Basic Knowledge Standardization in Industry 4.0
The prerequisites for interoperability in an Industry 4.0 environment are globally applicable norms and standards. Therefore, the reference architecture model for Industry 4.0 has been developed to describe the system environment. This paper provides a first structured overview of developments in the field of Industry 4.0 standardization.
Our world is undergoing a digital transition phase that will penetrate and change all areas of industry. The term Industry 4.0 stands for the fourth industrial revolution. One of the basic prerequisites of this transition is the interaction of technical objects with each other and the integrated application of cloud-based platforms. This rethinking in a digital world requires a consistent networking and offers many possibilities of virtual representation of the real world.
A prerequisite for successful cooperation is the interoperability of the interacting components. This requires norms and standards that combine both a common understanding of the data to be exchanged and the rules of interaction. For the globally operating and export-oriented German industry, the definition of technical requirements in globally standardized systems is of particular importance. The aim is to gradually anchor all the essential specifications for uniform technical function and applicability in international standards. The most important target standardization organizations are IEC and ISO.
Reference Architecture Becomes a Necessity
The reference architecture model Industry 4.0 (RAMI 4.0) and the Industry 4.0 component thus form the core pillars of Industry 4.0 and serve as the basis for the development of networked products and services based on new business models.
There are already different heterogeneous software tools, partial models and autonomously operating solution approaches available in the broad field of industrial applications. To fully integrate the value chains both horizontally and vertically and to ensure a continuous data flow within the process chains, the entire system environment must be thoroughly documented - based on globally recognized norms and standards. As a result, one of the central tasks of this future topic is the necessity to develop the reference architecture model for Industry 4.0 applications.
For this purpose, members of the Industry 4.0 Platform launched the project "DIN SPEC 91345 Reference Architecture Model Industry 4.0". The technical report was already adopted and published in April 2016 . RAMI 4.0 ensures inter-operability on demand through a coherent and complete description of the entire solution space of technical assets from their development, production, use and maintenance to their removal from the market.
Three-Dimensional Model Represents Industry 4.0 Solution Space
One of the fundamental notions of the reference architecture of Industry 4.0 is the combination of different aspects in a joint model. This serves as an orientation for a systematic approach and is the basis for the successful implementation of Industry 4.0 in different companies and different industries.
A reference architecture describes the structure of a system with its element types, their structures and interaction types among themselves and with their environment. Basic concepts or properties are defined and together with its components and their interaction form the framework for the development, structuring and classification of relevant technical systems.
RAMI 4.0 is a three-dimensional reference architecture model that represents the Industry 4.0 solution space. It can be used to locate applications and their norms and standards in the three axes of product life cycle, functional hierarchy and architecture hierarchy. All relevant information and aspects of an Industry 4.0 system can be clearly structured, defined and transparently represented along these defined axes.
Structure of RAMI 4.0
The architectural hierarchy is represented on the right horizontal axis. It serves the functional classification of an application in the formal structure of technical assets. In detail, these are the products, the resources, structured into their different functionalities within a factory, as well as the interconnected world outside the factory.
The left horizontal axis shows the time axis of the life cycle. The properties of a technical asset can therefore vary depending on the stage of the lifecycle. An instance is comparable to a copy of the declared type for a special application with specific functional requirements. When a product is manufactured, functional properties are assigned to the digital type in the instance declaration.
The vertical axis represents the functional hierarchy of a technical asset. The integration layer is located above the actual asset layer to implement a virtual representation. It secures the access of information systems to the properties of physical assets. The communication layer contains protocols for transmitting data and serves as a link between the integration layer and the information layer. The information layer contains a description of all necessary function-related data and services of technical assets as well as semantics as a common language and is therefore the source and target of the data to be transmitted. The function layer contains all the formally described functions and the relevant business process is represented in the business layer.
The "Hardware Store" for Industrial 4.0 Applications
RAMI 4.0 describes the essential elements of a technical object using a three-dimensional layer model. The benefit of a reference architecture model lies in:
- the classification of the assets of the production scenario,
- positioning within the reference architecture,
- identification of correlations and special challenges,
- simplification through allocation,
- classification of existing technologies,
- location of relevant standards and norms,
- communication with partners on the basis of common terminology.
The functionality of the RAMI 4.0 can be explained by taking a hardware store as a metaphor: A hardware store specializes in materials for handymen and sorts its various product groups, such as tools and nails, paints and wallpapers, wood and building materials, in different aisles and shelves. Depending on the requirements, the customer then takes the products required for the individual project from the individual shelves in the aisles and thus compiles his individual shopping basket. The assignment of a technical asset and the required standards to the three axes in the individual, individual Industry 4.0 application case works just like that.
Industry 4.0 Component
Another important element is the generic description of the Industry 4.0 component model. This represents a specialization of a cyberphysical system and describes how a real technical asset can be transformed into a globally identifiable and communication-capable Industry 4.0 component by means of a virtual administration shell.
The management shell is the virtual-digital and active representation of an asset in an Industry 4.0 system. They and their objects can be integrated into one of the assets in the form of an embedded system or can be distributed on one or more higher-level IT systems. It also contains the manifest and the component manager. The manifesto is a clearly identifiable table of contents containing all the information, data and functions of the management shell. The component manager, on the other hand, organizes addressing and identification and secures the connection to the technical IT services of the Industry 4.0 component.
An Industry 4.0 component comprises a logical image of one or more items and one administration shell. The concept is that such a component can logically integrate other components, act as a unit, and logically abstract them for a superordinate system. This makes it possible to logically assign other Industry 4.0 components (for example, components of a machine) to an Industry 4.0 component (for example, an entire machine), resulting in a (temporary) nesting.
The state of an Industry 4.0 component can always be retrieved by other participants of an Industry 4.0-compliant communication. The management shell functions as the interface linking the Industry 4.0 communication with the asset and follows a defined state model. It is clearly identifiable in the network and its physical objects are identified by means of unique identifiers.
The management shell serves as the data memory containing all information relating to the asset, such as design data, operating instructions or manuals. A lot of this information is provided by the manufacturers. These in turn can be complemented by service providers or operators of machines, plants and factories with important additional information. Moreover, the administrative shell provides additional functions such as planning, project planning, configuration, operation, maintenance or complex functions about business logic. The management shell thus functions as a database over the entire product lifecycle of an asset.
The administrative shell contains at least the component manager and the administrative manifest and consists of header and body. The header contains information about the identification and designation of the concrete asset in the Industry 4.0 system and also information about the management and application of the asset. The body contains the component manager, which manages the delimited submodels and their characteristics and functions in different domains. Each submodel contains structured characteristics, which in turn access functions that are available in different data formats. The basic features include a minimum of features that are indispensable for the management of the assets.
The aim of the submodels is to connect components, assemblies, devices, machines and systems of different types and manufacturers in order to ensure interoperability of the value chain. The submodels contain the semantic descriptions of the technical assets located on the vertical axis of RAMI 4.0 which were defined with the help of the management shell. The purpose of the submodels is to describe the characteristics to be used with their structures as well as their networked data and function objects.
The content of the features must be developed and finally orchestrated based on the specifications of the Industry 4.0 reference architecture. Characteristics that are mandatory and standardized for all management scales are referred to as basic characteristics. In addition, both mandatory features to be provided permanently and optional features can be defined for individual technical assets. The administrative shell ought to be able to take characteristics from different sets of characteristics and domains and differentiate them from each other. It must be possible to assign a version to individual characteristics and maintain them independently of each other.
This approach to standardization by using Industry 4.0 offers the opportunity to use the development of new technical systems across industries and sectors. The administrative shell must be designed in such a way that a suitable representation of different submodels and feature sets can be realized. This means that existing sets of characteristics can be used in different domains. Advantages for the user result, for example, from the commissioning and integration of machines and plants in a perfect factory environment.
Semantics and Interaction
Application scenarios for Industry 4.0 systems are always characterized by a high degree of flexibility, adaptability and autonomy of the components involved in the operation. The effective and secure cooperation between the individual administrative shells of the Industry 4.0 components can ultimately orchestrate the value chains of such a system. To do so, they need a common language based on interaction patterns. It is made up of a vocabulary and a defined grammar, the contents and effects of which must be clearly described semantically.
Industry 4.0 components exchange messages that can affect their behavior. The message elements are part of a basic ontology required for interactions and different domain ontologies. The contents of ontology are listed in the Industry 4.0 component manifest. The ontologies are known and unique within the Industry 4.0 system. They can be based on taxonomies or feature catalogs or, if necessary, use other technological concepts.
Such a specification focuses on interactions to proceed and to use application-related functionalities contained in submodels. Interaction is the combination of state transitions between at least two systems in which the output messages of one system (sender) represent the input message values of the other system (receiver). This description does not specify which interactions the Industry 4.0 components can provide. However, it determines how the interactions proceed if the corresponding application-specific functionality is to be provided.
Innovations are considered the origin and crucial driver of this economic revolution. They are the basis for new products and services or serve to streamline and efficiently design existing processes. The basic objective for small and medium-sized enterprises (SMEs) is to use the existing standardization landscape as a basis and to rapidly implement the standards and norms newly developed within the framework of the Industry 4.0 strategy. However, it is precisely these companies that often find it difficult to keep up with the speed of standardization, to adequately participate in the standardization process and to implement it in good time.
Digital transformation entails both opportunities and new risks. This paper provides a first structured overview of developments in the field of Industry 4.0 standardization. The described information serves as an orientation and provides a rough overview. The german book "Industry 4.0" can provide deeper insights and a basis for a step-by-step approach and introduction of new Industry 4.0 technologies: Industry 4.0 has not yet fully covered this transformation path. There is little doubt that this is the right path - even for small and medium-sized enterprises.
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2) DIN SPEC 91345:2016-04 Reference Architectural Model Industry 4.0 (RAMI4.0). Berlin: Beuth Verlag, April 2016.
3) Structure of the administrative shell, further development of the reference model for Industry 4.0 components, findings paper. Berlin, Federal Ministry of Economics and Energy (BMWi), April 2016.
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5) Further development of the interaction model for Industry 4.0 components, discussion paper. Berlin: Federal Ministry of Economics and Energy (BMWi), November 2016.
6) Schulz, Thomas [ed.]: Industry 4.0: Identifying and Implementing Potentials. Würzburg: Vogel Business Media, 378 pages, 2017.
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* Thomas Schulz is Channel Manager Central and Eastern Europe for GE Digital at General Electric in 60313 Frankfurt am Main, Germany
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