Engineering framework for service-oriented automation systems

Tese de doutoramento. Engenharia Informática. Universidade do Porto. Faculdade de Engenharia. 201

An approach to task coordination for hyperflexible robotic workcells

2014 - 2015The manufacturing industry is very diverse and covers a wide range of specific processes ranging from extracting minerals to assembly of very complex products such as planes or computers, with all intermediate processing steps in a long chain of industrial suppliers and customers. It is well know that the introduction of robots in manufacturing industries has many advantages. Basically, in relation to human labor, robots work to a constant level of quality. For example, waste, scrap and rework are minimized. Furthermore they can work in areas that are hazardous or unpleasant to humans. Robots are advantageous where strength is required, and in many applications they are also faster than humans. Also, in relation to special-purpose dedicated equipment, robots are more easily reprogrammed to cope with new products or changes in the design of existing ones. In the last 30-40 years, large enterprises in high-volume markets have managed to remain competitive and maintain qualified jobs by increasing their productivity with the incremental adoption and use of advanced ICT and robotics technologies. In the 70s, robots have been introduced for the automation of a wide spectrum of tasks such as: assembly of cars, white goods, electronic devices, machining of metal and plastic parts, and handling of workpieces and objects of all kinds. Robotics has thus soon become a synonym for competitive manufacturing and a key contributing technology for strengthening the economic base of Europe . So far, the automotive and electronics industries and their supply chains are the main users of robot systems and are accounting for more than 60% of the total annual robot sales. Robotic technologies have thus mainly been driven by the needs of these high-volume market industries. The degree of automation in the automotive industries is expected to increase in the future as robots will push the limits towards flexibility regarding faster change-over-times of different product types (through rapid programming generation schemes), capabilities to deal with tolerances (through an extensive use of sensors) and costs (by reducing customized work-cell installations and reuse of manufacturing equipment). There are numerous new fields of applications in which robot technology is not widespread today due to its lack of flexibility and high costs involved when dealing with varying lot sizes and variable product geometries. In such cases, hyper-flexible robotic work cells can help in providing flexibility to the system and making it adaptable to the different dynamic production requirements. Hyper-flexible robotic work cells, in fact, can be composed of sets of industrial robotic manipulators that cooperate to achieve the production step that characterize the work cell; they can be programmed and re-programmed to achieve a wide class of operations and they may result versatile to perform different kind of tasks Related key technology challenges for pursuing successful long-term industrial robot automation are introduced at three levels: basic technologies, robot components and systems integration. On a systems integration level, the main challenges lie in the development of methods and tools for instructing and synchronising the operation of a group of cooperative robots at the shop-floor. Furthermore, the development of the concept of hyper flexible manufacturing systems implies soon the availability of: consistent middleware for automation modules to seamlessly connect robots, peripheral devices and industrial IT systems without reprogramming everything (”plug-and-play”) . In this thesis both innovative and traditional industrial robot applications will be analyzed from the point of view of task coordination. In the modeling environment, contribution of this dissertation consists in presenting a new methodology to obtain a model oriented to the control the sequencing of the activities of a robotic hyperflexible cell. First a formal model using the Colored Modified Hybrid Petri Nets (CMHPN) is presented. An algorithm is provided to obtain an automatic synthesis of the CMHPN of a robotic cell with detail attention to aircraft industry. It is important to notice that the CMHPN is used to model the cell behaviour at a high level of abstraction. It models the activities of each cell component and its coordination by a supervisory system. As more, an object oriented approach and supervisory control are proposed to implement industrial automation control systems (based on Programmable Logic Controllers) to meet the new challenges of this field capability to implement applications involving widely distributed devices and high reuse of software components. Hence a method is proposed to implement both controllers and supervisors designed by Petri Nets on Programmable Logic Controllers (PLCs) using Object Oriented Programming (OOP). Finally preliminary results about a novel cyber-physical approach to the design of automated warehouse systems is presented. [edited by author]XIV n.s

Logic programming for deliberative robotic task planning

Over the last decade, the use of robots in production and daily life has increased. With increasingly complex tasks and interaction in different environments including humans, robots are required a higher level of autonomy for efficient deliberation. Task planning is a key element of deliberation. It combines elementary operations into a structured plan to satisfy a prescribed goal, given specifications on the robot and the environment. In this manuscript, we present a survey on recent advances in the application of logic programming to the problem of task planning. Logic programming offers several advantages compared to other approaches, including greater expressivity and interpretability which may aid in the development of safe and reliable robots. We analyze different planners and their suitability for specific robotic applications, based on expressivity in domain representation, computational efficiency and software implementation. In this way, we support the robotic designer in choosing the best tool for his application

Software Engineering and Petri Nets

This booklet contains the proceedings of the Workshop on Software Engineering and Petri Nets (SEPN), held on June 26, 2000. The workshop was held in conjunction with the 21st International Conference on Application and Theory of Petri Nets (ICATPN-2000), organised by the CPN group of the Department of Computer Science, University of Aarhus, Denmark. The SEPN workshop papers are available in electronic form via the web page:http://www.daimi.au.dk/pn2000/proceeding

Modeling, Simulation, and Realization of Cognitive Technical Systems

This thesis presents a novel approach for the modeling, simulation, and realization of Cognitive Technical Systems. In contrast to other approaches, in this thesis, the structure and dynamic of the real world is initially formalized my means of an intermediate level instead of implementing a technical model directly. Furthermore, human cognition is investigated in an integrated manner and based on experiments with a mobile robot, as an example for a complex technical system. The formal description of human interaction and cognition is realized by Situation-Operator-Modeling (SOM), which can be implemented technically by patterns of high-level Petri Nets. With the state space of a SOM-based Petri Net, Human-Machine-Interaction can be analyzed, e.g., in order to detect human errors automatically. Furthermore, several cognitive functions, like planning, execution, perception, and learning, can be simulated. The different cognitive functions and related representations, which are all based on the same methodical background, are combined within an integrated cognitive architecture. Only the interplay among several functions and a novel kind of knowledge structuring, which contributes significantly to reduce the complexity of the real world, enable the realization of human-like behavior for technical systems. The system's capability to establish and to refine goal-directed behavior from interaction with the environment, also if no system-specific initial knowledge is available, is demonstrated by experiments with a mobile robot interacting within a dynamic office environment. An additional value of this thesis for further research is especially given by the proposed generic approach for modeling, simulation, and analysis of Human-Machine-Interaction. Moreover, the formal description and implementation of the cognitive functions, the developed knowledge structuring, and the cognitive architecture may be applied to arbitrary kind of technical systems.'Modellbildung, Simulation und Realisierung von Kognitiven Technischen Systemen' In dieser Arbeit wird ein neuartiger Ansatz zur Modellbildung, Simulation und Realisierung von Kognitiven Technischen Systemen präsentiert. Gegenüber bestehenden Ansätzen setzt sich diese Arbeit insbesondere dadurch ab, dass die Struktur und Dynamik der realen Welt zuerst über eine methodische Zwischenebene formal beschrieben und erst danach technisch implementiert wird. Zudem wird menschliche Kognition ganzheitlich untersucht und direkt mit Hilfe von Experimenten mit einem mobilen Roboter, als Beispiel für ein komplexes technisches System, erprobt und entwickelt. Die formale Beschreibung von menschlicher Interaktion und Kognition erfolgt über Situations-Operator-Modellbildung (SOM), welche über spezielle Muster höherer Petrinetze technisch implementiert werden kann. Durch den Zustandsraum eines SOM-basierten Petrinetzes ist es möglich, Mensch-Maschine-Interaktion zu analysieren, um beispielsweise menschliche Fehler automatisiert zu erfassen. Zudem können verschiedene kognitive Funktionen, wie Planen, Handeln, Wahrnehmung und Lernen simuliert werden. Die verschiedenen kognitiven Funktionen und entsprechenden Repräsentationen, welche auf der gleichen methodischen Grundlage basieren, werden in einer kognitiven Architektur zusammengeführt. Erst das Zusammenspiel verschiedener Funktionen und ein neuartiger Ansatz zur Wissensstrukturierung, wodurch insbesondere die Komplexität der realen Welt reduziert wird, ermöglicht die Realisierung menschenähnlichen Verhaltens für technische Systeme. Durch Experimente mit einem mobilen Roboter, der in einer dynamischen Büroumgebung interagiert, kann gezeigt werden, dass das vorgestellte System ohne anwendungsspezifisches Vorwissen in der Lage ist, zielführendes Verhalten aus der Interaktion mit der Umgebung zu erhalten und zu verbessern. Ein Mehrwert aus dieser Arbeit für weiterführende Forschungsarbeiten ergibt sich insbesondere durch den vorgestellten generischen Ansatz zur Modellbildung, Simulation und Analyse von Mensch-Maschine-Interaktion. Zudem können die formale Beschreibung und die Implementierung der kognitiven Funktionen, der entwickelten Wissensstrukturierung und der darauf aufbauenden kognitiven Architektur auf beliebige technische Systeme übertragen werden

Workflow-Net Based Cooperative Multi-Agent Systems

Workflow-nets are mathematical frameworks that are used to formally describe, model and implement workflows. First, we propose critical section workflow nets (abbreviated WFCSnet). This framework allows feedbacks in workflow systems while ensuring the soundness of the workflow. Feedback is generally not recommended in workflow systems as they threaten the soundness of the system. The proposed WFCSnet allows safe feedback and limits the maximum number of activities per workflow as required. A theorem for soundness of WFCSnet is presented. Serializability, Separability, Quasi-liveness and CS-Properties of WFCSnet are examined and some theorems and lemmas are proposed to mathematically formalize them. In this thesis, we define some formal constructs that we then build upon. We define the smallest formal sub-workflow that we call a unit. We propose some mathematical characteristics for the unit and show how it can be used. We study similarities between units and whether two units can be used interchangeably or not. We then use composites out of simple units to build more complex constructs and we study their properties. We define the concept of cooperation and propose a mathematical definition of the concept. We discuss the concept of task coverage and how it affects cooperation. We claim that task coverage is necessary for any task to be achieved and therefore, a necessity for cooperation. We use mathematical methods to determine the task coverage and the candidate cooperative partners based on their capabilities that can contribute to the desired task. Workflow-net based cooperative behaviour among agents is proposed. First, we propose a cooperative algebra, which takes the desired objective of cooperation as a plan and then transforms this plan into a workflow-net structure describing dependencies and concurrency among sub-workflow elements constituting the overall plan. Our proposed cooperative algebra converts the plan into a set of matrices that model the cooperative workflow among agents. We then propose a cooperative framework with operators that assign tasks to agents based on their capabilities to achieve the required task

A component-based virtual engineering approach to PLC code generation for automation systems

In recent years, the automotive industry has been significantly affected by a number of challenges driven by globalisation, economic fluctuations, environmental awareness and rapid technological developments. As a consequence, product lifecycles are shortening and customer demands are becoming more diverse. To survive in such a business environment, manufacturers are striving to find a costeffective solution for fast and efficient development and reconfiguration of manufacturing systems to satisfy the needs of changing markets without losses in production. Production systems within automotive industry are vastly automated and heavily rely on PLC-based control systems. It has been established that one of the major obstacles in realising reconfigurable manufacturing systems is the fragmented engineering approach to implement control systems. Control engineering starts at a very late stage in the overall system engineering process and remains highly isolated from the mechanical design and build of the system. During this stage, control code is typically written manually in vendor-specific tools in a combination of IEC 61131-3 languages. Writing control code is a complex, time consuming and error-prone process. [Continues.

Evaluating Resilience of Cyber-Physical-Social Systems

Nowadays, protecting the network is not the only security concern. Still, in cyber security, websites and servers are becoming more popular as targets due to the ease with which they can be accessed when compared to communication networks. Another threat in cyber physical social systems with human interactions is that they can be attacked and manipulated not only by technical hacking through networks, but also by manipulating people and stealing users’ credentials. Therefore, systems should be evaluated beyond cy- ber security, which means measuring their resilience as a piece of evidence that a system works properly under cyber-attacks or incidents. In that way, cyber resilience is increas- ingly discussed and described as the capacity of a system to maintain state awareness for detecting cyber-attacks. All the tasks for making a system resilient should proactively maintain a safe level of operational normalcy through rapid system reconfiguration to detect attacks that would impact system performance. In this work, we broadly studied a new paradigm of cyber physical social systems and defined a uniform definition of it. To overcome the complexity of evaluating cyber resilience, especially in these inhomo- geneous systems, we proposed a framework including applying Attack Tree refinements and Hierarchical Timed Coloured Petri Nets to model intruder and defender behaviors and evaluate the impact of each action on the behavior and performance of the system.Hoje em dia, proteger a rede não é a única preocupação de segurança. Ainda assim, na segurança cibernética, sites e servidores estão se tornando mais populares como alvos devido à facilidade com que podem ser acessados quando comparados às redes de comu- nicação. Outra ameaça em sistemas sociais ciberfisicos com interações humanas é que eles podem ser atacados e manipulados não apenas por hackers técnicos através de redes, mas também pela manipulação de pessoas e roubo de credenciais de utilizadores. Portanto, os sistemas devem ser avaliados para além da segurança cibernética, o que significa medir sua resiliência como uma evidência de que um sistema funciona adequadamente sob ataques ou incidentes cibernéticos. Dessa forma, a resiliência cibernética é cada vez mais discutida e descrita como a capacidade de um sistema manter a consciência do estado para detectar ataques cibernéticos. Todas as tarefas para tornar um sistema resiliente devem manter proativamente um nível seguro de normalidade operacional por meio da reconfi- guração rápida do sistema para detectar ataques que afetariam o desempenho do sistema. Neste trabalho, um novo paradigma de sistemas sociais ciberfisicos é amplamente estu- dado e uma definição uniforme é proposta. Para superar a complexidade de avaliar a resiliência cibernética, especialmente nesses sistemas não homogéneos, é proposta uma estrutura que inclui a aplicação de refinamentos de Árvores de Ataque e Redes de Petri Coloridas Temporizadas Hierárquicas para modelar comportamentos de invasores e de- fensores e avaliar o impacto de cada ação no comportamento e desempenho do sistema