[pt] A pesquisa e desenvolvimento de um acionamento para motor de passo operando em baixa tensão apresenta o desenvolvimento de um mecanismo de acionamento para motores de passo de 2 fases, destinado a operar na faixa de 12 a 18 V, tornando-se muito útil para automações em veículos, embarcações ou robôs que operam com baterias. O acionamento desenvolvido implementa o controle da corrente via chopper, como é usual nos acionamentos de motores de passo. Mas, ao contrário do usual, o tempo do ciclo ativo da onda responsável por ativar a corrente nas fases é pré-programado em microcontroladores, evitando-se a instabilidade e criticalidade típica dos circuitos responsáveis pelo sensoramento da corrente e sua realimentação para controle do ciclo ativo. Outro aspecto inovador do trabalho foi a utilização do integrado TD340 da ST Microeletronics, desenvolvido para utilização no controle de motores de corrente contínua, e que está sendo empregado com motores de passo. Os resultados experimentais apresentados no trabalho confirmam a adequação e utilidade do acionamento desenvolvido, tornando-o compacto e robusto. / [en] The research and development of an driver for step motor operating in low tension presents the development of a chopper driver intended to drive 2- phase step motors. The driver was designed to operate between 12 and 18 V which makes it very attractive for automations in vehicles and robots which carry their own batteries. Contrary to the usual design, where the duty cycle of phase current is controlled by sensing this current and feed backing its value to the chopper, the present driver uses fixed value duty cycle, which varies step by step according to a table stored in the memory of a microcontroller. In so doing, we avoid most of the troubles due to noise and voltage fluctuation in the feedback line, typical of usual drivers. Another innovation presented in this work, is to use the H-Bridge MOSFET driver TD340 in driving step motors. This component, manufactured by ST Microeletronics, was originally designed for driving CC motors. Experimental results presented in this work show that the driver developed in this research has performed successfully according with the intended goal.

abstract: Soft Poly-Limb (SPL) is a pneumatically driven, wearable, soft continuum robotic arm designed to aid humans with medical conditions, such as cerebral palsy, paraplegia, cervical spondylotic myelopathy, perform activities of daily living. To support user's tasks, the SPL acts as an additional limb extending from the human body which can be controlled to perform safe and compliant mobile manipulation in three-dimensional space. The SPL is inspired by invertebrate limbs, such as the elephant trunk and the arms of the octopus. In this work, various geometrical and physical parameters of the SPL are identified, and behavior of the actuators that comprise it are studied by varying their parameters through novel quasi-static computational models. As a result, this study provides a set of engineering design rules to create soft actuators for continuum soft robotic arms by understanding how varying parameters affect the actuator's motion as a function of the input pressure. A prototype of the SPL is fabricated to analyze the accuracy of these computational models by performing linear expansion, bending and arbitrary pose tests. Furthermore, combinations of the parameters based on the application of the SPL are determined to affect the weight, payload capacity, and stiffness of the arm. Experimental results demonstrate the accuracy of the proposed computational models and help in understanding the behavior of soft compliant actuators. Finally, based on the set functional requirements for the assistance of impaired users, results show the effectiveness of the SPL in performing tasks for activities of daily living. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018

Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-25Bitstream added on 2014-06-13T18:08:24Z : No. of bitstreams: 1 menezes_jpc_me_ilha.pdf: 3284910 bytes, checksum: c8578da11e5d14cfc4d1f4eaaafb100b (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Atuadores piezoelétricos convertem energia elétrica em energia mecânica, sendo amplamente utilizados como transdutores de deslocamento micrométricos ou sub-micrométricos de elevada precisão. Neste trabalho, atuadores piezoelétricos flextensionais (APFs), projetados pelo método de otimização topológica, são caracterizados em termos de linearidade entre a tensão de excitação e o deslocamento gerado, bem como em termos de resposta em frequência, utilizando-se um interferômetro de Michelson homódino e em malha aberta. Interferômetros homódinos não realimentados têm seu desempenho prejudicado pelo fenômeno de desvanecimento, causado por perturbações ambientais espúrias que incidem aleatoriamente entre seus braços. Nesta dissertação, enfatizam-se métodos de demodulação de fase óptica baseados em relações envolvendo as componentes espectrais do sinal de saída do interferômetro que são imunes ao problema do desvanescimento. Dentre estes, destacam-se métodos clássicos como J1... J4, J1... J4 modificado, J1... J6 neg e J1... J6 pos. Estes métodos permitem a medição direta de deslocamentos microscópicos, sem a necessidade de qualquer procedimento de calibração. Além disso, não são afetados por instabilidades da fonte óptica, da responsividade do fotodiodo e da visibilidade das franjas de interferência. Contudo, apresentam reduzidas faixas dinâmicas de demodulação de fase. A fim de superar esta deficiência, investiga-se um método adicional de detecção direta, baseado na análise do espectro do sinal fotodetectado, exibindo todas as vantagens dos demais métodos, mas que é capaz de estender a faixa dinâmica de demodulação a valores tão elevados quanto 100 rad. Simulações computacionais são executadas com este método, levando-se em consideração o efeito do desvanecimento e tensões de ruído eletrônico do tipo 1/f, evidenciando... / Piezoelectric actuators convert electrical energy into mechanical energy, being widely used as micrometric or sub-micrometric displacement transducer of high accuracy. In this work, piezoelectric flextensional actuators (PFA’s), designed by the topology optimization method, are characterized in terms of linearity between the drive voltage and the corresponding displacement, as well as in terms of frequency response, using a homodyne, open-loop, Michelson interferometer. Homodyne interferometers without feedback have their performance spoiled by signal fading, caused by spurious environmental disturbances that occur randomly between their arms. This thesis emphasizes methods of optical phase demodulation, based on relations involving the spectral components of the interferometer output signal, which are immune to signal fading. Among these methods, it is detailed here the classical ones, such as J1... J4, modified J1... J4, J1... J6 neg e J1... J6 pos. These methods allow direct measurements of microscopic displacements, free of calibration procedures. Besides, they are not affected by optical source oscillations, photodiode responsivity and interferometric fringe visibility. However, they have reduced dynamic range for phase demodulation. In order to overcome this, this work investigates an additional method for direct detection, based on spectral analysis drawback of the photodetected signal. The method has all the advantages of the others, but it is able to span its demodulation dynamic range to values as high as 100 rad. Numerical simulations are done using this method (considering the signal fading and the 1/f electronic noise voltage), showing its viability to characterize PFA’s. Experiments are performed in laboratory, involving tests with different PFA’s. The method validation is carried out with the aid of an electrooptic intensity modulator, whose phase characteristics can... (Complete abstract click electronic access below)

Esta dissertação apresenta o projeto e a construção de atuadores elásticos em série para o acionamento das juntas de um exoesqueleto para membros inferiores, baseado em uma órtese comercial. Inicialmente, considerou-se como dispositivo de testes a parte do exoesqueleto referente à junta do tornozelo, ou seja, a construção de uma órtese tornozelo-pé ativa. Atuadores elásticos em série são considerados neste trabalho, pois tais dispositivos apresentam características ideais para a sua utilização em órteses ativas: controle de força, controle de impedância (possibilidade de impedância baixa), absorção de impactos, baixo atrito e largura de banda que se aproxima da movimentação muscular. Um primeiro protótipo do atuador elástico em série foi construído e resultados experimentais de controle de força, impedância e posição foram obtidos com sucesso, através de uma interface de acionamento e controle entre o atuador, os sensores (encoders e sensores de força) e o computador. Também foi construída uma órtese tornozelo-pé ativa acionada pelo atuador elástico em série construído, sendo apresentados os primeiros resultados experimentais obtidos com este dispositivo. / This dissertation deals with the design and construction of series elastic actuators for driving the joints of an exoskeleton for lower limbs, based on a commercial orthosis. Initially, it was considered the construction of the exoskeleton\'s ankle joint, that is, the construction of an active ankle-foot orthosis. Series elastic actuators are considered in this work since these devices have ideal characteristics for use in active orthoses: force control, impedance control (possibility of low impedance), impact absorption, low friction and bandwidth that approximates the muscle movement. A first prototype of the series elastic actuator was constructed and experimental results of force, impedance, and position control were successfully obtained trough of a control interface between the actuators, the sensors (encoders and force sensors) and the computer. Also, an active ankle-foot orthosis, driven by the series elastic actuator, was constructed and the first experimental results achieved with this device are presented.

Os atuadores hidráulicos são usados em muitas aplicações e áreas de trabalho devido à sua capacidade para manipular grandes forças com baixa inércia, pouca vibração e capacidade de trabalho por longos períodos de tempo. Entretanto, o maior problema no uso destes tipos de atuadores são as características dinâmicas tais como não-linearidade e variação de parâmetros, as quais dificultam seu controle em malha fechada. Assim, para controlar sistemas hidráulicos, é necessário o uso de modelos matemáticos não lineares e a aplicação de leis de controle complexas para obter um seguimento de trajetória com alta precisão. O objetivo principal deste trabalho é a obtenção de um sistema que siga com precisão as trajetórias de referência do tipo senoidais. Para tanto, este trabalho aborda o projeto de uma lei de controle por realimentação de estados (feedback linearization) combinada com o princípio do modelo interno para aplicar no sistema hidráulico de atuação de uma máquina de ensaios de fadiga. O princípio do modelo interno é aplicado utilizando um compensador dinâmico (que contém pólos imaginários com a mesma freqüência que o sinal de referência) num laço externo do sistema linearizado por realimentação de estados. Uma lei de controle do tipo realimentação de estados, considerando os estados do sistema linearizado e os do compensador dinâmico, é projetada para garantir estabilidade no sistema de malha fechada. A fim de avaliar a estratégia de controle proposta são discutidos e apresentados simulações do modelo experimental. / Hydraulic actuators are used in many applications due to their ability in driving large forces with low inertia and little vibration for a long period of time. However, the main problem in controlling these kinds of systems concerns their dynamics, which presents several nonlinearities and parameters variations. Thus, to control hydraulic systems, appropriated nonlinear models and complex control techniques to achieve a stable force regulation with a specified performance are necessary. The purpose of this work is the application of a feedback linearization scheme in the design of a force controller for a hydraulic actuator used in a fatigue test machine. The main control objective considered regards the achievement of sinusoidal force reference tracking. With this aim the internal model principle is applied by using a dynamic compensator (containing imaginary poles with the same frequency of the force reference) in an outer regulation loop. A state feedback control law, considering both the states of the feedback linearized hydraulic system and the ones of the dynamic compensator, is therefore designed in order to stabilize the whole closed-loop system. Experimental model identification and simulation control results are presented and discussed.

Trata do desenvolvimento de um porta-ferramenta translativo (PFT). Objetiva o microposicionamento relativo ferramenta/peça durante a usinagem de ultraprecisão, para atender à tolerâncias nanométricas. Define esse microposicionamento com o emprego de atuador piezelétrico. Mostra alguns aspectos de projeto aplicados à engenharia de precisão que foram usados no desenvolvimento do PFT. Relata as técnicas de controle aplicadas como PID e compensador por atraso de fase. Realiza uma análise para verificação dos modos de vibrar do PFT, identificando assim as freqüências naturais do sistema. Apresenta um modelo ideal, ou seja, todos os componentes foram fabricados e montados para a realização dos testes. Propõe que a estratégia de controle seja baseada em processar sinais adquiridos ao longo do microposicionamento da ferramenta para identificar a condição de posicionamento relativo ferramenta/peça e obter informações que foram posteriormente usadas em um controlador PID, para realimentação de posição. Conclui com a avaliação e testes experimentais de deslocamento da ferramenta de corte, até 25 &#956m; com freqüência, até 10 Hz, realizados com o PFT projetado. / This work deals with the development of a tool post (PFT) for the micropositioning of a tool during ultraprecision machining in the nanometric range. Micropositioning employing piezoelectric actuators is defined. Precision engineering designs aspects applied to the development of the PFT are discussed. Control techniques such as PID and phase-lag compensator are addressed. A computer simulation for the verification of the vibrating modes of the PFT, with the simultaneous identification of the natural frequencies is carried out. An ideal model - all components will be manufactured and assembled - is presented. A control strategy based on the processing of signals acquired during the micropositioning of the tool to identify the positioning condition and to obtain information to be used by a PID controller is proposed. Experimental tests are performed with displacement of the tool, up to 25 &#956m, with frequency, up to 10 Hz.

Orientadores: Katia Lucchesi Cavalca, Rainer Nordmann / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T14:22:54Z (GMT). No. of bitstreams: 1 Furtado_RogerioMendonca_D.pdf: 2160863 bytes, checksum: 4c54a9ce5fcded113554dc24287e591a (MD5) Previous issue date: 2008 / Resumo: Um atuador magnético como fonte de excitação em sistemas rotativos é desenvolvido para emprego na análise modal e em outros estudos, envolvendo a excitação sem contato. Embora os sistemas magnéticos para aplicação de forças em máquinas rotativas sejam empregados com alto desempenho (como por exemplo os mancais magnéticos), o desenvolvimento de um sistema simples, para aplicações laboratoriais, se apresenta como uma contribuição experimental útil, para ser empregado numa bancada de testes utilizada no desenvolvimento de projetos de máquinas rotativas. O conceito apresentado é simples, mas permite a excitação externa sem contatos ou mesmo o controle das amplitudes de vibração, quando associado a um sistema de controle. Contudo, a calibração e o estudo do desempenho dinâmico do sistema não são análises simples. Neste sentido, o trabalho apresenta uma experiência prática e discussões sobre o desenvolvimento do atuador magnético utilizado para testes em máquinas rotativas. A influência da corrente elétrica, entreferro, superfície do pólo do atuador e também da freqüência de excitação, são apresentadas. A força magnética é estimada, baseando-se na medida da densidade de fluxo magnético, medida por sensores hall. / Abstract: A magnetic actuator as excitation source in rotating systems is developed, in order to accomplish modal analysis and other studies involving contacless excitation. Although the use of magnetic systems to apply forces onto rotating machinery has been carried out with high performance level (for example, magnetic bearings), the development of a conveniently easy and simples device for laboratory application presents interesting contribution to experimental methods used in test rigs based on similarity design to rotating machinery. The initial concept of the magnetic actuator proposed here is simple, but enables either the external excitation without contact or the vibration control when associated with a controller system. However, the performance characteristics tunning to attend the dynamic demand of the system is not so trivial. Following this focus, the work brings practical experience and discussion about the development and performance analysis of a magnetic actuator used for rotating machinery tests. The influence of the electrical current in the actuator coils, the air-gap between actuator and rotative system, thetype of surface of the actuator poles (flat or curved) as well as excitation frequency was verified. Force estimation was based on the magnetic flux density, measured by hall sensors. / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

This dissertation presents a free-space, long-range, passive optical communication system that uses electrostatically modulated microelectromechanical systems (MEMS) structures coupled with a glass total internal reflection (TIR)-type corner cube retroreflector (CCR) as a non-emitting data transmitter. A CCR consists of three mirrors orthogonal to each other, so that the incident beam is reflected back to the incident beam, source. The operational concept is to have a MEMS modulator fusion with TIR CCR, such that the modulators are working periodically to disrupt the evanescent waves at the air interface of one of the three back glass faces of a TIR CCR. The MEMS chip has two primary components: (1) an array of movable light scattering silicon structures with nano roughness and (2) a glass lid with a transparent conductive indium tin oxide (ITO) film. The MEMS structures are bonded to a glass lid using flip-chip bonding. Once bonded, the MEMS structures can be modulated either toward or away from the glass lid, thus disrupting evanescent energy delivered from a probing laser beam. The MEMS structure is precisely bonded to the TIR CCR with an accuracy of 10-30 arc-seconds using a Michelson interferometry feedback system. This is a novel step by which an existing passive commercial CCR can be converted into a modulating active CCR. This CCR-MEMS unit acts as the key element of the transmitter. To illustrate the concept of a low-power, unattended, sensor-monitoring system, we developed a sensor board containing temperature, humidity, and magnetic sensors along with a microprocessor and other electronics. The sensor board and CCR board are packed together and act as the transmitter unit. We developed a benchtop system and an improved portable receiver system. The receiver system contains the laser (as source), a collimating lens (to collect retroreflected signal), an optical, narrow band pass filter, and a detector. The detector signal was amplified and filtered and sent either to the oscilloscope, a lock-in-amplifier, or a laptop to display the sensor data. Using the receiver system, a sensor-CCR-based transmitter unit, and receiver with 635 nm as source, we achieved retroreflective communication over a distance of 300 m.

Les nouvelles générations d’avions, tant civils que militaires, sont désormais pleinement engagées dans l’électrification des commandes de vol. Afin d’atteindre les nouveaux objectifs et critères mis en place pour le bon développement de ces actionneurs électro-mécaniques, il est nécessaire d’effectuer des études en amont. Ces études portent principalement sur le comportement mécanique et tribologique des pièces en contact afin d’éviter l’évènement le plus redouté qui est le grippage, au sens blocage irréversible du système. En effet, ces actionneurs électro-mécaniques sont soumis à des sollicitations de chargement vibratoires qui induisent des déplacements de très faibles amplitudes entre les pièces en contact. Ces micro-glissements peuvent induire de l’usure, de la fissuration, de l’écaillage, etc. Pour répondre à ces objectifs, les travaux de recherche menés dans cette thèse, ont porté sur quatre axes majeurs. Le premier axe consiste à étudier et déterminer le comportement tribologique des premiers corps en milieu sec, puis en incorporant des traitements de surface. Le second axe a permis de déterminer les différents régimes de lubrification du contact lubrifié à la graisse. Nous avons montré que le régime de lubrification totale est caractérisé par la formation d’un tribofilm lubrifiant et protecteur. Des analyses plus poussées ont portées sur les cinétiques de formation et destruction de ce tribofilm ainsi que sa nature. Le troisième axe est consacré à l’étude du comportement tribologique du contact revêtu en milieu graissé. Le dernier axe de travail est destiné à la mise en place d’outils de simulation et de prévision de l’usure, et donc à posteriori du grippage, en fonction des conditions de chargement. Ces quatre axes d’études complémentaires ont donc permis de mettre en place des outils de comparaison de graisses et de revêtements, de comprendre le comportement du contact étudié ainsi que de développer des outils de simulation. / Electrification of flight controls represents an important milestone for both civil and military next-generation aircraft. A successful development of electro-mechanical actuators used for this type of application not only requires the establishment of a set of appropriate objectives and criteria but also the study of fundamental aspects. These studies mainly focus on the mechanical and tribological behavior of parts in contact with the objective to prevent seizing. Seizing is defined as an irreversible blockage of the system and it can be considered as the worst-case scenario. As a matter of fact, the considered electro-mechanical actuators are subjected to vibrational loads which induce small displacements between the parts in contact. These micro-slidings can result in wear, cracking, scaling and other undesirable phenomena. This PhD thesis is divided into four major topics that each contributes to prevent seizing. More precisely, the first part of this thesis deals with the tribological behavior of the first bodies in dry condition both with and without surface treatments. As a second axis the different lubrication regimes of the greased lubricated interface were determined. We have shown that the total lubrication regime is characterized by the formation of a lubricant and protective tribofilm. A detailed analysis on the nature of the tribofilm as well as on its kinetics of formation and destruction was carried out. The third area is devoted to the study of the tribological behavior of the coated and greased contact. Finally, the fourth axis of this research deals with the question of how we can simulate and predict wear, and seizing as its most severe form, under multiple loading conditions. These four complementary areas allowed us to establish tools for comparison for greases and coatings in order to understand the behavior of the fretted interface and to develop simulation tools.

Cette thèse traite de deux projets en rapport avec la microfluidique. Le premier est consacré à la réalisation d'actionneurs à base d'hydrogel thermosensible. Avec une approche technologique basée sur le greffage et la structuration d'un hydrogel thermosensible sur des surfaces en verre, nous montrons comment un matériau capable de subir de fortes variations de volume peut être utilisé comme actionneur microfluidique dans les milieux aqueux. D'abord, en tant que vanne, nous démontrons que la stratégie de greffage des structures permet d'obtenir des actionneurs robustes et durables capables de réguler la circulation de fluides en micro-canaux avec une réponse rapide en miniaturisant la stimulation thermique. Ensuite, une autre configuration, dite de compartimentation libre, est mise en oeuvre et appliquée en biologies moléculaire et cellulaire. Le second est quant à lui dédié à l'étude du glissement par nanovélocimétrie en utilisant la technique de microscopie de fluorescence par réflexion totale interne. Cette technique permet de suivre les écoulement de nanoparticules à proximité immédiate de la paroi d'un micro-canal (dans les premiers 800nm de fluide). En utilisant les modèles de Langevin, nous avons été en mesure de prendre en compte différents artéfacts expérimentaux et les corriger. Nous confirmons l'absence de glissement de l'eau pure sur surface hydrophile et l'existence du glissement sur surface hydrophobe. Cette partie est traitée sous la forme d'une brève introduction, suivie d'un article publié dans Journal of Fluid Mechanics. / In this work, we have addressed two projects related to microfluidics.The first one is dedicated to the integration of hydrogel-based actuators in microsystems. Thanks toa technological approach based on the grafting and patterning of a thermosensitive hydrogel on glasssubstrates, we show how a material that can undergo large volume changes can be embedded as anactuator for aqueous solutions. First as a valve, we prove that the strategy consisting in grafting patternsof hydrogel enables us to obtain robust actuators able to regulate flows in micro-channels, and with afast response by miniaturising the thermal stimulation. Then we report another configuration called freecompartmentalization, applied to molecular and cellular biology. The second part of this manuscript deals with the study of slippage by nanovelocimetry using the totalinternal reflection fluorescence microscopy technique. This method enables us to follow fluorescent nanoparticlesflowing near the wall of a microchannel (within the first 800nm ). Using Langevin simulations,we have been able to take several experimental biases into account and correct them. We can confirmthe no-slip condition of water on hydrophilic surfaces and the actual slippage over hydrophobic surfaces.This part is made of a brief introduction followed by an publication in Journal of Fluid Mechanics.