Design and implementation of a modular supervisory control system of a batch process

The paper addresses the design and implementation of the logic control functions of a multi-recipe batch process. A hierarchical control structure is adopted, with one supervisor module co-ordinating many “slave” controllers. Suitable rules are given based on supervisory control theory for the synthesis of the supervisor, described with Petri nets. As for the slave controllers, it is shown that Grafcet/SFC models are more compact and appropriate to the purpose, provided that a suitable interface with the supervisor is provided. Finally, the implementation of the supervisor-control structure is described, using the IEC1131-compliant Ladder Diagram language.