Perceptions of digital twins

The interviewees were asked about their perceptions of the digital twins: what do they think DT is and what does it require. The given answers were quite various (Table 7) and some of the interviewees emphasized that they cannot represent the entire company’s opinion as there are differing views of DT inside the companies too.

Table 7. Perceptions of the digital twin Company Perceptions of the digital twins

#1 DT represents a structure or a product model.

#2 DT is when something is done to a physical product and the changes go back into the digital model.

#3 DT represents a real product.

#4 Not a single DT but multiple different DTs, such as simulation model, 3D model and usage data model.

#5 DT is a simulation model which consists of sensors and measurement data.

#6 DT represents an actual process which can be simulated on a computer and where the used models are similar in the system as in practice. Another view of DT is connecting a system or a device to an actual system.

#7 DT means any IT "node" for data measured from device sensors.

#8 Many interpretations on DTs. One: a physic based, real-time or non-real-time simulation model.

Another view: a DT produces additional information based on a vast data flow. Third view: the DT is involved through the whole product life cycle from planning phase to use. If real product goes through some modifications, these changes are updated into DT as well.

As shown in Table 7, interviewee from company #1 found the DT being a structure. According to him, company’s need for DT ends when the device to which it is connected is disassembled, though the DT can be utilized still in the disassembling phase. The interviewee also presented an example of the DT in his mind as a product model: the model can be a light version, such as Power Point presentation or a heavier, more complex version with multiple actors in ecosystem, depending on the application. Their company does not use DT in operational monitoring.

Interviewee from company #2 presented a rather simplistic view of DT: he stated that DT is in question when something is done to a physical product and the changes go back into the digital model.

Simulation and modelling were popular perceptions of the digital twin in for many interviewees.

Representative from company #3 pointed the DT as 3D model from real object. Interviewee from company #4 raised the view of many different DTs: he thought that there is not just a single DT but multiple different DTs, such as simulation model, 3D model, and usage data model. He highlighted the variability of DT definitions depending on who is being asked.

Company #5 representative thought DT is a simulation model which consists of sensors and measurement data. This simulation model interacts with reality through limited number of sensors and the status changes based on the data.

Company #6 had three interviewees representing them: one found the DT as an actual process which can be simulated on a computer and where the used models are similar in the system as in practice. Another view of DT was that it connects a system or device to an actual system.

For him the connection is important as he stated that only the connection makes a digital twin, otherwise it is just a simulation. The third interviewee did not express her view.

For a representative from company #7 the DT means any IT "node" for data which is measured from a device sensor. His example of DT was an asset hub which consists of rows in database.

These rows contain data fields: some field is connected to device design information, other to manufacturing information, third to maintenance procedures, fourth to usage data etc. In summary, the DT for interviewee #7 is device's digital performance which is formed during the design, production and usage. It is a digital object linked to real object with real-time data.

“I see the digital twin as a row of databases which connects the device as comprehensively as possible to the digital representation. It has arisen during the design, manufacturing, and use of the [device]… The key feature is that it has a connection to a [real] device in the field: an object which is connected to the data, or which collects the data, it is the digital twin.” - #7

The broadest view came from company #8’s representative. This interviewee saw many interpretations on the meaning of the digital twins. One view: a physic based, real-time or non-real-time simulation model, which imitates processes and produces information which increases knowledge. It is used to describe certain things and can be for example a basic model of a machine or device. It links to process model as well as the ERP it operates. Basically, it imitates a function of a real device in a real process. Another view: the DT produces additional information based on a vast data flow. This means that the digital twin must create more value than the data itself is able to. It is not just parameters in 3D model but contains added data analytics or data-based value. And lastly: the DT is involved through the whole product life cycle from planning phase to use. This means that when a real product goes through some modifications, these changes are updated into DT as well. This digital twin holds device information such as how it is built and what parts does it contain. It is not just a design model but functioning 3D model which increases service knowledge as well.

“[With the digital twin] something that happens can be simulated on a computer.

The system contains similar models as in practice.” - #6

As seen, the meaning of a digital twin varied quite a lot between interviewees. One view of the DT is structural understanding in which data, such as exact dimensions of customized products, can be stored while other required up-to-date information flow in both directions, from real object to digital version and vice versa.