Digital Twin – Modeling Interrelated Devices
O VERVIEW
Digital Twin, i.e. the real time representation of physical things/devices in a cloud environment,
is at the core of Internet of Things (IoT) solutions. The digital twin of a thing/device could be as
simple as a JavaScript Object Notation (JSON) document or as complex as a CAD simulated model
that interact with the real time data.
In this article we focus on public cloud vendors such as Microsoft Azure®, Amazon AWS® and
Google GCP® as they are big enablers for IoT applications because they provide cost effective
store and compute infrastructure for batch and real time analytics.
Connected Devices and Connected Factory IoT solutions model real physical devices/things such
as pumps, generators, vending machines, etc., to their corresponding digital twin representation.
The picture below shows the JSON representation of a physical device (a Power Generator Gen
Set) through its digital twin equivalent in a prototypical Industrial Internet Reference Architecture
(IIRA) 1 based IoT platform in the cloud.
Public cloud IoT platforms work very well for ‘atomic’ representation of things/devices but they
lack the ability to model hierarchical relationships among the thing/devices, e.g., modeling a
pump station that contains a pump and a tank device as digital twin in the IoT platform.
The challenges of modeling interrelated devices in digital twins includes:
Modeling the relationship between system and components.
Modeling the Inheritance between system components.
Issues related to embodiment of system structure into digital twin.
Current tools are inadequate due to incomplete knowledge transfer of requirements
between OT and IT teams.
Leverage existing semantic representation of plant floor devices (OPC UA Information
Modeling, SensorML, and S95).
Etc.
This article presents a unique approach on how these challenges could be addressed to generate
the digital twin representation of a complex system, such as a factory.
1
IIRA: The Industrial Internet Reference Architecture (IIRA) is a standards-based open architecture defined by the Industrial
Internet Consortium (IIC). Its objective is to have broad applicability to drive interoperability, map applicable technologies and to
guide technology and standards development. http://www.iiconsortium.org/IIC_PUB_G1_V1.80_2017-01-31.pdf
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March 2018