Samenvatting

Small and medium-sized production companies face many challenges in decision making about
planning, maintenance, and other operational processes due to challenges of high variety in customer
demand, configurations of the production processes, technologies used and so on. Operation Digital
Twinning is seen as a possible solution to cope with these challenges. However, the variety of influences
inside and outside the production process create obstacles, hindering the design of a practical Digital Twin.
The twinning system is identified as a socio-technical system where humans and machines work together.
In multiple research projects, we identified three factors related to the design obstacles. These are related
to 1) the predictability of the system, 2) the detectability of variations in process and environment, and 3)
the usability of regulating the physical counterpart of the twin. We combined these three socio-technical
factors of Predictability, Detectability and Usability to regulate in the PDU model. This model supports
development of Operation Digital Twins to identify issues and steer system design.