Power line communication systems for industrial control applications

For almost as long as the electricity distribution industry itself has existed, so also has the idea of utilising the transmission grid, be it over a wide area or on a local basis, for the transmission of 'intelligence'. This might be in the form of voice transmissions, or for the purposes of monitoring or controlling electrical devices attached to the network. This thesis specifically concerns itself with the potential applications of power-line-carrier (PLC) communications technology within the field of industrial plant/equipment control, as it is within this field that the author works. We look at the entire subject area of industrial control, starting from a historical viewpoint, and consider the special needs and requirements that a proposed PLC solution must offer for this application, especially based on the noise conditions likely to be experienced on a `real' power line. A proposal is made for a `Power Bus', intended for use within certain areas of industrial control, and decisions are made based on the projected link response times for such applications. The experimental phase of the research is practical in nature and consists of a raft of tests and evaluations of the performance of power line modem technologies, under controlled and repeatable noise conditions. To complement these results, further tests are carried out under `real world' conditions, within an actual factory environment. Based on the results of all of these tests, the suitability of a PLC solution for this type of industrial control application is considered. The Thesis concludes with a look at recent developments in, as well as the future of, Power Line Communication techniques

Timing analysis of an embedded architecture for a real-time power line communications network

Tese de mestrado. Engenharia Electrotécnica e de Computadores (Área de especialização de Telecomunicações). Faculdade de Engenharia. Universidade do Porto, Instituto Superior de Engenharia. Instituto Politécnico do Porto.. 200

Durchführbarkeitsanalyse und Validierung eines Feldbussystems mit einer großen Anzahl an Busteilnehmern mit formalen Methoden

The complexity of large scale fieldbus systems is two-fold: message-sending concurrency and emergent bus behavior. On the one hand, an increase in the number of accumulating nodes within one fieldbus system expands its message-sending concurrency; on the other hand, the growth of emergent bus behavior causes a temporary or lasting message burst on the fieldbus channel. The message sequences in turn have an increased burst behavior, aggravating the traffic density. Therefore, this dissertation evaluates the performability of large scale fieldbus systems by presenting a busload validation procedure by formal methods. The model concept is conceptualized and formulated by UMLCD and OSI Model. Furthermore, the validation procedure is formalized and structurally specified by applying the attribute hierarchy and BMW principle. Based on sorting the message-sending occurrences from the log data of a real fieldbus-based building automation system, the validation procedure is thus quantified with the real system timed-parameters. In addition, the stochastic distributions of message transmissions are determined by the goodness of fit method. The entire work is based on DSPN as formal means of descriptions and models. The corresponding Petri net communication model is hierarchically constructed, which has been further parameterized, integrated and simulated. The analysis of system complexity is provided by the programming-based extension of the Petri net communication model. In addition, the results of Monte-Carlo-Simulation have been sorted, analyzed and evaluated regarding the validation aspects of system performability. Finally, the emergent message burst generated from the function interrelations has also been observed and evaluated. The result of this work will make a formal contribution to the improvement the fieldbus specification.Insbesondere für Feldbussysteme mit einer großen Anzahl an Busteilnehmern wird die Komplexität über zwei Kenngrößen charakterisiert. Einerseits stellt die Erhöhung der Anzahl akkumulierter Feldbusknoten innerhalb eines Feldbussystems eine gestiegene Message-Sendung-Nebenläufigkeit dar. Andererseits steigt diese auch durch Zuwachs des emergenten Busverhaltens, die temporäre oder dauerhafte Nachrichtenfolgen mit sich führen. Die Nachrichtenfolgen wiederum können ein erhöhtes Burst-Verhalten auf dem Feldbus-Kanal, d.h. eine erhöhte Busauslastung verursachen. Ziel der vorliegenden Arbeit ist es, ein komplexes Feldbussystem formal zu beschreiben und ein formales Buslastvalidierungsverfahren darzustellen. Das Modellkonzept wird zunächst durch das UMLCD und das OSI-Modell formuliert, und anschließend wird das Validierungsverfahren mit der Attributhierarchie und dem BMW-Prinzip formalisiert und spezifiziert. Aufgrund der Sortierung des Sendungsverhaltens mittels Logdaten eines realen Feldbus-basierten Gebäudeautomationssystems, wird das Validierungsverfahren durch die quantitative Analyse weitergeführt. Zusätzlich werden die stochastischen Verteilungen der Sendungsverhaltene durch die Goodness-of-Fit Methode angepasst. Die gesamte Arbeit basiert auf DSPN als formales Beschreibungsmittel und Modellierungsmittel. Das entsprechende Petrinetz-Kommunikationsmodell wird vorgestellt, welches hierarchisch konstruiert, parametriert und simuliert wurde. Die Systemkomplexität wird mit Hilfe der Programmierung-basierten Erweiterung des Petrinetz-Kommunikationsmodells analysiert. Dazu werden die Monte-Carlo-Simulationsergebnisse dieses erweiterten Modells vorgestellt, analysiert und bewertet und in Bezug zu den Validierungsaspekten der Systemleistung gesetzt. Schließlich wird das erzeugte Nachrichten-Burst-Verhalten von den Funktionsverknüpfungen beobachtet und bewertet. Die Ergebnisse werden von dieser Arbeit nach der Vervollständigung der formalen Feldbusspezifikation zurückgeführt und verbessert

Compact information technology enabled systems for intelligent process monitoring

The use of computers in industrial process applications is ever-increasing. Initially used to provide help to the machine operator, their application has evolved through automatic process control to monitoring of process health and performance. The latter, together with the quality control of the end product directly affect plant economics and ultimately the financial viability of the company. The research reported in this thesis is a contribution towards providing a cost-effective method of calculating a measure of the current health of a process and predicting any maintenance issues that may arise in the near future. Embedded systems are utilised and the monitoring system is designed to work automatically with a minimal input from the operator. This eliminates the need for peripherals such as keyboards, mice, and monitors thus reducing the overall system price and footprint. User interfaces are provided via the Internet and mobile phones giving remote access to multiple users. Single chip microcontrollers are at the heart of the embedded system rather than microprocessors, thereby reducing the relative system cost and size at the expense of localised processing power. The microcontrollers are distributed in a hierarchical network to attain the required processing power whilst minimising data storage and communications and to improve signal-to-noise ratios. The Controller Area Network (CAN) bus was selected, and used for the inter-microcontroller communications, for its robust performance in noisy environments. In the developed system architecture, each microcontroller node acquires one of the required process sensor signals and applies initial signal processing. A novel sweeping filter technique is developed to perform frequency analysis using the microcontrollers. The processed data from all nodes are then combined using situation-based criteria to reach conclusions often not evident from single sensor data. The Internet-based system is provided with the capability to upload any monitoring software or updates. Plug & play capability of the monitoring nodes is also provided so that the system can be seamlessly adapted to new or changed applications. The design and development of the system are detailed along with its deployment on various applications. Fault detection, isolation, and prediction were achieved on batch and continuous processes. A machine tool application proved the frequency analysis and network traffic reduction capabilities. On-line monitoring of an industrial valve was also performed

Kommunikation und Bildverarbeitung in der Automation

In diesem Open Access-Tagungsband sind die besten Beiträge des 11. Jahreskolloquiums "Kommunikation in der Automation" (KommA 2020) und des 7. Jahreskolloquiums "Bildverarbeitung in der Automation" (BVAu 2020) enthalten. Die Kolloquien fanden am 28. und 29. Oktober 2020 statt und wurden erstmalig als digitale Webveranstaltung auf dem Innovation Campus Lemgo organisiert. Die vorgestellten neuesten Forschungsergebnisse auf den Gebieten der industriellen Kommunikationstechnik und Bildverarbeitung erweitern den aktuellen Stand der Forschung und Technik. Die in den Beiträgen enthaltenen anschauliche Anwendungsbeispiele aus dem Bereich der Automation setzen die Ergebnisse in den direkten Anwendungsbezug

Comunicações confiáveis sem-fios para redes veiculares

Vehicular communications are a promising field of research, with numerous potential services that can enhance traffic experience. Road safety is the most important objective behind the development of wireless vehicular networks, since many of the current accidents and fatalities could be avoided if vehicles had the ability to share information among them, with the road-side infrastructure and other road users. A future with safe, efficient and comfortable road transportation systems is envisaged by the different traffic stakeholders - users, manufacturers, road operators and public authorities. Cooperative Intelligent Transportation Systems (ITS) applications will contribute to achieve this goal, as well as other technological progress, such as automated driving or improved road infrastructure based on advanced sensoring and the Internet of Things (IoT) paradigm. Despite these significant benefits, the design of vehicular communications systems poses difficult challenges, mainly due to the very dynamic environments in which they operate. In order to attain the safety-critical requirements involved in this type of scenarios, careful planning is necessary, so that a trustworthy behaviour of the system can be achieved. Dependability and real-time systems concepts provide essential tools to handle this challenging task of enabling determinism and fault-tolerance in vehicular networks. This thesis aims to address some of these issues by proposing architectures and implementing mechanisms that improve the dependability levels of realtime vehicular communications. The developed strategies always try to preserve the required system’s flexibity, a fundamental property in such unpredictable scenarios, where unexpected events may occur and force the system to quickly adapt to the new circumnstances.The core contribution of this thesis focuses on the design of a fault-tolerant architecture for infrastructure-based vehicular networks. It encompasses a set of mechanisms that allow error detection and fault-tolerant behaviour both in the mobile and static nodes of the network. Road-side infrastructure plays a key role in this context, since it provides the support for coordinating all communications taking place in the wireless medium. Furthermore, it is also responsible for admission control policies and exchanging information with the backbone network. The proposed methods rely on a deterministic medium access control (MAC) protocol that provides real-time guarantees in wireless channel access, ensuring that communications take place before a given deadline. However, the presented solutions are generic and can be easily adapted to other protocols and wireless technologies. Interference mitigation techniques, mechanisms to enforce fail-silent behaviour and redundancy schemes are introduced in this work, so that vehicular communications systems may present higher dependability levels. In addition to this, all of these methods are included in the design of vehicular network components, guaranteeing that the real-time constraints are still fulfilled. In conclusion, wireless vehicular networks hold the potential to drastically improve road safety. However, these systems should present dependable behaviour in order to reliably prevent the occurrence of catastrophic events under all possible traffic scenarios.As comunicações veiculares são uma área de investigação bastante promissora, com inúmeros potenciais serviços que podem melhorar a experiência vivida no tráfego. A segurança rodoviária é o objectivo mais importante por detrás do desenvolvimento das redes veiculares sem-fios, visto que muitos dos atuais acidentes e vítimas mortais poderiam ser evitados caso os veículos tivessem a capacidade de trocar informação entre eles, com a infraestrutura rodoviária e outros utilizadores da estrada. Um futuro com sistemas de transporte rodoviário seguros, eficientes e confortáveis é algo ambicionado pelas diferentes partes envolvidas - utilizadores, fabricantes, operadores da infraestrutura e autoridades públicas. As aplicações de Sistemas Inteligentes de Transporte (ITS) cooperativas vão contribuir para alcançar este propósito, em conjunto com outros avanços tecnológicos, nomeadamente a condução autónoma ou uma melhor infraestrutura rodoviária baseada em sensorização avançada e no paradigma da Internet das Coisas (IoT). Apesar destes benefícios significativos, o desenho de sistemas de comunicações veiculares coloca desafios difíceis, em grande parte devido aos ambientes extremamente dinâmicos em que estes operam. De modo a atingir os requisitos de segurança crítica envolvidos neste tipo de cenários, é necessário um cuidadoso planeamento por forma a que o sistema apresente um comportamento confiável. Conceitos de dependabilidade e de sistemas de tempo-real constituem ferramentas essenciais para lidar com esta desafiante tarefa de dotar as redes veiculares de determinismo e tolerância a faltas. Esta tese pretende endereçar alguns destes problemas através da proposta de arquitecturas e da implementação de mecanismos que melhorem os níveis da dependabilidade das comunicações veiculares de tempo-real. As estratégias desenvolvidas tentam sempre preservar a necessária flexibilidade do sistema, uma propriedade fundamental em cenários tão imprevisíveis, onde eventos inesperados podem ocorrer e forçar o sistema a adaptar-se rapidamente às novas circunstâncias.A contribuição principal desta tese foca-se no desenho de uma arquitectura tolerante a faltas para redes veiculares com suporte da infraestrutura de beira de estrada. Esta arquitectura engloba um conjunto de mecanismos que permite detecção de erros e comportamento tolerante a faltas, tanto nos nós móveis como nos nós estáticos da rede. A infraestrutura de beira de estrada desempenha um papel fundamental neste contexto, pois fornece o suporte que permite coordenar todas as comunicações que ocorrem no meio sem-fios. Para além disso, é também responsável pelos mecanismos de controlo de admissão e pela troca de informação com a rede de transporte. Os métodos propostos baseiam-se num protocolo determinístico de controlo de acesso ao meio (MAC) que fornece garantias de tempo-real no accesso ao canal semfios, assegurando que as comunicações ocorrem antes de um determinado limite temporal. No entanto, as soluções apresentadas são genéricas e podem ser facilmente adaptadas a outros protocolos e tecnologias sem-fios. Neste trabalho são introduzidas técnicas de mitigação de interferência, mecanismos para assegurar comportamento falha-silêncio e esquemas de redundância, de modo a que os sistemas de comunicações veiculares apresentem elevados níveis de dependabilidade. Além disso, todos estes métodos são incorporados no desenho dos componentes da rede veicular, guarantindo que as restrições de tempo-real continuam a ser cumpridas. Em suma, as redes veiculares sem-fios têm o potential para melhorar drasticamente a segurança rodoviária. Contudo, estes sistemas precisam de apresentar um comportamento confiável, de forma a prevenir a ocorrência de eventos catastróficos em todos os cenários de tráfego possíveis.Programa Doutoral em Telecomunicaçõe