Automatic transformation of simple user commands to hierarchical Petri nets

Petri nets represent a highly effective tool for the development of control systems for flexible manufacturing cells (FMC) due to their graphical modeling technique, compact representation, the availability of mathematical analysis tools and the direct transformability to PLC (programmable logic controller) programs. Since FMC control systems are required to be modifiable by low-qualified operators on the shop floor and Petri nets are too complex for them, this paper describes a concept to overcome this problem; it is based on strategic commands and information about the manufacturing system which can be specified in object-oriented following the morphological concepts commonly used by the operators and are then automatically transformed to Petri nets. An example shows how the methodology works in practice.