An object-oriented and Petri net based approach for real time control of FMSs

This paper shows how to design a high quality software structure for real time control of flexible manufacturing systems (FMS). To increase the software quality factors, an object-oriented (OO) design methodology is used: HOOD/PNO (Hierarchical Object-Oriented Design with Petri Nets and Objects). It merges object abstraction principles and Petri net formalism. When designing FMS control, this methodology leads to define a control structure which is based on three abstraction hierarchies: a composition hierarchy, a classification hierarchy and a service hierarchy. The OO design is based on a control strategy which ensures an efficient integration between both real time manufacturing and forecast control