Delay-dependent output feedback compensators for a class of networked control systems

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2014Sistemas de controle via rede (NCS, do inglês Networked Control Systems) são uma classe especial de sistemas amostrados digitalmente, nos quais os dispositivos do sistema de controle se comunicam através de uma rede de comunicação (como mostrado na Fig. I). Significantes avanços tecnológicos tem levado a um maior interesse tanto na utilização de NCS em ambiente industrial (MOYNE; TILBURY, 2007), quanto em pesquisas relacionadas ao assunto (HESPANHA; NAGHSHTABRIZI; XU,2007; HEEMELS; WOUW, 2010; ZHANG; GAO; KAYNAK, 2013). Algumas das vantagens oferecidas por tais sistemas, com relação a sistemas de controle tradicionais, compreendem menor custo de implementação, flexibilidade e facilidade de manutenção. Apesar disso, inerentemente alguns efeitos indesejados também podem ocorrer, tais como atrasos na comunicação e intervalos de amostragem variantes, ocasionando degradação no desempenho do sistema em malha fechada. Devido a esses efeitos, a análise de estabilidade e também o projeto de controladores para NCS tornam-se mais desafiadores (TANG; YU, 2007). De modo geral, os estudos sobre NCS podem ser divididos em duas grandes áreas: controle da rede e controle via rede (GUPTA; CHOW, 2010). A primeira está mais interessada em proporcionar uma melhor qualidade no serviço de transmissão de dados realizado pela rede de comunicação, enquanto a segunda objetiva uma melhor qualidade do desempenho dos sistemas de controle sob determinadas condições induzidas pelos efeitos da utilização da rede. Embora tipicamente tratadas de forma separada, recentemente alguns esforços têm sido empreendidos de modo a integrar algumas características de ambas as áreas em fase de projeto, as chamadas estratégias de co-design (TORNGREN et al., 2006). Uma abordagem integrada é necessária de modo a se obter uma maior compreensão do funcionamento de um NCS, podendo assim obter um melhor desempenho geral do sistema. Neste contexto, especialmente levando em consideração que o uso rede de comunicação é limitado, tal recurso deve ser corretamente distribuído entre os sistemas de controle de modo a garantir um funcionamento adequado. Além disso, requisitos de desempenho individuais de cada planta também devem ser cumpridos, mesmo sujeitos a tais restrições de limites de recursos.Abstract: Networked control system (NCS) is a special class of sampled-data system where control systems devices are interconnected through a communication network. Despite the advantages, such as lower cost, flexibility and easy of maintenance compared to a more traditional implementation, some undesired effects may be induced by the use of a shared medium in the feedback loop, for instance, time-varying sampling intervals and delays. Due to the multidisciplinary nature of an NCS, the analysis and design of such systems also demand a more comprehensive approach. Thus, the main objective of this thesis is to propose some strategies for the synthesis of dynamic output feedback compensators, assuming an industrial network control system environment with temporal behavior features and requirements. Throughout this document, the NCS is modeled considering unknown time-varying delays, which leads to an uncertain system representation, later overapproximated by a convex polytope with additional norm-bounded uncertainty. Based on parameter dependent Lyapunov functions, closed-loop stability conditions are provided, which can be verified in terms of feasibility of a set of linear matrix inequalities (LMIs). The control designs are then promptly derived from the stability conditions, leading to delay-dependent compensators. Furthermore, an integrated control design and resource management strategy is proposed, taking into account the controller design while also addressing the shared nature of the communication network. This co-design strategy assumes that a supervisor task has the knowledge of all devices that access the network, as well as their allocated bandwidths. Numerical examples and simulations are provided to illustrate the effectiveness of the proposed design methodologies

Understanding Technological, Pedagogical, and Content Knowledge in an Educational Technology Course: A Case Study of Social Studies Preservice Teacher\u27s Beliefs and Dispositions

As beliefs and dispositions form the foundation of practice, the situations in which teachers develop belief is an important factor in their development (Roth, 1999). One aspect shaping the beliefs of teacher candidates is their experience with education. Lortie (2002) refers to this as the problem of “apprenticeship of observation”, the learning that occurs from watching teachers in the 12 or more years spent in school as a student. School experiences greatly affect the preconceptions teacher candidates have about teaching and learning. Richardson and Placier (2001) state most preservice teacher beliefs consist of unexamined assumptions. These views tend to focus on the affective quality of teachers they experienced, favorite teaching styles, and what certain children do. Teacher candidates tend not to think about the social contexts, subject matter, or pedagogy involved. Thus, preconceptions left unexplored are difficult to change later. This qualitative case study investigates how a new iteration of an educational technology class influences the preconceptions, beliefs, and dispositions of five secondary social studies teacher candidates’ implementation of Technological, Pedagogical, and Content Knowledge framework (Mishra & Koehler, 2006). The suitability of this class as a space to challenge teacher candidate preconceptions is discussed. Through interview, survey data, class observations, and student produced artefacts, issues of teacher candidate preconceptions, belief, and disposition toward their future teaching are examined. How aspects of the class influenced participants’ developing understanding of TPACK as well as challenging their beliefs about teaching social studies are discussed. Implications for teacher educators regarding teacher candidate belief, the learning of meaningful educational technology integration, and programmatic issues concerning appropriate course placement also arise because of this study

Réseaux de communication et applications de contrôle-commande

Cette thèse se situe dans le domaine des Systèmes Commandés en Réseaux, systèmes pluridisciplinairesqui connaissent un grand développement dans le contexte technologique actuel etqui introduisent de nouveaux problèmes de recherche, en particulier, pour les communautés Automatiqueet Réseau de Communication. L objectif est de montrer l intérêt de considérer un lienbidirectionnel entre la Qualité de Contrôle (QdC) (stabilité et performance des applications decontrôle-commande) et la Qualité de Service (QdS) (retards dans les transmissions) en se focalisantsur les réseaux locaux et plus particulièrement sur l ordonnancement des trames dans la souscouche MAC où on considère des protocoles MAC de type CSMA.Notre travail se situe tout d abord dans le cadre du réseau CAN où nous faisons trois propositions.La première proposition consiste en des solutions de QdS pour des applications decontrôle-commande sur la base du concept de priorité hybride, pour l ordonnancement de trames,dans laquelle nous définissons une partie priorité dynamique qui dépend d un paramètre de QdC.Ceci permet de réaliser une relation QdC->QdS. La deuxième proposition consiste en des solutionsde QdC par une méthode de compensation de retard (maintenance des pôles dominants)ce qui permet de réaliser une relation QdS->QdC. La troisième proposition consiste à réaliserune relation QdC QdS qui assure lors de l implantation de plusieurs applications, une propriétéd équité comportementale. Nous abordons ensuite le cadre particulier des réseaux locaux sans filoù, d une part, nous définissons des protocoles MAC de type CSMA sans collision sur la basede priorités et, d autre part, nous montrons la faisabilité des idées développées dans le cadre duréseau CANThis thesis is in the field of Networked Controlled Systems, which are multidisciplinary systemsand which experience a great development in the context of the current technology andintroduce new research problems, particularly for the communities of Automatic Control andCommunication Network. The aim is to show the interest in considering a bidirectional link betweenthe Quality of Control (QoC) (stability and performance of process control applications) andQuality of Service (QoS) (delays in the transmissions) and to focus on Local Area Networks and,more particularly, on the scheduling of frames in the MAC layer in which we consider CSMAMAC protocols.Our work first concerns a CAN network where we have three proposals. The first proposalconsists of solutions for QoS, for process control applications, which are based on the conceptof hybrid priority for the frame scheduling in which we define a dynamic priority part which dependson a QoC parameter. This allows to implement a relation QoC->QoS. The second proposalconsists of QoC solutions by using a compensation method for time delays (maintenance of dominantpoles) which allows to implement a relation QoS->QoC. The third proposal consists inimplementing a relation QoS QoC that ensures, for the implementation of several applications,a fairness property. We then discuss the specific context of Wireless LANs, where, on the onehand, we define collision-free CSMA MAC protocols on the basis of priorities and, on the otherhand, we show the feasibility of the ideas developed in the CAN networkTOULOUSE-INSA-Bib. electronique (315559905) / SudocSudocFranceF

ERP implementation methodologies and frameworks: a literature review

Enterprise Resource Planning (ERP) implementation is a complex and vibrant process, one that involves a combination of technological and organizational interactions. Often an ERP implementation project is the single largest IT project that an organization has ever launched and requires a mutual fit of system and organization. Also the concept of an ERP implementation supporting business processes across many different departments is not a generic, rigid and uniform concept and depends on variety of factors. As a result, the issues addressing the ERP implementation process have been one of the major concerns in industry. Therefore ERP implementation receives attention from practitioners and scholars and both, business as well as academic literature is abundant and not always very conclusive or coherent. However, research on ERP systems so far has been mainly focused on diffusion, use and impact issues. Less attention has been given to the methods used during the configuration and the implementation of ERP systems, even though they are commonly used in practice, they still remain largely unexplored and undocumented in Information Systems research. So, the academic relevance of this research is the contribution to the existing body of scientific knowledge. An annotated brief literature review is done in order to evaluate the current state of the existing academic literature. The purpose is to present a systematic overview of relevant ERP implementation methodologies and frameworks as a desire for achieving a better taxonomy of ERP implementation methodologies. This paper is useful to researchers who are interested in ERP implementation methodologies and frameworks. Results will serve as an input for a classification of the existing ERP implementation methodologies and frameworks. Also, this paper aims also at the professional ERP community involved in the process of ERP implementation by promoting a better understanding of ERP implementation methodologies and frameworks, its variety and history

Design of Networked Control Systems (NCSs) on the basis of interplays between Quality of Control and Quality of Service

International audienceThe goal of this paper is to consider a co-design approach between the controller of a process control application and the frame scheduling of a Local Area Network (LAN). More precisely we present a bi directional relation between the Quality of Control (QoC) provided by the controller and the Quality of Service (QoS) provided by the LAN (relation noted QoS⇋QoC). We present, first, the implementation of the relation QoS→QoC on the basis of a compensation method for time delays called dominant pole method, and second, the implementation of the relation QoC→QoS on the basis of the hybrid priorities for the frame scheduling. The final objective is the implementation of the bidirectional relation QoS⇋QoC which is the combination of the both relations QoS→QoC and QoC→QoS in order to have a more efficient NCSs design

Business process modelling in ERP implementation literature review

Business processes are the backbone of any Enterprise Resource Planning (ERP) implementation. Business process modelling (BPM) has become essential for modern, process driven enterprises due to the vibrant business environments. As a consequence enterprises are dealing with a substantial rate of organizational and business processes change. Business process modelling enables a common understanding and analysis of the business processes, which is the first step in every ERP implementation methodology (blueprint phase). In order to represent enterprise processes models in an accurate manner, it is paramount to choose a right business process modeling technique and tool. The problem of many ERP projects rated as unsuccessful is directly connected to a lack of use of business process models and notations during the blueprint phase. Also, blueprint implementation phase is crucial in order to fit planned processes in an organization with processes implemented in the solution. However, business analysts and ERP implementation professionals have substantial difficulties to navigate through a large number of theoretical models and representational notations that have been proposed for business process modeling (BPM). As the availability of different business process modeling references is huge, it is time consuming to make review and classification of all modeling techniques. Therefor, in reality majority of ERP implementations blueprint documents have no business process modeling included in generating blueprint documents. Choosing the right model comprise the purpose of the analysis and acquaintance of the available process modelling techniques and tools. The number of references on business modelling is quit large, so it is very hard to make a decision which modeling notation or technique to use. The main purpose of this paper is to make a review of business process modelling literature and describe the key process modelling techniques. The focus will be on all business process modeling that could be used in ERP implementations, specifically during the blueprint phase of the implementation process. Detailed review of BPM (Business process modeling) theoretical models and representational notations, should assist decision makers and ERP integrators in comparatively evaluating and selecting suitable modeling approaches

A conceptual framework for capability sourcing modeling

Companies need to acquire the right capabilities from the right source, and the right shore, at the right cost to improve their competitive position. Capability sourcing is an organizing process to gain access to best-in-class capabilities for all activities in a firm's value chain to ensure long-term competitive advantage. Capability sourcing modeling is a technique that helps investigating sourcing alternative solutions to facilitate strategic sourcing decision making. Our position is applying conceptual models as intermediate artifacts which are schematic descriptions of sourcing alternatives based on organization's capabilities. The contribution of this paper is introducing a conceptual framework in the form of five views (to organize all perspectives) and a conceptualisation (to formulate a language) for capability sourcing modelling

The creation of business architecture heat maps to support strategy-aligned organizational decisions

The realization of strategic alignment within the business architecture has become increasingly important for companies. Indeed, it facilitates business-IT alignment as a well-designed business architecture helps both to identify the appropriate requirements for IT systems and to discover new business opportunities that can be realized by IT. However, there is a lack of alignment techniques that support organizational (re) design decisions during the operation phase as the actual performance of business architecture elements is neglected. Capability heat maps provide a useful starting point in this respect as they focus on the creation of a hierarchy of prioritized capabilities, which are characterized by a performance measure. In this paper, these techniques will be extended to support strategy-aligned decisions within the business architecture. The identification of the relevant business architecture elements is based on state-of-the-art enterprise modelling languages, which enable the development of enterprise models on distinct layers of the business architecture. Strategic alignment between these elements will be realized by using prioritization according to the Analytic Hierarchy Process (AHP), while performance measurement will enable the creation of a proper decision support system. Afterwards, the proposed heat map will be applied on a case example to illustrate its potential use. This results in the completion of a first build-and-evaluate loop within the Design Science methodology