Dual protocol performance using WiFi and ZigBee for industrial WLAN

The purpose of this thesis is to study the performance of a WNCS based on utilizing IEEE 802.15.4 and IEEE 802.11 in meeting industrial requirements as well as the extent of improvement on the network level in terms of latency and interference tolerance when using the two different protocols, namely WiFi and ZigBee, in parallel. The study evaluates the optimum performance of WNCS that utilizes only IEEE 802.15.4 protocol (which ZigBee is based on) without modifications as an alternative that is low cost and low power compared to other wireless technologies. The study also evaluates the optimum performance of WNCS that utilizes only the IEEE 802.11 protocol (WiFi) without modifications as a high bit network. OMNeT++ simulations are used to measure the end-to-end delay and packet loss from the sensors to the controller and from the controller to the actuators. It is demonstrated that the measured delay of the proposed WNCS including all types of transmission, encapsulation, de-capsulation, queuing and propagation, meet real-time control network requirements while guaranteeing correct packet reception with no packet loss. Moreover, it is shown that the demonstrated performance of the proposed WNCS operating redundantly on both networks in parallel is significantly superior to a WNCS operating on either a totally wireless ZigBee or WiFi network individually in terms of measured delay and interference tolerance. This proposed WNCS demonstrates the combined advantages of both the IEEE 802.15.4 protocol (which ZigBee is based on) without modifications being low cost and low power compared to other wireless technologies as well the advantages of the IEEE 802.11 protocol (WiFi) being increased bit rate and higher immunity to interference. All results presented in this study were based on a 95% confidence analysis

A Comprehensive Review on Time Sensitive Networks with a Special Focus on Its Applicability to Industrial Smart and Distributed Measurement Systems

The groundbreaking transformations triggered by the Industry 4.0 paradigm have dramati-cally reshaped the requirements for control and communication systems within the factory systems of the future. The aforementioned technological revolution strongly affects industrial smart and distributed measurement systems as well, pointing to ever more integrated and intelligent equipment devoted to derive accurate measurements. Moreover, as factory automation uses ever wider and complex smart distributed measurement systems, the well-known Internet of Things (IoT) paradigm finds its viability also in the industrial context, namely Industrial IoT (IIoT). In this context, communication networks and protocols play a key role, directly impacting on the measurement accuracy, causality, reliability and safety. The requirements coming both from Industry 4.0 and the IIoT, such as the coexistence of time-sensitive and best effort traffic, the need for enhanced horizontal and vertical integration, and interoperability between Information Technology (IT) and Operational Technology (OT), fostered the development of enhanced communication subsystems. Indeed, established tech-nologies, such as Ethernet and Wi-Fi, widespread in the consumer and office fields, are intrinsically non-deterministic and unable to support critical traffic. In the last years, the IEEE 802.1 Working Group defined an extensive set of standards, comprehensively known as Time Sensitive Networking (TSN), aiming at reshaping the Ethernet standard to support for time-, mission-and safety-critical traffic. In this paper, a comprehensive overview of the TSN Working Group standardization activity is provided, while contextualizing TSN within the complex existing industrial technological panorama, particularly focusing on industrial distributed measurement systems. In particular, this paper has to be considered a technical review of the most important features of TSN, while underlining its applicability to the measurement field. Furthermore, the adoption of TSN within the Wi-Fi technology is addressed in the last part of the survey, since wireless communication represents an appealing opportunity in the industrial measurement context. In this respect, a test case is presented, to point out the need for wirelessly connected sensors networks. In particular, by reviewing some literature contributions it has been possible to show how wireless technologies offer the flexibility necessary to support advanced mobile IIoT applications

Survey on wireless technology trade-offs for the industrial internet of things

Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment

Petri Nets at Modelling and Control of Discrete-Event Systems Containing Nondeterminism - Part 1

Discrete-Event Systems are discrete in nature, driven by discrete events. Petri Nets are one of the mostly used tools for their modelling and control synthesis. Place/Transitions Petri Nets, Timed Petri Nets, Controlled Petri Nets are suitable when a modelled object is deterministic. When the system model contains uncontrollable/unobservable transitions and unobservable/unmeasurable places or other failures, such kinds of Petri Nets are insufficient for the purpose. In such a case Labelled Petri Nets and/or Interpreted Petri Nets have to be used. Particularities and mutual differences of individual kinds of Petri Nets are pointed out and their applicability to modelling and control of Discrete-Event Systems are described and tested

On the Use of LoRaWAN for Indoor Industrial IoT Applications

Low-Power Wide-Area Networks (LPWANs) have recently emerged as appealing communication systems in the context of the Internet of Things (IoT). Particularly, they proved effective in typical IoT applications such as environmental monitoring and smart metering. Such networks, however, have a great potential also in the industrial scenario and, hence, in the context of the Industrial Internet of Things (IIoT), which represents a dramatically growing field of application. In this paper we focus on a specific LPWAN, namely, LoRaWAN, and provide an assessment of its performance for typical IIoT employments such as those represented by indoor industrial monitoring applications. In detail, after a general description of LoRaWAN, we discuss how to set some of its parameters in order to achieve the best performance in the considered industrial scenario. Subsequently we present the outcomes of a performance assessment, based on realistic simulations, aimed at evaluating the behavior of LoRaWAN for industrial monitoring applications. Moreover, the paper proposes a comparison with the IEEE 802.15.4 network protocol, which is often adopted in similar application contexts. The obtained results confirm that LoRaWAN can be considered as a strongly viable opportunity, since it is able to provide high reliability and timeliness, while ensuring very low energy consumption

Advanced micro and nano fabrications for engineering applications

This document is a compilation of my selected research publications in micro and nano fabrications. The papers are largely arranged in chronological order to show the development of research interests. The research works are grouped into three sections. Section one consists of 34 research papers on micro fabrication in various materials. The research was motivated by the development of a finger nail sized micro engine as explained in Papers 1 and 2. Section two of the document includes some research activities and achievements on nanocomposite materials embedded in metallic and ceramic matrices. Section 3 includes the papers to reflect the research in developing nanostructure fabrication processes. The research contained in this DSc submission shows a continuous exploration and development of novel micro/nano fabrication processes. Although the submission covers research activities spanning 15 years, from 2000 to 2015, many of the research results represent the top technology of the time. They have contributed to the ever progressing manufacturing capability of the world. The research has encompassed both theoretical and experimental studies, contributing to the understanding of the processes and materials involved

A Knowledge Graph Based Integration Approach for Industry 4.0

The fourth industrial revolution, Industry 4.0 (I40) aims at creating smart factories employing among others Cyber-Physical Systems (CPS), Internet of Things (IoT) and Artificial Intelligence (AI). Realizing smart factories according to the I40 vision requires intelligent human-to-machine and machine-to-machine communication. To achieve this communication, CPS along with their data need to be described and interoperability conflicts arising from various representations need to be resolved. For establishing interoperability, industry communities have created standards and standardization frameworks. Standards describe main properties of entities, systems, and processes, as well as interactions among them. Standardization frameworks classify, align, and integrate industrial standards according to their purposes and features. Despite being published by official international organizations, different standards may contain divergent definitions for similar entities. Further, when utilizing the same standard for the design of a CPS, different views can generate interoperability conflicts. Albeit expressive, standardization frameworks may represent divergent categorizations of the same standard to some extent, interoperability conflicts need to be resolved to support effective and efficient communication in smart factories. To achieve interoperability, data need to be semantically integrated and existing conflicts conciliated. This problem has been extensively studied in the literature. Obtained results can be applied to general integration problems. However, current approaches fail to consider specific interoperability conflicts that occur between entities in I40 scenarios. In this thesis, we tackle the problem of semantic data integration in I40 scenarios. A knowledge graphbased approach allowing for the integration of entities in I40 while considering their semantics is presented. To achieve this integration, there are challenges to be addressed on different conceptual levels. Firstly, defining mappings between standards and standardization frameworks; secondly, representing knowledge of entities in I40 scenarios described by standards; thirdly, integrating perspectives of CPS design while solving semantic heterogeneity issues; and finally, determining real industry applications for the presented approach. We first devise a knowledge-driven approach allowing for the integration of standards and standardization frameworks into an Industry 4.0 knowledge graph (I40KG). The standards ontology is used for representing the main properties of standards and standardization frameworks, as well as relationships among them. The I40KG permits to integrate standards and standardization frameworks while solving specific semantic heterogeneity conflicts in the domain. Further, we semantically describe standards in knowledge graphs. To this end, standards of core importance for I40 scenarios are considered, i.e., the Reference Architectural Model for I40 (RAMI4.0), AutomationML, and the Supply Chain Operation Reference Model (SCOR). In addition, different perspectives of entities describing CPS are integrated into the knowledge graphs. To evaluate the proposed methods, we rely on empirical evaluations as well as on the development of concrete use cases. The attained results provide evidence that a knowledge graph approach enables the effective data integration of entities in I40 scenarios while solving semantic interoperability conflicts, thus empowering the communication in smart factories

Are Formal Contracts a useful Digital Twin of Software Systems?

Digital Twins are a trend topic in the industry today to either manage runtime information or forecast properties of devices and products. The techniques for Digitial Twins are already employed in several disciplines of formal methods, in particular, formal verification, runtime verification and specification inference. In this paper, we connect the Digital Twin concept and existing research areas in the field of formal methods. We sketch how digital twins for software-centric systems can be forged from existing formal methods

Wireless Communication in Process Control Loop: Requirements Analysis, Industry Practices and Experimental Evaluation

Wireless communication is already used in process automation for process monitoring. The next stage of implementation of wireless technology in industrial applications is for process control. The need for wireless networked control systems has evolved because of the necessity for extensibility, mobility, modularity, fast deployment, and reduced installation and maintenance cost. These benefits are only applicable given that the wireless network of choice can meet the strict requirements of process control applications, such as latency. In this regard, this paper is an effort towards identifying current industry practices related to implementing process control over a wireless link and evaluates the suitability of ISA100.11a network for use in process control through experiments

Modellgestützter Entwurf von Feldgeräteapplikationen

Die Entwicklung von Feldgeräten ist ein äußerst komplexer Vorgang, welcher auf vielen Vorrausetzungen aufsetzt, diverse Anforderungen und Randbedingungen mitbringt und bisher wenig beachtet und veröffentlicht wurde. Angesichts der fortschreitenden Digitalisierung drängen immer mehr Anbieter auf den Automatisierungsmarkt. So sind aktuell zunehmend Technologien und Ansätze aus dem Umfeld des Internet of Things im Automatisierungsbereich zu finden. Diese Ansätze reichen von Sensoren ohne die in der Industrie üblichen Beschreibungen bis hin zu Marktplätzen, auf denen Integratoren und Anwender Softwareteile für Anlagen kaufen können. Für die neuen Anbieter, die häufig nicht aus dem klassischen Automatisierungsgeschäft kommen, sind die bisher bestehenden Modelle, Funktionalitäten, Profile und Beschreibungsmittel nicht immer leicht zu verwenden. So entstehen disruptive Lösungen auf Basis neu definierter Spezifikationen und Modelle. Trotz dieser Disruptivität sollte es das Ziel sein, die bewährten Automatisierungsfunktionen nicht neu zu erfinden, sondern diese effektiv und effizient in Abhängigkeit der Anforderungen auf unterschiedlichen Plattformen zu verwenden. Dies schließt ihre flexible Verteilung auf heterogene vernetzte Ressourcen explizit ein. Dabei können die Plattformen sowohl klassische Feldgeräte und Steuerungen sein, als auch normale Desktop-PCs und IoT-Knoten. Ziel dieser Arbeit ist es, eine Werkzeugkette für den modellbasierten Entwurf von Feldgeräteapplikationen auf Basis von Profilen und damit für den erweiterten Entwurf von verteilten Anlagenapplikationen zu entwickeln. Dabei müssen die verschiedenen Beschreibungsmöglichkeiten evaluiert werden, um diese mit detaillierten Parameter- und Prozessdatenbeschreibungen zu erweitern. Außerdem sollen modulare Konzepte genutzt und Vorbereitungen für die Verwendung von Semantik im Entwurfsprozess getroffen werden. In Bezug auf den Geräteengineeringprozess soll der Anteil des automatisierten Geräteengineerings erweitert werden. Dies soll zu einer Flexibilisierung der Geräteentwicklung führen, in der die Verschaltung der funktionalen Elemente beim Endkunden erfolgt. Auch das Deployment von eigenen funktionalen Elementen auf die Geräte der Hersteller soll durch den Endkunden möglich werden. Dabei wird auch eine automatisierte Erstellung von Gerätebeschreibungen benötigt. Alle diese Erweiterungen ermöglichen dann den letzten großen Schritt zu einer verteilten Applikation über heterogene Infrastrukturen. Dabei sind die funktionalen Elemente nicht nur durch die Gerätehersteller verteilbar, sondern diese können auch auf verschiedenen Plattformen unterschiedlicher Gerätehersteller verwendet werden. Damit einher geht die für aktuelle Entwicklungen wie Industrie 4.0 benötigte geräteunabhängige Definition von Funktionalität. Alle im Engineering entstandenen Informationen können dabei auf den unterschiedlichen Ebenen der Automatisierungspyramide und während des Lebenszyklus weiterverwendet werden. Eine Integration diverser Gerätefamilien außerhalb der Automatisierungstechnik wie z. B. IoT-Geräte und IT-Geräte ist damit vorstellbar. Nach einer Analyse der relevanten Techniken, Technologien, Konzepte, Methoden und Spezifikationen wurde eine Werkzeugkette für den modellgestützten Entwurf von Feldgeräten entwickelt und die benötigten Werkzeugteile und Erweiterungen an bestehenden Beschreibungen diskutiert. Dies Konzept wurde dann auf den verteilten Entwurf auf heterogener Hardware und heterogenen Plattformen erweitert, bevor beide Konzepte prototypisch umgesetzt und evaluiert wurden. Die Evaluation erfolgt an einem zweigeteilten Szenario aus der Sicht eines Geräteherstellers und eines Integrators. Die entwickelte Lösung integriert Ansätze aus dem Kontext von Industrie 4.0 und IoT. Sie trägt zu einer vereinfachten und effizienteren Automatisierung des Engineerings bei. Dabei können Profile als Baukasten für die Funktionalität der Feldgeräte und Anlagenapplikationen verwendet werden. Bestehende Beschränkungen im Engineering werden somit abgeschwächt, so dass eine Verteilung der Funktionalität auf heterogene Hardware und heterogene Plattformen möglich wird und damit zur Flexibilisierung der Automatisierungssysteme beiträgt.The development of field devices is a very complex procedure. Many preconditions need to be met. Various requirements and constrains need to be addressed. Beside this, there are only a few publications on this topic. Due to the ongoing digitalization, more and more solution providers are entering the market of the industrial automation. Technologies and approaches from the context of the Internet of Things are being used more and more in the automation domain. These approaches range from sensors without the typical descriptions from industry up to marketplaces where integrators and users can buy software components for plants. For new suppliers, who often do not come from the classical automation business, the already existing models, functionalities, profiles, and descriptions are not always easy to use. This results in disruptive solutions based on newly defined specifications and models. Despite this disruptiveness, the aim should be to prevent reinventing the proven automation functions, and to use them effectively, and efficiently on different platforms depending on the requirements. This explicitly includes the flexible distribution of the automation functions to heterogeneous networked resources. The platforms can be classical field devices and controllers, as well as normal desktop PCs and IoT nodes. The aim of this thesis is to develop a toolchain for the model-based design of field device applications based on profiles, and thus also suitable for the extended design of distributed plant applications. Therefore, different description methods are evaluated in order to enrich them with detailed descriptions of parameters and process data. Furthermore, c oncepts of modularity will also be used and preparations will be made for the use of semantics in the design process. With regard to the device engineering process, the share of automated device engineering will be increased. This leads to a flexibilisation of the device development, allowing the customer to perform the networking of the functional elements by himself. The customer should also be able to deploy his own functional elements to the manufacturers' devices. This requires an automated creation of device descriptions. Finally, all these extensions will enable a major step towards using a distributed application over heterogeneous infrastructures. Thus, the functional elements can not only be distributed by equipment manufacturers, but also be distributed on different platforms of different equipment manufacturers. This is accompanied by the device-independent definition of functionality required for current developments such as Industry 4.0. All information created during engineering can be used at different levels of the automation pyramid and throughout the life cycle. An integration of various device families from outside of Automation Technology, such as IoT devices and IT devices, is thus conceivable. After an analysis of the relevant techniques, technologies, concepts, methods, and specifications a toolchain for the model-based design of field devices was developed and the required tool parts, and extensions to existing descriptions were discussed. This concept was then extended to the distributed design on heterogeneous hardware and heterogeneous platforms. Finally, both concepts were prototypically implemented and evaluated. The evaluation is based on a two-part scenario from both the perspective of a device manufacturer, and the one of an integrator. The developed solution integrates approaches from the context of Industry 4.0 and IoT. It contributes to a simplified, and more efficient automation of engineering. Within this context, profiles can be used as building blocks for the functionality of field devices, and plant applications. Existing limitations in engineering are thus reduced, so that a distribution of functionality across heterogeneous hardware and heterogeneous platforms becomes possible and contributing to the flexibility of automation systems