Using Ptolemy II as a Framework for Virtual Entity Integration and Orchestration in Digital Twins

The concept of Digital Twin (DT) is increasingly getting attention due to its support for digital transformation as part of Industry 4.0. A core component of a DT is the virtual entity (VE) that is meant to ‘mirror’ the physical entity (PE). A particular challenge for developing this VE is the integration between the different models that typically make up such a VE. These models, covering different disciplines or aspects of a system, commonly are developed by different engineers and expressed in different formalisms given their strengths and weaknesses. This makes integration between these models and formalisms a challenge. Such integration has two aspects: the communication among the models, and their orchestration, which concerns the order of model step execution and data exchange. In this paper, we consider the suitability of Ptolemy II, an open source framework based on an actor-oriented structure, to implement such integration. We use the Ptolemy II framework to reproduce the implementation of a DT of an autonomous scaled-down truck, which originally required a more manual configuration and execution and was developed in a monolithic way. The results show that Ptolemy II can be used to implement different communication technologies as actors, and show the expressiveness of the orchestrators by reproducing the existing DT’s behavior. This shows Ptolemy II in principle to be suitable as an integration and orchestration tool for models in the context of DTs. As future work, we plan to apply the framework to more complex DTs using different communication technologies, so as to validate its broader suitability for VE orchestration in DTs.