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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

Robust controller design for lightly damped systems with feedback delay

Hung, Donald Lu-Cheng January 1991 (has links)
No description available.
2

Robust Controller Design For A Fixed Wing Uav

Prach, Anna 01 September 2009 (has links) (PDF)
This study describes the design and implementation of the pitch and roll autopilots for a fixed wing unmanned vehicle. A Tactical Unmanned Aerial Vehicle (TUAV), which is designed at the Middle East Technical University (METU), is used as a platform. This work combines development of the classical and robust controllers, which are used for the pitch and roll autopilots. One of the important steps in the thesis is development of the non-linear dynamic model of the UAV, which is developed in MATLAB/Simulink environment. Two different strategies of the controller design imply development of the PID and controllers. Simulation results illustrate the performances of the designed controllers. Simulation is performed for the nominal model of the UAV and for the model that includes uncertainties and sensor noises.
3

Synchrophasor-based robust power system stabilizer design using eigenstructure assignment

KONARA MUDIYANSELAGE, ANUPAMA 11 December 2015 (has links)
Power system stabilizers (PSSs) provide the most economical way to improve damping of electro-mechanical oscillations in electrical power systems. Synchrophasor technology enables the use of remotely measured signals in the PSS allowing for greater flexibility in the design of the PSS. Issues related to the transmission of remote signals should be addressed before implementing such systems in practice. This study investigates two of the data transmission issues: (i) delays, and (ii) data dropout; using a synchrophasor-based PSS designed for a two-area four-generator power system model. A time delayed system is modeled using discrete transformation and the effect of the constant delay on the control action of improving damping of an electro-mechanical oscillation is determined analytically. The effect of random delays and data dropout is investigated using non-linear simulations considering viable remedies to overcome these effects. This research also identifies effective means of using synchrophasor signals for improving the performance of PSSs. Primarily, this research introduces a novel control design algorithm based on eigenstructure assignment that could utilize remotely measured signals to design a robust PSS considering different operating conditions at the design stage. Remote signals could be used as additional inputs to the controller, which introduces extra degrees of freedom. In eigenstructure assignment, these additional degrees of freedom are used to assign eigenvalues and eigenvectors to have adequate damping performance of the system over different operating conditions. The algorithm is formulated as a derivative-free non-linear optimization problem and solved using a single step of optimization by eliminating the use of eigenvalue sensitivities. The proposed algorithm is tested for the 68 bus model of the interconnected New England test system and New York power system. Three different control configurations that use local and remote signals are considered in the design. The algorithm is solved using non-linear simplex optimization considering different initial points for seeking a global solution. Delays in the remote signals are also incorporated into the design. The designed controllers are verified in a non-linear simulation platform. Finally, the reliability of synchrophasor-based PSS is discussed in brief. / February 2016
4

Flight Control System Design For An Over Actuated Uav Against Actuator Failures

Isik, Sinem 01 February 2010 (has links) (PDF)
This thesis describes the automatic flight control systems designed for a conventional and an over actuated unmanned air vehicle (UAV). A nonlinear simulation model including the flight mechanics equations together with the interpolated nonlinear aerodynamics, environmental effects, mass-inertia properties, thrust calculations and actuator dynamics is created / trim and linearization codes are developed. Automatic flight control system of the conventional UAV is designed by using both classical and robust control methods. Performances of the designs for full autonomous flight are tested through nonlinear simulations for different maneuvers in the presence of uncertainties and disturbances in the aircraft model. The fault tolerant control of an over actuated UAV is the main concern of the thesis. The flight control system is designed using classical control techniques. Two static control allocation methods are examined: Moore-Penrose pseudo inverse and blended inverse. For this purpose, an aircraft with three sets of ailerons is employed. It is shown that with redundant control surfaces, fault tolerant control is possible. Although both of the static control allocation methods are found to be quite successful to realize the maneuvers, the new blended inverse algorithm is shown to be more effective in controlling the aircraft when some of the control surfaces are lost. It is also demonstrated that, with redundant control surfaces it is possible to recover the aircraft during a maneuver even some of the control surfaces are damaged or got stuck at a particular deflection.
5

Aeroservoelastic Analysis And Robust Controller Synthesis For Flutter Suppression Of Air Vehicle Control Actuation Systems

Alper, Akmese 01 June 2006 (has links) (PDF)
Flutter is one of the most important phenomena in which aerodynamic surfaces become unstable in certain flight conditions. Since the 1930&amp / #8217 / s many studies were conducted in the areas of flutter prediction in design stage, research of design methods for flutter prevention, derivation and confirmation of flutter flight envelopes via tests, and in similar subjects for aircraft wings. With the use of controllers in 1960&amp / #8217 / s, studies on the active flutter suppression began. First the classical controllers were used. Then, with the improvement of the controller synthesis methods, optimal controllers and later robust controllers started to be used. However, there are not many studies in the literature about fully movable control surfaces, commonly referred to as fins. Fins are used as missile control surfaces, and they can also be used as a horizontal stabilizer or as a canard in aircraft. In the scope of this thesis, controllers satisfying the performance and flutter suppression requirements of a fin are synthesized and compared. For this purpose, H2, Hinf, and mu controllers are used. A new flutter suppression method is proposed and used. In order to assess the performance of this method, results obtained are compared with the results of another flutter suppression method given in the literature. or the purpose of implementation of the controllers developed, aeroelastic model equations are derived by using the typical section wing model with thin airfoil assumption. The controller synthesis method is tested for aeroelastic models that are veloped for various flow regimes / namely, steady incompressible subsonic, unsteady incompressible subsonic, nsteady compressible subsonic, and unsteady compressible supersonic.
6

Formulações convexas para problemas de controle H2 - robusto relativo a pertubações não-paramétricas / Convex formularizations for robust H2 control problems relative to non-parametric pertubations

Freire, Emerson Souza 04 December 2006 (has links)
Made available in DSpace on 2015-03-04T18:50:47Z (GMT). No. of bitstreams: 1 tese completa.pdf: 1208568 bytes, checksum: c0cd1bce0998cd8116d5ae8f7429ef23 (MD5) Previous issue date: 2006-12-04 / Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / In this work, performance analysis and control synthesis for good performance are studied for systems subject to non-parametric perturbations which satisfy a prescribed norm bound. First, the performance analysis problem is considered for a given controller that ensures robust stability in presence of such perturbations.. The performance index used is the so-called worst-case index. Due to the the character of the correspondent non-convex problem, convex optimization problems in function spaces are formulated whose solutions are upper bounds on the worst-case index. Next, it is shown that when the decision variables are confined to finite dimensional subspaces, these problems can be formulated in terms of linear optimization problems in euclidean spaces with constraints defined by linear matrix inequalities (LMI s). On the basis of the upper bounds obtained, procedures for controller synthesis can be formulated, which consist of a D-K iteration procedure for minimization problems with respect to multipliers and robust satabilizing controllers. Using the Youla parametrization of these controllers, for a given set of multipliers it is shown that when the Youla parameter is confined to finite dimensional subspace, the synthesis formulations are equivalent to linear optimization problems in euclidean spaces with constraints defined by LMIs. In both the cases (analysis and synthesis) heuristics to iterative modify the confining subspaces are suggested. An approach analogous to the one robust problems was applied to robust filtering problems leading to similar results. It is worth noting that in this case, due to the fact that only open-loop systems are involved, the correspondent synthesis procedures do not require D-K itearation.. / Neste trabalho são estudados problemas de controle correspondentes à análise de desempenho e síntese de controladores para bom desempenho no sentido da norma de sistemas sujeitos a perturbações não-paramétricas e limitadas na norma . Inicialmente é considerado o problema de análise de desempenho de um dado controlador que assegure a estabilidade de um sistema sujeito a estas perturbações. O índice de desempenho utilizado é o chamado pior-caso . Dada a dificuldade de resolução do correspondente problema não-convexo , são formulados problemas de otimização convexa em espaços de funções cujas soluções são limitantes superiores para o pior-caso . A seguir, mostra-se que quando as variáveis de decisão são confinadas a subespaços de dimensão finita, estes problemas podem ser formulados em termos de problemas de otimização linear em espaços euclidianos com restrições definidas por desigualdades matriciais lineares (LMI s). Com base nos limitantes obtidos, podem ser formulados procedimentos de síntese de controladores, que consistem essencialmente em procedimentos do tipo D-K iteration para problemas de minimização com respeito a multiplicadores e controladores robustamente estabilizantes. Utilizando a parametrização de Youla destes controladores, mostra-se que, para um dado conjunto de multiplicadores, quando o parâmetro de Youla é confinado a um subespaço de dimensão finita, as formulações para síntese também são equivalentes a problemas de otimização linear em espaços euclidianos, com restrições definidas por LMI s. Em ambos os casos (análise e síntese) são sugeridos heurísticas para a modificação iterativa dos subespaços aos quais as variáveis de decisão serão confinadas. A mesma metodologia utilizada para os problemas de controle robusto aqui considerados, pode ser aplicada a problemas de filtragem robusta. Neste caso, devido ao fato de se tratar de sistemas em malha aberta, não há necessidade de procedimentos do tipo D-K iteration . In this work, performance analysis and control synthesis for good performance are studied for systems subject to non-parametric perturbations which satisfy a prescribed norm bound. First, the performance analysis problem is considered for a given controller that ensures robust stability in presence of such perturbations.. The performance index used is the so-called worst-case index. Due to the the character of the correspondent non-convex problem, convex optimization problems in function spaces are formulated whose solutions are upper bounds on the worst-case index. Next, it is shown that when the decision variables are confined to finite dimensional subspaces, these problems can be formulated in terms of linear optimization problems in euclidean spaces with constraints defined by linear matrix inequalities (LMI s). On the basis of the upper bounds obtained, procedures for controller synthesis can be formulated, which consist of a D-K iteration procedure for minimization problems with respect to multipliers and robust satabilizing controllers. Using the Youla parametrization of these controllers, for a given set of multipliers it is shown that when the Youla parameter is confined to finite dimensional subspace, the synthesis formulations are equivalent to linear optimization problems in euclidean spaces with constraints defined by LMIs. In both the cases (analysis and synthesis) heuristics to iterative modify the confining subspaces are suggested. An approach analogous to the one robust problems was applied to robust filtering problems leading to similar results. It is worth noting that in this case, due to the fact that only open-loop systems are involved, the correspondent synthesis procedures do not require D-K itearation..
7

Controle robusto com realimentação derivativa de sistemas não lineares via LMI /

Moreira, Manoel Rodrigo. January 2011 (has links)
Orientador: Marcelo Carvalho Minhoto Teixeira / Banca: Edvaldo Assunção / Banca: Celso Pascoli Bottura / Resumo: Em alguns problemas práticos, por exemplo, no controle de vibrações de sistemas mecânicos utilizando acelerômetros como sensores, é mais fácil obter a da derivada do vetor de estado do que o vetor de estado. Esta dissertação mostra que plantas lineares e invariantes no tempo descritas pelas matrizes {A,B,C,D}, cuja saída é a derivada do vetor de estado, são não observáveis e não estabilizáveis com realimentação da saída, quando det(A)=0. A impossibilidade de rejeição de distúrbios constantes, somados à entrada da planta quando det(A) 6= 0, realimentando-se a saída com controladores estáticos, foi também demonstrada. Adicionalmente, são propostas novas técnicas de controle para uma classe de sistemas não lineares com incertezas variantes no tempo. Condições na forma de desigualdades matriciais lineares, em inglês Linear Matrix Inequalities (LMIs), para o projeto de sistemas de controle empregando realimentação derivativa estática da derivada do vetor de estado, que ao mesmo tempo estabiliza a planta e maximiza o limite de incerteza do termo não linear, são estabelecidas com base em funções quadráticas de Lyapunov. Posteriormente estendem-se as condições de estabilidade robusta para sistemas não lineares com incertezas variantes no tempo e incertezas politópicas, que podem também representar falhas estruturais. O projeto do controlador é realizado através de condições baseadas em LMIs que, quando factíveis, podem ser resolvidas facilmente utilizando técnicas de programação convexa. Essa metodologia permite a inclusão de restrições de desempenho no projeto, como por exemplo, na taxa de decaimento e na norma de ganho dos controladores, de modo a atender às restrições do projeto. São apresentadas análises e resultados considerando o sinal de controle nulo e empregando realimentação derivativa estática do vetor de estado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In some practical problems, for instance in the control of mechanical systems using accelerometers as sensors, it is easier to obtain the state-derivative vectors than the state vectors. This dissertation shows that (i) linear time-invariant plants given by the state-space model matrices {A,B,C,D} with output equal to the state-derivative vector are not observable and can not be stabilizable by using an output feedback if det(A) = 0 and (ii) the rejection of a constant disturbance added to the input of the aforementioned plants, considering det(A) 6= 0, and a static output feedback controller is not possible. The proposed results can be useful in the analysis and design of control systems with state-derivative feedback. Additionally, a new procedure for the control of a class of nonlinear systems with time-varying uncertainties using static statederivative feedback is proposed. Conditions based on Linear Matrix Inequalities (LMIs) for the design of robust controllers using state-derivative feedback, which simultaneously stabilizes the system and maximizes the uncertainty bound of the nonlinear term are proposed. Robust stability conditions for nonlinear systems with uncertainties and time-varying polytopic uncertainties, known as structural failures, are also presented. The controller design are based on LMIs which, when feasible, can be easily solved using convex programming techniques. This methodology allows the inclusion of performance constraints on the design, such as the decay rate and gain bounds in order to meet the design requirements. The dissertation considered cases where the control signal is equal to zero and with a state-derivative feedback. The elaboration of the theory for systems with n nonlinearities is illustrated through examples covering a single nonlinearity, with and without two polytopic uncertainties (and structural failures), and two nonlinearities... (Complete abstract click electronic access below) / Mestre
8

Formulações convexas para problemas de controle H2 - robusto relativo a pertubações não-paramétricas / Convex formularizations for robust H2 control problems relative to non-parametric pertubations

Emerson Souza Freire 04 December 2006 (has links)
Neste trabalho são estudados problemas de controle correspondentes à análise de desempenho e síntese de controladores para bom desempenho no sentido da norma de sistemas sujeitos a perturbações não-paramétricas e limitadas na norma . Inicialmente é considerado o problema de análise de desempenho de um dado controlador que assegure a estabilidade de um sistema sujeito a estas perturbações. O índice de desempenho utilizado é o chamado pior-caso . Dada a dificuldade de resolução do correspondente problema não-convexo , são formulados problemas de otimização convexa em espaços de funções cujas soluções são limitantes superiores para o pior-caso . A seguir, mostra-se que quando as variáveis de decisão são confinadas a subespaços de dimensão finita, estes problemas podem ser formulados em termos de problemas de otimização linear em espaços euclidianos com restrições definidas por desigualdades matriciais lineares (LMIs). Com base nos limitantes obtidos, podem ser formulados procedimentos de síntese de controladores, que consistem essencialmente em procedimentos do tipo D-K iteration para problemas de minimização com respeito a multiplicadores e controladores robustamente estabilizantes. Utilizando a parametrização de Youla destes controladores, mostra-se que, para um dado conjunto de multiplicadores, quando o parâmetro de Youla é confinado a um subespaço de dimensão finita, as formulações para síntese também são equivalentes a problemas de otimização linear em espaços euclidianos, com restrições definidas por LMIs. Em ambos os casos (análise e síntese) são sugeridos heurísticas para a modificação iterativa dos subespaços aos quais as variáveis de decisão serão confinadas. A mesma metodologia utilizada para os problemas de controle robusto aqui considerados, pode ser aplicada a problemas de filtragem robusta. Neste caso, devido ao fato de se tratar de sistemas em malha aberta, não há necessidade de procedimentos do tipo D-K iteration. In this work, performance analysis and control synthesis for good performance are studied for systems subject to non-parametric perturbations which satisfy a prescribed norm bound. First, the performance analysis problem is considered for a given controller that ensures robust stability in presence of such perturbations.. The performance index used is the so-called worst-case index. Due to the the character of the correspondent non-convex problem, convex optimization problems in function spaces are formulated whose solutions are upper bounds on the worst-case index. Next, it is shown that when the decision variables are confined to finite dimensional subspaces, these problems can be formulated in terms of linear optimization problems in euclidean spaces with constraints defined by linear matrix inequalities (LMIs). On the basis of the upper bounds obtained, procedures for controller synthesis can be formulated, which consist of a D-K iteration procedure for minimization problems with respect to multipliers and robust satabilizing controllers. Using the Youla parametrization of these controllers, for a given set of multipliers it is shown that when the Youla parameter is confined to finite dimensional subspace, the synthesis formulations are equivalent to linear optimization problems in euclidean spaces with constraints defined by LMIs. In both the cases (analysis and synthesis) heuristics to iterative modify the confining subspaces are suggested. An approach analogous to the one robust problems was applied to robust filtering problems leading to similar results. It is worth noting that in this case, due to the fact that only open-loop systems are involved, the correspondent synthesis procedures do not require D-K itearation.. / In this work, performance analysis and control synthesis for good performance are studied for systems subject to non-parametric perturbations which satisfy a prescribed norm bound. First, the performance analysis problem is considered for a given controller that ensures robust stability in presence of such perturbations.. The performance index used is the so-called worst-case index. Due to the the character of the correspondent non-convex problem, convex optimization problems in function spaces are formulated whose solutions are upper bounds on the worst-case index. Next, it is shown that when the decision variables are confined to finite dimensional subspaces, these problems can be formulated in terms of linear optimization problems in euclidean spaces with constraints defined by linear matrix inequalities (LMIs). On the basis of the upper bounds obtained, procedures for controller synthesis can be formulated, which consist of a D-K iteration procedure for minimization problems with respect to multipliers and robust satabilizing controllers. Using the Youla parametrization of these controllers, for a given set of multipliers it is shown that when the Youla parameter is confined to finite dimensional subspace, the synthesis formulations are equivalent to linear optimization problems in euclidean spaces with constraints defined by LMIs. In both the cases (analysis and synthesis) heuristics to iterative modify the confining subspaces are suggested. An approach analogous to the one robust problems was applied to robust filtering problems leading to similar results. It is worth noting that in this case, due to the fact that only open-loop systems are involved, the correspondent synthesis procedures do not require D-K itearation..
9

Controle robusto com realimentação derivativa de sistemas não lineares via LMI

Moreira, Manoel Rodrigo [UNESP] 28 February 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-28Bitstream added on 2014-06-13T18:49:28Z : No. of bitstreams: 1 moreira_mr_me_ilha.pdf: 1357345 bytes, checksum: 0cd0261b936a9aacf1f408322f1ec3be (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Em alguns problemas práticos, por exemplo, no controle de vibrações de sistemas mecânicos utilizando acelerômetros como sensores, é mais fácil obter a da derivada do vetor de estado do que o vetor de estado. Esta dissertação mostra que plantas lineares e invariantes no tempo descritas pelas matrizes {A,B,C,D}, cuja saída é a derivada do vetor de estado, são não observáveis e não estabilizáveis com realimentação da saída, quando det(A)=0. A impossibilidade de rejeição de distúrbios constantes, somados à entrada da planta quando det(A) 6= 0, realimentando-se a saída com controladores estáticos, foi também demonstrada. Adicionalmente, são propostas novas técnicas de controle para uma classe de sistemas não lineares com incertezas variantes no tempo. Condições na forma de desigualdades matriciais lineares, em inglês Linear Matrix Inequalities (LMIs), para o projeto de sistemas de controle empregando realimentação derivativa estática da derivada do vetor de estado, que ao mesmo tempo estabiliza a planta e maximiza o limite de incerteza do termo não linear, são estabelecidas com base em funções quadráticas de Lyapunov. Posteriormente estendem-se as condições de estabilidade robusta para sistemas não lineares com incertezas variantes no tempo e incertezas politópicas, que podem também representar falhas estruturais. O projeto do controlador é realizado através de condições baseadas em LMIs que, quando factíveis, podem ser resolvidas facilmente utilizando técnicas de programação convexa. Essa metodologia permite a inclusão de restrições de desempenho no projeto, como por exemplo, na taxa de decaimento e na norma de ganho dos controladores, de modo a atender às restrições do projeto. São apresentadas análises e resultados considerando o sinal de controle nulo e empregando realimentação derivativa estática do vetor de estado... / In some practical problems, for instance in the control of mechanical systems using accelerometers as sensors, it is easier to obtain the state-derivative vectors than the state vectors. This dissertation shows that (i) linear time-invariant plants given by the state-space model matrices {A,B,C,D} with output equal to the state-derivative vector are not observable and can not be stabilizable by using an output feedback if det(A) = 0 and (ii) the rejection of a constant disturbance added to the input of the aforementioned plants, considering det(A) 6= 0, and a static output feedback controller is not possible. The proposed results can be useful in the analysis and design of control systems with state-derivative feedback. Additionally, a new procedure for the control of a class of nonlinear systems with time-varying uncertainties using static statederivative feedback is proposed. Conditions based on Linear Matrix Inequalities (LMIs) for the design of robust controllers using state-derivative feedback, which simultaneously stabilizes the system and maximizes the uncertainty bound of the nonlinear term are proposed. Robust stability conditions for nonlinear systems with uncertainties and time-varying polytopic uncertainties, known as structural failures, are also presented. The controller design are based on LMIs which, when feasible, can be easily solved using convex programming techniques. This methodology allows the inclusion of performance constraints on the design, such as the decay rate and gain bounds in order to meet the design requirements. The dissertation considered cases where the control signal is equal to zero and with a state-derivative feedback. The elaboration of the theory for systems with n nonlinearities is illustrated through examples covering a single nonlinearity, with and without two polytopic uncertainties (and structural failures), and two nonlinearities... (Complete abstract click electronic access below)
10

H Infinity - Based Robust Controller For Aerospace Vehicles

George, K Koshy 11 1900 (has links) (PDF)
No description available.

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