Cross-vendor interoperability within reach – Will education tip the scales?
The golden calf of digitalization, absolute, vendor-independent interoperability between devices, components and software applications of all kinds, remains out of reach for the time being. Despite all the progress made – and there is plenty of it, just look at the steadily rising star of OPC UA, for example – some goals on users' wish lists remain unfulfilled. Among them the semantic description of the capabilities of a system. There is a technology that promises to change that, but it has been overshadowed by other technologies deemed more important. Can the field of education play a pivotal role in bringing this subject to the forefront and driving its progress? Introducing tomorrow's engineers to visionary possibilities could lay the foundation for the industry of the future.
Have you heard of the asset administration shell (AAS)? If you deal with topics related to the digitalization of industry on a frequent basis, then chances are good. If you don’t, then the topic is likely to be unfamiliar. A simple Google Trends search (1) proves the lower popularity of the asset administration shell compared to the digital twin – a virtual representation of a real-world object, process, or system, used for analysis, monitoring, and simulation to gain insights and optimize performance. But what is the reason for this discrepancy? It's probably related to the fact that the Digital Twin is a vague concept, with no concrete technological manifestation, which can accordingly be easily applied to any products and solution approaches. On the other hand, the asset administration shell has been on a standardization course for years and has reached the point where it is possible to say exactly whether something is an asset administration shell or not.
What is an asset administration shell and how does it work?
First things first: What is an asset administration shell? The buzzword started out as a thought construct just as nebulous as the digital twin, sometimes used as a synonym, sometimes with more or less subtle differences to it. What all interpretations have in common is that the asset administration shell forms an interface to the data and functionalities of an "asset" – an object of value to its owner. The asset administration shell should make this data and functionality accessible in a standardized, manufacturer-independent manner so that added value can be generated from it. And it should do so along the entire value chain, throughout the asset's lifecycle and across all business units. No small challenge. In a nutshell: The asset administration shell represents a concrete implementation of a Digital Twin. The sharp comparison we made above is honestly not appropriate.
In November 2018, a technical specification was developed to define the core of what constitutes the administrative shell. The specification describes a metamodel that allows for the modeling of a wide variety of information and functions about the associated asset. This document has been enhanced several times since its first release: Now available is version 3.0RC02 with an impressive 160 pages of content plus appendices. Part 2 of the specification, which defines the interfaces for accessing the asset administration shell, has been added.
Interoperability between different systems is not only ensured by a standardized metamodel, but also by the semantic annotation (2) of almost all elements of the information model. In the future, this will not only make information accessible but also make it comprehensible and amenable for analysis by algorithms. The metamodel provides the necessary tools, but the semantic models used for annotation are highly domain-specific. They must therefore be agreed upon by experts from the individual application fields. This, of course, is also the crux of the matter, because scientists have been working on semantic modeling of industrial systems for longer than the term Industry 4.0 has existed. Nevertheless, the major breakthrough has not yet been achieved: There is still a great need for research (3).
For those who would like to delve deeper into the topic, the official introductory page of the Plattform Industrie 4.0 (4) is highly recommended, with links to the specification documents and the helpful “Reading Guide”, which points out relevant publications depending on the reader’s interests.
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A practical application example
To understand the versatile promises of the asset administration shell for the business world, it is worthwhile to use a (currently hypothetical) example. For the sake of simplicity, we'll limit ourselves to the world of factory automation since the overwhelming majority of research on the topic is also in this field. Nevertheless, note that the asset administration shell metamodel is fully applicable to other business fields. This example is adapted from the six-hour introductory theoretical course (6) on the asset administration shell on Festo LX.
Let's say you want to enter the market for customizable jigsaw puzzles, and you start planning a production line. As part of the production, you will need, among other things, a printer to print the customized motifs and a laser cutter to cut out the puzzle pieces.
Your requirements for the components (for example, cutting speed and material compatibility of the laser cutter) result from the process planning. You now enter these requirements into the search mask of a database of asset administration shells (a so-called registry) from a wide variety of manufacturers. The semantic annotations ensure that all suitable machine types are now found, even if the concrete modeling of the technical data differs from machine to machine.
You select the most suitable machine and download the corresponding asset administration shell. Your designer loads the asset administration shell into his CAD tool and can immediately start integrating the model it contains into the plant. It’s the same with electrical design. The control developers integrate the machine into your project, carry out the parameterization and can already test the project planning. Finally, even your simulation tool can make predictions about process speed and reliability using the models from the asset administration shell. The parameterization is stored in the asset administration shell and is immediately transferred to the physical machine when it is commissioned.
This example only scratches the surface, but it presents the added value of the asset administration shell in outline. For more detailed information, you can refer to the publication "Usage View of Asset Administration Shell" by Plattform Industrie 4.0 (7), which addresses this issue much more comprehensively.
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Lifting the shadow technology into the limelight
Now that the benefits of the asset administration shell have become clear, let's look at how we can lift the technology from its largely shadowy existence into the limelight. To this end, we postulate in advance that Industry 4.0 has now advanced to become an integral part of curricula in higher education. However, practical applications in the form of internships or exercises are coming up shorter than would be desirable, as implementations of the associated concepts are still thin on the ground.
The asset administration shell, however, offers an implementation of a digital twin and initial tools are available, free and open-source. These include the AASX Package Explorer (8) and Papyrus4Manufacturing (9), both intended for modeling asset administration shells, but with different focuses. Further development of these freely available tools is just one of Festo’s contributions towards a broader availability and adoption of AAS.
We do not want to hide the fact that complete mappings of the life cycle of an asset will remain out of reach until commercial engineering tools also support the asset administration shell. This does not detract from the importance of the topic for teaching – and the importance of teaching for the topic.
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Festo learning solutions in the context of asset administration shells
This is why we, at Festo, have developed a learning package with asset administration shells and associated orchestration software that controls a simple production process. ?We’ve designed a comprehensive ready-to-use bundle for educators who share our assessment of the potential of asset administration shells that helps teachers and trainers to introduce the topic of asset administration shells in their classes. This bundle includes the so-called "Robotino 4 add-on for AAS" and an approximately nine-hour hands-on course on Festo LX – Festo’s?digital learning portal. The course starts with the basics and progresses to the creation of an entire asset administration shell, catering to those who prefer not to build practical courses from scratch. Such learning solutions enable students to implement the industrial application of asset administration shells at their future employers, helping to drive the digitalization of industry. In this way, the often-promised interoperability may one day become a reality.
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References:
(2) Semantic annotation means that the model contains descriptions of the meaning of these data in addition to bare data. Example: The datum "Torque = 100 Nm" of a drive is more useful if it is additionally clarified that this value refers to the torque at nominal speed of the drive. For this purpose, ?asset administration shells make use of established databases of such semantic descriptions (for example, ECLASS, https://eclass.eu/).
(3) J. Nilsson und F. Sandin, "Semantic Interoperability in Industry 4.0: Survey of Recent Developments and Outlook," 2018 IEEE 16th International Conference on Industrial Informatics (INDIN), 2018, S. 127-132.
(4) https://www.plattform-i40.de/IP/Redaktion/EN/Standardartikel/specification-administrationshell.html
(5) Industrial Digital Twin Association IDTA – working together to promote the Digital Twin (industrialdigitaltwin.org)