abstract: The problem of systematically designing a control system continues to remain a subject of intense research. In this thesis, a very powerful control system design environment for Linear Time-Invariant (LTI) Multiple-Input Multiple-Output (MIMO) plants is presented. The environment has been designed to address a broad set of closed loop metrics and constraints; e.g. weighted H-infinity closed loop performance subject to closed loop frequency and/or time domain constraints (e.g. peak frequency response, peak overshoot, peak controls, etc.). The general problem considered - a generalized weighted mixed-sensitivity problem subject to constraints - permits designers to directly address and tradeoff multivariable properties at distinct loop breaking points; e.g. at plant outputs and at plant inputs. As such, the environment is particularly powerful for (poorly conditioned) multivariable plants. The Youla parameterization is used to parameterize the set of all stabilizing LTI proper controllers. This is used to convexify the general problem being addressed. Several bases are used to turn the resulting infinite-dimensional problem into a finite-dimensional problem for which there exist many efficient convex optimization algorithms. A simple cutting plane algorithm is used within the environment. Academic and physical examples are presented to illustrate the utility of the environment. / Dissertation/Thesis / M.S. Electrical Engineering 2013

Orientador: Alberto Luiz Serpa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T04:19:56Z (GMT). No. of bitstreams: 1 HuamanOrtiz_RonaldRichard_M.pdf: 3700691 bytes, checksum: e0c35e9a16c6fd36ae433ab9a61c6cbb (MD5) Previous issue date: 2015 / Resumo: O projeto de sistemas de controle ativo de vibrações para estruturas flexíveis envolve a síntese de controladores que, geralmente, reduzem certos picos da resposta em frequência do sistema em malha fechada. Em alguns casos é requerido controlar unicamente um modo de vibrar específico do sistema em análise que pode estar associado a uma faixa de baixa, média ou alta frequência, o que demanda de um controle modal de vibrações. Neste trabalho, propõem-se três métodos alternativos para sintetizar controladores modais utilizando a teoria de controle H-infinito em uma configuração de controle por realimentação de saída. O primeiro método é implementado utilizando funções de ponderação as quais são introduzidas no problema de controle H-infinito para definir as características do controlador de maneira que este atenue a vibração do sistema na região em frequência correspondente ao modo que se deseja controlar (modo de interesse). O segundo método procura sintetizar controladores modais de menor ordem, utilizando uma planta reduzida. Essa planta reduzida contém unicamente a informação dinâmica do modo que se deseja controlar e é obtida através de uma transformação modal. O terceiro método procura melhorar o desempenho do controlador modal (conseguir uma maior redução da vibração do modo de interesse). Este método propõe sintetizar o controlador modal formulando um problema de otimização não linear onde as variáveis do controlador modal são as variáveis de otimização e a função objetivo é definida com valores específicos da resposta em frequência do sistema dinâmico. A solução deste problema de otimização é obtida utilizando o algoritmo de programação quadrática sequencial (SQP). Os três métodos são verificados utilizando o modelo de uma viga flexível engastada que é modelada através do método dos elementos finitos. Finalmente, os resultados obtidos são discutidos analisando as vantagens e desvantagens dos métodos propostos / Abstract: The design of active vibration control systems for flexible structures involves the tuning of controllers that reduce, generally, certain frequency resonance peaks of the close loop system. In some cases it is required to control a specific vibration mode of the system from a low, middle or high frequency range, demanding a modal vibration control. In this study it is proposed three alternative modal control methods using the H-infinity control theory in an output feedback control configuration. The first method is implemented using weighting functions which are introduced into the H-infinity control problem to define the characteristics of the controller so that it mitigates the system vibration in the frequency region that corresponds to a specific vibration mode (mode of interest). The second method attempts to synthesize lower order modal controllers, using a reduced plant. This reduced plant contains only the dynamic information of the vibration mode you want to control and is obtained through a modal transformation. The third method aims to improve the performance of the modal controller (to achieve a further reduction of the vibration mode of interest). This method proposes to synthesize the modal controller formulating a non-linear optimization problem where the variables of the modal controller are defined as the optimization variables and the objective function is defined with specific values of the frequency response of the dynamic system. The solution to this optimization problem is obtained using the sequential quadratic programming (SQP) algorithm. The three methods are verified using the model of a cantilever flexible beam that is modeled by the finite element method. Finally, the results are discussed considering the advantages and disadvantages of the proposed methods / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

This paper presents the development of building up a controlled MEMS acceleration sensor. The first samples have archived a resolution of better than 500 ug and a bandwidth of more than 200 Hz. A theoretical model is built from the physical principles of the complete sensor system, consisting of the MEMS sensor, the charge amplifier and the PWM driver for the sensor element. A reduced order model of the system is used to design a robust control with the Mixed-Sensitivity H-infinity Approach. Limitations for the control design are given since the system contains time delays and an unstable pole imposed by the electrostatic spring softening effect. The theoretical model might be inaccurate or lacks of completeness, because the parameters for the theoretical model building vary from sample to sample or might be not known. A new two-stage identification scheme is deployed to obtain directly the system parameters from the samples. The focus of this paper is the complete system development and identification process including practical tests in a DSP TI-TMS320C3000 environment with 12/14-bit A/D-D/A converters. / Der Artikel beschreibt die Entwicklungsschritte eines geregelten MEMS-Beschleunigungssensors. Die ersten Prototypen erreichten dabei eine Auflösung von weniger als 500 ug und eine Bandbreite von mehr als 200 Hz. Ein theoretisches Modell für den Reglerentwurf wird aus den physikalischen Zusammenhängen des Gesamtsystems, bestehend aus dem mechanischen Sensorelement, dem Ladungsverstärker und der PWM-Treiberstufe, gebildet. Für den Reglerentwurf wird der H-Infinity Mixed-Sensitivity Approach verwendet. Wegen Systemtotzeiten und dem Effekt der elektrostatischen Federerweichung sind Grenzen für die Wahl der Bandbreite zu beachten. Da Parameter für das theoretische Modell stark variieren oder schwer zu bestimmen sind, wird eine 2-Stufen-Identifikationsmethode vorgeschlagen, um ein Modell für den Reglerentwurf zu erhalten. Praktische Tests wurden mit einem DSP TI-TMS320C3000 mit 12/14-Bit A/D-D/A Wandlerstufen durchgeführt.

Due to increasingly difficult threats, current air defense missile systems are pushed to the limits of their performance capabilities. In order to defend against these more stressing threats, interceptor missiles require greater maneuverability, faster response time, and increased robustness to more severe environmental conditions. One of the most critical missile system elements is the flight control system, since its time constant is typically half of the total missile system time constant. Conventional autopilot design techniques have worked well in the past, but in order to satisfy future and more stringent design specifications, new design methods are necessary. Robust control techniques (in particular, H-Infinity Control and Mu-Synthesis) and their application to the design of missile autopilots are addressed in this thesis. In addition, conventional autopilot designs are performed as comparative benchmarks. This paper reviews the missile autopilot design problem and presents descriptions of the classical and H-Infinity/Mu design methods. Missile autopilot designs considering both rigid-body dynamics and elastic-body dynamics are presented. Comparisons of the design approaches and results are also discussed. The results show that the application of robust control techniques to the design of missile autopilots can improve the performance and stability robustness characteristics of the flight control system. / Master of Science

In this dissertation, we seek to improve the dynamic modeling and control of autonomous underwater vehicles (AUVs). We address nonlinear hydrodynamic modeling, simplifying modeling assumptions, and robust control for AUVs. In the literature, various hydrodynamic models exist with varying model complexity and with no universally accepted model. We compare various hydrodynamic models traditionally employed to predict the motion of AUVs by estimating model coefficients using least-squares and adaptive identifier techniques. Additionally, we derive several dynamic models for an AUV employing varying sets of simplifying assumptions. We experimentally assess the efficacy of invoking typical assumptions to simplify the equations of motion. For robust control design, we develop a procedure for designing robust attitude controllers based on loop-shaping ideas. We specifically address the challenge of adjusting the desired actuator bandwidth in a loop-shaping design framework. Finally, we present a novel receding horizon H-infinity control algorithm to improve the control of autonomous vehicle systems working in high-disturbance environments, employing a Markov jump linear system framework to model the stochastic and non-stationary disturbances experienced by the vehicle. Our main results include a new Bounded Real Lemma for stability analysis and an output feedback H-infinity control synthesis algorithm. This work uses numerical simulations and extensive field trials of autonomous underwater vehicles to identify and verify dynamic models and to validate control algorithms developed herein. / Ph. D. / In this dissertation, we seek to improve the dynamic modeling and control of autonomous underwater vehicles (AUVs). We compare different models employed to predict the motion of AUVs, and we derive several dynamic models for an AUV employing varying sets of simplifying assumptions. We experimentally assess the efficacy of invoking typical assumptions to simplify the equations of motion. For robust control design, we develop a procedure for designing robust controllers that do not produce excessive fin movements. Finally, we present a novel robust control algorithm to improve the control of autonomous vehicle systems working in high-disturbance environments. This work uses numerical simulations and extensive field trials of autonomous underwater vehicles to identify and verify dynamic models and to validate control algorithms developed herein.

This thesis describes the design of an inexpensive autonomous vehicle system using a small scaled model vehicle. The system is capable of operating in two different modes: telerobotic manual mode and automated driving mode. In telerobotic manual mode, the model vehicle is controlled by a human driver at a stationary remote control station with full-scale steering wheel and gas pedal. The vehicle can either be an unmodified toy remote-control car or a vehicle equipped with wireless radio modem for communication and microcontroller for speed control. In both cases the vehicle also carries a video camera capable of transmitting video images back to the remote control station where they are displayed on a monitor. In automated driving mode, the vehicle's lateral movement is controlled by a lateral control algorithm. The objective of this algorithm is to keep the vehicle in the center of a road. Position and orientation of the vehicle are determined by an image processing algorithm identifying a white middle marker on the road. Two different algorithm for image processing have been designed: one based on the pixel intensity profile and the other on vanishing points in the image plane. For the control algorithm itself, two designs are introduced as well: a simple classical P-control and a control scheme based on H-Infinity. The design and testing of this autonomous vehicle system are performed in the Flexible Low-cost Automated Scaled Highway (FLASH) laboratory at Virginia Tech. / Master of Science

Currently, renewable energy sources are the main driver for future electricity generation. This trend is growing faster in the developed countries in order to reduce the green house effect and also in response to the limited supply of oil, gas and coal which are currently the major sources for electric generation. For example, the main renewable energy sources are from wind energy and solar energy but these energies are only available to those countries that are exposed to these resources. In this thesis an alternative energy source is investigated where it can be generated from the moving objects or in form of kinetic energy. The idea is to convert the kinetic energy during landing aircraft into electrical energy which it can also be stored and transferred to the existing electrical network. To convert this kinetic energy to electrical energy, the linear generator (LG) and uncontrolled rectifier have been used for energy conversion. The LG have been modelled in 3-phase model or in dq model and combined with the diode rectifier that is used to generate the dc signal outputs. Due to the uncontrolled rectifier the electrical outputs will have decaying amplitude along the landing time. This condition also happen to the LG outputs such as the force and the power output. In order to control these outputs the cascaded buck-boost converter has been used. This converter is responsible to control the output current at the rectifier and also the LG output power during landing to more controllable power output. Here, the H∞ current control strategy has been used as it offers a very good performance for current tracking and to increase the robustness of the controller. During landing, huge power is produced at the beginning and when the landing time is increased, the generated input power from LG is reduced to zero. Due to this, the energy storage that consists of ultracapacitor, bidirectional converter and boost converter are used in order to store and to release the energy depends on the input power source and load grid power. The voltage proportional-integral (PI) control strategy has been used for both the converters. The last part is to transfer the energy from the source and at the ultracapacitor to the load by using the inverter as the processing device. The power controller and current controller are used at the inverter in order to control the power ?ow between the inverter and the grid. This is when the reference power is determined by the load power in order to generate the reference currents by using the voltage oriented controller (VOC), while the H∞ current controller is used to regulate the inverter currents in order to inject the suitable amount of current that refer to the load power. Finally, a complete energy recovery system for landing aircraft with the grid connection have been put together to make the whole system to be as a new renewable energy source for the future electricity generation.

This paper presents the whole process of building up a high precision, high dynamical MEMS acceleration sensor. The first samples have achieved a resolution of better than 500 micro g and a bandwidth of more than 200 Hz. The sensor fabrication technology is shortly covered in the paper. A theoretical model is built from the physical principles of the complete sensor system, consisting of the MEMS sensor, the charge amplifier and the PWM driver for the sensor element. The mathematical modeling also covers problems during startup. A reduced order model of the entire system is used to design a robust control with the Mixed-Sensitivity H-infinity Approach. Since the system has an unstable pole, imposed by the electrostatic field and time delay, caused by A/D-D/A conversation delay and DSP computing time, limitations for the control design are given. The theoretical model might be inaccurate or lacks of completeness, because the parameters for the theoretical model building vary from sample to sample or might be not known. A new identification scheme for open or closed-loop operation is deployed to obtain directly from the samples the parameters of the mechanical system and the voltage dependent gains. The focus of this paper is the complete system development and identification process including practical tests in a DSP TI-TMS320C3000 environment.

Orientador: Alberto Luiz Serpa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-10T21:19:29Z (GMT). No. of bitstreams: 1 Pereira_DanielAugusto_M.pdf: 6268866 bytes, checksum: 3faebe29f9ec8e8f665d11ac095420f8 (MD5) Previous issue date: 2008 / Resumo: Esta dissertação aborda a aplicação de técnicas modernas de controle de sistemas dinâmicosao problema de detecção de falhas. Duas diferentes abordagens de detecção são utilizadas: estimação da falha e geração de resíduo. Tanto na estimação de falha quanto na geração de resíduo é formulado um problema H1 cujo objetivo é encontrar um filtro que garanta robustez a distúrbios.No caso da geração de resíduos, o índice H- é utilizado como critério de desempenho adicional para garantir a sensibilidade à falha e é transformado em um critério H1. O projeto H1 é abordado sob o ponto de vista de desigualdades matriciais lineares. Falhas e distúrbios devem apresentar comportamento em freqüência distintos para que os filtros consigam separar os efeitos dos mesmos. Para garantir o desempenho nas regiões em freqüência de interesse são utilizados filtros de ponderação. Em contraposição a essa abordagem, os resultados recentes da literatura sobre o lema generalizado de Kalman-Yakubovi?c-Popov e o controle H1 restrito na freqüência também são usados como ferramentas de projeto independentes de filtros de ponderação. Os métodos sãocomparados usando modelos de simulação e experimentos no âmbito de estruturas flexíveis / Abstract: This dissertation adresses the application of modern techniques from control of dynamicsystems to the problem of fault detection. Two different approaches are used: fault estimation and residual generation. Both fault estimation and residual generation are formulated as an H1 problem whose objective is to find a filter ensuring robustness to disturbance. In the case of residual generation, theH- index is used as an additional performance criterion to ensure fault sensitiveness and is transformed into an H1 criterion. The H1 design is treated from the point of view of linear matrix inequalities. Faults and disturbances must have distinct frequency distributions so the filter is able to separate them. Weighting functions are used to guarantee performance at the frequency region of interest. In contrast with this approach, recent results from literature on the generalisedKalman-Yakubovi?c-Popov lemma and frequency restricted H1 control are also used as design methods whose application is independent of weighting functions. All methods are compared using simple simulation models and experiments with flexible / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Alberto Luiz Serpa / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-22T23:18:09Z (GMT). No. of bitstreams: 1 Medeiros_MarianeMendes_M.pdf: 1617094 bytes, checksum: d2be1eafefa6985fbd91c7c052f71868 (MD5) Previous issue date: 2013 / Resumo: O presente trabalho propõe o estudo de estruturas flexíveis e controle de vibrações sob a ótica da otimização simultânea de ambos. Iniciando pela modelagem da estrutura, é apresentada a justificativa para o uso de Elementos Finitos e modelagem no Espaço de Estados, passando ainda pela realização balanceada e redução de ordem do sistema. Na sequência, é descrita a síntese do controlador ??, que parte do princípio da minimização da Norma ?? do sistema. A solução do problema é então apresentada sob a abordagem das Desigualdades Matriciais Lineares, enfoque mais atual devido às suas propriedades de linearidade e convexidade quando aplicada dentro da teoria de controle. Em se tratando do processo de otimização, é desenvolvido um estudo sobre o método simultâneo, onde parâmetros da estrutura são otimizados juntamente com os do controlador de maneira a diminuir os efeitos negativos entre as dinâmicas quando otimizadas separadamente. Ainda assim, são apresentadas duas outras abordagens como forma de comparação: a Ativa Serial e a Passiva Estrutural. Para todos os três casos, a técnica escolhida para a resolução do problema de otimização foi o Algoritmo Genético, cujas vantagens e desvantagens são mostradas junto com toda a descrição de conceitos envolvidos, considerando seus operadores, fluxo algorítmico e até mesmo critérios de parada. Por fim, serão apresentados os resultados analisados sobre um modelo de uma viga engastada, submetida à distúrbios externos, através de uma simulação em MATLAB que engloba todos os conceitos estudados / Abstract: The present work proposes the study of flexible structures and vibration control under the light of simultaneous optimization. Starting by structure modeling, it presents the reason for use Finite Element and State-Space modeling, passing also through the balanced realization and order reduction of the system. Sequentially, it describes the synthesis of ?? controller, which considers the minimization of ?? norm of the system. The solution of the problem is then presented under Linear Matrix Inequalities approach, the most up-to-date method due to linearity and convexity properties when applied to control theory. Regarding optimization process, it is developed a study of a simultaneous optimization method where structure parameters are optimized along with the controller ones, aiming to diminish negative influence between dynamics when separately optimized. Even tough, two other approaches are presented by means of comparison: Serial Active and Structural Passive. For all three cases, the chosen technique to solve the optimization problem was the Genetic Algorithm whose advantages and disadvantages are shown along with a description of all involved concepts, considering its operators, algorithmic flux and even stopping criteria. Last, the results analysed over a clamped beam model subjected to external disturbances are shown, through a MATLAB simulation that encloses all studied concepts / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica