Object-oriented event-graph modeling formalism to simulate manufacturing systems in the Industry 4.0 era

In the event-based modeling formalism a system is modeled by defining the changes that occur at event times and the system dynamics can be described using an ‘Event Graph’. An event graph model is a network of event nodes describing the events that take place in the system and the relationships among these events. In the paper we extend the Event Graph framework by proposing an event-graph modeling formalism suitable to represent discrete event simulation models developed through the object-oriented approach, named Object-Oriented Event Graph (OOEG). The importance of Object–Oriented simulation is recently growing under the Industry 4.0 paradigm, in which optimization via simulation, real-time simulation, automatic decisions systems based on simulation, on line scenario analysis play a relevant role. The OOEG representation provides the same compactness of the EG representation. The advantage of the OOEG representation is that allows supporting a modelling methodology where systems are described by linking components analogously as the system components are linked, and the dynamic of the systems can be visualized in terms of interactions between objects, which have their physical correspondence in the real world.