Cyber-physical Systems Integration in a Production Line Simulator

Digital Twin represents a simulated model of a production line which allows making analyses of future states concerning the real factory. More in details, these analyses are related to the variability of production quality, prediction of the maintenance cycle, the accurate estimation of energy consumption and other extra-functional properties of the system. This is the core of what is so called Industry 4.0. Every single node of the manufacturing process needs to be modelled as a Cyber-physical system to be able to make the mentioned analyses. However, Manufacturing simulators represent these systems with a high level of abstraction, making impossible precise analyses. In the state of the art, some solutions try to solve the problem connecting multiple domain-specific simulators, to preserve details but requiring complex co-simulation environments. This paper presents a methodology for the integration of Cyber-Physical Systems in production line simulators, avoiding these issues. The proposed solution is based on a new promising technology: the Function Mockup Interface (FMI). This standard defines an interface to exports models as blocks called Functional Mockup Units (FMUs). These FMUs can be easily integrated together composing heterogeneous systems. The methodology is composed of two steps: 1) Exporting Digital and Physical systems as different FMUs 2) Integration of the FMUs into a production line simulator. A running example is used to validate our solution which clearly shows the limitations of the production line simulator without the integration of CPSs. This paper aims at producing Cyber-Physical Production Systems (CPPS) to make more accurate simulations, and hence more accurate analysis of the production line.