Digital Twins, Digital Threads, Digital Ghosts and Digital Shadows
The proliferation of IOT devices,
the ability to gather and manage big data, and the emergence of sophisticated
analysis and prediction technologies, are now pushing the adoption of digital
technologies. As enterprises gear themselves for the digital transformation,
new terminologies such as — Digital Twins, Digital Threads, Digital Ghosts and
Digital Shadows — are becoming mainstream.
The new terminologies and the
jargons can often leave us confused. Given the early stages and lack of
standardisation, there will be more fluidity in the definition and usage. Let’s
not worry too much about it and get to understanding the fundamentals. The
basics will provide a better grasp of the concepts.
Digital twin (or digital twins) is
a concept, not a single product or a piece of technology. Multiple technologies
— 3D simulation, IOT, 4G/5G, big data, blockchain, edge and cloud computing,
and artificial intelligence — come together to make the concept a reality.
The core principle is, for a
physical entity or an asset, a digital equivalent exists in the virtual world.
With the world being fitted with sensors, it is now possible to replicate the
physical properties and characteristics in the digital form. Practically any
physical entity or an asset — a car, an airplane, an entire factory and even
human beings — can have sensors transmitting information on a real-time basis
to its digital twin. The digital twin, feeds the physical twin with
opportunities for optimization.
The real-time two-way communication
and synchronization between the physical twin and the digital twin enables a
variety of prognostics and diagnostics opportunities for the enterprises.
According to Deloitte, “a digital
thread is a single seamless strand of data that stretches from the initial
design to the finished part”. What could it mean?
From inception to decommissioning,
a part (or a product), goes through a life cycle. Initially, the part is
digitised and information captured in an inventory tool. From there, the part
moves through a variety of stages in the life cycle – the digitised
information also travels across different systems, functions and processes.
Digital thread enables a “one-view”
of a product or part data through its life. By providing an integrated view, a
digital thread offers – full traceability, one version of truth
across multiple systems and eliminates duplicate and discrepant data of the
part across the life cycle.
Digital shadows definition is
contentious – from defined as the predecessor to digital twins, to a
subset of digital twins. Digital shadows have some characteristics of digital
Fraunhofer Austria Research GmbH,
handles the definition well. Digital shadows have one-way data flow between the
physical and digital, compared to the two-way exchange in digital twins. A
digital shadow reflects the changes in the physical objects in
the digital, and not vice versa.
General Electric (GE) is coming up
with a digital ghost. Digital twins take a security avatar in digital ghosts.
Though digital ghosts are being developed for industrial control systems, the concept
is likely to extend into any equipment defending critical infrastructure from
The core idea is to create digital
twins for control systems and to learn their behavior over time. In a
normal scenario, when the control systems are being attacked – say
the attacker spoofs the reading from a set of sensors – the anomalies
would lead to the infrastructure behaving erratically.
In a similar situation, the digital
ghosts on detecting an anomaly would replace the “spoofed readings” with
expected ones. Since the digital ghosts know how the machine normally operates,
it can isolate the problem and avoid serious repercussions to the infrastructure.
Maintenance staff can also work on fixing the anomalies without disruption to