Este trabalho consiste no desenvolvimento de uma metodologia de projeto ótimo de estruturas ativamente controladas (inteligentes), com o objetivo de suprimir as vibrações induzidas por perturbações externas. O projeto é realizado simultaneamente para a topologia estrutural e a localização de atuadores. O problema de otimização topológica é formulado para três fases materiais (dois materiais sólidos e vazio),com dois grupos de variáveis de projeto. Um material não piezelétrico elástico isotrópico forma a parte puramente estrutural, enquanto um material piezelétrico compõe a parte ativa. Uma vez que não há método eficiente para tratar as variáveis de projeto estruturais e de controle em um mesmo ambiente de otimização, este trabalho propõe uma abordagem de solução aninhada. Nesta solução, o posicionamento dos atuadores e a síntese do sistema controlador são considerados em um laco de projeto paralelo ao processo de otimização que lida com a topologia estrutural. O laço de otimização principal está relacionado `as variáveis de projeto estruturais, ou seja, ´e calculado onde deve haver material sólido e onde deve haver espaços vazios, através de um problema de minimização de flexibilidade. A localização de atuadores ´e determinada por uma otimização baseada em uma lei de controle que define onde o material deve ter propriedades piezelétricas, através da maximização de uma medida de controlabilidade. Os exemplos numéricos mostram que a abordagem utilizada neste trabalho pode produzir uma topologia estrutural bem definida com uma boa colocação para os atuadores. Além disso, as topologias ótimas encontradas são capazes de melhorar o amortecimento ativo da estrutura. / This work develops an optimal design methodology for actively controlled structures, aiming to suppress vibrations induced by external disturbances. Design is conducted simultaneously for the structural topology and actuator placement. A topology optimization problem is formulated for three material phases (two solid materials and void) with two design variables groups. A non-piezoelectric elastic isotropic material forms the structural only part of the design, while a piezoelectric material composes the active part. Since there is no efficient method to treat structural and control design variables in the same optimization framework, this work proposes a nested solution approach, where the actuator locations and controller syntheses are regarded as a parallel design to the main optimization process dealing with the structural topology. The main optimization loop designs the structural variables, i.e., it is decided where there should be solid material and where there should be voids, through a minimum compliance design problem. The actuators are placed by considering a control law optimization that defines where the material should have piezoelectric properties, through the maximization of a measure of controllability. Numerical examples show that the approach used in this paper can produce a clear structural topology with a good actuator placement. Besides, the optimal topologies can improve the active damping.

Este trabalho consiste no desenvolvimento de uma metodologia de projeto ótimo de estruturas ativamente controladas (inteligentes), com o objetivo de suprimir as vibrações induzidas por perturbações externas. O projeto é realizado simultaneamente para a topologia estrutural e a localização de atuadores. O problema de otimização topológica é formulado para três fases materiais (dois materiais sólidos e vazio),com dois grupos de variáveis de projeto. Um material não piezelétrico elástico isotrópico forma a parte puramente estrutural, enquanto um material piezelétrico compõe a parte ativa. Uma vez que não há método eficiente para tratar as variáveis de projeto estruturais e de controle em um mesmo ambiente de otimização, este trabalho propõe uma abordagem de solução aninhada. Nesta solução, o posicionamento dos atuadores e a síntese do sistema controlador são considerados em um laco de projeto paralelo ao processo de otimização que lida com a topologia estrutural. O laço de otimização principal está relacionado `as variáveis de projeto estruturais, ou seja, ´e calculado onde deve haver material sólido e onde deve haver espaços vazios, através de um problema de minimização de flexibilidade. A localização de atuadores ´e determinada por uma otimização baseada em uma lei de controle que define onde o material deve ter propriedades piezelétricas, através da maximização de uma medida de controlabilidade. Os exemplos numéricos mostram que a abordagem utilizada neste trabalho pode produzir uma topologia estrutural bem definida com uma boa colocação para os atuadores. Além disso, as topologias ótimas encontradas são capazes de melhorar o amortecimento ativo da estrutura. / This work develops an optimal design methodology for actively controlled structures, aiming to suppress vibrations induced by external disturbances. Design is conducted simultaneously for the structural topology and actuator placement. A topology optimization problem is formulated for three material phases (two solid materials and void) with two design variables groups. A non-piezoelectric elastic isotropic material forms the structural only part of the design, while a piezoelectric material composes the active part. Since there is no efficient method to treat structural and control design variables in the same optimization framework, this work proposes a nested solution approach, where the actuator locations and controller syntheses are regarded as a parallel design to the main optimization process dealing with the structural topology. The main optimization loop designs the structural variables, i.e., it is decided where there should be solid material and where there should be voids, through a minimum compliance design problem. The actuators are placed by considering a control law optimization that defines where the material should have piezoelectric properties, through the maximization of a measure of controllability. Numerical examples show that the approach used in this paper can produce a clear structural topology with a good actuator placement. Besides, the optimal topologies can improve the active damping.

Este trabalho consiste no desenvolvimento de uma metodologia de projeto ótimo de estruturas ativamente controladas (inteligentes), com o objetivo de suprimir as vibrações induzidas por perturbações externas. O projeto é realizado simultaneamente para a topologia estrutural e a localização de atuadores. O problema de otimização topológica é formulado para três fases materiais (dois materiais sólidos e vazio),com dois grupos de variáveis de projeto. Um material não piezelétrico elástico isotrópico forma a parte puramente estrutural, enquanto um material piezelétrico compõe a parte ativa. Uma vez que não há método eficiente para tratar as variáveis de projeto estruturais e de controle em um mesmo ambiente de otimização, este trabalho propõe uma abordagem de solução aninhada. Nesta solução, o posicionamento dos atuadores e a síntese do sistema controlador são considerados em um laco de projeto paralelo ao processo de otimização que lida com a topologia estrutural. O laço de otimização principal está relacionado `as variáveis de projeto estruturais, ou seja, ´e calculado onde deve haver material sólido e onde deve haver espaços vazios, através de um problema de minimização de flexibilidade. A localização de atuadores ´e determinada por uma otimização baseada em uma lei de controle que define onde o material deve ter propriedades piezelétricas, através da maximização de uma medida de controlabilidade. Os exemplos numéricos mostram que a abordagem utilizada neste trabalho pode produzir uma topologia estrutural bem definida com uma boa colocação para os atuadores. Além disso, as topologias ótimas encontradas são capazes de melhorar o amortecimento ativo da estrutura. / This work develops an optimal design methodology for actively controlled structures, aiming to suppress vibrations induced by external disturbances. Design is conducted simultaneously for the structural topology and actuator placement. A topology optimization problem is formulated for three material phases (two solid materials and void) with two design variables groups. A non-piezoelectric elastic isotropic material forms the structural only part of the design, while a piezoelectric material composes the active part. Since there is no efficient method to treat structural and control design variables in the same optimization framework, this work proposes a nested solution approach, where the actuator locations and controller syntheses are regarded as a parallel design to the main optimization process dealing with the structural topology. The main optimization loop designs the structural variables, i.e., it is decided where there should be solid material and where there should be voids, through a minimum compliance design problem. The actuators are placed by considering a control law optimization that defines where the material should have piezoelectric properties, through the maximization of a measure of controllability. Numerical examples show that the approach used in this paper can produce a clear structural topology with a good actuator placement. Besides, the optimal topologies can improve the active damping.

This work is a proposal for an alternative approach to working with print, making the printing process a key element within designing. It is an investigation into flat garment construction between fabric layers, as this enables for the printing to be used in place of sewing. Additionally, working with multiple textile layers connects with the reference of the peeling wallpaper, which is used as a base for material and form developments. The aim of the work is to develop a more holistic approach and new expressions in garment-making in relation to the application of printing processes within textile layers. The main objective is to present a new perspective of the relationship between garment pattern and print, bringing the later forward. Not only does the surface print, through the interaction of colour and texture provide an important element in terms of creating expression, but it additionally acts as a construction element. Moreover, by using the process of printing to create form the element of print becomes integrated into the process of garment-making.

Complex helicopter models that include effects typically ignored in control models, such as an analytical formulation for fuselage aerodynamics, blade lead-lagging and flexibility, and tail rotor aerodynamics, are derived. The landing gear, horizontal tailplane, a fully articulated main rotor, main rotor downwash, and blade flapping are also modeled. The modeling process is motivated by the desire to build control oriented, physics based models that directly result in ordinary differential equations (ODE) models which are sufficiently rich in dynamics information. A physics based model simplification procedure, which is called new ordering scheme, is developed to reduce the number of terms in these large nonlinear ODE models, while retaining the same number of governing equations of motion. The resulting equations are trimmed and linearized around several flight conditions (i.e. straight level flight, level banked turn, and helical turn) using Maple and Matlab. The resulting trims and model modes are validated against available literature data. The linearized models are first used for the design of variance constrained controllers with inequality constraints on outputs or inputs, output variance constrained controllers (OVC) and input variance constrained controllers (IVC), respectively. The linearized helicopter models are also used for the design of online controllers which exploit the constrained model predictive control (MPC) theory. The ability of MPC to track highly constrained, heterogeneous discontinuous trajectories is examined. The performance and robustness of all these controllers (e.g. OVC, IVC, MPC) are thoroughly investigated with respect to several modeling uncertainties. Specifically, for robustness studies, variations in the flight conditions and helicopter inertial properties, as well as blade flexibility effects, are considered. Furthermore, the effectiveness of adaptive switching between controllers for the management of sensor failure during helicopter operations is studied using variance constrained controllers. Finally, the simultaneous design of the helicopter and control system is examined using simultaneous perturbation stochastic approximation in order to save active control energy. / Ph. D.

Hall Effect Thrusters (HETs) are a form of electric propulsion device which uses external electrical energy to produce thrust. When compared to various other electric propulsion devices, HETs are excellent candidates for future orbit transfer and interplanetary missions due to their relatively simple configuration, moderate thrust capability, higher thrust to power ratio, and lower thruster mass to power ratio. Due to the short history of HETs, the current design process of a new HET is a largely empirical and experimental science, and this has resulted in previous designs being developed in a narrow design space based on experimental data without systematic investigations of parameter correlations. In addition, current preliminary low-thrust trajectory optimizations, due to inherent difficulties in solution procedure, often assume constant or linear performances with available power in their applications of electric thrusters. The main obstacles come from the complex physics involved in HET technology and relatively small amounts of experimental data. Although physical theories and numerical simulations can provide a valuable tool for design space exploration at the inception of a new HET design and preliminary low-thrust trajectory optimization, the complex physics makes theoretical and numerical solutions difficult to obtain. Numerical implementations have been quite extensively conducted in the last two decades. An investigation of current methodologies reveals that to date, none provide a proper methodology for a new HET design at the conceptual design stage and the coupled low-thrust trajectory optimization. Thus, in the first half of this work, an efficient, robust, and self-consistent numerical method for the analysis of HETs is developed with a new approach. The key idea is to divide the analysis region into two regions in terms of electron dynamics based on physical intuition. Intensive validations are conducted for existing HETs from 1 kW to 50 kW classes. The second half of this work aims to construct a simultaneous design optimization environment though collaboration with experts in low-thrust trajectory optimization where a new HET and associated optimal low-thrust trajectory can be designed simultaneously. A demonstration for an orbit raising mission shows that the constructed simultaneous design optimization environment can be used effectively and synergistically for space missions involving HETs. It is expected that the present work will aid and ease the current expensive experimental HET design process and reduce preliminary space mission design cycles involving HETs.