A digital twin, as mentioned, is composed of a digital model, a digital shadow and a digital thread. Each of these has its own specific technology challenges associated. In addition, we shouldn’t forget that in the coming years a digital twin is bound to extend its capabilities on one hand (making use of technologies like artificial intelligence) and on the other hand it will become the component of a superorganisms, the symbiosis of the physical and the digital twin. Both bring along technology challenges.
Depending on the application area there are different ways to create a digital model and this diversity is not helping the portability of models across different areas and sometimes within the same area. In most cases there are no standards, rather the modelling format is the consequence of the software supporting it (CAD). This is the result of a vertical growth, often driven by big companies imposing their processes and tools. There are areas, like the modelling of a city, where different components (like power infrastructures, the cadastral maps, telecom infrastructures…) are modelled in different, and incompatible ways. This increases the cost in creating interoperable applications spanning several components. It would be desirable to work out a bottom up approach to solve, manage this situation.
Another aspect is that the digital model can also be used by VR and AR applications connecting the digital with the physical part. Here again the existence of some interoperable models would boost the creation of applications.
The shadowing requires a synchronization between the physical twin and its digital one. This in turns requires the physical twin to provide data mirroring its status at suitable, meaningful intervals, and a communication channel of some sort to transfer these data. Communications is becoming more and more pervasive (and affordable) and various communications paradigms are also becoming available (synchronous – low latency, synchronous with latency, asynchronous, direct, mediated…). There is already a broad spread in “shadowing”, from windmills turbine signalling their status to semi-autonomous cars reporting their status once a day. Depending on where the physical twin operates, different communications infrastructures are used. Robots in a factory plant are most likely to use WiFi type of connectivity, whilst those operating in public space may rely on radio cell networks. At home, a person’s digital twin may use a variety of ambient sensors (including smart mirrors and smart toilets) to harvest that person’s data.
All data received by the digital twin may be stored, keeping track of the evolution of the physical twin. The storing would take place in a cloud, most of the time. However, in the case of a person’s digital twin there are proposal to encapsulate these data in a person’s directly controlled device, like a smartphone. We are just starting and there is no defined architecture for digital thread data storage. Given the amazing progress in data storage medium for the next decade the storing of data does not seem to be critical, in terms of capacity. Privacy, availability and ownership control seem to dominate the discussion and steer solutions. This may change in a longer term. Additionally, as digital twin will move to stage 4 they will start to clone themselves and roam the cyberspace bringing along with them their data, so different architectures may be required. Synchronization of instances will also become a major issue. Blockchain technology may also play a role in providing a certified digital thread.