analysis is discussed. An industrial application on a tobacco manufacturing plant, where the critical parameter is the weight is presented as an illustration.