An extension of high-level Petri nets for modelling batch systems

This paper deals with the modelling of batch systems by means of high-level Petri nets. Batch systems are systems that transform a continuous raw material through continuous equipment (as heat exchanger for example) and batch equipment (for instance, batch reactor). These systems are frequently used by chemical of food industry. Batch systems deal with concurrent activities and resource allocation mechanism. As a consequence a natural model for these systems are Petri nets. However they are not well suited for modelling continuous behaviour. The aim of this paper is to present an extension of Petri nets in order to model batch systems. Based on a toy example of a billiard table [14], the paper shows the limits of Petri nets. Hybrid Petri nets are not satisfactory because, although they are well suited for modelling vessels, they do not cover the range of batch systems. High-level nets, as coloured Petri nets [12], are a common model for batch systems. However, based on the toy example, the limits of coloured Petri net is illustrated. An extension of high-level Petri nets is presented through the billiard example: differential-predicate-transition nets [3]. The new concept introduced by this model is that it is a Petri net with continuous variables whose evolution is dynamic and represented through sets of differential algebraic equations. Key-Words: Petri nets, high-level nets, hybrid systems IMACS/IEEE CSCC'99 Proceedings, Pages:2621-2625