Este trabalho trata do desenvolvimento de um sistema de controle para um módulo do instrumento astronômico BTFI (Brazilian Tunable Filter Imager), um filtro óptico sintonizável altamente versátil que está instalado no telescópio SOAR, localizado no Chile. Será empregado neste instrumento um novo interferômetro Fabry-Perot, capaz de realizar observações em uma ampla faixa de resoluções espectrais. Para operar com resolução espectral variável, o Fabry-Perot proposto neste projeto terá uma faixa mais ampla de ajuste do vão entre suas placas refletivas, utilizando atuadores piezelétricos amplificados com grande capacidade de deslocamento e sensores capacitivos de alta precisão. O novo controlador apresenta uma malha de controle totalmente digital, implementada com um DSP (Digital Signal Processor) sintetizado num dispositivo FPGA (Field-programmable Gate Array). Na primeira etapa do desenvolvimento, trabalhou-se com um sistema de posicionamento nanométrico utilizando um protótipo simplificado com um canal composto por um sensor capacitivo de distância e um atuador piezelétrico. A partir dos bons resultados obtidos no sistema de um canal, realizou-se a expansão para um sistema de controle multi-malha de três canais com protótipo do Fabry-Perot, mas sem o uso das placas de vidro refletivas definitivas. O sistema permite controlar o posicionamento para cada canal individualmente ou os três em simultâneo, com desempenho adequado para os requisitos do filtro óptico sintonizável Fabry-Perot. / This work aims the development of a control system for a module of the BTFI astronomical instrument (Brazilian Tunable Filter Imager), a highly versatile optical tunable filter, deployed on the SOAR Telescope. The instrument will employ a new Fabry-Perot interferometer, which is able to provide observations in a wide range of spectral resolutions. In order to achieve variable spectral resolution, the new Fabry- Perot proposed in this project will present a larger range for adjusting the air gap between its reflective plates, using amplified piezoelectric actuators presenting high stroke capability and high precision capacitive sensors. The new controller presents a full digital control loop, implemented in a DSP (Digital Signal Processor) synthesized through a FPGA device (Field-programmable Gate Array). During the first phase of the development, it was used a nanometric positioning system using a single channel prototype comprising one capacitive sensor and one piezoelectric actuator. The good results obtained using the single channel prototype led to the expansion to a 3- channel multi-loop control system on a Fabry-Perot prototype which comprises dummy plates. The system allows controlling the position of each channel separately or simultaneously, presenting performance in accordance with the requirements of a Fabry-Perot optical tunable filter.

Previous studies show that the Piezoelectric-Driven Stick-Slip (PDSS) actuator is a promising device in many micropositioning and micromanipulation applications, where positioning with a long range and a high resolution is required. However, research in this area is still in its early stage and many issues remain to be addressed. One key issue is the representation of the dynamic displacement of the end-effector. It is known that such factors as the dynamics of piezoelectric actuator (PEA) and the presliding friction involved can significantly contribute to the displacement dynamics. Although this has been widely accepted, specific quantitative relationship between the aforementioned factors and the displacement dynamics has rarely been defined. The aim of this research is to develop a model to represent the displacement of the end-effecter of the PDSS actuators, in which both the presliding friction and the PEA dynamics are addressed. <p>In order to represent the presliding friction, the models reported in literatures, including Dahl model [Olsson, et al., 1998], Reset Integrator model [Haessig and Friedland 1991], LuGre model [Canudas de Wit et al., 1995] and Elastoplastic model [Dupont et al., 2002] were reviewed and examined; and the LuGre model was chosen to be used because of its efficiency and simple formulation. On the other hand, a linear second order dynamic system model was employed to represent the combination of a PEA and its driven mechanism. On the basis of the pre-sliding friction model and the linearized PEA dynamics model, a model representative of the end-effector displacement of the PDSS actuator model was developed. <p>In order to validate experimentally the developed PDSS model, a displacement measuring and data acquisition experiment system was established and a prototype was developed based on dSPACE and Simulink. On the prototyped actuator, two experiments were designed and conducted to identify the parameters involved in the model. One experiment is for the determination of the parameters of the second order system for the dynamics of the combination of a PEA and its driven mechanism; and other one is for the determination of the parameters of the chosen friction model. The identified parameters were then employed in the developed PDSS model to simulate the displacements and the results were compared with the experimental results that were obtained under the same operating conditions as the simulation. The comparison suggests that the model developed in this study is promising for the end-effector displacement of the PDSS actuator.

Previous studies show that the Piezoelectric-Driven Stick-Slip (PDSS) actuator is a promising device in many micropositioning and micromanipulation applications, where positioning with a long range and a high resolution is required. However, research in this area is still in its early stage and many issues remain to be addressed. One key issue is the representation of the dynamic displacement of the end-effector. It is known that such factors as the dynamics of piezoelectric actuator (PEA) and the presliding friction involved can significantly contribute to the displacement dynamics. Although this has been widely accepted, specific quantitative relationship between the aforementioned factors and the displacement dynamics has rarely been defined. The aim of this research is to develop a model to represent the displacement of the end-effecter of the PDSS actuators, in which both the presliding friction and the PEA dynamics are addressed. <p>In order to represent the presliding friction, the models reported in literatures, including Dahl model [Olsson, et al., 1998], Reset Integrator model [Haessig and Friedland 1991], LuGre model [Canudas de Wit et al., 1995] and Elastoplastic model [Dupont et al., 2002] were reviewed and examined; and the LuGre model was chosen to be used because of its efficiency and simple formulation. On the other hand, a linear second order dynamic system model was employed to represent the combination of a PEA and its driven mechanism. On the basis of the pre-sliding friction model and the linearized PEA dynamics model, a model representative of the end-effector displacement of the PDSS actuator model was developed. <p>In order to validate experimentally the developed PDSS model, a displacement measuring and data acquisition experiment system was established and a prototype was developed based on dSPACE and Simulink. On the prototyped actuator, two experiments were designed and conducted to identify the parameters involved in the model. One experiment is for the determination of the parameters of the second order system for the dynamics of the combination of a PEA and its driven mechanism; and other one is for the determination of the parameters of the chosen friction model. The identified parameters were then employed in the developed PDSS model to simulate the displacements and the results were compared with the experimental results that were obtained under the same operating conditions as the simulation. The comparison suggests that the model developed in this study is promising for the end-effector displacement of the PDSS actuator.

Gradient Enhanced Piezoelectric Actuators (GEPAC) are thin piezoelectric plates embedded between two composites layers having different thermal properties. Compared to standard unimorph bending actuators, GEPACs offer superior performances for operations at low frequencies. Potential applications are in the area of multifunctional aircraft skins. In practice, delaminations or debonding within the actuator itself can occur, and it is highly desirable to develop an ultrasonic nondestructive method to monitor the integrity of the actuator in real time. For this study, the composite material is unidirectional Kevlar-epoxy, with fibers oriented at 90 and 0 for the upper and lower layers to achieve different coefficient of thermal expansion. A thin PZT plate is inserted between the two layers, and extended copper foil is used for electrodes on the PZT. The first objective of the research is to demonstrate that, by using segmented electrodes, one can simultaneously launch an ultrasonic pulse (1 MHz) for NDE testing while the actuator is undergoing low frequency actuation (less than 100 Hz). The second objective is to show that the ultrasonic signal can be used to detect damage induced during fatigue testing of the actuator. The third objective is to use the technique to monitor the integrity of a composite plate containing several embedded GEPACs.

This thesis deals with the design, fabrication and analysis of a novel actuator for a fish-like swimming mini robot. The developed actuator is tested on a mini boat. The actuator relies on a novel piezoelectric ultrasonic motor, developed according to the design requirements of actuator for fish-like swimming mini robots. Developed motor is within the dimensions of 25x6x6 mm in a simple mechanical structure with simple driving circuitry compared to its predecessor. Bidirectional rotation of the motor is transformed to a flapping tail motion for underwater locomotion in a simple mechatronic structure. The simplicity in the motor and actuator enables further development on the miniaturization, improvement on the performances as well as easy and low cost manufacturing. The developed actuator is a candidate to be used in mini swimming robot with fish- like locomotion.

Atuadores piezelétricos são dispositivos que permitem a conversão de energia elétrica em energia mecânica. Dentre os atuadores piezelétricos, destacam-se os bilaminares, que consistem em duas piezocerâmicas de polarização oposta (ou excitadas com cargas de sinal contrário) com um substrato entre elas. Os atuadores piezelétricos também podem ser miniaturizados, alcançando a escala de MEMS (Micro-Electric-Mechanical System). Este trabalho tem por objetivo desenvolver uma metodologia utilizando o Método de Otimização Topológica (MOT) para o projeto de atuadores piezelétricos com múltiplos graus de liberdade baseados no princípio bilaminar. A fase de projeto consiste na utilização do MOT para a determinação de uma configuração de atuadores que maximizem o deslocamento numa direção e sentido especificados para uma restrição na quantidade de material utilizado em cada camada, considerando a polarização da cerâmica piezelétrica presente nessa configuração e o acoplamento e simetria entre as camadas. Para a simulação do atuador é utilizado o Método dos Elementos Finitos (MEF) através de um elemento de placa piezelétrica isoparamétrico de oito nós expandido. O MOT, neste trabalho, utiliza o modelo de material denominado PEMAP-P (Material Piezelétrico com Penalização e Polarização). A técnica de projeção é utilizada junto ao MOT para a obtenção de um resultado com uma geometria bem definida. O problema de otimização é resolvido através de Programação Matemática Sequencial (PMS) através do algoritmo GCMMA (Globally Convergent Method of Moving Asymptotes). Como exemplo é estudado o projeto de um atuador piezelétrico para microespelhos. Dentre as configurações obtidas pelo MOT, uma é fabricada utilizando as técnicas de corte a laser e colagem e, posteriormente, é caracterizada. Finalmente, é realizada a comparação entre os resultados de simulação e experimentais do protótipo. / Piezoelectric actuators are devices that allow the conversion of electric energy to mechanical energy. Among the piezoelectric, the bimorph stands. It consists of two piezoceramic plates with opposite polarization (or excited with opposite sign charges) with a substrate between them. The piezoelectric actuators can also be miniaturized in a MEMS scale. This work aims the design of a methodology using the Topology Optimization Method (TOM) for the design of piezoelectric actuators with multiple degrees of freedom using the bimorph principle. The design phase applies the TOM to determine an optimized configuration of actuators that maximizes the output displacement in a specified direction and orientation for a constraint in the amount of material used at each layer, by considering the polarization of the piezoelectric ceramic present on this configuration and the coupling and symmetry between layers. The Finite Element Method (FEM) is applied for actuator simulation through an extended piezoelectric plate isoparametric element with 8 nodes. The TOM in this work employs a material model called PEMAP-P (Piezoelectric Material with Penalization and Polarization). The projection technique is implemented with TOM to obtain a result with a well-defined geometry. The optimization problem is solved by using Sequential Mathematical Programming (SMP) through the GCMMA algorithm (Globally Convergent Method of Moving Asymptotes). As an example, the design of a piezoelectric actuator for micromirrors is studied. Among the configurations obtained by the TOM, one is manufactured using laser cutting and bonding techniques and it is tested. Finally, a comparison between the simulated and experimental results from prototype is performed.

Bombas de fluxo são dispositivos importantes em áreas como a Bioengenharia, Medicina, Farmácia, entre outras aplicações clássicas de Engenharia. Princípios para o bombeamento de fluidos baseados em atuadores piezelétricos estão sendo estudados no Departamento de Engenharia Mecatrônica e de Sistemas Mecânicos da Escola Politécnica, que permitem a construção de bombas de fluxo de pequena escala, ou seja, bombas de fluxo de pequena potência para deslocamento de pequenos volumes de fluido com baixo consumo de energia. O presente trabalho estuda bombas de fluxo piezelétricas de diafragma do tipo valve-less para geração de vazão. A bomba de fluxo piezelétrica de diafragma utiliza cerâmica piezelétrica como atuador para mover uma membrana (diafragma) para cima e para baixo como um pistão, que causa uma seqüência de aumento e diminuição do volume da câmara da bomba, forçando a entrada e a saída do fluido na bomba. A direção do fluxo é garantida por válvulas que privilegiam o fluxo em apenas um sentido. O objetivo deste trabalho é o estudo da metodologia de desenvolvimento de uma bomba de fluxo piezelétrica de diafragma de baixo custo do tipo valve-less. Para tanto, será utilizado a modelagem por Método dos Elementos Finitos (MEF) para a realização de análises de sensibilidade dos parâmetros geométricos e construtivos da bomba de fluxo. Serão realizadas simulações de escoamento de fluido pelo Método de Volumes Finitos (MVF) para a realização de análises de sensibilidade dos parâmetros geométricos dos elementos difusor/bocal e o levantamento das curvas características da bomba de fluxo. Por fim, protótipos serão construídos e caracterizados para validação dos resultados computacionais. Serão apresentadas a metodologia empregada e a discussão dos resultados obtidos, de forma a analisar o princípio proposto e os fenômenos físicos em questão. / Flow pumps act as important devices in areas as Bioengineering, Medicine, Pharmacy, among other areas of Engineering. Principles for pumping fluids based on piezoelectric actuators have been studied in the Department of Mechatronic and Mechanical Engineering of Escola Politécnica da Universidade de São Paulo, that allow the construction of small flow pumps, in other words, pumps for displacement of small fluid volumes with low power consumption. The present work studies valveless piezoelectric diaphragm flow pumps for flow generation. The piezoelectric diaphragm flow pump uses a piezoelectric ceramic as actuator to move a membrane (diaphragm) up and down as a piston. Consequently, there is a sequence of increase and decrease in the chamber volume that will force the fluid in and out of the pump. The direction of the flow is guaranteed by valves that privilege the flow in just one pumping direction. The main objective of this work is the study of a methodology to develop a low cost valve-less piezoelectric diaphragm flow pump. A sensitivity analysis is carried using computational simulation through the Finite Element Method (FEM) to study how construction parameters and assembly affect diaphragm flow pump performance. Using CFD simulations through the Finite Volume Method (FVM), a sensitivity analysis is done around nozzle/diffuser element geometrical parameters and pump characteristic curves are obtained. Finally, computational results are validated by prototype construction and characterization. The text presents methodologies employed and discusses the obtained results, analyzing the principle and the related physical phenomena.

Digital holographic microscopy is an interferometric imaging technique, the principle of which is the off-axis image plane holography. The principle of this technique enables to reconstruct both the image intensity and the image phase from the output interferencesignal. The reconstruction can be carried out on the basis of a single image plane hologram. This leads to the possibility of a realtime image reconstruction. The speed of the reconstruction depends on the detection and the computing process. The aim of this diploma thesis is to develop user software for the control of the detection camera and for the image plane hologram reconstruction. The effort was to achieve the highest number of image reconstructions per time unit, with the maximum utilization of the data transfer between the camera and the computer.The next aim of this thesis is the stabilization of the optical table position. The method of stabilization is based on the image phase information, which is used for the control loop feedback between reconstructed image phase and the piezoelectric actuator placed inside of the optical table. Experimental results, which prove the functionality of the stabilization, are presented.

This thesis presents the design and development of two switching amplifiers used to drive the so-called smart material actuators. Different from conventional circuits, a smart material actuator is ordinarily a highly capacitive load. Its capacitance is non-linear and its strain is hysteretic with respect to its electrical control signal. This actuator's reactive load property usually causes a large portion of reactive power circulating between the power amplifier and the driven actuator, thus reduces the circuit efficiency in a linear power amplifier scenario. In this thesis, a switching amplifier design based on the PWM technique is proposed to develop a highly efficient power amplifier, and peak current mode control is proposed to reduce the actuator's hysteretic behavior. Since the low frequency current loop gain tends to be low due to the circuit's capacitive load, average current mode control is further proposed to boost the low frequency current loop gain and improve the amplifier's low frequency performance. Both of the circuits have been verified by prototype design and their experimental measurement results are given. / Master of Science

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