NOVA Asset Administration Shell

The NOVA Asset Administration Shell (NOVAAS) is an open source reference implementation and execution environment - developed by NOVA School of Science and Technology - for the Asset Administration Shell (AAS) concept proposed by the Reference Architectural Model for Industrie 4.0 (RAMI4.0).. The AAS is an implementation of the concept of Digital Twin for industrial applications - in the context of the Industrie 4.0 - and establishes the cornerstone for interoperability between production assets . NOVAAS is a new age IT solution that takes extensive use of internet-based technologies and standards, No code / Low code development paradigm, cloud-native tools and technologies and more.

The Context

In 2019, Plattform Industrie 4.0 considered interoperability between industrial assets a key issue and fundamental requirement for the next generation of manufacturing production systems . As a result, interoperability has been set as one of the main strategic fields for 2030 . As a matter of fact, even if data are nowadays everywhere (generated within industrial domains and the product consumer ambience), it is rarely used within business due to the lack of a supporting infrastructure that ensures and enables the bi-directional information flow from field to business levels and vice-versa. Interoperability presupposes the standardisation of the communication interfaces, protocols, as well as, the data formats to avoid the creation of information silos. It is necessary to comprehend that today's problem is no longer networking (protocols, connectivity, etc.) nor is it hardware (CPU/memory power is already there, at low-cost and low-power consumption) but rather it is on how to link, integrate and easily connect disparate heterogeneous data sources to the specific needs and interaction forms of applications and platforms .

Interoperability requires standards to enable integration of individual solutions within the Industrie 4.0 systemic solutions. In this context, NOVAAS provides a standardised and - thus - homogenous way for service provisioning and data sharing while helping to overcome the information silo problem.

Main Features

NOVAAS is a software component that implements the asset digital integration and exhibits the following features:

• It is intended to provide a standardised digital representation of industrial physical assets (End-to-End digitisation of production equipment) that are now accessible by using a common and clearly defined communication interface (End-to-End communication to enable transparency all over the distinct layers of the ISA-95 pyramid);
• It establishes the cornerstone for the interoperability within the applications managing industrial systems by providing a kind of lingua franca to facilitate the access to the asset data;
• It holds digital models (sub-models) for describing selected views/perspectives of the physical asset as well as technical elements for accessing these perspectives;
• It provides all the necessary mechanisms for extracting, finding and interpreting specific data from the underlying physical asset;
• Containerisation of manufacturing applications; and
• Environment for deploying and running Artificial Intelligence (AI) solutions to compute and solve highly complex learning, monitoring and decision-making tasks within manufacturing production systems.

Domain Model

The RAMI4.0 Functional layer contains services that support the business processes and provide functional access to the physical assets. In this sense, the RAMI4.0 has defined the concept of asset administration shell that provides the functional access to the assets. In the industrial context, assets are any factory plant, machinery, equipment including sensors, actuators, mechanical parts, etc.. Sensors monitor the asset and play the role of data source in a factory. Actuators, in turn, can act on assets to control the behaviour according to the data provided by sensors. An asset is part of an I4.0 component , which has two parts: the asset, and the administration shell of the asset. The AAS is the virtual representation of the asset in the Information Technology (IT) world. An AAS has two main parts: an electronic description of the asset (sometimes referred as manifest and/or AAS environment), and a component manager. The manifest/AAS environment comprises a set of sub-models that electronically describe data and digital processes about the concerned asset. This description acts as a management information base (MiB) accessible from the outside. The component manager handles requests for actions related to the asset’s capabilities, and responds to them. It administers the sub-models within the manifest/AAS environment as well as links the information in the AAS to both physical and IT world. Furthermore, it provides all the necessary mechanisms and logic to ensure the correct functioning the AAS. An AAS can contain other administration shells to create the composite asset administration shell. A whole factory can have an AAS as the result of the composition of the AASs of every machine.

Architecture

A comprehensive framework for the AAS has been proposed by the German Plattform Industrie 4.0 which serves as the fundamental skeleton for structuring the NOVAAS

The AAS is constituted by two core entities/components namely:

• Manifest: provides a standardised electronic description/information (e.g. sub-models) about the underlying physical entity i.e. the concerned asset. This description acts as a management information base (MiB) accessible from the outside. It consists of 2 main parts: Header and the Body. The Header administrative information for the identification of the asset and AAS. The Body is divided into several sub-models. Each sub-model describes a set of properties related with the asset capabilities.
• Component Manager: handles the requests for specific properties and sub-models within the Manifest. It provides all the necessary mechanisms and logic to ensure the correct functioning the AAS.

NOVAAS follows the above model and further extends it by specifying, two interfaces that will ensure the data flow to/from the AAS, namely:

• External Interface: provides a standardized interface that manages communication to/from external entities (e.g., other AAS, applications, platform, etc.), i.e., manages inter-process communication mechanisms by using request/reply (REST API) and message-based communication patterns;
• Internal Interface: provides a vendor-specific interface that manages the communication to/from the physical entity attached to the AAS.

The key idea in the AAS interaction model is that the interaction with the asset and/or between AASs and between AASs and other applications is based only on the information AASs include within the defined MiB. The hexagonal architecture is ideal to explain the AAS in general and NOVAAS in particular interaction model. The Internal logic provides one or more ports. Ports - in turn - defines a set of generic operations that characterise how the NOVAAS interacts with the external world. Finally, the NOVAAS is surrounded by inbound and outbound adapters. The former handles requests from the outside world and the latter handles requests from the AAS to the external world.

NOVAAS provides a REST API to interact with it. The REST API that is exposed to the outside world i.e. to external applications is unique. However, internally the NOVAAS manages a set of domain specific interfaces to interact with the underlying physical entity. To ensure the separation of the logic from the specific physical entity while providing a unique access endpoint to the physical entity, NOVAAS will be designed following API Gateway microservice pattern (equivalent to the Façade pattern in object-oriented design) where the NOVAAS is the single-entry point for all the clients while handling all the requests to the asset – doing protocol translation if necessary – composing/(pre-)processing the replies and returning them to the client. In this scenario, NOVAAS has other responsibilities such as: security, authentication, load balancing, monitoring, etc.

NOVAAS can be deployed to a computer infrastructure in different ways based on the characteristics of the industrial asset, as well as, to the cardinality of the relation. As a matter of fact, industrial assets that have no communication capabilities for external access need an Asset-based Deployment where NOVAAS is deployed next to those assets and a local connection is created. On the contrary, for industrial assets that natively provide communication capabilities for external access an edge-based deployment can be used – where NOVAAS is available in the edge and connected to the asset through the Local Area Network (LAN). In respect to the cardinality relation, NOVAAS can be designed and deployed in a one-to-one and/or one-to-many relation with the underlying physical asset.

Technical Details

NOVAAS has been developed by using the following technologies and software development principles:

• No code/Low code development platform (e.g. Node-RED);
• Deep use of internet-based technologies and standards such as JavaScript, JSON format, http(s) protocol, etc.; and
• Deep use of cloud-native tools and technologies for building the NOVAAS app e.g. containerisation, virtualisation, container orchestration, etc.. In particular NOVAAS development has been focused on deeply applying cloud software development methods, architectures and container technology while scaling-down them appropriately to smaller systems i.e. from cloud to enterprise, edge until embedded systems.

References

This article "NOVA Asset Administration Shell" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:NOVA Asset Administration Shell. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.

---