Dissertations / Theses: 'Sensors and controls'

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Tong, Jingbo. "MEASUREMENT AND MODELING OF HUMIDITY SENSORS." UKnowledge, 2014. http://uknowledge.uky.edu/ece_etds/59.

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Humidity measurement has been increasingly important in many industries and process control applications. This thesis research focus mainly on humidity sensor calibration and characterization. The humidity sensor instrumentation is briefly described. The testing infrastructure was designed for sensor data acquisition, in order to compensate the humidity sensor’s temperature coefficient, temperature chambers using Peltier elements are used to achieve easy-controllable stable temperatures. The sensor characterization falls into a multivariate interpolation problem. Neuron networks is tried for non-linear data fitting, but in the circumstance of limited training data, an innovative algorithm was developed to utilize shape preserving polynomials in multiple planes in this kind of multivariate interpolation problems.

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Yu, Rui. "A REDUNDANT MONITORING SYSTEM FOR HUMAN WELDER OPERATION USING IMU AND VISION SENSORS." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/128.

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In manual control, the welding gun’s moving speed can significantly influence the welding results and critical welding operations usually require welders to concentrate consistently in order to react rapidly and accurately. However, human welders always have some habitual action which can have some subtle influence the welding process. It takes countless hours to train an experienced human welder. Using vision and IMU sensor will be able to set up a system and allow the worker got more accurate visual feedback like an experienced worker. The problem is that monitor and measuring of the control process not always easy under a complex working environment like welding. In this thesis, a new method is developed that use two different methods to compensate each other to obtain accurate monitoring results. Vision sensor and IMU sensor both developed to obtain the accurate data from the control process in real-time but don’t influence other. Although both vision and IMU sensor has their own limits, they also have their own advantage which can contribute to the measuring system.

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Vera, Carrasco Luciano. "Sensory quality control of alcoholic beverages using fast chemical sensors." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/9061.

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Control de calidad sensorial de bebidas alcohólicas utilizando rápidos sensores químicos
En la presente tesis Doctoral, han sido aplicados dos sensores artificiales para el análisis de
bebidas alcohólicas: la nariz electrónica basada en la espectrometría de masas (MS) y la lengua
electrónica basada en la espectroscopía infrarroja con transformada de Fourier (FTIR). El
propósito fue desarrollar nuevas estrategias para analizar la autenticidad de estos productos,
desde un punto de vista sensorial, por medio de técnicas las espectrales antes mencionadas.
Adicionalmente, ha sido utilizado un espectrofotómetro UV-visible como ojo electrónico. El
trabajo presentado pretende ser un avance significativo hacia el desarrollo de un catador
electrónico mediante la fusión de los tres sensores químicos: nariz electrónica, lengua
electrónica y ojo electrónico.
Sensory quality control of alcoholic beverages using fast chemical sensors
In the present Doctoral Thesis, two chemical artificial sensors are applied to the analysis of
alcoholic beverages: the Mass Spectrometry (MS)-based electronic-noses and Fourier
transform infrared (FTIR)-based electronic-tongue. The aim was developing new strategies to
test the authenticity of these products, from a sensory point of view, by means of the spectral
techniques above mentioned. Additionally, has been used an UV-visible spectrophotometer as
electronic eye. The work presented wants to be a significant advance towards the development
of an electronic taster through the fusion of three chemical sensors: electronic nose, electronic
tongue and electronic eye.

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Rossi, Anderson Rodrigo 1981. "Uma nova técnica de comunicação e alimentação de transdutores inteligentes utilizando apenas um fio baseada no padrão IEEE 1451." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258976.

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Orientador: Elnatan Chagas Ferreira
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-23T02:42:42Z (GMT). No. of bitstreams: 1 Rossi_AndersonRodrigo_M.pdf: 49446456 bytes, checksum: e180d104b943e830a31e17128fa88249 (MD5) Previous issue date: 2013
Resumo: Sabe-se que atualmente, transmissores de loop de corrente, alimentados por um host ou data logger (equipamentos de leitura e/ou armazenamento de dados) são as técnicas mais utilizadas para medição e controle distribuído. Essa transmissão, normalmente, consiste na conexão individual por meio de, no mínimo, um fio, conectando os sensores remotos ao equipamento de leitura de dados. Ressalta-se que, se faz necessária a utilização de um fio terra para o retorno da corrente elétrica juntamente a esse fio de sinal, sendo descrito no texto como "um fio". Consequentemente, com a complexidade envolvida em um processo industrial, tem-se uma grande quantidade de sensores envolvidos, de modo que a ligação de todos os sensores ocasiona uma grande quantidade de fios que convergem para o equipamento de leitura de dados, gerando uma enorme complexidade nas decisões a serem tomadas em relação à instalação e manutenção do sistema. O trabalho tem como objetivo utilizar apenas um fio para a conexão entre vários sensores e atuadores remotos e o equipamento de leitura de dados, a fim de obter, com a diminuição da quantidade de cabeamento, melhoria no controle, precisão nas decisões a serem tomadas, consequentemente, uma maior simplicidade na manutenção e expansão do sistema, além de ser bastante estável às interferências eletromagnéticas, pois o fio recebe a mesma interferência eletromagnética em toda sua extensão e esse efeito se anula permitindo a comunicação entre grandes distâncias. Trata-se de um sistema de interfaceamento de sensores inteligentes a equipamentos de leitura de dados baseado nos padrões IEEE 1451, o qual emprega uma técnica para envio e recebimento de dados e a própria alimentação dos sensores remotos utilizando apenas um fio. O sistema proposto é formado por um NCAP (Network Capable Application Processor), um TII (Transducer Independent Interface), um TIM (Transducers Interface Module), 64 sensores e 64 atuadores caracterizando 128 TransducerChannels. Foi realizado um comparativo com um sistema utilizado pela FEAGRI-UNICAMP (Faculdade de Engenharia Agrícola) para a medição de temperatura no processo de armazenamento com secagem de grãos em silos por aeração forçada para a validação do sistema. Com isso pôde-se verificar as vantagens com relação à rapidez na instalação, facilidade de manutenção, redução de materiais (fios) e confiabilidade no sistema
Abstract: It's known that nowadays, current loop transmitters, fed by a host or a data logger are the most commonly used techniques to distributed measurement and control. Usually this transmission consists of an individual connection through at least a wire pair, connecting the remote sensors to the data logger. It's noted that it's necessary the use of the ground wire to electric current return with this signal wire, it's described at the text as "1 wire". Consequently, with the complexity involved in an industrial process, there is a great amount of involved sensors, in a way that all sensors connection causes a need of a great amount of wires that converge to the data reading equipment, causing a tremendous complexity around the decisions to be taken about the installation and maintenance of the system. This work has as objective using just 1-Wire (a source/communication wire and a common wire) to connect many remote sensors and actuators to the data logger, causing, with the reduction of the cabling amount, a control improvement, accuracy in the decisions to be taken, consequently, a great simplicity in the system maintenance and expansion, besides it's very stable against electromagnetic interference (EMI), because 1-Wire receives the similar EMI and it cancel this effect allowing taking possible to communicate for greater distances. This work discusses the smart sensors interface to data logger based on IEEE1451 standard and it uses a sending/receiving data and sourcing technique using just 1-Wire. The proposed system is formed by a NCAP (Network Capable Application Processor), a TII (Transducer Independent Interface), a TIM (Transducers Interface Module), 64 sensors and 64 actuators, characterizing 128 TransducerChannels. A comparison was made with a system that is used by FEAGRI-UNICAMP (College of Agricultural Engineering - University of Campinas) to measure the temperature at the storage process with grain drying in recipients by forced aeration to validate the system. Thus it can be verified the advantages related to the velocity in the installation, easier maintenance, materials reduction (wires) and reliability on the system
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica

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Andersson, Mike. "SiC based field effect sensors and sensor systems for combustion control applications." Doctoral thesis, Linköping : S-SENCE and Division of Applied Physics, Department of Physics, Chemistry, and Biology, Linköping University, 2007. http://www.bibl.liu.se/liupubl/disp/disp2007/tek1077s.pdf.

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Júnior, José Batista de Oliveira. "Controle de uma plataforma inercial estabilizada com três graus de liberdade." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-27062016-154420/.

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Esta dissertação apresenta o desenvolvimento de uma plataforma inercial autônoma com três graus de liberdade para aplicação em estabilização de sensores - por exemplo, gravimétricos estacionários e embarcados - podendo ser utilizada também para estabilização de câmeras. O sistema é formado pela Unidade de Medida Inercial, IMU, desenvolvida utilizando um sensor micro eletromecânico, MEMS - que possui acelerômetro, giroscópio e magnetômetros nos três eixos de orientação - e um microcontrolador para aquisição, processamento e envio dos dados ao sistema de controle e aquisição de dados. Para controle dos ângulos de inclinação e orientação da plataforma, foi implementado um controlador PID digital utilizando microcontrolador. Este recebe os dados da IMU e fornece os sinais de controle utilizando as saídas PWM que acionam os motores, os quais controlam a posição da plataforma. Para monitoramento da plataforma foi desenvolvido um programa para aquisição de dados em tempo real em ambiente Matlab, por meio do qual se pode visualizar e gravar os sinais da IMU, os ângulos de inclinação e a velocidade angular. Testou-se um sistema de transmissão de dados por rádio frequência entre a IMU e o sistema de aquisição de dados e controle para avaliar a possibilidade da não utilização de slip rings ou fios entre o eixo de rotação e os quadros da plataforma. Entretanto, verificou-se a inviabilidade da transmissão em razão da baixa velocidade de transmissão e dos ruídos captados pelo receptor de rádio frequência durante osmovimentos da plataforma. Sendo assim, dois pares de fios trançados foram utilizados fios para conectar o sensor inercial ao sistema de aquisição e processamento.
This work presents the development of a three-degree of freedom autonomous inertial platform for the use in sensors stabilization - for example, stationary and embedded gravimeters. It can also be used to stabilize cameras. The system is composed by the Inertial Measurement Unit, IMU, developed using a micro electromechanical sensor, MEMS - which has an accelerometer, a gyroscope and a magnetometer in the three axes of orientation - and a microcontroller for data acquisition, data processing and data sending to the control and data acquisition system. To control the platform angles and its orientation, a digital PID controller was implemented using a microcontroller. It receives data from the IMU and provides the control signals using the PWM outputs that drive the motors to control the platform position. In order to supervise the platform operation, a real time data acquisition software was developed in Matlab, where IMU signals, inclination angles and angular velocities can be displayed and recorded. Data transmission via radio frequency between the IMU and the data acquisition and control system was tested in order to evaluate the possibility of not using slip rings or wires between the rotation axis and platform frames. This approach was unsuccessful due to the low speed of data transmission and to the noise that affected the radio frequency receiver during the platform\'s movements. In view of that wire was used to directly connect the inertial sensor to the acquisition and processing system.

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Sugathevan, Suranthiran. "Nonlinear and distributed sensory estimation." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2246.

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Methods to improve performance of sensors with regard to sensor nonlinearity, sensor noise and sensor bandwidths are investigated and new algorithms are developed. The necessity of the proposed research has evolved from the ever-increasing need for greater precision and improved reliability in sensor measurements. After describing the current state of the art of sensor related issues like nonlinearity and bandwidth, research goals are set to create a new trend on the usage of sensors. We begin the investigation with a detailed distortion analysis of nonlinear sensors. A need for eﬃcient distortion compensation procedures is further justiﬁed by showing how a slight deviation from the linearity assumption leads to a very severe distortion in time and in frequency domains. It is argued that with a suitable distortion compensation technique the danger of having an inﬁnite bandwidth nonlinear sensory operation, which is dictated by nonlinear distortion, can be avoided. Several distortion compensation techniques are developed and their performance is validated by simulation and experimental results. Like any other model-based technique, modeling errors or model uncertainty aﬀects performance of the proposed scheme, this leads to the innovation of robust signal reconstruction. A treatment for this problem is given and a novel technique, which uses a nominal model instead of an accurate model and produces the results that are robust to model uncertainty, is developed. The means to attain a high operating bandwidth are developed by utilizing several low bandwidth pass-band sensors. It is pointed out that instead of using a single sensor to measure a high bandwidth signal, there are many advantages of using an array of several pass-band sensors. Having shown that employment of sensor arrays is an economic incentive and practical, several multi-sensor fusion schemes are developed to facilitate their implementation. Another aspect of this dissertation is to develop means to deal with outliers in sensor measurements. As fault sensor data detection is an essential element of multi-sensor network implementation, which is used to improve system reliability and robustness, several sensor scheduling conﬁgurations are derived to identify and to remove outliers.

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Hol, Jeroen D. "Sensor Fusion and Calibration of Inertial Sensors, Vision, Ultra-Wideband and GPS." Doctoral thesis, Linköpings universitet, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-66184.

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The usage of inertial sensors has traditionally been confined primarily to the aviation and marine industry due to their associated cost and bulkiness. During the last decade, however, inertial sensors have undergone a rather dramatic reduction in both size and cost with the introduction of MEMS technology. As a result of this trend, inertial sensors have become commonplace for many applications and can even be found in many consumer products, for instance smart phones, cameras and game consoles. Due to the drift inherent in inertial technology, inertial sensors are typically used in combination with aiding sensors to stabilize andimprove the estimates. The need for aiding sensors becomes even more apparent due to the reduced accuracy of MEMS inertial sensors. This thesis discusses two problems related to using inertial sensors in combination with aiding sensors. The first is the problem of sensor fusion: how to combine the information obtained from the different sensors and obtain a good estimate of position and orientation. The second problem, a prerequisite for sensor fusion, is that of calibration: the sensors themselves have to be calibrated and provide measurement in known units. Furthermore, whenever multiple sensors are combined additional calibration issues arise, since the measurements are seldom acquired in the same physical location and expressed in a common coordinate frame. Sensor fusion and calibration are discussed for the combination of inertial sensors with cameras, UWB or GPS. Two setups for estimating position and orientation in real-time are presented in this thesis. The first uses inertial sensors in combination with a camera; the second combines inertial sensors with UWB. Tightly coupled sensor fusion algorithms and experiments with performance evaluation are provided. Furthermore, this thesis contains ideas on using an optimization based sensor fusion method for a multi-segment inertial tracking system used for human motion capture as well as a sensor fusion method for combining inertial sensors with a dual GPS receiver. The above sensor fusion applications give rise to a number of calibration problems. Novel and easy-to-use calibration algorithms have been developed and tested to determine the following parameters: the magnetic field distortion when an IMU containing magnetometers is mounted close to a ferro-magnetic object, the relative position and orientation of a rigidly connected camera and IMU, as well as the clock parameters and receiver positions of an indoor UWB positioning system.
MATRIS (Markerless real-time Tracking for Augmented Reality Image), a sixth framework programme funded by the European Union
CADICS (Control, Autonomy, and Decision-making in Complex Systems), a Linneaus Center funded by the Swedish Research Council (VR)
Strategic Research Center MOVIII, funded by the Swedish Foundation for Strategic Research (SSF)

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Hoesel, Lodewijk Frans Willem van. "Sensors on speaking terms schedule-based medium access control protocols for wireless sensor networks /." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57885.

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Myronidi, Despoina. "LIGHT-BEAT: REACTIVE LIGHT FOR THE EMOTIONAL COMFORT OF NEWBORN BABIES." Thesis, KTH, Ljusdesign, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297961.

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This is a project-based thesis focusing on the investigation of topics related to human newborns and the factors found in their surrounding environment that need to be assessed so as to provide them with a feeling comfort. The objective is to boost their emotional development by the means of light in a close relation to sound so as to provide them with a type of intelligence allowing them to normally interact within a society during their adult life, reassuring social equality and eliminating potential social exclusion due to unexpected behaviours. After researching topics to have a better understanding of the newborn baby and its enclosing environment, a luminaire design solution -functioning with a reactive scheme performed with integrated sound sensors- provided further results to the main topic investigation. The conceptual scheme for the product development was inspired by the connection between the newborn and their life-giver, closely linked to the cross-modality of sensory development before and after birth. Additional results were obtained with light measurement assessments and a parent survey targeting both the intended light quality subjective evaluations and the marketing strength of the designed product. This survey was used -along with other means- as a design evaluation tool at the final stage of the design process. Potential further improvements as well as considerations for a distinct spatial application are discussed in the final part of the thesis. The sustainability aspect covered within this degree project is closely linked to good physical and mental health aspects, clean energy use and efficiency achieved by the integration of input sound sensors and controls, and conscious production and consumption by the proposal of low global footprint materials for the luminaire design. In the conclusions, an overall summary of the thesis outcomes is presented and further research is proposed regarding both the main topic investigation as well as a greater user category that can be related to the light metric assessments that were carried out for this research.

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Bazzo, João Paulo. "Avaliação da influência da temperatura de junção no desempenho de um módulo IGBT empregando sensores a fibra ótica." Universidade Tecnológica Federal do Paraná, 2010. http://repositorio.utfpr.edu.br/jspui/handle/1/225.

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Este trabalho tem por objetivo principal avaliar a influência da temperatura de junção nas perdas de potência de um módulo IGBT (Insulated Gate Bipolar Transistor), monitorando a temperatura através de medida direta, empregando sensores a fibra ótica. O monitoramento direto da temperatura é realizado por meio de sensores óticos baseados em rede de Bragg instalados no interior do módulo, posicionados sobre a pastilha semicondutora que forma o IGBT. Para que as análises experimentais possam ser realizadas sob condições de temperatura controlada, foi desenvolvido um sistema de controle de temperatura digital com base em um módulo termoelétrico de efeito Peltier, que permite regular a temperatura com um erro percentual de 0,1%, numa faixa de valores que podem variar de -16 °C a 150 °C. O acionamento do módulo IGBT é realizado através de um circuito de teste capaz de variar os parâmetros elétricos do dispositivo, como largura do pulso, tensão e corrente de carga. As formas de onda que descrevem o comportamento do IGBT são obtidas por meio de um osciloscópio digital, o que proporciona a verificação do desempenho do dispositivo durante os processos de comutação e condução de corrente elétrica. O acionamento do IGBT sob temperaturas controladas permite verificar as faixas de temperatura que apresentam influência significativa nas perdas do dispositivo. O emprego do sensor ótico proporciona identificar o aquecimento gerado na junção do dispositivo em função das perdas. A medição da temperatura de forma direta também contribui para o desenvolvimento de uma técnica simples e de boa precisão para obtenção dos parâmetros térmicos da estrutura do IGBT. Os parâmetros obtidos serviram de base para elaboração de um modelo térmico preciso, que permite simular fielmente o comportamento térmico do dispositivo, onde o erro percentual máximo é de aproximadamente 0,3%. A utilização do modelo facilita a análise de pequenas variações de temperatura, inferiores à 0,01 °C, onde a medição através do sensor torna-se complicada. A associação dos resultados da análise de influência da temperatura no desempenho do IGBT, com o monitoramento e simulação do aquecimento gerado durante a operação do dispositivo pode contribuir, de fato, para o desenvolvimento semicondutores de potência mais eficientes.
This study aims to evaluate the temperature influence on power losses of an IGBT module (Insulated Gate Bipolar Transistor), monitoring the temperature through direct measurement, using optical sensors. The direct monitoring of temperature is accomplished by means of optical sensors based on fiber Bragg grating installed inside the module, positioned on the semiconductor wafer, which forms the IGBT structure. For the experimental analysis to be performed under controlled temperature conditions, a digital temperature control system based on a Peltier effect thermoelectric module was developed, which can regulate the temperature in a range between -16 °C to 150 °C, with an percentage error of 0.1%. The drive of the IGBT module is done by a test circuit that can vary the device electrical parameters, such as pulse width, voltage and load current. A digital oscilloscope, providing verification of device performance during the switching and conduction of electrical current, obtains the waveforms that describe the IGBT behavior. The drive of the IGBT under controlled temperature allows checking the temperature ranges that have significant influence on the device power losses. The use of optical sensor provided to identify the heat generated on the device junction due to the power losses. The direct measurement of junction temperature also contributed to the development of a simple technique with great precision to obtain the thermal parameters of the IGBT structure. The parameters obtained were the basis for developing a precise thermal model that faithfully simulates the device thermal behavior, where the maximum percentage error is 0.3%, approximately. The model facilitates the analysis of small variations in temperature, lower than 0.01 °C, where measurement by the sensor becomes more complicated. The association of the temperature influence analysis on the IGBT performance with monitoring and simulation of generated heat on the structure during device operation, can contribute to the research on design of novel power semiconductor devices.

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Fakir, Felipe. "Controle preditivo multi-rate para eficiência energética em sistema de controle via rede sem fio /." Bauru, 2017. http://hdl.handle.net/11449/150992.

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Orientador: Eduardo Paciência Godoy
Banca: Diego Colon
Banca: Mariza Antunes de Lemos
Resumo: A tecnologia de comunicação wireless vem se tornando parte fundamental do cotidiano das indústrias de processos, onde o uso de transmissores wireless aplicados à monitoração e controle já é uma realidade. A arquitetura de Sistema de Controle via Rede Sem Fio (WNCS) possui vantagens em relação às arquiteturas tradicionais ponto-a-ponto e às arquiteturas de redes cabeadas devido à facilidade de instalação, configuração e manutenção. No entanto, a evolução desta tecnologia introduziu novos desafios para a implementação da malha de controle fechada por um instrumento wireless como as não linearidades, perda de pacote de dados e restrições da comunicação de dados nas redes sem fio. Outro fator crítico relacionado à implementação de WNCSs é a fonte de energia limitada destes transmissores, que possuem vida útil dependente da quantidade de acessos e dados transmitidos. Este trabalho apresenta o estudo e o desenvolvimento de um controlador preditivo multi-rate como alternativa para melhorar a eficiência energética em aplicações industriais de WNCSs. A estratégia proposta não necessita receber constantemente os valores reais das variáveis do processo transmitidos pelos transmissores wireless, pois o controlador preditivo baseado em modelo (MPC) se utiliza do submodelo interno das variáveis de processo para estimar os valores das variáveis quando estas não são transmitidas. Dessa forma, uma diminuição da frequência de transmissão de dados na rede sem fio pode ser obtida e, consequentem... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Wirelles communication technology has become a fundamental part of the every day life of process industries, where the use of wereless transmitters for monitoring and control is already a reality. The archiecture of Wireless Networked Control Systems (WNCSs) has advantages over point-to-point and wiered networks architectures due to the ease of installation, configuration and maintenance. However, the evolution of this technology has introduced new challenges to the implementation of the closed loop control with a wiereless instrument as nonlinearities, packet losses and data communication constraints in the wiereless networks. Another critical factor related to implementation of WNCSs is the energy source of these transmitters, which have limited lifetime dependent on the amount of access and data transmitted. This work presents the study and the development of a multi-rate predictive controller as an alternative to improve energy efficiency in industrial applications of WNCSs. The proposed strategy does not need to frequently receive process variables transmitted by wireless transmitters, because the model predictive controller (MPC) uses the internal submodel of the process variables to estimate the variables values when they are not transmitted. Thus, a decrease in the frequency of data transmission on the wireless network can be obtained and consequently a reduction of energy consumption of wereless devices. Simulation results for different operating conditions of a multivariable WNCS of coupled tanks shows that the multi-rate MPC provides robusstness and it is effective for WNCS applications, ensuring control and stability requirements even with the reduction of the transmission frequency of the feddback data in the wiereless network. In addition, energy consumption results from the WNCS devices showed that MPC multi-rate provides 20% of energy... (Complete abstract click electronic access below)
Mestre

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Pimenta, Iuri Saulo de Castro. "Avaliação do equilíbrio em indivíduos com défice visual e normovisuais." Bachelor's thesis, [s.n.], 2016. http://hdl.handle.net/10284/5738.

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Projeto de Graduação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciado em Fisioterapia
Objetivo: Avaliar o equilíbrio em indivíduos com Défice Visual (DV) e Normovisuais (NV) durante a execução de diferentes testes de avaliação e verificar se os testes aplicados são apropriados para a avaliação do equilíbrio em sujeitos com DV. Metodologia: Neste estudo participaram 22 indivíduos, do sexo feminino e masculino, com mais de 50 anos de idade e com diferentes condições visuais. Para avaliar as oscilações posturais, utilizou-se um sistema de centrais inerciais. Os participantes realizaram 5 testes de equilíbrio, tendo sido colocada uma venda a todos os participantes para retirar o estímulo visual. Resultados: A comparação entre o grupo DV e NV apenas revelou diferenças significativas no Tandem Preferido (Tandem Pre). Dos três componentes avaliados, o ântero-posterior foi o que registou mais oscilação. Conclusão: Os participantes com DV apresentam melhor equilíbrio no teste Tandem Pre. Para a amostra estudada, os testes de Tandem revelaram-se mais desafiantes na avaliação do equilíbrio em indivíduos com DV.
Aim: To evaluate balance in Visual Impairment (VI) and sighted (NV) people during the execution of different assessment tests and to verify if the applied tests were appropriate for the assessment of balance in subjects with VI. Methodology: The study included 22 individuals, both male and female, aged above 50 years and with different visual conditions. To assess postural oscillations, a inertial measurement system was used. Participants performed five balance tests, and all participants were blindfolded to remove the visual input. Results: The comparison between VI and NV groups showed significant differences in the Tandem Preferred (Tandem Pre). Between the three assessed components, the anteroposterior was the most unstable. Conclusions: VI participants evidenced better balance in the test Tandem Pre. In general, the Tandem tests revealed more challenging in the assessment of balance in VI individuals.
N/A

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Foina, Aislan Gomide. "Monitoração de rede de sensores com transponders." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-08052007-163603/.

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Este trabalho apresenta os resultados obtidos no desenvolvimento de um sistema capaz de estabelecer um controle adequado do fluxo da informação e a supervisão de uma rede de sensores. O sistema se caracteriza pelo alto grau de flexibilidade possuindo uma camada de comunicação de dispositivos, uma camada de gerenciamento de regras de negócio para controlar o fluxo de processos, uma camada de interface homem - máquina e de interface com outros sistemas. A camada de comunicação com os dispositivos é responsável pela interface entre os mesmos e o núcleo do sistema, integrando, de forma transparente, diferentes equipamentos, tecnologias e fabricantes. A interface do usuário foi projetada em um único módulo para facilitar modificações sem comprometer o funcionamento geral do sistema. A interface com outros sistemas é feita por meio de drivers de comunicação, permitindo qualquer tipo de integração. O núcleo do sistema faz todo o controle de eventos, do fluxo do processo e geração alarmes, assim como recebimento e envio das informações da camada de dispositivos e da camada de interface. São descritas as diversas camadas da interface e sua implementação analisando as possíveis aplicações do sistema, juntamente com um estudo de caso do controle do processo de descarga de carga a granel no porto de Santos, usando tecnologia RFID. Os resultados obtidos nessa aplicação são descritos e comprovam a utilidade prática do sistema. Apresentam-se inicialmente alguns conceitos básicos necessários ao entendimento deste projeto como: sistemas distribuídos, estrutura webservice, linguagem XML e de tecnologias passíveis de integração com o sistema.
This paperwork presents the results obtained with the development of a system capable of establishing a proper control of information flow and supervision of a sensors network. The system characterizes itself due to its great flexibility degree by having a devices communication layer, a business management layer to do the process flow control, a man-machine interface and interface with other systems layer. The devices communication layer is responsible for the interface between other devices and the system core, integrating in a transparent way, different equipment, technologies and manufactures. The user\'s interface was designed in a single module to facilitate modifications without compromising the system\'s general functioning. The interface with other systems is made throughout communication drivers, allowing any type of integration. The system core makes a control of all events, process flow and alarm generation, as well as receiving and sending information from the devices layer and interface layer. The several interface layers and its implementation are described analyzing the system\'s possible applications along with a case study of loading discharge in a bulk process control at Santos Port using RFID technology. The results obtained with this application are described and prove the practical utility of the system. Some necessary basic concepts to understand this project are presented initially as: distributed systems, web service structure, XML language and technologies subjected to integration with the system.

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15

Gautier, Nicolas. "Flow control using optical sensors." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066640/document.

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Le contrôle d'écoulement en utilisant des capteurs optiques est étudié dans un contexte expérimental. Le calcul de champs de vitesses en temps réel en utilisant une caméra pour l'acquisition et une carte graphique pour le calcul est détaillé. La validité de l'approche en terme de rapidité et de précision est étudiée. Un guide complet pour l'optimisation logicielle et matérielle est donné. Nous démontrons que le calcul dynamique de champs de vitesse est non seulement possible mais plus facile à gérer que l'utilisation d'un appareillage (PIV) classique. Un canal hydrodynamique est utilisé pour toutes les expériences. Celui-ci comporte une marche descendante pour le contrôle d' écoulements décollés. Les actionneurs sont des jets. Dans le cas de la marche descendante une étude paramétrique approfondie est faite pour qualifier les effets d'une injection en amont des jets, celle-ci étant traditionnellement effectuée à l'arrête de la marche.Plusieurs méthodes de contrôle sont étudiées. Un algorithme de contrôle basique de type PID est mis en place pour démontrer la viabilité du contrôle d'écoulement en boucle fermée par capteurs optiques. La zone de recirculation située derrière la marche est calculée en temps réel dans un plan vertical et horizontal. La taille de cette région est manipulée avec succès. Une approche basée sur des observations de la dynamique de l'écoulement est présentée.Des résultats précédents dans la littérature montrent que la recirculation peut être réduite avec succès en agissant sur l'écoulement à la fréquence naturelle de lâchés tourbillonnaires liés à l'instabilité de Kelvin-Helmholtz de la couche cisaillée crée par la marche. Une éthode basée de détection de vortex est introduite pour calculer cette fréquence, qui est ensuite utilisée dans une boucle de contrôle qui assure que l'écoulement est toujours pulsé à la bonne fréquence. Ainsi en utilisant des capteurs optiques la recirculation est réduite de façon simple.Ensuite nous implémentons un contrôle de type feed-forward dont l'efficacité a préalablement été démontrée en simulation. Cette approche vise à prévenir l'amplification de perturbations amont par la couche cisaillée. Nous montrons comment une telle méthode peut être implémentée avec succès dans un contexte expérimental. Enfin, nous implémentons également une approche radicalement différente basée sur un algorithme génétique. Des lois de contrôle aléatoires sont testées et évaluées. Les meilleurs sont répliquées, mutées et croisées. Ce processus se poursuit itérativement jusqu'à ce que le coût soit minimisé. Bien que lente à converger cette approche donne des résultats encourageants à travers une loi de commande originale
Flow control using optical sensors is experimentally investigated. Real-time computation of flow velocity fields is implemented. This novel approach featuring a camera for acquisition and a graphic processor unit (GPU) for processing is presented and detailed. Its validity with regards to speed and precision is investigated. A comprehensive guide to software and hardware optimization is given. We demonstrate that online computation of velocity fields is not only achievable but offers advantages over traditional particle image velocimetry (PIV) setups. It shows great promise not only for flow control but for parametric studies and prototyping also.A hydrodynamic channel is used in all experiments, featuring a backward facing step for separated flow control. Jets are used to provide actuation. A comprehensive parametric study is effected to determine the effects of upstream jet injection. It is shown upstream injection can be very effective at reducing recirculation, corroborating results from the literature.Both open and closed loop control methods are investigated using this setup. Basic control is introduced to ascertain the effectiveness of this optical setup. The recirculation region created in the backward-facing step flow is computed in the vertical symmetry plane and the horizontal plane. We show that the size of this region can be successfully manipulated through set-point adaptive control and gradient based methods.A physically driven control approach is introduced. Previous works have shown successful reduction recirculation reduction can be achieved by periodic actuation at the natural Kelvin-Helmholtz frequency of the shear layer.A method based on vortex detection is introduced to determine this frequency, which is used in a closed loop to ensure the flow is always adequately actuated. Thus showing how recirculation reduction can be achieved through simple and elegant means using optical sensors. Next a feed-forward approach based on ARMAX models is implemented. It was successfully used in simulations to prevent amplification of upstream disturbances by the backward-facing step shear layer. We show how such an approach can be successful in an experimental setting.Higher Reynolds number flows exhibit non-linear behavior which can be difficult to model in a satisfactory manner thus a new approach was attempted dubbed machine learning control and based on genetic programming. A number of random control laws are implemented and rated according to a given cost function. The laws that perform best are bred, mutated or copied to yield a second generation. The process carries on iteratively until cost is minimized. This approach can give surprising insights into effective control laws

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Mourão, Kellen Taziani Fernandes. "Posicionamento de sensores/atuadores e escolha de funções de ponderação no controle H-infinito de vibrações." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264987.

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Orientador: Alberto Luiz Serpa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica.
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Resumo: Neste trabalho foi utilizado o controle H'infinito' para atenuar vibrações em estruturas mecânicas. São utilizadas desigualdades matriciais lineares para encontrar o controlador ótimo. Sensores e atuadores são incorporados ao projeto e para determinar o melhor local onde devem ser fixados na estrutura são utilizadas duas metodologias: uma pela menor norma H'infinito' de malha fechada e a outra pela maior norma H''infinito' de malha aberta. Para modelar a estrutura a ser controlada é usado o método de elementos finitos. Após determinadas as posições ótimas para alocar sensores e atuadores, foram projetados controladores H''infinito' com filtros de ponderação escolhidos via algoritmos genéticos. Para projetar o controlador H'infinito' utilizou-se o modelo reduzido da planta, desconsiderando os modos residuais. São escolhidos filtros de ponderação via algoritmos genéticos para determinar as faixas de frequência de interesse com o intuito de projetar um controlador menos conservador e evitar o fenômeno de spillover, e consequentemente, que a malha fechada se torne instável. Os exemplos de aplicação foram realizados sobre uma estrutura flexível do tipo viga. Os resultados mostraram que os controladores projetados, após o posicionamento ótimo de sensores e atuadores e escolhidas das funções de ponderação via algoritmos genéticos, minimizaram a amplitude de vibração da estrutura garantindo a estabilidade do sistema
Abstract: In this work it was used the H'infinite' control to atenuate vibrations in mechanical structures. Linear matrix inequalities are used to find the optimal controller. Sensors and actuators are incorporated into the project. To determine the best place to allocate them in the structure two methods are used: the first is based on the highest closed-loop H'infinite' norm and the second is based on the lowest open-loop H'infinite' norm. The structure to be controlled was modeled through the finite element method. After determining the optimal placement to allocate sensors and actuators, the loop was closed and H'infinite' controllers were designed with weighting filters that were chosen via genetic algorithms for both cases of positioning. To design the H'infinite' controller, a reduced model of the plant was used, disregarding the residual modes. Weighting filters are found through genetic algorithms to determine the frequency bands of interest in order to design a controller with less conservatism and avoiding the phenomenon of spillover, and consequently, unstable closed loop. The application examples were based in a flexible beam structure. The results showed that the designed controllers, after the optimal placement of sensors and actuators and choosing the best parameters for the weighting functions, minimized the amplitude of vibration of the structure, ensuring system stability
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica

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17

Pereira, Daniel Augusto 1983. "Detecção de falhas de sensores em estruturas flexíveis com controle ativo de vibração." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264923.

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Orientador: Alberto Luiz Serpa
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Partindo-se do princípio de que detectar falhas em sistemas realimentados pode ser considerada tarefa difícil, nessa tese é proposto um método para detecção de falhas de sensores em estruturas flexíveis sujeitas a controle ativo de vibração. O método é baseado num esquema com banco de estimadores para geração de resíduos e no uso de indicadores para a análise quantitativa desses resíduos. O esquema de banco de estimadores permite o isolamento das falhas. Os estimadores utilizados são observadores de saída, filtros de Kalman e filtros H-infinito. Já os indicadores propostos são versões modificadas da diferença entre os valores RMS das saídas medidas e estimadas, a soma do módulo do erro de estimativa, a soma quadrática do erro de estimativa e o modal assurance criterion. É proposto um reescalamento dos indicadores e também um novo indicador, definido pelo produto das versões modificadas e reescaladas dos indicadores clássicos. Inicialmente a técnica foi validada em simulações, primeiro com um modelo de elementos finitos de uma estrutura de placa e posteriormente com um modelo de placa identificado experimentalmente, ambos sob controle ativo de vibração. Experimentos com a estrutura de placa também foram realizados e comprovaram a eficácia da técnica
Abstract: Assuming that fault detection in feedback systems can be considered a hard task, it is proposed in this thesis a method for sensor fault detection in flexible structures subjected to active vibration control. The method is based on a scheme with bank of estimators for residual generation and indicators for quantitative analysis of residues. The bank estimators scheme allows the fault isolation. The estimators used are output observers, Kalman filters and H-infinity filters. The proposed indicators are modified versions of the difference between RMS values of measured and estimated outputs, the sum of the modulus of the estimation error, the quadratic sum of the estimation error and the modal assurance criterion. It is proposed a rescaling of the indicators and also a new indicator, defined by the product of the modified and rescaled versions of classical indicators. Initially the technique is validated in simulations, first with a finite element model of a plate structure and latter with an experimentally identified plate model, both under active vibration control. Experiments with the plate were also performed and proved the effectiveness of the technique
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica

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18

Ernst, Andreas [Verfasser], and Roland [Akademischer Betreuer] Zengerle. "Non-contact process control sensors for nanoliter dispensing systems = Kontaktfreie Sensoren zur Prozesskontrolle von Nanoliter Dosiersystemen." Freiburg : Universität, 2013. http://d-nb.info/1123474974/34.

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19

Dota, Mara Andréa. "Modelo para a classificação da qualidade da água contaminada por solo usando indução por árvore de decisão." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-14082015-151933/.

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A possibilidade de avaliar remotamente e de forma instantânea alterações na qualidade das águas em função da entrada de solos permite o monitoramento de processos ecológicos como o assoreamento, perdas e solos, carreamento de pesticidas e degradação de habitats aquáticos. Com a utilização de um modelo automatizado, torna-se possível um monitoramento em tempo real remoto coletando dados por meio de Redes de Sensores Sem Fio. Esta pesquisa propõe um modelo de classificação da qualidade da água contaminada por solo usando técnicas de Árvore de Decisão. Com este modelo torna-se possível acompanhar alterações que venham a ocorrer em águas superficiais indicando o nível de contaminação por solo com maior rapidez do que a forma convencional que necessita de análise em laboratório e coleta de amostra manual. A classificação proposta considera sete classes de qualidade da água, conforme dados de um experimento conduzido em laboratório. Foram utilizadas técnicas de Inteligência Artificial com o intuito de realizar a Fusão de Sensores para avaliar, em tempo real, as leituras dos sensores, indicando a qual classe de qualidade a amostra se enquadra. Na verificação de quantas classes seria o ideal, utilizou-se o algoritmo k-means++. Para a construção do modelo de classificação foram usadas técnicas de Indução por Árvore de Decisão, tais como: Best-First Decision Tree Classifier BFTree, Functional Trees FT, Naïve Bayes Decision Tree NBTree, Grafted C4.5 Decision Tree J48graft, C4.5 Decision Tree J48, LADTree. Os testes realizados indicam que a classificação proposta é coerente, visto que os diferentes algoritmos comprovaram uma relação estatística forte entre as instâncias das classes, garantindo que o modelo proposto irá predizer saídas para entradas de dados desconhecidas com acurácia. Os algoritmos com melhores resultados foram FT, J48graft e J48.
The possibility to remotely and instantaneously evaluate changes in water quality due to soil contamination allows monitoring ecological processes such as siltation, soil losses, loading of pesticides and degradation of aquatic habitats. Using an automated model to classify soil-contaminated water quality allows for a remote realtime monitoring by collecting data using Wireless Sensor Networks. This study proposes a model to classify soil-contaminated water quality by using Decision Tree techniques. With this model, it is possible to track changes that may occur in surface waters indicating the level of contamination by soil faster than the conventional way, which requires laboratory analysis and manual sampling. The classification proposed considers seven classes of water quality, according to data from an experiment carried out in laboratory. Artificial Intelligence techniques were used in order to implement Sensor Fusion to evaluate, in real time, sensor readings to which class the sample quality fits. By checking how many classes would be ideal, the k-means + + algorithm was used. To build the classification model, Decision Tree Induction techniques were used, such as: Best-First Decision Tree Classifier BFTree, Functional Trees FT, Naïve Bayes Decision Tree NBTree, Grafted C4.5 Decision Tree J48graft, C4.5 Decision Tree J48, LADTree. Tests indicated that the proposed classification is consistent because different algorithms results confirmed a strong statistical relationship between instances of classes, ensuring that this model will predict outputs to unknown inputs accurately. The algorithms with best results were FT, J48graft and J48.

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Cheng, Yongqiang. "Wireless mosaic eyes based robot path planning and control : autonomous robot navigation using environment intelligence with distributed vision sensors." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4421.

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As an attempt to steer away from developing an autonomous robot with complex centralised intelligence, this thesis proposes an intelligent environment infrastructure where intelligences are distributed in the environment through collaborative vision sensors mounted in a physical architecture, forming a wireless sensor network, to enable the navigation of unintelligent robots within that physical architecture. The aim is to avoid the bottleneck of centralised robot intelligence that hinders the application and exploitation of autonomous robot. A bio-mimetic snake algorithm is proposed to coordinate the distributed vision sensors for the generation of a collision free Reference-snake (R-snake) path during the path planning process. By following the R-snake path, a novel Accompanied snake (A-snake) method that complies with the robot's nonholonomic constraints for trajectory generation and motion control is introduced to generate real time robot motion commands to navigate the robot from its current position to the target position. A rolling window optimisation mechanism subject to control input saturation constraints is carried out for time-optimal control along the A-snake. A comprehensive simulation software and a practical distributed intelligent environment with vision sensors mounted on a building ceiling are developed. All the algorithms proposed in this thesis are first verified by the simulation and then implemented in the practical intelligent environment. A model car with less on-board intelligence is successfully controlled by the distributed vision sensors and demonstrated superior mobility.

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Mansano, Raul Katayama. "Controle adaptativo multi-rate para eficiência energética em sistemas de controle via redes sem fio /." Sorocaba, 2016. http://hdl.handle.net/11449/144597.

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Orientador: Eduardo Paciencia Godoy
Coorientador: Diego Colón
Banca: Everson Martins
Banca: Bruno Augusto Angélico
Resumo: Com os recentes avanços das tecnologias sem fio e a proliferação de sensores sem fio, há um crescente interesse na implementação de Sistemas Controle via Redes Sem Fio (WNCSs), que fornecem vantagens em relação às arquiteturas tradicionais ponto-a-ponto e às arquiteturas de redes cabeadas. Apesar das vantagens, a inserção de redes industriais na malha de controle impõe não-linearidades e restrições que afetam o desempenho e a estabilidade do WNCS. Além disto, uma questão fundamental para aplicações de WNCS é a vida útil da bateria de alimentação dos sensores sem fio, uma vez que é uma fonte limitada de energia. Como a transmissão da informação na rede sem fio requer um alto gasto energético pelo dispositivo, deve-se restringir a quantidade de comunicações para poupar bateria. Esta restrição inviabiliza o uso de sensores sem fio em diversas aplicações de WNCS. Neste contexto, este trabalho apresenta o desenvolvimento de um controlador adaptativo multi-rate para eficiência energética em aplicações industriais de WNCSs, através da diminuição da frequência de transmissão de dados na rede e, portanto, redução do consumo energético dos dispositivos sem fio. Um controlador adaptativo auto-ajustável foi implementado para identificar o modelo do WNCS, simular tal modelo e sintonizar os parâmetros do controlador a cada passo de controle, fornecendo robustez contra distúrbios e não-linearidades inerentes ao WNCS. O diferencial do controlador adaptativo é a incorporação das técnicas de i... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Recent advances in wireless technologies and the proliferation of wireless sensors led to an increasing interest in the implementation of Wireless Networked Control Systems (WNCS), which provide advantages over traditional peer-to-peer and cabled networks archiectures. Despite these advantages, inserting a communication network in the control loop impose nonlinearities and constraints which affect stability and performance of the system. Furthermore, a major issue in wireless applications is the lifetime of the sensors batteries, which are a limited source of power. As transmitting data over the network requires high-energy expenditure, it is imperative to reduce the number of communications, in order to save battery. This constraint makes it unfeasible to use wireless sesors in most WNCS applications. In this context, this work aims to develop a multi-rate adaptative controller to enhance energy efficiency in industrial WNCS applications, by reducing frequency of data transmission over the network, thus reducing power expenditure of the wireless devices. A self-tuning adaptive controller is implemented, which can identify the WNCS model, simulate such model and tune the controller parameters at each control step, them prividing robustness to disturbance and inherent nonlinearities of the WNCS. The adaptative controller is augmented with a multi-rate control tehcnique and packet-based identification. The packet-based identification consists is transmitting messages with a pack of data (instead of only transmitting the most recent one) sampled during the inter-samples period, thus improving identification of the WNCS model and, consequently, improviding control performance. The multi-rate control technique consists in using virtual feedback data, provided by the simulated model fo the WNCS, then enabling, actuation faster than wireless sampling, allowing the reduction of wireless transmissions... (Complete abstract electronic access below)
Mestre

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22

Maciel, Wlisses Matos. "Montagem e instalação de um sistema de controle automático de irrigação." reponame:Repositório Institucional da UFC, 2005. http://www.repositorio.ufc.br/handle/riufc/18072.

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MACIEL, Wlisses Matos. Montagem e instalação de um sistema de controle automático de irrigação. 2005. 85 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2005.
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This work had as objectives to set up and to install overhead irrigations with different automation levels: automatic intelligent, automatic for temporizador and no automatic. An experiment was driven in the experimental area of the Laboratory of Hydraulics and Irrigation of the Federal University of Ceará, in Fortaleza, CE, in the period of October of 2004 to January of 2005. Those three systems were distributed in a statistical delineamento in blocks casualizados. The delineamento consisted of 6 blocks and three treatments distributed in 18 experimental portions measuring 4m of width and 12m of length, occupying a total area of 1600m2. The assembly was divided in two phases, the first phase consisted of the assembly of the electronic and electric systems composed for sensor of humidity (resistance blocks), sensor of temperature (termopares), datalogger, multiplexador, digital plate of E/S pattern ISA, conditioning plate of relés, temporizador, contactores, relés, departure key, cabeamento, aterramento and Monday of the waterworks and of irrigation composed of bombs, piping, reservoirs, manômetros, hydrometers, venturis, pressure sockets and connections; all of the extolled systems were mounted and installed in the field.
Este trabalho teve como objetivos montar e instalar sistemas de irrigação com diferentes níveis de automação: automático inteligente, automático por temporizador e não automático. Foi conduzido um experimento na área experimental do Laboratório de Hidráulica e Irrigação da Universidade Federal do Ceará, em Fortaleza, CE, no período de outubro de 2004 a janeiro de 2005. Esses três sistemas foram distribuídos em um delineamento estatístico em blocos casualizados. O delineamento constou de 6 blocos e três tratamentos distribuídos em 18 parcelas experimentais medindo 4m de largura e 12m de comprimento, ocupando uma área total de 1600m2. A montagem foi dividida em duas fases, a primeira fase consistiu na montagem dos sistemas eletrônico e elétrico composto por sensores de umidade (blocos de resistência), sensores de temperatura (termopares), datalogger, multiplexador, placa digital de E/S padrão ISA, placa condicionadora de relés, temporizador, contactores, relés, chave de partida, cabeamento, aterramento e a segunda dos sistemas hidráulico e de irrigação composto de bombas, tubulações, reservatórios, manômetros, hidrômetros, venturis, tomadas de pressão e conexões; todos os sistemas preconizados foram montados e instalado no campo.

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23

Baghalian, Amin. "Detecting Structural Defects Using Novel Smart Sensory and Sensor-less Approaches." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3560.

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Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of such methods require a priori knowledge of the characteristics of the defects under consideration. This makes the whole enterprise of detecting structural defects logically circular, as there is usually limited a priori information about the characteristics and the locations of defects that are yet to be detected. Furthermore, the majority of SHM techniques rely on sensors for response collection, with the very same sensors also prone to structural damage. The Surface Response to Excitation (SuRE) method is a broadband frequency method that has high sensitivity to different types of defects, but it requires a baseline. In this study, initially, theoretical justification was provided for the validity of the SuRE method and it was implemented for detection of internal and external defects in pipes. Then, the Comprehensive Heterodyne Effect Based Inspection (CHEBI) method was developed based on the SuRE method to eliminate the need for any baseline. Unlike traditional approaches, the CHEBI method requires no a priori knowledge of defect characteristics for the selection of the excitation frequency. In addition, the proposed heterodyne effect-based approach constitutes the very first sensor-less smart monitoring technique, in which the emergence of mechanical defect(s) triggers an audible alarm in the structure with the defect. Finally, a novel compact phased array (CPA) method was developed for locating defects using only three transducers. The CPA approach provides an image of most probable defected areas in the structure in three steps. The techniques developed in this study were used to detect and/or locate different types of mechanical damages in structures with various geometries.

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Barbosa, Erilson de Sousa. "Desenvolvimento de um sistema de controle de baixo custo para rastreamento de concentradores cilÃndrico-parabÃlicos." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3507.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
Um concentrador solar parabÃlico Ã um tipo de refletor usado para aumentar a intensidade da radiaÃÃo em uma superfÃcie. Para que ocorra a reflexÃo adequada da radiaÃÃo solar, o refletor parabÃlico deve constantemente rastrear a posiÃÃo do sol de tal forma que os raios solares sejam refletidos em um tubo que se encontra na posiÃÃo de foco da parÃbola. A proposta deste trabalho Ã desenvolver um sistema eletrÃnico de controle de baixo custo para concentradores parabÃlicos aplicados Ã refrigeraÃÃo e proporcionar autonomia ao equipamento. TambÃm Ã apresentado um sistema mecÃnico para acionamento do rastreador. Por ser parte de um sistema de refrigeraÃÃo, o tubo colocado no foco da parÃbola deve sofrer processos de aquecimento e resfriamento. O sistema Ã constituÃdo de uma placa de controle com um microcontrolador em seu nÃcleo, sensores de luminosidade e sensores limitadores de movimento e um motor de passo responsÃvel pelo acionamento da estrutura mÃvel do concentrador solar. AtravÃs do sistema desenvolvido, pode-se fazer com que sejam atingidas temperaturas em torno de 180ÂC na superfÃcie externa do tubo coletor colocado na posiÃÃo de foco da parÃbola
A parabolic solar concentrator is a type of reflector utilized to increase the radiation intensity on a surface. In order to have a proper reflection of solar radiation, the parabolic reflector should constantly track the sunâs position so that solar rays are converged to a tube that is at the focus position of the parabola. The purpose of this study is to develop an electronic control system for low-cost parabolic trough concentrators applied to refrigeration process, and to provide autonomy to the equipment. It also is presented a mechanical system to guide the tracker. As part of a refrigeration device, the tube placed at the parabolaâs focus should experiment heating and cooling processes. The electronic system consists of a control plate with a microprocessor at its core, motion limiting and light sensors, and a step motor responsible for move the solar concentrator structure. Through this developed system, temperatures close to 180oC can be reached on external surface of the heat adsorption tube, which is placed on the position of parabolaâs focus

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Munn, Jacqueline Marie. "Virtual sensors for active noise control /." Title page, abstract and table of contents only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phm9668.pdf.

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Kotzeva, Vega Petrova. "Chemical sensors for automotive emission control." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620419.

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Neto, Hélio Jacinto da Cruz. "Otimização do posicionamento de sensores e atuadores para o controle com realimentação de saída utilizando critério de desempenho quadrático." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-25052018-174813/.

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Estruturas flexíveis estão sujeitas a excitações desconhecidas que podem causar danos. Um dos possíveis artifícios para lidar com este problema é a teoria de controle de sistemas dinâmicos. Em particular, uma técnica que suscita o interessa para aplicação nesta classe de sistemas é o controle ótimo, devido às suas boas propriedades de resposta e factibilidade, podendo ser aplicado até através de circuitos analógicos. O contratempo desta técnica é a necessidade de um número de sensores igual ao número de estados do sistema, o que para estruturas é inviável. Como uma alternativa, pode se empregar os procedimentos usuais de restrição de realimentação do sinal medido. No entanto, estes casos não consideram o projeto das matrizes de saída e entrada, fator determinante para o controle de vibrações em estruturas. O objetivo deste trabalho é preencher esta lacuna. Inicialmente, são introduzidos alguns conceitos das teorias de controle ótimo, dinâmica estrutural e sobre métodos de discretização em séries. Em seguida, determinam-se as condições necessárias de otimalidade considerando como variáveis de otimização o ganho e as posições dos sensores e atuadores. Determinadas as condições, investigam-se os principais desafios para solução destas equações, dados pela existência de parâmetros que estabilizem o sistema e a dependência do ponto ótimo em relação à condição inicial do sistema. O primeiro é resolvido a partir da especificação do sistema linear para uma forma modal e utilizando funções de controle de Lyapunov, o que adicionalmente proporciona o resultado de que o controle colocalizado é um controle ótimo. Para o segundo são propostas duas soluções, sendo uma utilizada para determinar as posições dos atuadores para projetar um controle LQR com desempenho satisfatório, e a outra para determinar os ganhos e posições dos sensores de modo a obter um controle com realimentação de saída com desempenho próximo ao LQR projetado. Os resultados obtidos a partir da aplicação da metodologia desenvolvida em exemplos da dinâmica estrutural revelaram um desempenho notável. Mesmo para uma razão pequena entre o número de sensores pelo número de estados obteve-se um desempenho equivalente ao LQR, exibindo também propriedades robustez consideráveis em relação às variáveis de otimização. Conclui-se que a metodologia desenvolvida é uma boa alternativa para as técnicas de controle LQR e LQG.
Flexible structures are subject to unknown excitations that may cause damage. One of the possible artifices to deal with this problem is the control theory of dynamical systems. In particular, a technique that raises the interest for application in this class of systems is the optimal control, due to its good properties of response and feasibility, as it can be applied even through analog circuits. A drawback of this technique is the need for a number of sensors equal to the number of states, which for structures is impracticable. As an alternative, the usual procedures of using only measured signals for feedback can be employed. However, these cases do not consider the design of the input and output matrices, a determining factor for vibration control in structures. The purpose of this paper is to fill this gap. Initially, some concepts of the theories of optimal control, structural dynamics and series discretization methods are introduced. Then, the optimality conditions are determined considering the gain and locations of sensors and actuators as the optimization variables. Given these conditions, we investigate the main challenges to solve these equations, given by the existence of parameters that stabilize the system and the dependence of the optimum point in relation to the initial condition of the system. The first one is solved from the specification of the linear system to a modal form and using Lyapunov control functions, which additionally provides the result that the collocated control is an optimal control. For the second two solutions are proposed, one being used to determine the positions of the actuators to design a LQR control with satisfactory performance, and the other to determine the gains and positions of the sensors in order to obtain an output feedback control with close performance to the designed LQR. The results obtained from the application of the methodology developed in structural dynamics examples revealed a remarkable performance. Even for a small ratio between the number of sensors by the number of states a performance equivalent to the LQR was obtained, also exhibiting considerable robustness properties in relation to the optimization variables. It is concluded that the developed methodology is a good alternative for LQR and LQG control techniques.

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Caldiéri, Marcos Rogério. "Implementação do modbus para aplicações de sistemas de controle via rede sem fio /." Bauru, 2016. http://hdl.handle.net/11449/146695.

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Orientador: Eduardo Paciência Godoy
Banca: Paulo José Amaral Serni
Banca: Maria Luiz Tronco
Resumo: A recente introdução de transmissores sem fio na indústria provocou um novo interesse em técnicas de medição e controle, porém a maioria das aplicações está restrita a medições de variáveis de processo em malha aberta ou aplicações de monitoramento. O motivo é a falta de confiabilidade devido aos problemas inerentes ao meio de transmissão, que pode ser a perda de pacotes de informação, atrasos de comunicação variantes no tempo, atualização muito lenta e não periódica da medição e vários tipos de interferências. A maior parte dos controladores industriais em controle de processos assumem que o ciclo de controle é executado de forma periódica e que uma nova medição está disponível para ser usada em intervalos de tempo conhecidos. No entanto esta situação não pode ser garantida quando sensores ou transmissores sem fio são usados em aplicações de controle em malha fechada, denominadas de Sistemas de Controle via Redes sem fio (WNCS - Wireless Networked Control Systems). Nesses tipos de aplicações, os transmissores sem fio devem transmitir novas medições de forma não periódica e somente se a medição da variável do processo tiver alterado significativamente. Para tornar esta tecnologia de WNCS mais confiável, muitas técnicas de controle têm sido pesquisadas, entre elas o PIDPlus que representa uma modificação do algoritmo PID para controle via rede sem fio. Este trabalho apresenta a implementação do protocolo Modbus para aplicações de WNCS. O protocolo Modbus TCP foi embarcado em h... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The recent introduction of wirelless transmitters in the industry has driven a new interest in measuring and control techniques, but most applications are restricted to measurements of process variables in open loop or monitoring applications. The reason in the lack of reliability due to problems inherent to the transmition medium, which may be the packet loss, tie varying delay, slow and aperiodic measurement updates and interference. Most industrial process controllers assume that the control cycle is performed periodically and that a new measurement is available to be used at known time intervals. However is cannot be guaranteed when wireless sensors or transmitters are used in closed loop controle applications, called Wireless Networket Control Systems (WNCS). In these type of applications, wirelless transmitters shall new measurments not periodically and only if the process variable measurments has changed significantly. In order to enable and make this WNCS technology reliable, many control techniques have been researched including the PIDPlus that is a modified PID algorithm for wireless control. This paper presents the implementation of the Mobdus protocol for WNCS applications. The Modbus TCP was embedded in dedicated hardware enabling the transmisstion of data via Ethernet TCP/IP and Wi-Fi. A comparison and evaluation of PID controllers for WNCS were done considering situations of variable sampling and communication delays and packet losses. The results are analyzed from the point of view of control performance and robustness. Experimental results in a pilot plant prove the efficiency of the implementation of a wireless control loop using a Wi-Fi network embledded Modbus protocol and PIDPlus controller
Mestre

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Maciel, Wlisses Matos. "Montagem e instalaÃÃo de um sistema de controle automÃtico de irrigaÃÃo." Universidade Federal do CearÃ, 2005. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2278.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Este trabalho teve como objetivos montar e instalar sistemas de irrigaÃÃo com diferentes nÃveis de automaÃÃo: automÃtico inteligente, automÃtico por temporizador e nÃo automÃtico. Foi conduzido um experimento na Ãrea experimental do LaboratÃrio de HidrÃulica e IrrigaÃÃo da Universidade Federal do CearÃ, em Fortaleza, CE, no perÃodo de outubro de 2004 a janeiro de 2005. Esses trÃs sistemas foram distribuÃdos em um delineamento estatÃstico em blocos casualizados. O delineamento constou de 6 blocos e trÃs tratamentos distribuÃdos em 18 parcelas experimentais medindo 4m de largura e 12m de comprimento, ocupando uma Ãrea total de 1600m2. A montagem foi dividida em duas fases, a primeira fase consistiu na montagem dos sistemas eletrÃnico e elÃtrico composto por sensores de umidade (blocos de resistÃncia), sensores de temperatura (termopares), datalogger, multiplexador, placa digital de E/S padrÃo ISA, placa condicionadora de relÃs, temporizador, contactores, relÃs, chave de partida, cabeamento, aterramento e a segunda dos sistemas hidrÃulico e de irrigaÃÃo composto de bombas, tubulaÃÃes, reservatÃrios, manÃmetros, hidrÃmetros, venturis, tomadas de pressÃo e conexÃes; todos os sistemas preconizados foram montados e instalado no campo.
This work had as objectives to set up and to install overhead irrigations with different automation levels: automatic intelligent, automatic for temporizador and no automatic. An experiment was driven in the experimental area of the Laboratory of Hydraulics and Irrigation of the Federal University of CearÃ, in Fortaleza, CE, in the period of October of 2004 to January of 2005. Those three systems were distributed in a statistical delineamento in blocks casualizados. The delineamento consisted of 6 blocks and three treatments distributed in 18 experimental portions measuring 4m of width and 12m of length, occupying a total area of 1600m2. The assembly was divided in two phases, the first phase consisted of the assembly of the electronic and electric systems composed for sensor of humidity (resistance blocks), sensor of temperature (termopares), datalogger, multiplexador, digital plate of E/S pattern ISA, conditioning plate of relÃs, temporizador, contactores, relÃs, departure key, cabeamento, aterramento and Monday of the waterworks and of irrigation composed of bombs, piping, reservoirs, manÃmetros, hydrometers, venturis, pressure sockets and connections; all of the extolled systems were mounted and installed in the field.

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Souccar, Karim. "Transmission power control for wireless sensors networks." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001664.

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Gonzaga, João Carlos Bastos. "Desenvolvimento de procedimento e Soft-Sensors para controle de plantas de PET." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266832.

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Orientador: Rubens Maciel Filho
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
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Resumo: Neste trabalho são apresentados três estudos distintos de aplicação de Plantwide Control. A primeira aplicação trata-se de um controle antecipativo (feedforward) para controlar os níveis dos reatores na etapa de polimerização, a fim de reduzir suas variabilidades e, consequentemente, a produção de refugo, sendo que, em uma planta de Politereftalato de Etileno (PET), a variação de nível dos polimerizadores interfere na viscosidade e está diretamente relacionada com a capacidade e com a qualidade de produção. A segunda aplicação mostra como desenvolver e utilizar um modelo computacional da planta de PET para possibilitar que alterações de parâmetros de processo, como temperatura e pressão, possam ser feitas sem que haja a necessidade de testes na planta real, uma vez que a existência de um modelo computacional que tenha o mesmo comportamento qualitativo da planta real permite que o efeito de perturbações e outros tipos de alterações na condição do processo sejam avaliados. A terceira aplicação trata-se da implantação de um sensor virtual (soft-sensor), utilizando redes neurais artificiais (RNA) para atuar como um medidor redundante da viscosidade, podendo substituir o sensor físico no caso deste vir a falhar. Estes estudos têm em comum a apresentação de procedimentos para controle do processo de produção de PET, que por possuir muitas particularidades, torna-se um assunto complexo, sendo um desafio modelar e controlar cada única unidade de produção
Abstract: In this work are presented three separate studies of application of Plantwide Control. The first application is a feedforward control to control the levels of reactors in polymerization step, in order to reduce their variability and, consequently, the production of waste, because, in a plant of PET, the variance of level of polymerizing interferes in viscosity and is directly related to the capacity and quality of production. The second application shows how to develop and use a computational model of a PET plant to enable changes to process parameters such as temperature and pressure, without the need of tests in actual plant, once the existence of a computational model has the same qualitative behavior of actual plant, and it allows the effect of disturbance and other types of changes in the condition of the process to be evaluated. The third application is the implantation of a virtual sensor (soft-sensor), using RNA, to act as a redundant viscosity meter that, in the case of possible failures, has as main function to detect physical sensor failures and replace it in the control system monitoring. Generally, the three studies have in common the presentation of procedures to control the production process of polyester. Process control for the production of polymers presents many particularities and, therefore, becomes a complex matter, being a challenge to model and to control every single production unit
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química

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32

Logan, Jeffery Jay. "Control and Sensor Development on a Four-Wheel Pyramidal Reaction Wheel Platform." DigitalCommons@CalPoly, 2008. https://digitalcommons.calpoly.edu/theses/27.

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The Pyramidal Reaction Wheel Platform, or PRWP, is used to simulate three-axis controls in a torque free space-like environment. The primary purpose of the system will be to evaluate the effects of conjoining sensors to maximize pointing accuracy. Furthermore, the system will incorporate a star tracker in conjunction with a Simulated Star Field (SSF) to better estimate the PRWP orientation. For the sake of this document, however, the goal is to implement a gyroscope, wheel rate sensors, and a make-shift accelerometer—to the PRWP—and integrate a controls algorithm such that three-axis controls are achieved for the PRWP. Three sensors were either better integrated into the system or added altogether. Tachometers were created as a form of hardware circuitry to measure each wheel rate with an accuracy of approximately 2.5 Hz (nearly 15 radians per second). The TAC board circuitry converted each motors encoder output into a speed by use of a frequency to voltage converter. Additionally, although three gyroscopes had been implemented previously, the system was better incorporated into the model such that it was directly transformed via a ROBOSTIX ADC converter before being relayed to SIMULINK via a Bluetooth link. The MEMS gyroscopes allowed for very accurate rate measurements—with a minimum resolution of approximately 0.25 radians per second. Finally, a makeshift accelerometer was incorporated into the system for the purpose of system identification. The accelerometer was incorporated into the system by utilizing a discrete time derivative of the gyroscope readings. However, thankfully a system of two accelerometers can be later utilized to achieve an accuracy of approximately 6 degrees per second-second in the x-axis and 2-3 degrees per second-second in the y- and z-axes. A controls test was performed where the starting location was qo=[0, 0, sqrt(2)/2, sqrt(2)/2] and the target location was qc=[0, 0, 0, 1]. At 80 seconds, the pointing accuracy was 70 degrees around the target and the system was unable to settle during the 80 second trial. The inaccuracy was because of the low frequency of operation of the system—1 Hz. Additionally, the platform reacts slowly to sensor readings and commands. The coupling of these issues causes the pointing accuracy to high. Furthermore, through experimental testing, the maximum wheel rate was found to be approximately 6400 RPM at a duty cycle of 50% at an 8000Hz PWM application due to the Pololu MD01B design limitations: low voltage range (up to 16V), low limit current limiter (5A), and high susceptibility to overheating for large currents.

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Ghouila-Houri, Cécile Juliette Suzanne. "Développement de micro-capteurs de frottement pariétal et de pression pour les mesures en écoulements turbulents et le contrôle de décollement." Thesis, Ecole centrale de Lille, 2018. http://www.theses.fr/2018ECLI0010.

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Le contrôle des écoulements vise à modifier le comportement naturel d’un écoulement fluidique. Dans le domaine des transports, contrôler les phénomènes fluidiques tels que le décollement peut permettre d’économiser du carburant, d’améliorer les performances des véhicules ou encore d’assurer davantage la sécurité des passagers. Dans ce contexte, des capteurs avec de fines résolutions temporelle et spatiale sont requis afin de connaître l’écoulement à contrôler et adapter en temps réel le contrôle. Dans ce travail, l’objectif a été de développer des micro-capteurs de frottement et de pression pour les mesures en écoulements turbulents et le contrôle de décollement. Tout d’abord un micro-capteur calorimétrique a été conçu et réalisé par des techniques de microfabrication pour mesurer simultanément le frottement pariétal et la direction de l’écoulement. Le micro-capteur a ensuite été intégré en paroi d’une soufflerie afin de réaliser son étalonnage statique et dynamique et d’étudier sa sensibilité à la direction de l’écoulement. Troisièmement, le micro-capteur calorimétrique a été utilisé pour caractériser des écoulements décollés. Plusieurs micro-capteurs avec électronique miniaturisée ont été intégrés avec succès dans une maquette de volet et des essais de contrôle actif ont été réalisés. Enfin, la quatrième partie concerne le développement d’un micro-capteur de pression et d’un micro-capteur multi-paramètres réunissant les deux technologies. L’ensemble de ces micro-capteurs ont été caractérisés avec succès et montrent des résultats prometteurs pour caractériser les écoulements turbulents et permettre la mise en place de contrôle d’écoulement en boucle fermée
Flow control aims at artificially changing the natural behaviour of a flow. In transport industries, controlling fluidic phenomena such as boundary layer separation allows saving fuel and power, improving vehicles performances or insuring passenger’s safety. In this context, sensors with accurate spatial and temporal resolution are required. Such devices enable to estimate the flow to control and allow real-time adaptation of the control. In this work, the objective is to develop wall shear stress and pressure micro-sensors for turbulent flows measurements and flow separation control.Firstly, a calorimetric micro-sensor was designed and realized using micromachining techniques for measuring simultaneously the wall shear stress amplitude and the flow direction. Secondly, the micro-sensor was flush-mounted at the wall of a wind tunnel for static and dynamic calibrations. Thirdly, it was used to characterized separated flows. Several configurations were studied: separation on airfoil profile, separation and reattachment downstream a 2D square rib and the separation on a flap model. Several micro-sensors with embedded electronics were successfully integrated on a flap model and active flow control experiments were performed. Finally, the fourth part of the document concerns the development of a pressure micro-sensor and the development of a multi-parameter micro-sensor combining both technologies.All these micro-sensors have been successfully realized and characterized and demonstrate promising results for measuring turbulent flows and implementing closed loop reactive flow control

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Perini, Efrain Araujo [UNESP]. "Redução de vibrações de rotores utilizando atuadores magnéticos e sistema de controle feedforward." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/94510.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Este trabalho apresenta o desenvolvimento de uma análise teórica do desempenho de um sistema de controle ativo utilizando mancais magnéticos como atuadores de não-contato para a redução de vibrações em rotores. São analisados três modelos de rotores, sendo que em um deles aplica-se apenas o controle feedback e os outros são suportados apenas por mancais magnéticos, os quais também são os atuadores do controlador. Assim, Luna arquitetura de controle tipo feedforward é empregada sobreposta ao sistema de controle feedback dos atuadores nestes dois modelos, sendo urna análise realizada em relação ao desempenho do sistema de controle quanto às diferentes geometrias de distribuição de massa acopladas ao eixo do rotor. O enfoque principal deste trabalho é voltado para a análise do desempenho do sistema de controle em função da posição e quantidade dos sensores de erro (onde se deseja minimizar as vibrações) em relação à posição dos atuadores e das forças de excitação. As excitações são do tipo síncronas e sub-síncronas que normalmente aparecem em rotores com elevadas velocidades de rotação, como as turbomáquinas. Também é realizada urna análise das forças de controle necessárias a serem aplicadas pelos atuadores para se obter urna redução dos níveis de vibração do rotor na posição dos sensores de erro do sistema feedforward. A análise é executada empregando modelos de rotores desenvolvidos pelo método da matriz de impedância. Esta pesquisa também apresenta Luna aplicação da técnica de controle Feedforward em acústica, que realiza a depuração da voz para comunicação em ambientes ruidosos.
This research work brings a theoretical analysis of a control system performance that uses magnetic bearings as non-contact actuators to reduce rotor vibrations. It is analyzed three rotor models, in which one of them operates under the feedback control only. The other models are supported by magnetic bearings only, which also are the controller system actuators. Thus, a feedforward control scheme is applied over the feedback control inherent to the AMB control circuit. The analysis is carried out over these two last models regarding to the control performance for different geometry of mass distribution along the rotor. The focus of this work is to analyze the controller performance according to the sensor quantity and placement (where the vibrations are desired to be minimized) regarding to the actuator position and to the exciting forces. The subsynchronous and synchronous excitations are considered here since they frequently occur in high rotating speed rotors, as in the turbomachinery scenario. Also, the control force required by the actuators is monitored according to the sensors placement to reduce the local vibrations level and the analysis was carried out using the impedance matrix rotor modeling. Further, this work brings a modeling and an application of the feedforward active control scheme in the acoustics field used for voice extraction for communication in noisy environments.

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Masiero, Bruno Sanches. "Controle ativo de ruído para transformadores de potência em campo." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-09012008-112327/.

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É cada vez maior a preocupação com a poluição sonora gerada pelos transformadores de potência de subestações elétricas. Atualmente, o controle desse tipo de ruído é feito utilizando-se métodos passivos, que são caros e dificultam a manutenção dos transformadores. Uma alternativa para os métodos passivos é o controle ativo de ruído (ANC). Apesar de extensas pesquisas realizadas nas últimas três décadas, ainda não existem soluções comercialmente viáveis para o ANC de transformadores. As dificuldades para a aplicação bem sucedida do ANC para transformadores foram investigadas por meio de simulações e de testes com protótipo. Os três maiores obstáculos identificados foram: o posicionamento dos transdutores eletroacústicos; a obtenção de atenuação em uma região longe do transformador, usando um número reduzido de fontes de controle e de sensores de erro, os últimos colocados ainda na região de campo acústico próximo; e a identificação robusta do caminho secundário com baixa razão sinal/ruído. Os dois primeiros problemas foram abordados, analisando-se algumas alternativas de soluções. Algoritmos genéticos (GA) foram utilizados para a otimização da posição dos transdutores do sistema ANC. O desempenho desses algoritmos depende fortemente da modelagem acústica realizada e verificou-se que o método de Usry, escolhido para modelar o campo primário do transformador, não forneceu estimativa adequada. Usando um modelo mais simples de fonte primária, constatou-se a importância da função de mérito para o desempenho do GA. Também foi verificado que a otimização conjunta das posições dos transdutores fornece o mesmo resultado, e em menor tempo, que a otimização das posições das fontes de controle e dos sensores de erro separadamente. Simulações realizadas com uma nova estratégia de sensores virtuais (baseada no janelamento das fontes de controle) mostra que é possível aumentar o nível de atenuação longe do transformador, mesmo com um número pequeno de fontes de controle e sensores de erro. Testes com um protótipo de sistema ANC foram feitos em laboratório e em campo e os resultados desses testes são discutidos detalhadamente.
Concern regarding noise pollution caused by power transformers in electrical substations is increasing. Nowadays, this kind of noise is controlled using passive methods, which are expensive and make transformer maintenance more difficult. An alternative to passive methods is active noise control (ANC). However, despite extensive research undertaken in the last three decades, there is still no viable commercial solution for the active control of transformer noise. The difficulties for a successful implementation of an ANC solution in the case of power transformer noise are investigated through simulations and tests with a prototype. The three main obstacles found were: the positioning of the electro-acoustic transducers; the achievement of sufficient attenuation in a region far from the transformer, using a small number of control sources and error sensors (when the latter are positioned on the region of acoustic near-field); and the robust identification of the secondary path in a low signal/noise situation. The two former problems were dealt with, and some alternative solutions were analyzed. Genetic algorithms (GA) were used for the optimization of the transducers\' position. The performance of these algorithms is strongly related to the acoustical model used and it was verified that the Usry method, used for modelling the transformers primary field, did not result in an adequate estimate. Using a simplified model for the primary source, the importance of the cost function in the GA\'s performance was made evident. It was also verified that the joint optimization of transducers\' position provides the same result, and in shorter time, as the independent optimization of control source and error sensor positions. Simulations with a new virtual sensor strategy (based on windowing the control sources) show that it is possible to increase attenuation levels in a region far from the transformer, even with a small number of control sources and error sensors. Laboratory and field tests with an ANC system prototype were undertaken and the results of these tests are thoroughly discussed.

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Stubbings, Clive Anthony. "Control of sensory assembly workstations." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278391.

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Flitcroft, Daniel Ian. "Sensory control of ocular accommodation." Thesis, University of Oxford, 1988. http://ora.ox.ac.uk/objects/uuid:9533e285-150f-4bc9-90d8-4a4a870a7f0e.

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DeVylder, Jordan. "Sensory gain control at fixation." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26656.

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Thesis (M. S.)--Psychology, Georgia Institute of Technology, 2009.
Committee Chair: Corballis, Paul; Committee Member: Schumacher, Eric; Committee Member: Spieler, Daniel. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Verdaguer, Ferrer Ariadna. "Química del Oxígeno en el eutéctico 44.5% Plomo 55.5% Bismuto fundido. Aplicación a reactores ADS." Doctoral thesis, Universitat Ramon Llull, 2012. http://hdl.handle.net/10803/83862.

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a gestió dels residus nuclears de vida llarga i alta activitat és una de les principals preocupacions al voltant de l’energia nuclear. En el marc del projecte europeu IP EUROTRANS (EURATOM 6th Framework Programme) i dels projectes espanyols COMETA (ENE2005-08611-C02-02) i COPLOGEN (ENE2009-14223-C02-02) s’ha proposat utilitzar reactors ADS (Accelerator Driven Systems) per a transmutar aquest tipus de residus. En aquest tipus de residus, protons d’alta energia, col•lisionarien amb el blanc d’espal•lació produint neutrons ràpids que serien capaços de transmutar elements radioactius de vida llarga en altres de vida curta. En aquests reactors, es proposa utilitzar l’eutèctic plom - bismut (44.5% Pb – 55.5 % Bi) com a refrigerant degut al seu punt de fusió baix i a què pot ser utilitzat com a blanc d’espal•lació per a produir neutrons ràpids. No obstant, aquest aliatge és altament corrosiu dels materials estructurals, especialment els acers inoxidables. Per això es fa necessària una capa d’òxid de passivació que els protegeixi. En aquest entorn, s’haurà de controlar l’oxigen del medi, que ha ser suficient per a formar la capa de passivació però inferior al de formació de PbO. Ha de tenir-se en compte que el plom - bismut, en les condicions d’operació, serà un líquid en moviment i que no convé tenir partícules sòlides d’òxid que pugin erosionar o bloquejar parts del reactor. Amb l’objectiu de poder mesurar pressions parcials d’oxigen de l’ordre de 10-20 bar, en aquesta Tesi Doctoral, es proposa utilitzar sensors potenciomètrics d’oxigen amb electròlit sòlid de ZrO2 dopat amb Y2O3, YSZ, conductor del ió O2-. Per al seu ús en circuits experimentals és necessari establir un mètode de calibratge de sensors durant la seva operació i desenvolupar prototips que puguin ser usats en condicions dinàmiques. Per altra banda, degut a què a temperatures baixes (T<400ºC) l’ electròlit sòlid utilitzat perd la seva capacitat conductora d’oxigen s’han adaptat els sensors per a la seva possible utilització a temperatures de l’ordre de 300ºC. Per a estudiar la corrosió del material estructural i controlar la química de l’eutèctic en aquests reactors s’ha determinat la solubilitat i la difusió d’oxigen en el metall fos i la influència d’ impureses metàl•liques (In, Ni, Cr i Fe) en la solubilitat d’oxigen en plom - bismut. A més, com que centres d’investigació de diversos països participen en el projecte IP EUROTRANS, s’ha comparat la resposta de dos sensors d’oxigen fabricats per diferents laboratoris, amb diferent sistema de referència i fabricació de l’electròlit sòlid en les mateixes condicions experimentals.
La gestión de los residuos nucleares de vida larga y alta actividad es una de las mayores preocupaciones acerca de la energía nuclear. En el marco del proyecto europeo IP EUROTRANS (EURATOM 6th Framework Programme) y de los proyectos españoles COMETA (ENE2005-08611-C02-02) y COPLOGEN (ENE2009-14223-C02-02) se ha propuesto utilizar reactores ADS (Accelerator Driven Systems) para transmutar este tipo de residuos. En estos reactores, protones de alta energía colisionarían con el blanco de espalación produciendo neutrones rápidos que, a su vez, serían capaces de transmutar elementos radioactivos de vida larga en otros de vida corta. En estos reactores, se propone usar el eutéctico plomo-bismuto (44.5 % Pb – 55.5 % Bi) como refrigerante debido a su bajo punto de fusión y a que puede ser usado como blanco de espalación para producir neutrones rápidos. No obstante, esta aleación es altamente corrosiva de los materiales estructurales, especialmente los aceros inoxidables. Por ello, se hace necesaria una capa de óxido de pasivación que los proteja. En este entorno, se deberá controlar el oxígeno del medio, que tiene que ser suficiente para formar la capa de pasivación pero inferior al de formación de PbO. Debe tenerse en cuenta que el plomo-bismuto, en las condiciones de operación, será un líquido en movimiento y no conviene tener partículas sólidas de óxido que puedan erosionar o bloquear partes del reactor. Con el objetivo de poder medir presiones parciales de oxígeno del orden de 10-20 bar, en esta Tesis Doctoral, se propone utilizar sensores potenciométricos de oxígeno con electrolito sólido de ZrO2 dopado con Y2O3, YSZ, conductor del ión O2-. Para su uso en circuitos experimentales es necesario establecer un método de calibración de sensores durante su operación y desarrollar prototipos que puedan ser usados en condiciones dinámicas. Por otro lado, debido a que a temperaturas bajas (T<400ºC) el electrolito sólido utilizado pierde su capacidad conductora de oxígeno se han adaptado los sensores para su posible utilización a temperaturas del orden de 300ºC. Para estudiar la corrosión del material estructural y controlar la química del eutéctico en estos reactores se ha determinado la solubilidad y la difusión de oxígeno en el metal fundido y la influencia de impurezas metálicas (In, Ni, Cr y Fe) en la solubilidad de oxígeno en el plomo-bismuto. Además, dado que centros de investigación de diversos países participan en el proyecto IP EUROTRANS se ha comparado la respuesta de dos sensores de oxígeno fabricados por distintos laboratorios, con diferente sistema de referencia y fabricación del electrolito sólido en las mismas condiciones experimentales.
The management of long-lived and high activity nuclear waste is one of the major concerns related with nuclear energy. In the framework of the European Project IP EUROTRANS (EURATOM 6th Framework Program) and Spanish Projects COMETA (ENE2005-08611-C02-02) and COPLOGEN (ENE2009-14223-C02-02), accelerator driven system (ADS) reactors have been proposed for transmutating the long-lived nuclear waste. In this type of reactors, protons of high energy collide with a spallation target and fast neutrons are produced. These fast neutrons, in turn, can be used in subcritical reactors, where radioactive elements of long life can be transmuted to elements of short life. Lead – bismuth eutectic alloy, LBE. (44.5% Pb – 55.5% Bi) is proposed as a coolant for ADS reactors. The advantages of using this alloy are its low melting point and that it can also be used as spallation target for producing fast neutrons. However, this alloy is highly corrosive. For this reason, it is important to maintain a passivation layer on the structural material. In this type of reactors molten LBE is flowing then solid particles could erode or block parts of the circuit. In order to maintain this passivation layer avoiding PbO formation, it is necessary controlling and monitoring the oxygen content in LBE between these two limits. In this work, a potentiometric oxygen sensor with ZrO2 / Y2O3 solid electrolyte (YSZ) is used to measure oxygen partial pressure inside LBE. In order to improve the reliability of these sensors it is necessary to improve its design in order to use them in experimental circuits under dynamic conditions and to develop a method for checking its condition during operation. On the other hand, at low temperatures (T<400ºC), YSZ loses its ionic conductivity, so sensors have been adapted to be used at temperatures around 300ºC In order to study structural material corrosion and to control eutectic chemistry in this type of reactors, solubility and diffusivity of oxygen in the molten metal have been determined. The effect of metallic impurities (In, Fe, Cr, Ni) in oxygen solubility in lead bismuth is also studied. Furthermore, in order to compare sensors from different institutions in the framework of the European project, two prototypes of oxygen sensors have been studied under same stagnant conditions. One of the sensors was proposed by KIT and the second one was proposed by IQS. Different reference systems and YSZ suppliers have been compared.

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Marciszko, Fredrik. "Torque Sensor based Powertrain Control." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2248.

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The transmission is probably the drivetrain component with the greatest impact on driveability of an automatic transmission equipped vehicle. Since the driver only has an indirect influence on the gear shift timing, except for situations like kick-down accelerations, it is desirable to improve shift quality as perceived by the driver. However, improving shift quality is a problem normally diametrically opposed to minimizing transmission clutch energy dissipation. The latter has a great impact on transmission lifetime, and has to be defined and taken into consideration along with the notion of shift quality. The main focus of this thesis is the modeling of a drivetrain of an automatic transmission vehicle, and the implementation in MatLab/Simulink, including the first to second gear upshift. The resulting plant based on the derived equations is validated using data from a test vehicle equipped with a torque sensor located at the transmission output shaft. The shaft torque is more or less proportional to the driveline jerk, and hence of great interest for control purposes. Control strategies are discussed and a PID controller structure is developed to control the first to second gear upshift, as opposed to the traditional open-loop upshift control. Furthermore, the proposed controller structure uses the transmission output torque and the differential speed of the engaging clutch as inputs, to control the clutch pressure and the engine output torque, respectively. The structure is unsophisticated and transparent compared to other approaches, but shows great theoretical results in terms of improved shift quality and decreased clutch wear.

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Johnson, Martin Eric. "Active control of sound transmission." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243189.

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Hills, M. "Solid state sensors for gas monitoring and control." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604069.

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A probe for the continuous on-line measurement of hydrogen dissolved in liquid aluminium has been developed using the perovskite proton conductor CaZrO₃-In, in conjunction with a Zr,ZrH₂ solid state reference. The probe has been designed to an industrial prototype standard, and measurements were in good agreement with established (but cumbersome) hydrogen measurement methods such as the AISCAN analyser, LECO analysis, and the Straube-Pfeiffer technique. The electrolytic domain of CaZrO₃-In has been investigated using a novel double-cell arrangement to simultaneously fix the chemical potential of both hydrogen and oxygen at the electrodes of a pellet of the electrolyte. As predicted from the defect equilibria, the electrolyte makes the transition from the hydrogen ion conduction domain to the oxygen ion domain under conditions of low oxygen partial pressure and high hydrogen partial pressure. The pO₂ corresponding to the Zr,ZrO₂ equilibrium is low enough to locate CaZrO₃-In in the oxygen ion conduction domain. Sodium b-alumina was employed to measure the pO₂developed under operating conditions at the sensor reference electrode by a sample zirconium containing dissolved oxygen. This was found to be many orders of magnitude higher than the pO₂ corresponding to the Zr,ZrO₂ equilibrium, and was five magnitude higher than the pO₂ marking the H⁺/O^2- conduction domain boundary for CaZrO₃-In, suggesting that Zr, ZrH₂ may be suitable as a reference material. Hydrogen sensors manufactured using CaZrO₃-In as the solid electrolyte and a Zr,ZrH₂ solid state reference were found to provide stable, reproducible emfs at constant temperature and pH₂, and showed full Nernstian response following a change in pH₂ at the measuring electrode. The recently developed Current Reversal Mode can accurately determine the emf of a solid electrolyte sensor, and also provides additional information in the form of the sensor resistance. A detailed study has identified how the CRM parameters should be selected in order to make accurate measurements. The sensor resistance measurement was used to improve measurement accuracy and stability of an internally heated yttria stabilised zirconia oxygen sensor. When applied to a commercially available probe for measuring hydrogen dissolved in liquid aluminium it was found that erroneous emf readings, measured after prolonged use in the melt, were accompanied by a corresponding increase in the sensor resistance, opening up the possibility of using CRM as an on-line diagnostic tool.

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Birch, S. W. "Novel sensors for alcohol fermentation monitoring and control." Thesis, Cranfield University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233437.

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Barsky, Michael F. "Robot gripper control system using PVDF piezoelectric sensors." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/77897.

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A novel robot gripper control system is presented which uses PVDF piezoelectric sensors to actively damp exerted force. By using a low-input-resistance amplifier to sense the current developed by the PVDF sensor, an output proportional to the rate of change of the force exerted by the gripper is obtained. The signals from the PVDF sensor and a strain gauge force sensor are arranged in a proportional and derivative (PD) control system for the control of force. The control system was tested on an instrumented Rhino XR-1 manipulator hand. The capabilities of the control system are analyzed analytically, and verified experimentally. The results for this particular gripper indicate that as much as 900% improvement in force step response rise time, and 300% reduction in overshoot are possible by inclusion of the PVDF sensor.
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Eriksson, Jens, and Olov Jacobsen. "Brain activity sensors and health-care systems control." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199346.

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Mangels, John Donald III, Syed Ammar Raza, Kevin Mueller, Namrah Habib, Josh Raymond, Daniel Brauer, Mohammed Azri Adb Rahim, et al. "Micro-Air Vehicle Control Using Microelectromechanical Systems Sensors." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625078.

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Micro Air Vehicles (MAV) are small unmanned aircraft that are highly sensitive to environmental disturbances causing dynamic changes in attitude and flight stability compared to more traditional unmanned air vehicles. Controlling the stability of an MAV is difficult and a significant research issue. The goal of this project is to perform a proof of concept study based on literature to demonstrate that Microelectromechanical Systems (MEMS) sensors can control the longitudinal stability of an MAV. MEMS sensors, specifically flow sensors used in this project, predict perturbations and aerodynamic effects which is critical for MAV performance because flight predictions can be used to prevent stall and failure in an MAV. The project focused on developing a control system that implemented MEMS sensors on a wing section and was tested in The University of Arizona's Educational Wind Tunnel.

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Raza, Syed Ammar, Kevin Mueller, Daniel Brauer, Namrah Habib, John Mangels, Azri Rahim, Joshua Raymond, et al. "Micro-Air Vehicle Control Using Microelectromechanical Systems Sensors." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625128.

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Micro Air Vehicles (MAV) are small unmanned aircraft that are highly sensitive to environmental disturbances causing dynamic changes in attitude and flight stability compared to more traditional unmanned air vehicles. Controlling the stability of an MAV is difficult and a significant research issue. The goal of this project is to perform a proof of concept study based on literature to demonstrate that Microelectromechanical Systems (MEMS) sensors can control the longitudinal stability of an MAV. MEMS sensors, specifically flow sensors used in this project, predict perturbations and aerodynamic effects which is critical for MAV performance because flight predictions can be used to prevent stall and failure in an MAV. The project focused on developing a control system that implemented MEMS sensors on a wing section and was tested in The University of Arizona’s Educational Wind Tunnel.

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Barriquello, Carlos Henrique. "Concepção de um nó sensor/atuador sem-fio para uma rede de gerenciamento de iluminação pública." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/8469.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this thesis, changes to be done into the photoelectric relays used on street lighting systems are proposed. It is intended to improve those systems, bringing social and economical benefits. Most of street lighting systems is comprised by high pressure sodium lamps, electromagnetic ballasts and photoelectric relays, which must turn on/off lamps on due time. Although simple, such a method has many drawbacks, as lack of fault diagnosis, energy measurement, time monitoring and remote control. By employing wireless communication and embedded computing, an innovative solution is presented. When such changes are applied into the photoelectric relay, a new device comes out - a wireless sensor/actuador node for street lighting management. Development steps of the device are reported. Testing procedures are undertaken to validate it and justify its use on the street lighting systems.
Neste trabalho, propõem-se modificações nos relés fotoelétricos utilizados nos sistemas de iluminação pública presentes nos municípios brasileiros. Pretende-se, assim, melhorar tais sistemas, de forma a trazer benefícios sociais e econômicos. Em sua maioria, os sistemas de iluminação pública são compostos por lâmpadas de vapor de sódio de alta pressão empregadas em conjunto com reatores eletromagnéticos e relés fotoelétricos que controlam o acionamento destas lâmpadas nos horários devidos. Apesar de simples e eficaz, este método de acionamento possui muitas limitações, como a falta de diagnóstico de falhas dos elementos do sistema, a falta de métodos de medição de consumo de energia elétrica, a falta de monitoramento de tempos de funcionamento e a impossibilidade de acionamento à distância. Através do emprego de tecnologias de comunicação sem-fio e computação embarcada se apresenta uma alternativa de solução para os problemas citados. As modificações aplicadas ao relés fotoelétrico dão origem a um novo dispositivo - o nó sensor/atuador sem-fio para gerenciamento de iluminação pública. Relatam-se as etapas de desenvolvimento deste novo dispositivo e os testes realizados como forma de validar e justificar seu emprego nos sistemas atuais de iluminação pública.

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McKenzie, James Stuart. "Optical actuation and control-by-light systems." Thesis, Brunel University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286728.

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Silva, Cristiano Rocha da. "Estudo multivariável do controle postural humano em resposta a pistas sensoriais somestésicas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-05012017-104731/.

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Todo ser humano apresenta oscilações posturais aleatórias durante a postura ereta quieta advindas de mecanismos centrais e periféricos. Um toque suave (LT do inglês light touch) de um dos dedos sobre uma superfície fixa ao solo resulta em uma pista sensorial adicional, que promove uma diminuição das oscilações posturais. Entretanto, há necessidade de se obter maiores conhecimentos sobre mecanismos associados ao LT, tanto no que tange a aspectos sensoriais quanto motores associados ao fenômeno. O presente estudo teve como objetivo avançar no entendimento sobre a influência do LT sobre o comportamento de múltiplas variáveis extraídas durante a postura ereta quieta. O primeiro capítulo investigou quantificadores de oscilações posturais com base em medidas como o centro de pressão (CP), centro de massa (CM) e ângulos segmentares e corporais durante experimentos com condições em superfície estável e instável, com olhos abertos e olhos fechados, comparando as condições com e sem LT. Adicionalmente, foi analisada a coerência espectral entre sinais de eletromiograma de diferentes músculos do corpo e os quantificadores acima elencados nas diferentes condições. Os resultados mostraram que o LT diminui o nível de ativação de alguns músculos, principalmente o músculo gastrocnêmico medial, importante na manutenção do controle postural. A variabilidade dos ângulos segmentares e corporais, conjuntamente com variáveis extraídas do CP e do CM diminuíram em condições com LT. Na análise de coerência o LT promoveu algumas alterações nos padrões de oscilação entre ângulos, CP, CM e sinais de eletromiograma, porém com poucas modificações na fase entre os sinais. Na análise de coerência intermuscular, comparando pares de músculos do lado direito e esquerdo do corpo, observou-se que para os membros inferiores a coerência ocorre geralmente na faixa de 0 a 1-2 Hz (em fase), podendo aumentar a faixa de frequência em situações mais instáveis (sem visão e superfície instável), em que o LT passa a influenciar de maneira mais significativa a coerência entre os sinais. O segundo capítulo deste estudo foi motivado por estudos que mostraram ser possível manipular as entradas sensoriais geradas pelo dedo durante o LT. O presente estudo investigou se a retirada de uma entrada sensorial proprioceptiva associada ao dedo é capaz de alterar a oscilação postural, possibilitando a separação e quantificação da contribuição sensorial cutânea da contribuição proprioceptiva dos músculos do terceiro dedo. O controle postural foi avaliado com os sujeitos de olhos fechados e sobre uma superfície instável. Os resultados indicaram que a retirada da informação sensorial proprioceptiva do dedo diminuiu a variabilidade e a velocidade do CP, indicando que a informação cutânea sem a adição de interferências proprioceptivas pode diminuir as oscilações posturais
Human subjects during upright stance show random postural oscillations which are controlled by the central nervous system. A light touch of an index finger (LT) on a surface fixed to the ground results in an additional sensory cue, which promotes a decrease in postural oscillations. However, there is a need to improve the knowledge about mechanisms associated with LT, both with respect to sensory and motor aspects associated with the phenomenon. This study aimed to further the understanding of the influence of LT on the behavior of multiple variables measured during upright stance. The first chapter analyzed variations of some quantifiers of postural sway based on the center of pressure (CP), center of mass (CM) and joint and body angles during experiments with different surface and vision conditions, with and without LT. In addition, the spectral coherence was analyzed between electromyogram signals from different muscles of the body and the previously listed sway quantifiers. The results showed that LT decreases the level of activation of some muscles, particularly the medial gastrocnemius, an important muscle for the maintenance of posture. Segmental and body angle variability and variables extracted from the CP and CM decreased in conditions with LT. In coherence analysis LT promoted some changes in patterns of oscillation between angles, CP, CM and EMGs, but with few modifications in the phase between the signals. The intermuscular coherence analysis (comparing the right and left muscles pairs of the body) showed that significant changes usually occured in the range of 0 to 1-2 Hz (in phase) for the lower limbs and may increase the frequency range in unstable situations (without vision and unstable surface). In these cases LT starts to affect more significantly the coherence between signals. The second chapter of this study was motivated by results from studies that have shown that it is possible to manipulate the sensory inputs generated by the finger during LT. This study investigated whether the withdrawal of a finger proprioceptive input affects postural sway, allowing an analysis of the effects of cutaneous sensory inputs of the third finger muscles. Postural control was evaluated with the subjects with the eyes closed and on an unstable surface. The results showed that removal of proprioceptive information from the finger flexor muscles decreased the variability and speed of the CP, indicating that cutaneous inputs without proprioceptive information may decrease postural sway

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