Timo Müller

Zusammenfassung

The creation of a Digital Twin for existing manufacturing systems, so-called brownfield systems, is a challenging task due to the needed expert knowledge about the structure of brownfield systems and the effort to realize the digital models. Several approaches and methods have already been proposed that at least partially digitalize the information about a brownfield manufacturing system. A Digital Twin requires linked information from multiple sources. This paper presents a graph-based approach to merge information from heterogeneous sources. Furthermore, the approach provides a way to automatically identify templates using graph structure analysis to facilitate further work with the resulting Digital Twin and its further enhancement.

Zusammenfassung

Digital Twins, which serve as virtual representations, are becoming increasingly important to meet the needs of future industrial automation. Digital Twins are mostly created for specific use cases, facing various requirements e.g. reliable intellectual property protection, interoperability, flexibility, or extendability during implementation. For this purpose, decisions regarding structure and technology have to be made before implementation. In this paper, we discuss relevant requirements based on a proposed procedure for the derivation of project-specific intelligent Digital Twin implementations. The influences and correlations of project requirements are discussed concerning the choice of intelligent Digital Twins implementation structure and technology. In addition, the paper outlines their advantages and disadvantages. The proposed procedure is exemplarily illustrated using an intelligent Digital Twin utilized for a modular offshore-platform producing green hydrogen and derivatives.

Zusammenfassung

Während der Engineering- und Betriebsphase modularer Produktionssysteme entstehen zunehmend Modelle. Der Digitale Zwilling kann diese Modelle für Anwendungen wie die virtuelle Inbetriebnahme, Optimierung, Prognose oder betriebsparallele Simulation zur Verfügung stellen. Durch unvorhersehbare Veränderungen in der Betriebsphase verschlechtert sich die Realitätsnähe der Modelle des Digitalen Zwillings, bspw. aufgrund von Anforderungsänderungen, neuen Anwendungen oder sich ändernden Umwelteinflüssen wie etwa Temperatur- oder Druckschwankungen und eine Modelladaption wird notwendig. Die Adaption der Modelle des Digitalen Zwillings weist einige Herausforderungen auf, die in diesem Beitrag aufgezeigt werden. Um diesen Herausforderungen zu begegnen und dem Adaptionsaufwand während der Betriebsphase entgegenzuwirken, wird ein Konzept präsentiert, welches es dem Digitalen Zwilling ermöglicht, die Abweichung zur Realität zu erkennen und sich durch eine anschließende Modelladaption realitätsnah zu halten.

Zusammenfassung

The demand for reconfigurations of production systems is increasing, driven by shorter innovation and product life cycles and economic volatility. Another trend in the domain of industrial automation is the emergence of cyber-physical production systems, which offer promising potentials, for example, self-organization capabilities. A suitable cyber-physical production system architecture that incorporates knowledge modelling and management concerns, plus a reconfiguration management methodology, is crucial for realizing self-organized reconfiguration management. In this paper, first reference architectures, architectural patterns, and basic principles, as well as knowledge modelling and management approaches, are discussed in general. Afterwards, these are examined concerning the reconfiguration management use case focusing on UML/XML-based and ontology-based approaches. A novel approach comprising a multi-agent system and the MAPE-K concept for reconfiguration management is presented. In addition, the approach contains a service-oriented architecture for a deterministic plant control within a layered architecture. The knowledge modelling is realized through a UML information model, which can be integrated into the system utilizing XML files. Furthermore, the provided tool support is described. It enables a user to describe system components in an effort-reduced manner and conform to the schema defined by the information model and its restrictions via a GUI.

Zusammenfassung

Current industrial automation systems are facing increasing dynamics. Thus, acquiring and managing heterogeneous data within the Digital Twin to enable decision making is necessary although challenging. Knowledge Graphs unify and relate data, enabling the derivation of new insights. In this contribution, an approach for context-enriched modeling of cyber-physical production systems is proposed, in order to realize a Knowledge Graph enhanced intelligent Digital Twin further considering the context. Therefore, the modeling approach of the Knowledge Graph considers context and serves as a base for the graph embeddings to gain further knowledge about the production system. This knowledge is used within the architecture of the intelligent Digital Twin. The resulting benefits, i.e. diverse manifestations of an improved decision making, are highlighted by the use case of self-organized reconfiguration management.

Zusammenfassung

Die Produktion von Wasserstoff und Folgeprodukten unter Nutzung erneuerbarer Energien gilt als großer Hoffnungsträger für das Erreichen einer Klimaneutralität. Im Rahmen des Leitprojekts H2Mare soll der Betrieb einer Offshore-Plattform für Power-to-X-Produktionsprozesse erforscht und erprobt werden. Im vorliegenden Beitrag wird zunächst das Projektkonzept einer modularen Offshore-Plattform skizziert. Anschließend werden mit dem Digitalen Zwilling und dem System zur optimalen Betriebsführung zwei Forschungsansätze präsentiert, die zur Effizienzsteigerung dieser Produktionsprozesse beitragen sollen.

Zusammenfassung

The frequency of changes in production requirements is continuously increasing due to economic volatility, shorter innovation cycles and product life cycles. Therefore, a prediction of all goals of a production system at development time is impossible, which is leading to an increased reconfiguration demand during operation. Currently, there are still some weaknesses concerning the reconfiguration of production systems, which are highlighted in this article. The future of industrial automation will be dominated by Cyber-Physical Production Systems, which offer many promising potentials. Hence, this contribution discusses the Cyber-Physical Production Systems and some of their potentials regarding the reconfiguration issues. Corresponding concepts are required to utilize these theoretical potentials. Therefore, this research provides a basic concept for self-organized reconfiguration management.

Zusammenfassung

Shorter product life cycles and increasing individualization of production leads to an increased reconfiguration demand in the domain of industrial automation systems, which will be dominated by cyber-physical production systems in the future. In constantly changing systems, however, not all configuration alternatives of the almost infinite state space are fully understood. Thus, certain configurations can lead to process instability, a reduction in quality or machine failures. Therefore, this paper presents an approach that enhances an intelligent Digital Twin with a self-organized reconfiguration management based on adaptive process models in order to find optimized configurations more comprehensively.

Zusammenfassung

Ensuring high availability despite the growing frequency of changes in production requirements leads to an increased reconfiguration demand in the domain of industrial automation systems, which will be dominated by Cyber-Physical Production Systems (CPPS) in the future. Therefore, a concept, covering a methodology containing four steps, is utilized to answer the research question how to enhance CPPS with a self-organized reconfiguration management. This contribution focuses on the first two steps of this concept: the identification of reconfiguration demand and the generation of alternative configurations. A condensed presentation of the related work reveals that an interface-oriented formalized process description depicts an appropriate conceptual basis. Building upon this, the presented concept contains a capability model of the CPPS and the reasoning to determine a potential reconfiguration demand, as well as a procedure for the generation of alternative configurations. To evaluate the concept, an agent-based implementation is given, which uses an OPC-UA controlled simulated modular production system as a substitute CPPS in discrete manufacturing.

Zusammenfassung

Advances in the domain of industrial automation systems and artificial intelligence research have brought autonomous systems into the focus of industrial automation research. However, as Hrabia et al. state, there is no common understanding of what autonomous systems are and what characterizes them: “there is still a lack of a widely accepted concept of autonomous systems or robots that contains a detailed definition according to different aspects and a clear distinction to other system concepts” 1. They conclude “the capability of adapting to the environment is strongly interconnected with autonomy”1. However, they do not derive a comprehensive definition. On the one hand, some systems are advertised as autonomous systems, although they are only highly automated systems. On the other hand, some autonomous systems are not labeled as such. In addition, a number of different properties have emerged that characterize an autonomous system as well as abilities attributed to autonomous systems. In order to provide a differentiated view on this topic, the relevant literature in the domain of industrial automation systems was investigated for this survey. The methodology of the investigation is described in Section 2. Starting with the historical development of the term autonomy, in Section 3, various definitions of autonomy are compared, and a summarizing definition is elaborated. From the definition in the narrow sense, the characteristics of industrial autonomous systems are derived (Section 3.1) and a distinction from intelligent industrial automation systems and classic automation systems is proposed (Section 3.2). Reviewing the abilities attributed to industrial autonomous systems in the literature, the abilities are categorized according to the characteristics (Section 4). In order to provide an example for the classification of systems as industrial autonomous systems based on the four derived characteristics, their manifestation is explored by three real-world examples (Section 5). Finally, Section 6 provides a conclusion and an outlook.

Zusammenfassung

Cyber-Physical Systems, characterized by networking capabilities and digital representations, offer many promising potentials for industrial automation. In an attempt to further enrich the system's digital representation by incorporating interdisciplinary models and considering a continuous and synchronized representation of it within the cyber layer, the concept of the Digital Twin emerged, enabling system monitoring, virtual commissioning, failure diagnosis and simulations by managing the Cyber-Physical Systems data along its lifecycle. To add further intelligence into the Digital Twin, the architecture of the intelligent Digital Twin was proposed. Nevertheless, managing and relating the complex and dynamic digital models as well as the heterogeneous data of the intelligent Digital Twin present open challenges. Due to their inherent extensibility and adaptability as well as their semantic expressiveness, Knowledge Graphs are a suitable concept to overcome these challenges and enable reasoning to gain new insights. Prominent applications of Knowledge Graphs are recommendation systems and exploratory search within the semantic web. However, there seems to be a lacking yet potential applicability for Knowledge Graphs in the industrial domain. Therefore, this contribution proposes a Knowledge Graph enhanced architecture of the intelligent Digital Twin, offering capabilities, which are internal linking and referencing, knowledge completion, error detection, collective reasoning and semantic querying. Based on the proposed concept, potential application fields for Knowledge Graph enhanced intelligent Digital Twin are addressed.

Zusammenfassung

Reconfiguration demand is increasing due to frequent requirement changes for manufacturing systems. Recent approaches aim at investigating feasible configuration alternatives from which they select the optimal one. This relies on processes whose behavior is not reliant on e.g. the production sequence. However, when machine learning is used, components’ behavior depends on the process’ specifics, requiring additional concepts to successfully conduct reconfiguration management. Therefore, we propose the enhancement of the comprehensive reconfiguration management with transfer learning. This provides the ability to assess the machine learning dependent behavior of the different CPPS configurations with reduced effort and further assists the recommissioning of the chosen one. A real cyber-physical production system from the discrete manufacturing domain is utilized to demonstrate the aforementioned proposal.

Zusammenfassung

Recurrent neural networks and exceedingly Long short-term memory (LSTM) have been investigated intensively in recent years due to their ability to model and predict nonlinear time-variant system dynamics. The present paper delivers a comprehensive overviewof existing LSTM cell derivatives and network architectures for time series prediction. A categorization in LSTM with optimized cell state representations and LSTM with interacting cell states is proposed. The investigated approaches are evaluated againstdefined requirements being relevant for an accurate time series prediction.These include short-term and long-term memory behavior, the ability for multimodal and multi-step ahead predictions and the according error propagation.Sequence-to-sequencenetworks with partially conditioning outperform the other approaches, such as bidirectional or associative networks, and are best suited to fulfill therequirements.

Zusammenfassung

Softwarearchitekturen sind mit Blick auf die Komplexität von Softwaresystemen ein zentraler Ansatzpunkt, um die Entwicklung, spätere Erweiterungen und die Wartung durchführen zu können. Daher wird in diesem Beitrag wird eine service-orientierte Architektur (SOA) vorgestellt, die dezentrale Logistikmodule in Form von dezentralen Intralogistiksystemen organisiert, sodass Werkstücke auf ihrem individuellen Weg durch das Produktionssystem gesteuert werden können. Dabei bieten einzelne Logistikmodule ihre Transportfähigkeiten in Form von sogenannten Services an. Der individuelle Transport wird durch die Koordinierung der Logistikmodule in einer service-orientierten Architekturermöglicht. Um die Koordinierung zu ermöglichen, wird hierfür ein schlankes und dadurch echtzeitfähiges, busunabhängiges, Kommunikations-Protokoll beschrieben.

Zusammenfassung

Due to the increasing agility in the development process, shorter life cycles, and changing customer and legislator requirements, production systems must be adaptable. In addition to the ability to react flexibly to changing production requirements, the behavior of the production system must be reassured after a change. Formal verification methods are suitable for safeguarding safety-critical functions. However, this requires a high modeling effort, which inhibits the use of formal verification methods in practice. For reliable verification results, the quality and correctness of the models is decisive. Therefore, it is reasonable to analyze the underlying models. This paper presents two promising and mutually complementing approaches for the lifecycle-spanning safeguarding of production systems to overcome the challenges for the verification that a reconfiguration of the production systems brings with it during operation.

Zusammenfassung

Die Häufigkeit von Änderungen der Produktionsanforderungen nimmt aufgrund wirtschaftlicher Volatilität, kürzerer Innovationszyklen und Produktlebenszyklen kontinuierlich zu. Daher ist eine Vorhersage aller möglichen Ziele eines Produktionssystems zur Entwurfszeit unmöglich und es ergibt sich erhöhter Rekonfigurationsbedarf zur Betriebszeit. Derzeit weist die Rekonfiguration von Produktionssystemen jedoch einige Schwachstellen auf, die in diesem Beitrag aufgezeigt werden. Außerdem wird die Zukunft der industriellen Automatisierung von Cyber-Physischen Produktionssystemen dominiert werden, welche vielversprechende Potentiale bieten. Folglich werden die Cyber-Physischen Produktionssysteme und einige ihrer Potentiale im Hinblick auf Rekonfiguration diskutiert. Um diese theoretischen Potentiale tatsächlich nutzen zu können, sind allerdings entsprechende Konzepte erforderlich, weshalb dieser Forschungsbeitrag ein grundlegendes Konzept für ein selbstorganisiertes Rekonfigurationsmanagement präsentiert.

Zusammenfassung

The capabilities of a cyber-physical production system are determined by their physical and virtual elements and their interaction. The interaction between virtual and physical entities must be precisely defined, and it is therefore necessary to develop capability models and requirements that enable self-reconfiguration of different elements and their relationships. Furthermore, an ultra-flexible production system requires communication and analysis of huge amounts of data as well as flexible, near-real-time communication between elements. This paper discusses and describes the functional and technical requirements of an ultra-flexible factory and presents an approach to the semantic structuring of elements and capabilities.

Zusammenfassung

The paradigm of multi-agent systems is used in various application scenarios like manufacturing control or multi-agent assistance systems that aim at providing assistance to the user of the system in a specific task or situation. With an increasing number of applications of multi agent assistance systems in the industrial automation domain, the different architectures of these applications can be compared and differences and similarities can be identified. This paper presents the results of the literature review of 18 agent-based assistance systems from different domains. Within the reviewed architectures, seven different agent types could be identified. In a further step, design patterns based on the application domain and the level of automation have been identified and discussed. These design patterns can be used to facilitate the development of future multi agent assistance systems.

Zusammenfassung

In diesem Beitrag wird eine dezentral aufgebaute Methodik zur integrierten System- und Layoutplanung vorgestellt. Das Konzept für die Systemplanung basiert auf intelligenten Planungsobjekten, welche die autonomen Einheiten innerhalb der Planung logistischer Systeme darstellen. Diese intelligenten Planungsobjekte werden in einem agentenbasierten Assistenzsystem abgebildet. Basierend auf den intelligenten Planungsobjekten ist das Systembildungskonzept in die Phasen Komposition, Konfiguration und Adaption unterteilt. Diese werden als regelbasierte Interaktionen zwischen den intelligenten Planungseinheiten modelliert. Das Konzept der integrierten Layoutplanung basiert auf der Verwendung eines mathematischen Modells. Hierzu wurden entsprechende Agenten für die Layoutplanung konzipiert. Das im mathematischen Modell beschriebene Optimierungsproblem wird dabei mit Hilfe einer Heuristik gelöst. Ein Agentensystem organisiert die Ausführung des Heuristik-Algorithmus für alle möglichen Layout-Konstellationen und bewertet diese anschließend. So bietet es, in Form eines Assistenzsystems, Unterstützung von der Aufgabenstellung über die Ressourcenauswahl bis hin zur Layoutplanung.

Zusammenfassung

In the age of the Industrial Internet of Things, distributed subsystems are established in many domains, which bring added value through their networking. In the field of industrial automation this means a distribution of the control system. As the distribution involves an increase in complexity, new approaches are needed that address this problem. This paper presents a model-driven development approach that involves a Service Oriented Architecture.