Asset Administration Shell Tutorial
As you might be aware, in industrial production, there are many components involved in the value generating manufacturing process. Whereby, a component could be anything ranging from physical elements, such as Robotic Arm, Drilling Machine, to Software Applications, the Production Plant itself, the Production Process, and also the actual Products that is being manufactured. And in the context of Smart Manufacturing, these are referred to as industry 4.0 components.
A typical feature of an industry 4.0 component is that, in addition to its physical presence in a manufacturing facility, it also needs to have a digital presence that makes it integrate into the production process.
Hence, the reason why we have an Asset Layer and Integration Layer as separate entities in the layers axis of the Remi 4.0.
As I’ve already alluded to, in the previous session, the Integration layer is responsible for carrying that digital or virtual representation of the underlying physical asset. Now, because the potential of industry 4.0 relies on the ability of its components to communicate with each other, the digital representation of that physical component needs to reside on some platform that would enable it to deliver the digital information when required. And that digital platform could be inside of the physical machine itself, or an external physical object such as a computer.
Industrial components or systems that are equipped with such communicating capabilities are called Cyber Physical Systems and the production facility that incorporates Cyber Physical Systems is called a Cyber Physical Production System.
However, in addition to the requirement of the ability to communicate with other industry 4.0 components, a cyber physical system needs to have another property, and that is, it needs to be uniquely identifiable and addressable across the entire manufacturing value chain consisting of other cyber physical systems.
Simply put the requirements for a cyber-physical system to be called an industry 4.0 component are
- One – it needs to be able to communicate by means of industry 4.0 standards, and
- Two – it needs to be able to provide information to be at least uniquely identifiable in an industry 4.0 system.
- And three, it needs to be able to provide to other industry 4.0 components and interface to services that it offers.
In order to capture and present information about the abilities of a physical asset or cyber-physical system in order to turn it into an industry 4.0 component in a uniform and consistent manner, Industry 4.0 uses what is called an Asset Administration Shell.
To put it more formally: An Asset Administration Shell is a virtual representation of all the information and functionalities of an asset. The virtual representation provides an interface to a number of services that the asset provides. Some services are generic, and should be provided by all asset administration shells, including Identification, Configuration, Condition Monitoring, Events, etc. And others are specific, and include the capabilities or functions that can be performed by that particular asset.
Now, if you look at the Layers axis of the Reference Architecture Model for industry 4.0 described in a previous article, you can see that the physical properties of an Asset are at the bottom of the stack, followed by an Integration layer, which is where an administration shell of that asset lives, providing digital representation of the real asset, data about the current status of the asset, data which was generated during the lifecycle of the asset, and the functionalities of the asset.
So this also serves as an illustration that the administration shell is the element where the Communication layer, Information layer, Functional layer, and Business layer are deployed, thereby making it an access point of information and value added functions in industry. 4.0. From this description, you can see why Asset Administration Shell takes the role of a digital twin in Smart Manufacturing.
But what exactly does an administration shell look like? What structure does it follow to present this information about an asset. So the Asset Administration Shell is nothing but a data structure that consists of a header and a body. Whereby the header contains a list of properties about the shell and its asset, i.e. self description. And the body contains a list of sub modules that can provide industry 4.0 functions and services.
Now, to get a picture of what we’re talking about here, let us look at the structure of an Administration Shell for a robot.
As you can see here in the header, we have a list of properties for the robot, and then we have its Pick and Place functionality as a sub module in the body of its Administration Shell.
As you may have guessed, the main purpose of the Asset Administration Shell is to facilitate the exchange of asset related data between assets from different vendors along the production lifecycle of industry 4.0 systems, and making all manufacturing components interoperable so as to enable plug-and-produce in manufacturing facilities, analogous to the plug and play concept in desktop computers.
And all this makes possible division of a self-adapting factory where production lines can be reconfigured during runtime. If a piece of equipment breaks down, the operator can immediately pluck it out and replace it with a new one, which will automatically connect to the production system and perform the same tasks, much like how you can replace a mouse or keyboard for your PC without having to reconfigure anything.
Now the next question is, how do you implement an asset administration shell? Well, there are a couple of technologies that you could use, you can use AutomationML, an XML based data format to describe information in Asset Administration Shell sub modules, and you could also use a standard like OPC UA as the communication interface to exchange data between asset administration shells.
