Notes on Asset Administration Shell of Industrie 4.0

What is the Asset Administration Shell?

Industrie 4.0, also known as the Fourth Industrial Revolution, refers to the integration of digital technologies into manufacturing processes to create smart factories. It encompasses various advanced technologies that enhance automation, communication, and data exchange in manufacturing. One of the core concepts is the Asset Administration Shell (AAS). It aims to create a standardized and interoperable digital framework for managing and integrating assets in an Industrie 4.0 environment, supporting advanced manufacturing processes and services through comprehensive, transparent, and secure data management.

Type and Instance

The specification distinguishes between types and instances of assets. An asset type is defined first, with all defining properties and functionality and as such it is similar to a class in object oriented programming languages. An asset type is created with a strict reference to an asset type, also similar to creating an instance in code. The specification explains that the asset type should be regarded more as a template. For readers familiar with software development: it follows the paradigm of JavaScript more than that of strict object oriented languages.

The link between asset types and instances should be maintained with forwarded updates. A change to an asset type like adding a property could cascade to all instances to the type. The propagation could be automatic or on demand.

From a design perspective that seems a cumbersome idea and almost impossible to implement in a distributed system. It would make it almost impossible to implement some level of undo. Some version control of the changes of the asset type  with a corresponding version ID could mitigate the type drift of the asset instances. Nevertheless, it seems to me that you could only reliably implement the propagation if you limit the changes of the asset types. For example, you could only allow adding or extending properties. Changing existing properties, especially changing the type or validation of valued properties would be problematic, and would inescapably result in propagation errors.

Interfaces as projection templates

The concept of asset types is a basic and undeniably necessary concept. But instead of defining it with a permanent and authoritative type it would be a lot easier to implement and maintain if the asset types were defined like the interfaces of languages such as Java and C#. Similarly, asset types could be immutable, have an inheritance hierarchy and can be grouped into namespaces. It also opens the up the effective use of standardized, publicly available asset types. Asset instances can be created with a set of interfaces they implement that can initially be fairly abstract and be refined over time. Manufacturer specific interfaces could be based on the standard and public interfaces. The dependency of instances to asset types would be less strict and serve more as a projection template.​

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References

Plattform Industrie 4.0. (2019). Asset Administration Shell: A Reading Guide. Plattform Industrie 4.0.

Retrieved from https://www.plattform-i40.de/PI40/Redaktion/EN/Downloads/Publikation/asset-administration-shell-reading-guide.html

Plattform Industrie 4.0. (2020). Details of the Asset Administration Shell: Part 1—The exchange of information between partners in the value chain of Industrie 4.0 (Version 3.0). Plattform Industrie 4.0. Retrieved from https://www.plattform-i40.de/PI40/Redaktion/EN/Downloads/Publikation/Details-of-the-Asset-Administration-Shell-Part1.html.