Ontologies represent data domains as sets of concepts and the relationships between them. Ontologies are often created at different times, by different engineers with their own approaches and viewpoints. This leads to different developers using different vocabularies, something called semantic heterogeneity, which creates interoperability issues that limit an effective exchange of knowledge. Global or shared ontologies aim to identify common elements and can save time and resources by enabling sets of classes, properties and axioms to be reused.
There are, however, a number of challenges to creating global ontologies. Firstly, a balance needs to be struck between reusability and usability. Ontologies need to be sufficiently general that they can easily be applied to a range of applications, but not so general that they require extensive adaptation and customisation. In addition to this, global ontologies tend to be developed from scratch by domain experts and ontology engineers which demands significant investments of time and resources.
At the recent Eclipse Arrowhead workshop in Lübeck, Engineers from Mondragon University in Spain presented a unique approach that draws on principles used in the development of Software Product Lines and domain analysis of existing ontologies to generate ontologies for Industry 4.0. The approach draws on ontologies of legacy applications developed in the Industry 4.0 context to create new global ontologies that represent systems and manufacturing domains. This knowledge is then further classified into modules and layers and includes mappings between legacy ontologies.
The result is I40GO, a series of modules that can be reused or customized to develop ontologies for different applications in Industry 4.0 processes such as manufacturing automation and monitoring, distributed manufacturing, and production scheduling. The MODDALS methodology presented by Mondragon represents a significant step toward interoperable Industry 4.0 applications with shared vocabularies as well as interoperability between legacy systems that rely on already developed ontologies.
MODDALS methodology website: https://innoweb.mondragon.edu/ontologies/MODDALS/index-en.html
I40GO ontology website: https://innoweb.mondragon.edu/ontologies/i4go/index-en.html