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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Detecção e acomodação de falhas em sistemas incertos com atraso no sinal de controle utilizando modo deslizante /

Paula, André Luiz Alexandre de. January 2011 (has links)
Orientador: José Paulo Fernandes Garcia / Banca: Jean Marcos de Souza Ribeiro / Banca: Cristiano Quevedo Andrea / Resumo: Usando dois controladores digitais com modos deslizantes, é proposto neste trabalho dois esquemas que minimizam os efeitos degenerativos causados pelo atraso no tempo de compu- tação do sinal de controle, que aqui é tratado como falha. Um observador robusto com modos deslizantes é utilizado neste trabalho, uma vez que nem sempre é possível ter acesso a todos os estados do sistema. Neste trabalho o observador tem um papel fundamental na detecção e acomodação da falha, pois através de um banco de observadores é gerado um resíduo que pos- sibilita a detecção da falha e determina qual controlador deve estar atuando sobre o sistema a ser controlado. Para validar os métodos propostos, são realizadas simulações e experimentos nos modelos do pêndulo invertido e no helicóptero 3DOF; ambos equipamentos da Quanser / Abstract: Using two digital controllers with sliding mode schemes that minimizes the degenerative effects caused by the delay in the computation time of the control signal are proposed in this work, which is here treated as failure. A robust observer with sliding mode is shown in this work, since it is not always possible to have access to all system states, but in this work the observer has a key role in the failure detection and accommodation, as observers are generated through a residue that directs the performance of the controller on the system being controlled. To test the proposed methods, simulations and experiments are performed on models of the inverted pendulum and the helicopter 3DOF, both Quanser equipment / Mestre
2

Detecção e acomodação de falhas em sistemas incertos com atraso no sinal de controle utilizando modo deslizante

Paula, André Luiz Alexandre de [UNESP] January 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011Bitstream added on 2014-06-13T20:49:14Z : No. of bitstreams: 1 paula_ala_me_ilha.pdf: 1575411 bytes, checksum: 888f7fef0b727373d31bd42986d25a09 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Usando dois controladores digitais com modos deslizantes, é proposto neste trabalho dois esquemas que minimizam os efeitos degenerativos causados pelo atraso no tempo de compu- tação do sinal de controle, que aqui é tratado como falha. Um observador robusto com modos deslizantes é utilizado neste trabalho, uma vez que nem sempre é possível ter acesso a todos os estados do sistema. Neste trabalho o observador tem um papel fundamental na detecção e acomodação da falha, pois através de um banco de observadores é gerado um resíduo que pos- sibilita a detecção da falha e determina qual controlador deve estar atuando sobre o sistema a ser controlado. Para validar os métodos propostos, são realizadas simulações e experimentos nos modelos do pêndulo invertido e no helicóptero 3DOF; ambos equipamentos da Quanser / Using two digital controllers with sliding mode schemes that minimizes the degenerative effects caused by the delay in the computation time of the control signal are proposed in this work, which is here treated as failure. A robust observer with sliding mode is shown in this work, since it is not always possible to have access to all system states, but in this work the observer has a key role in the failure detection and accommodation, as observers are generated through a residue that directs the performance of the controller on the system being controlled. To test the proposed methods, simulations and experiments are performed on models of the inverted pendulum and the helicopter 3DOF, both Quanser equipment
3

Designing parsimonious representations of the maximally permissive deadlock avoidance policy for complex resource allocation systems through classification theory

Nazeem, Ahmed Mahmoud 27 July 2012 (has links)
Most of the past research on the problem of deadlock avoidance for complex resource allocation systems (RAS) has acknowledged the fact that the computation of the maximally permissive (optimal) deadlock avoidance policy (DAP) possesses super-polynomial complexity for most RAS classes, and therefore, it has resorted to solutions that trade off maximal permissiveness for computational tractability. In this work, we distinguish between the off-line and the on-line computation that is required for the effective implementation of the maximally permissive DAP, and we seek to develop representations of this policy that will require minimal on-line computation. The particular representation that we adopt is that of a compact classifier that will effect the underlying dichotomy of the reachable state space into safe and unsafe subspaces. Through a series of reductions of the derived classification problem, we are also able to attain extensive reductions in the computational complexity of the off-line task of the construction of the sought classifier. In a first study of the aforementioned problem, we restrict our attention to a particular RAS class that is motivated by an ongoing project called Gadara. This particular RAS class accepts the separation of the safe and unsafe subspaces of its instantiations through a set of linear inequalities. We propose design procedures that will construct a classifier employing the minimum possible number of linear inequalities, and we formally establish their "completeness", i.e., their ability to provide an effective classifier for every instance of the considered RAS class. We also offer heuristics that, if necessary, can alleviate the computational effort that is necessary for the construction of the sought classifier. We extend the aforementioned results to encompass more general RAS classes, where the sought dichotomy might not be represented by a set of linear inequalities. To this end, we propose new parametric and non-parametric classification schemes for this more complex case, and establish formally their completeness. We also provide effective and computationally efficient procedures for the synthesis of the sought classifiers. A bottleneck in the developments described above is defined by the fact that they presuppose the availability of the enumerations of the RAS safe and unsafe subspaces. To address this obstacle, we propose a novel approach for the deployment of the maximally permissive DAP for RAS, that is based on the identification and the efficient storage of a critical subset of states of the underlying RAS state space. In particular, the proposed algorithm provides those critical states, while avoiding the complete enumeration of the RAS state space. Furthermore, we extend the existing theory on maximally permissive deadlock avoidance, so that it can handle RAS with reader/writer (R/W) locks. A key challenge that is posed by this new RAS class stems from the fact that the underlying state space is not necessarily finite. We effectively address this obstacle by taking advantage of special structure that exists in the set of unsafe states and enables a finite representation of this set through its minimal elements. Finally, we would like to mention that numerical experimentation demonstrates the efficacy of the proposed approaches, and establishes their ability to support the deployment of maximally permissive DAP for RAS with very large structure and state spaces. To the best of our knowledge, these experiments also establish the ability of the proposed methodology to effectively compute tractable implementations of the maximally permissive DAP for problem instances significantly beyond the capacity of any other approach currently available in the literature. Moreover, this is the first work to address the RAS with R/W locks.
4

Z-Transformation auf Basis des Residuensatzes / Z-Transformation based on residue theorem

Geitner, Gert-Helge 17 June 2013 (has links) (PDF)
Die Z-Transformation ist ein wichtiges Werkzeug für diskontinuierliche Regelungen. Ein wenig beachteter Transformationsweg führt über die Berechnung von Residuen. Alle wichtigen Besonderheiten wie Mehrfachpole, Sprungfähigkeit, komplexe Pole oder Zeitverschiebung unterhalb der Abtastzeit (modifizierte Z-Transformation) können einbezogen werden. Die Vorgabe von Reihenabbruchkriterien oder das Auffinden von Summenformeln ist nicht notwendig. Der Weg ist prinzipiell für manuelle und maschinelle Berechnungen einsetzbar. Die Vorgehensweise wird durch drei ausführliche Beispiele verdeutlicht. / The Z-transformation is an important tool for the control of discontinuous systems. A seldom considered transformation way uses the residue computation. All relevant fea-tures as for instance multiple poles, process with feedthrough, complex poles or delay less than the sampling time (so called modified Z-transformation) may be included. There is no truncation criterion or search for a sum formula necessary. This way is always applicable for manual as well as for computer-aided computations. Three detailed examples demonstrate the use of the formulas.
5

Soft switching bidirectional isolated three-phase DC-DC converter using dual phase-shift control with variable duty cycle / Conversor CC-CC trifÃsico isolado bidirecional com comutaÃÃo suave utilizando dual phase-shift e razÃo cÃclica variÃvel

Herminio Miguel de Oliveira Filho 19 August 2015 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / This work presents the analysis, design example, simulations and experimental results on a soft-switching bidirectional isolated three-phase dc-dc converter using dual phase-shift control with variable duty cycle. The topology uses three single H-bridges in the primary side and a three-phase inverter in the secondary side. High-frequency isolation is ensured by using three single-phase transformers connected in open delta-wye configuration. The variation of both phase-shift (PS) angles between the H-bridge legs and/or primary and secondary sides allows controlling the power flow, while reduced reactive power flow is possible. The variable duty cycle is used to ensure a constant voltage bus and/or zero voltage switching (ZVS) operation. A detailed analysis is presented considering a model based on the fundamental components for the voltages and currents in the transformer and, aiming its validation, a second analysis from the operation stages of the converter has also been developed. Besides, the dynamic model of the converter, based on fundamental components and employing the gyrator theory has been developed. A design example with nominal values assumptions, stresses and specifications for components, discrete control system characterization and its FPGA programming are presented. Simulation and experimental results in steady state and closed-loop performance are presented and discussed to validate the proposed approach. / Este trabalho apresenta a anÃlise, exemplo de projeto, simulaÃÃes e resultados experimentais de um conversor CC-CC trifÃsico isolado bidirecional com comutaÃÃo suave, dual phase shift (DPS) e razÃo cÃclica variÃvel. A topologia utiliza trÃs pontes H monofÃsicas no lado primÃrio e um inversor trifÃsico no lado secundÃrio. A isolaÃÃo em alta frequÃncia à garantida utilizando-se trÃs transformadores monofÃsicos conectados em uma configuraÃÃo delta aberto/estrela. A variaÃÃo de ambos os Ãngulos de deslocamento de fase, entre os braÃos de uma ponte H e/ou entre os lados primÃrio e secundÃrio, permitem o controle do fluxo de potÃncia. Esta flexibilidade garante a obtenÃÃo de um baixo conteÃdo reativo na anÃlise de projeto da topologia. A razÃo cÃclica variÃvel à utilizada para assegurar um barramento constante e uma operaÃÃo dos interruptores com comutaÃÃo suave. Uma anÃlise matemÃtica da estrutura à apresentada considerando um modelo baseado em componentes fundamentais e, com o propÃsito de comprovar a validade deste modelo, uma segunda anÃlise a partir das etapas de operaÃÃo do conversor tambÃm foi desenvolvida. O modelo dinÃmico do conversor, baseado nas componentes fundamentais, tambÃm foi concebido com auxÃlio da teoria do gyrator. Um exemplo de projeto, com a obtenÃÃo de valores nominais, esforÃos e especificaÃÃes dos componentes, caracterizaÃÃo do sistema de controle discreto e sua programaÃÃo atravÃs de FPGA sÃo desenvolvidos. SimulaÃÃes e resultados experimentais do conversor operando em regime permanente e dinÃmico sÃo apresentados para validar o modelo proposto.
6

Robust Control of Teleoperated Unmanned Aerial Vehicles

Han, Chunyang January 2020 (has links)
In this thesis, we first use the reachability theory to develop algorithms for state predictionunder delayed state or output measurements. We next develop control strategies forcollision avoidance and trajectory tracking of UAVs based on the devised algorithms andthe model predictive control theory. Finally, simulations results for collision avoidanceand trajectory tracking problems are presented, for different communication delays,using a UAV model with 6 degrees of freedom. / I denna avhandling använder vi först tillgänglighetsteorin för att utveckla algoritmerför tillståndsförutsägelse under fördröjda tillstånds- eller utgångsmätningar. Därefterutvecklar kontrollstrategier för undvikande av kollision och spårning av UAV: er baseradepå de planerade algoritmerna och modellen förutsägbar kontrollteori. Slutligenpresenteras simuleringsresultat för att undvika kollision och problem med spårningav banan, för olika kommunikationsförseningar, med en UAV-modell med 6 frihetsgrader.
7

Sistematização do projeto de reatores eletrônicos para alimentação de lâmpadas de vapor de sódio em alta pressão para iluminação pública / Design of a commercial approach of electronic ballasts to supply high-pressure sodium lamps in public lighting

Costa, Rafael Eduardo da 27 February 2009 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / This thesis presents an electronic ballast prototype to supply high-pressure sodium lamps used in public lighting. The goal is to develop a commercial approach able to replace the still commonly used electromagnetic ballasts, performing improvements in the public lighting system. Along this thesis, the state of art in lighting area is presented, especially in public lighting. Following, a bibliographic review about electronic ballasts to supply highpressure sodium lamps is done. Special attention is given to the low frequency square waveform supplying method, which is used in this thesis. Also, the features desired in electronic ballasts so they can operate the lamp reliably and according to the standards are discussed. From this review, the proposed topology is defined and its design is presented. A discrete control method is developed to guarantee the safe operation of the ballast during all lamp stages. A microcontroller is used to perform the control routines. Finally, experimental results are obtained, validating the proposed work. / Este trabalho apresenta uma proposta de sistematização do projeto de um reator eletrônico para alimentação de lâmpadas de vapor de sódio em alta pressão, para aplicação em iluminação pública. Com isto, pretende-se criar um dispositivo que venha a substituir os reatores eletromagnéticos, ainda comumente utilizados nesta aplicação, de modo a proporcionar melhorias nos atuais sistemas de iluminação pública. Ao longo deste trabalho, é feita uma revisão do estado da arte na área de iluminação, dando ênfase à iluminação pública. Em seguida, é apresentada uma revisão bibliográfica acerca dos métodos de alimentação de lâmpadas de vapor de sódio a partir de reatores eletrônicos, destacando-se a alimentação deste tipo de lâmpada com forma de onda quadrada em baixa freqüência, método utilizado neste trabalho. Também são discutidas as características que um reator eletrônico deve possuir para enquadrar-se nas normas vigentes e alimentar a lâmpada de forma confiável. A partir desta revisão, a topologia proposta é definida e seu projeto é apresentado. Uma metodologia de controle discreto é desenvolvida de forma a garantir a operação adequada do reator durante todas as etapas de funcionamento da lâmpada. Um microcontrolador é utilizado para executar as rotinas de controle. Finalmente, resultados experimentais são obtidos, de forma a validar o trabalho proposto.
8

Controle discreto de fonte modular de corrente aplicada a magnetos de aceleradores de partículas

Oliveira, Fernando Henrique de 23 February 2018 (has links)
Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-05-23T18:23:25Z No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-05-24T17:33:19Z (GMT) No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) / Made available in DSpace on 2018-05-24T17:33:19Z (GMT). No. of bitstreams: 1 fernandohenriquedeoliveira.pdf: 7733433 bytes, checksum: ed0bfbea1ebdeec7443503ad20027a67 (MD5) Previous issue date: 2018-02-23 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta dissertação apresenta uma proposta de controle discreto baseado em reali-mentação de estados aplicado à fonte de alimentação das cargas magnéticas do Sirius. A fonte é formada por associações em série e em paralelo de módulos de menor po-tência para que, em conjunto, possam atender às exigências requeridas de tensão e de corrente dos magnetos. Cada módulo é constituído de dois estágios, um de entrada e outro de saída, em que o segundo é o objeto de estudo deste trabalho. O estágio de saída é constituído por um conversor ponte completa associado a um filtro de terceira ordem. Inicialmente é feita a modelagem do estágio de saída e apresentado um modelo apropriado a uma quantidade genérica de módulos associados em série. Em seguida é feita a discretização da planta e o controle em espaço de estados. Para a alocação dos pólos do sistema em malha fechada é utilizado o Regulador Quadrático Linear Digital. Entretanto, quando módulos são associados, aumenta-se consideravelmente a ordem do sistema e torna-se inviável a medição de todos os estados da planta. Então, é proposto um observador ótimo de ordem reduzida para que este seja capaz de fornecer ao con-trolador os estados que não são medidos. A análise de estabilidade permitiu verificar a robustez do controle em conjunto com o observador de estados. Na associação de módulos em paralelo foram consideradas que as correntes da saída de cada módulo são parcelas do estado que corresponde à corrente das cargas magnéticas. Baseado nesta premissa e no controle feito para o arranjo de módulos em série, foi proposta uma estratégia de controle para o arranjo em paralelo. Os resultados em simulação, tanto para a configuração de módulos em série quanto em paralelo, permitem verificar os desempenhos dinâmicos do controlador e observador de estados. / This dissertation presents a proposal of a discrete-time state-feedback control law applied to the Sirius magnetic source power supply. In order to meet the magnets' required voltage and current levels the source is formed by series and parallel associa-tion of modular converters. Each module is made up of two stages, input and output, in which the later is addressed this work. The output stage is constituted by a full bridge converter associated with a third-order filter. Initially a mathematical model is obtained for a single module. This model is later extended to represent the connection of several modules in series. Then the plant is discretized and state feedback law is designed to control the system. The optimal technique Digital Linear Quadratic Regu-lator was used to place the closed-loop poles. However, when modules are associated, due the order of the system it becomes impracticable to measure all the states. Then an optimal reduced order observer is proposed to provide to controller the states that are not measured. An stability analysis is performed in order to verify the controller robustness. For the association of modules in parallel was considered that the output currents of each module are the parcels of the state corresponding to the current of the magnetic loads. Based on this premise and in the previously control design for the series modules association, is proposed a control topology for the parallel arrange-ment. Simulation results were obtained, for the both configuration of modules series and parallel, and the performances of the controller and state-observer were verified.
9

Spojité a diskrétní řízení vozidla. / Continuous and discrete time attitude control of a vehicle

Najvarová, Lucie January 2009 (has links)
Kontrola řízení vozidla se stala významným problémem v automatizačních aplikacích v automobilovém průmyslu. Ta se stala reálnou díky zavedení různých "by-wire" subsystémů, jako je např. "steer-by-wire," "break-by-wire," atd. Tyto subsystémy reprezentují elektronické ekvivalenty již existujících mechanických a hydraulických subsystémů. Především pak může být zavedeno číslicové řízení, určené na základě vzorkování dynamiky vozidla. Výhodou periodického snímání vstupních veličin je vyvarování se určitých poruch spojitého řízení.
10

Z-Transformation auf Basis des Residuensatzes: Prof. Dr.-Ing. habil. Dr.-Ing. E.h. R. Schönfeld zum 65. Geburtstag

Geitner, Gert-Helge January 1999 (has links)
Die Z-Transformation ist ein wichtiges Werkzeug für diskontinuierliche Regelungen. Ein wenig beachteter Transformationsweg führt über die Berechnung von Residuen. Alle wichtigen Besonderheiten wie Mehrfachpole, Sprungfähigkeit, komplexe Pole oder Zeitverschiebung unterhalb der Abtastzeit (modifizierte Z-Transformation) können einbezogen werden. Die Vorgabe von Reihenabbruchkriterien oder das Auffinden von Summenformeln ist nicht notwendig. Der Weg ist prinzipiell für manuelle und maschinelle Berechnungen einsetzbar. Die Vorgehensweise wird durch drei ausführliche Beispiele verdeutlicht. / The Z-transformation is an important tool for the control of discontinuous systems. A seldom considered transformation way uses the residue computation. All relevant fea-tures as for instance multiple poles, process with feedthrough, complex poles or delay less than the sampling time (so called modified Z-transformation) may be included. There is no truncation criterion or search for a sum formula necessary. This way is always applicable for manual as well as for computer-aided computations. Three detailed examples demonstrate the use of the formulas.

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