Standardized and interoperable solutions for the digital twin

12.02.2024

Whether condition monitoring and predictive maintenance of machines or data-based optimization of manufacturing processes - the concept of the digital twin is crucial for digital industrial applications. However, implementing it for a heterogeneous machine park or broad product portfolio is technically challenging.

Therefore, industry- and manufacturer-neutral solutions have been developed to enable standardized and interoperable interfaces, which in turn are important tools for implementing digital twins, and to promote scalability. These include the Asset Administration Shell (AAS), the Open Platform Communications Unified Architecture (OPC UA) and the Automation Markup Language (AutomationML).

The question for companies now is: where and how can these solutions be used in the best possible way and what role do the individual solution components play in the overall picture of a digital twin? An insight into current research activities and results on standardized and interoperable solutions for the digital twin as well as industrial applications was provided in December 2023 in the webinar series "From research into practice" of the ZD.B thematic platform Digital Production & Engineering by Bayern Innovativ.

OPC UA, AAS and AML - an overview of their joint potential

Whether OPC UA, AAS or AML - all three are key technologies for Industry 4.0, as Maximilian Wagner, employee of the German Engineering Federation (VDMA) and project manager on the topic of European Data Spaces, makes clear in his presentation. Industry 4.0 is based on the idea of networking products, processes, factories, plants and platforms. The Industry 4.0 platform specifies this vision in more detail in the areas of autonomy, sustainability and, above all, interoperability. Interoperability means the ability of systems to communicate across devices or applications, including operational technology (OT) and information technology (IT), with standardized data models and interfaces. This is why these technologies are so important. It is also important to emphasize that they complement each other, especially in terms of interoperability. But what exactly are the technologies and how do they differ? Mr. Wagner gives a brief overview, starting with AutomationML (AML).

AutomationML: Tool2Tool exchange - specialized for the engineering phase

AutomationML is a neutral, XML-based data format for the storage and exchange of engineering data that uses a comprehensive XML-based object-oriented data modelling language. It enables the repeated exchange of data in the field of engineering, particularly with regard to geometry, kinematics, logic (PLC), etc. AutomationML thus ensures consistent, digital and loss-free data exchange in engineering tool chains

OPC UA as an established interoperable solution for machines from the field to the cloud

OPC UA is a platform-, manufacturer- and industry-independent framework. It enables the secure and reliable horizontal and vertical exchange of information between components, machines or systems and control systems, even across company boundaries. OPC UA supports various communication patterns (client/server and pub/sub) and transport protocols (such as TCP, UDP and MQTT) and scales from small units such as sensors right up to the cloud. Security by design ensures security in data transmission, visibility and access to information. It has a high level of international acceptance and is established as a standard in many countries. Domain-specific information models are already standardized in over 60 industry-specific companion specifications. The cross-domain specification OPC UA for Machinery serves as the basic specification for mechanical and plant engineering

The administration shell as a central information hub for the entire life cycle

The administration shell, or asset administration shell (AAS), is the digital representation of an asset throughout the entire product life cycle. It serves as a central information hub for types and instances and, thanks to its standardized software structure, interfaces and semantics, provides quick and easy access to data about an asset throughout its entire lifecycle using the latest security mechanisms. The asset administration shell enables communication between different asset administration shells via applications and structures data using standardized submodels.

Discussion paper - Interoperability with the asset administration shell, OPC UA and AutomationML

How can these three technologies work together effectively? In this context, Mr. Wagner refers to a discussion paper sponsored by AutomationML e.V., IDTA, OPC Foundation, VDMA and experts from Microsoft, KUKA and Siemens. It can be downloaded free of charge at www.vdma.org/viewer/-/v2article/render/78243357. This describes a target image or a "big picture of interoperability" that shows how the three technologies mentioned fit together, complement each other and how interoperability across domains is achieved through combined application in industrial automation. The focus of AutomationML is on the exchange of engineering data during the development (engineering) of assets and industrial systems, prior to the operation of a plant. It addresses the interoperability between proprietary engineering tools and simplifies the creation of consistency between plant design tools. The focus of OPC UA and its Companion Specifications is on standardized reporting and access to data during the operation of a plant or asset. The Companion Specifications provide semantic descriptions of the data and functions. The focus of the asset administration shell with its sub-models is on the digital representation of the asset and the standardized provision and access of features and information across the entire life cycle. In conclusion, Mr. Wagner states that when used appropriately, duplication of work and model overlaps are avoided and the development effort is reduced. Interoperability is achieved through a clever combination of different standards. Anyone interested in finding out more about this topic is cordially invited to register for the VDMA's Interoperability Summit 2024.

Making Industry 4.0 simple - Eclipse BaSyx as an enabler

The aim of the digital twins in Industry 4.0 is to establish a common language in which all systems can communicate and exchange information. This should enable interoperability between different machine components. In his presentation, Rene-Pascal Fischer from the Fraunhofer Institute for Experimental Software Engineering IESE explains how this can be achieved

Easy integration through open concepts

He focuses on the open source middleware Eclipse BaSyx (https://eclipse.dev/basyx/ & github.com/eclipse-basyx) and its role in the creation of digital twins based on the asset administration shell standard. Eclipse BaSyx offers not only a software development kit in various programming languages, but also "off-the-shelf" components. These enable both an easy way to try out the concepts of the administration shell without major entry hurdles and easy integration into existing systems. The focus is on open concepts that facilitate the connection of data from various sources, including sensors, the Industrial Internet of Things (I)IoT and other devices, to create a comprehensive digital representation of relevant assets.

The importance of a common language

Mr. Fischer explains the importance of a common language in Industry 4.0, comparable to the way people communicate with each other. The digital twin represents the real world and the virtual realm. It is a digital representation of a physical object or concept, such as a manufacturing process, with the relevant attributes. Various technologies can be used to transfer this to the digital world. However, the digital twin is only complete when the data is exchanged bidirectionally between the asset and the digital representation. This can also create possibilities for controlling the assets.

Digital representation through the asset administration shell

With regard to the asset administration shell, Mr Fischer emphasizes that it offers a digital representation of various components, is manufacturer-independent and is used in the open source sector as well as in international standardization. The aim is to create something interoperable, not only at national but also at international level. Mr. Fischer addresses various areas of application for digital twins - from machines and products to processes and the workforce. Quality assurance and explainability are key aspects, especially in the context of industries such as medical technology.

How do I track the carbon footprint of my products? The administration shell for mapping the entire production process

More and more manufacturing companies are facing the challenge of having to determine the CO2 footprint of their products. In this context, Christof Baumgartner from XITASO GmbH IT & Software Solutions focuses in his presentation on the administration shell, also known as the Asset Administration Shell (AAS). This makes it possible to map the entire production process. It provides the technological prerequisite for storing linked data in a structured manner. Not only components and products can be digitally mapped, but also information on supply chains, for example.

Utilizing potential across the entire life cycle

The three major potentials of the asset administration shell are the digital product passport, production-as-a-service and after-sales services. The idea behind the digital product passport is to record all relevant data from ordering to production and use. Particular attention is paid to the CO2 footprint of the products. The administration shell enables the configuration and control of production steps and machines as well as the recording of production-specific data with regard to Production-as-a-Service. Another important aspect is the consideration of a product's life cycle after use, particularly with regard to maintenance and support.

Demonstrator of the Labs Network Industrie-4.0

Now Mr. Baumgartner presents the demonstrator that was developed as part of the Labs Network Industrie-4.0 (LNI4.0). As part of this implementation, the decision was made to use a simple demonstrator: a customizable aluminium ballpoint pen. Even such a comparatively simple product undergoes a complex production process. In this case, the raw material comes from Abu Dhabi and the production process includes various steps such as transport, processing, individualization by laser engraving, renewed transport and delivery to the end customer. Mr. Baumgartner describes how the process can be transferred to the administration shell

Individual usability of the administration shell

Basically, the administration shell is used at type level during product development. For this purpose, a type is defined for the asset administration shell, which specifies the master data and general information of a ballpoint pen. When an order is received, an individual instance of a specific ballpoint pen is created from this type description and the master data is derived. This instance then runs through the life cycle of the product, with data being added gradually. The asset administration shell can also be handed over to a customer, who can use the instance in their own infrastructure. Standardized data formats allow information to be exchanged easily, which is particularly important when it comes to recycling

Making the best use of data through linking

In practice, the added value of the asset administration shell is demonstrated by various submodels that are filled at different times. These models include the product group footprint, the bill of materials, the production process, technical data and more. The linking of asset administration shells enables a comprehensive ecosystem in which data can be used seamlessly. A viewer provides an overview of the various production steps and CO2 emissions. In addition, data can be linked to other asset administration shells, e.g. to machines to monitor energy consumption. These links enable efficient work and integration with other applications, such as ERP systems or product configurators.

The webinar series "From research into practice"

In the event format of the ZD.B thematic platform Digital Production & Engineering from Bayern Innovativ, research institutions and companies provide insights into current research activities and discuss these with participants. The aim is to support small and medium-sized companies in particular in making meaningful use of digital technologies in their production processes and engineering.

The new year starts with news

In order to further bundle the network expertise at Bayern Innovativ, the topics and activities in the field of digitalization in production and engineering as well as Industry 4.0 will be continued in the Mechatronics and Automation Cluster from 01.01.2024. The successful webinar series "A bridge between science and industry - from research to practice" will continue as usual.

Contact details of the speakers:

Maximilian Wagner, VDMA e. V, Project Manager, Department Machine Information Interoperability
Contact by Mail

Rene-Pascal Fischer, Scientist, Department Virtual Engineering, Fraunhofer Institute for Experimental Software Engineering IESE
Contact by Mail

Christof Baumgartner, XITASO GmbH IT & Software Solutions
Contact by Mail