  While the Industry 4.0 is idolizing the potential of an artificial
intelligence embedded into "things", it is neglecting the role of the human
component, which is still indispensable in different manufacturing activities,
such as a machine setup or maintenance operations. The present research study
first proposes an Industrial Internet pyramid as emergent human-centric
manufacturing paradigm within Industry 4.0 in which central is the role of a
Ubiquitous Knowledge about the manufacturing system intuitively accessed and
used by the manufacturing employees. Second, the prototype of a
Service-oriented Digital Twin, which leverage on a flexible ontology-oriented
knowledge structure and on augmented reality combined to a vocal interaction
system for an intuitive knowledge retrieval and fruition, has been designed and
developed to deliver this manufacturing knowledge. Two test-beds, complimentary
for the problems in practice (the former on the maintenance-production
interface in a large enterprise, the latter majorly focused in production and
setups in a small and medium enterprise), show the significant benefits in
terms of time, costs and process quality, thus validating the approach
proposed. This research shows that a human-centric and knowledge-driven
approach can drive the performance of Industry 4.0 initiatives and lead a Smart
Factory towards its full potential.
