Ontology Alignment and System Models

Ontologies and knowledge graphs are increasingly used alongside system models in MBSE. For example, ontologies allow integrating the models with other knowledge sources, and knowledge graphs enable validating system models using graph queries, shapes and logical consistency checks. Currently, there is no clear best practice on how and when to connect a system model with an ontology. In this work, we give an overview of three different approaches: (1) The ontology can be directly referred to from the system model, (2) the ontology is only connected after the system model is serialized into a knowledge graph using a default mapping, and (3) the ontology is referred to in the mapping itself. We discuss the advantages and disadvantages of each approach and use a system model for an IoT device from the Oslo Fjord Digital Twin, originally modeled in IMF. The main contribution of this work is a comparison and discussion about possibilities for ontology alignment in system models.