• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 47
  • 29
  • 12
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 112
  • 112
  • 54
  • 33
  • 19
  • 17
  • 17
  • 15
  • 14
  • 13
  • 12
  • 12
  • 12
  • 11
  • 10
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Sistema de controle para termociclador

Corte, Angélico 19 September 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-12-23T11:33:24Z No. of bitstreams: 1 Angélico Corte_.pdf: 3793672 bytes, checksum: 4f2c36a99d97bd11708bd259e853a7fb (MD5) / Made available in DSpace on 2016-12-23T11:33:24Z (GMT). No. of bitstreams: 1 Angélico Corte_.pdf: 3793672 bytes, checksum: 4f2c36a99d97bd11708bd259e853a7fb (MD5) Previous issue date: 2016-09-19 / Nenhuma / O termociclador é um equipamento utilizado para realizar uma técnica de biologia molecular chamada PCR (Polymerase ChainReaction – Reação em Cadeia da Polimerase), que objetiva isolar e amplificar fragmentos alvo de DNA e é amplamente utilizada em pesquisas nas áreas das ciências biológicas, saúde, agropecuária, em diagnósticos animal, vegetal e humano, bem como na medicina forense.O funcionamento do equipamento consiste em realizar ciclos de temperatura variáveis, sendo que o sucesso da reação depende basicamente de três fatores: (1) a velocidade das rampas de subida e descida de temperatura; (2) a precisão e estabilidade da temperatura estipulada no programa; (3) oovershoot reduzido ao final das rampas de temperatura. Esta pesquisa foi desenvolvida como a primeira fase de um projeto de nacionalização de tecnologia. Osobjetivosforam descobrir qual o controlador que melhor atua para o controle de temperatura em termocicladores e montar um protótipo deste equipamento.Os controladores testados foram os tipos PID (Genérico, ISA, Paralelo e com Síntese de Dahlin) e GMV.Esses controladores foram simulados usando Matlab e posteriormente implementados em um sistema de hardware. Foram implementadas no controlador PID de Dahlin, durante esse trabalho, a inserção de duas variáveis de ganho na componente proporcional, uma componente proporcional extra, um saturador e um filtro para acelerar a rampa de descida.Essas melhorias permitiram a resolução dos problemas apresentados pelos controladores, já que nenhum dos testados apresentou resultados satisfatórios em sua forma original.O protótipo foi montado e testado no laboratório de biologia molecular da Unisinos. O mesmo apresentou resultados equivalentes aos do equipamento importado em uso no laboratório. / The thermocycler is an equipment used to perform a molecular biology technique called PCR (Polymerase Chain Reaction), which aims at amplifying target DNA fragments. It is widely used in biology, health and agriculture sciences, animal, plant and human diagnostics, as well as in forensics. The equipment completes variable temperature cycles, and the success of the technique relies on three factors: (1) increasing and decreasing ramp rates; (2) temperature accuracy and stability of the temperatures set in the program; (3) a reduced overshoot at the end of each temperature ramp. This research was developed as the first phase of a Technology Nationalization Project. The aim was to identify the best controller to regulate temperature in thermal cycles and assemble a prototype of such equipment. The controllers tested were PID(Generic, ISA, Parallel and Dahlin Synthesis) andGMV. These controllers were simulated using Matlab and then, implemented in a hardware system. The following improvements were implemented in the Dahlin PID Controller during this work: addition of two gain variables in the proportional component, an extra proportional component, one saturator and a filter to accelerate the decreasing ramp. Such improvements allowed us to solve the problems of the controllers, as none of them presented acceptable results in its original form. The prototype was assembled and tested in the Molecular Biology Laboratory of Unisinos. The PCR results obtained with the prototype were equivalent as those obtained from the imported equipment used regularly in the laboratory.
62

Control And Guidance Of An Unmanned Sea Surface Vehicle

Ahiska, Kenan 01 September 2012 (has links) (PDF)
In this thesis, control and guidance algorithms for unmanned sea surface vehicles are studied. To design control algorithms of different complexity, first a mathematical model for an unmanned sea surface vehicle is derived. The dynamical and kinematical equations for a sea surface vehicle are obtained, and they are adapted to real life conditions with necessary additions and simplifications. The forces and torques effecting on the vehicle are investigated in detail. Control algorithms for under-actuated six degrees-of-freedom model are designed. PID and LQR controllers are implemented to attain desired surge speed and yaw position. The autopilots are designed and their performances are compared. Based on the autopilots, a guidance algorithm is implemented to achieve desired motions of the vehicle. An obstacle avoidance algorithm is proposed for safe motion among the obstacles. A next-point generation algorithm is designed to direct the vehicle to the most appropriate next way-point if the one ahead is missed. The effects of disturbances on the motion of the vehicle are studied thoroughly on simulation results. PID controller for an unmanned sea surface vehicle is implemented on ArduPilot Mega v1.4 cart controlling a Traxxas Spartan model boat. The performance of the controller is validated. Simulations and experimental results are provided.
63

Gps Based Altitude Control Of An Unmanned Air Vehicle Using Digital Terrain Elevation Data

Atac, Selcuk 01 June 2006 (has links) (PDF)
In this thesis, an unmanned air vehicle (UAV) is used to develop a prototype base test platform for flight testing of new control algorithms and avionics for advanced UAV system development applications. A control system that holds the UAV at a fixed altitude above the ground is designed and flight tested. Only the longitudinal motion of the UAV is considered during the controller design, hence its lateral motions are controlled manually by a remote control unit from the ground. UAV&amp / #8217 / s altitude with respect to the mean sea level and position are obtained by an onboard global positioning system (GPS) and this information is transmitted to the ground computer via radio frequency (RF) communication modules. The altitude of the UAV above the ground is calculated by using the digital terrain elevation data (DTED). A controller is designed and its gains are tuned to maintain this flight altitude at a desired value by using the mathematical model developed to represent the longitudinal dynamics of the UAV. Input signals generated by the controller for elevator deflections are transmitted back to the UAV via RF communication modules to drive onboard servomotors to generate desired elevator deflections. All controller computations and RF communications are handled by a MATLAB&reg / based platform on a ground computer. UAV flight tests are carried out at two different autopilot modes / namely, mean sea level (MSL) altitude hold mode and above ground level (AGL) altitude hold mode. The developed platform worked properly during flight tests and proved to be reliable in almost every condition. Moreover, the designed controller system is demonstrated to be effective and it fulfills the requirements.
64

A Real Time Test Setup Design And Realization For Performance Verification Of Controller Designs For Unmanned Air Vehichles

Kureksiz, Funda 01 February 2008 (has links) (PDF)
In this thesis, a test platform based on real-time facilities and embedded software is designed to verify the performance of a controller model in real time. By the help of this platform, design errors can be detected earlier and possible problems can be solved cost-effectively without interrupting the development process. An unmanned combat air vehicle (UCAV) model is taken as a plant model due to its importance in current and future military operations. Among several autopilot modes, the altitude hold mode is selected since it is an important pilot-relief mode and widely used in aviation. A discrete PID controller is designed in MATLAB/Simulink environment for using in verification studies. To control the dynamic system in wide range, a gain scheduling is employed where the altitude and velocity are taken as scheduling variables. Codes for plant and controller model are obtained by using real time workshop embedded coder (RTWEC) and downloaded to two separate computers, in which xPC kernel and VxWorks operating system are run, respectively. A set of flight test scenarios are generated in Simulink environment. They are analyzed, discussed, and then some of them are picked up to verify the platform. These test scenarios are run in the setup and their results are compared with the ones obtained in Simulink environment. The reusability of the platform is verified by using a commercial aircraft, Boeing 747, and its controller models. The test results obtained in the setup and in Simulink environment are presented and discussed.
65

Contribution to the implementation of a process control system for continuous powder mixing

Zhao, Xiaojuan 26 November 2013 (has links) (PDF)
Powder mixing is an essential operation in various industrial fields, such as pharmaceuticals, agro-food, cements, etc. Continuous powder mixing, as an alternative to conventional batch mixing, has attracted a lot of interest mainly due to its capacity in handling high volume manufacturing. This work aims at the contribution to the implementation of process control applications for powder mixing in a pilot-scale continuous mixer. Prior to developing process control strategies, new developments have been presented for better understanding continuous mixing of two components. Hold-up weight and relative hold-up weight distribution of each component in the whole mixer have been experimentally investigated under different operating conditions. An improved Markov chain model has been finally presented to predict the mean concentration of the mixtures obtained at the mixer's outlet. The implementation of a proportional-integral-derivative (PID) controller has been experimentally performed as an initial attempt to real-time control the homogeneity of the mixture produced. The rotational speed of the stirrer, identified as an important deciding factor towards the mixer's efficiency, has been considered as the manipulated variable. The closed-loop control is based on either the mean concentration or the relative standard deviation. The performances of the proposed closed-loops have been evaluated for continuous mixing subjected to step changes in feed rates of the mixer. Four case studies have been defined and presented. The main challenge in the process control system is the tuning of PID parameters. The performance of closed-loop control of either the mean concentration or the relative standard deviation has been compared to open-loop operation.
66

Determinação da região robusta de estabilidade e de desempenho inspirada nos princípios da estatística clássica.

SILVA, José Nilton. 08 November 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-11-08T12:05:44Z No. of bitstreams: 1 JOSÉ NILTON SILVA - TESE (PPGEQ) 2013.pdf: 1910479 bytes, checksum: 59c6bfc5fdbee46bc17470e9b2c8c2e5 (MD5) / Made available in DSpace on 2018-11-08T12:05:44Z (GMT). No. of bitstreams: 1 JOSÉ NILTON SILVA - TESE (PPGEQ) 2013.pdf: 1910479 bytes, checksum: 59c6bfc5fdbee46bc17470e9b2c8c2e5 (MD5) Previous issue date: 2013-08-01 / Este trabalho trata do desenvolvimento de uma metodologia baseada nos conceitos clássicos de estatística e probabilidade para a análise e avaliação da robustez da estabilidade e do desempenho de sistemas de controle, particularmente àqueles que usam o PID (Proporcional, Integral, Derivativo) como lei de controle. Visando estabelecer as condições para a aplicação da metodologia, um sistema de identificação do processo foi desenvolvido de forma recursiva, no qual modelos de convolução e fenomenológico foram empregados como representação do modelo e processo, agrupado a um procedimento de auto sintonia, necessário para considerar os parâmetros de sintonia como variáveis aleatórias e, por conseguinte as raízes da equação característica do sistema em malha fechada.O mapeamento da região de robustez tem sido realizado a partir das raízes da equação característica, considerando a distância estatística como a métrica representativa da robustez da estabilidade a qual permite estabelecer a região com certo grau de significância.Os resultados obtidos demonstram o potencial analítico exigido pela metodologia, permitindo também a análise online, com baixo esforço computacional e operacional mostrando ser um poderoso instrumento de avaliação de sistema de controle. / This study discusses the development of a methodology based on classical concepts of statistics and probability to analyze and evaluate the robustness of the stability and performance of the control system, particularly those that use the PID as control law. To establish the conditions for the application of the methodology, a recursive system identification method process was developed, in which convolution and phenomenological models were used to represent model and process, together with a self-tuning procedure that is necessary to consider tuning parameters as random variables, and hence the roots of the characteristic equation of the closed loop system. The mapping of the region of robustness has been achieved from the roots of the characteristic equation, considering the statistical distance as the metric represented to the robustness of stability which allows the region to establish a degree of significance. The results obtained demonstrate the potential analytical and evaluation required by the methodology, allowing such analysis also "online" with low computational effort and operational proving to be a powerful tool in the analysis of control system.
67

Controle de posição com múltiplos sensores em um robô colaborativo utilizando liquid state machines

Sala, Davi Alberto January 2017 (has links)
A ideia de usar redes neurais biologicamente inspiradas na computação tem sido amplamente utilizada nas últimas décadas. O fato essencial neste paradigma é que um neurônio pode integrar e processar informações, e esta informação pode ser revelada por sua atividade de pulsos. Ao descrever a dinâmica de um único neurônio usando um modelo matemático, uma rede pode ser implementada utilizando um conjunto desses neurônios, onde a atividade pulsante de cada neurônio irá conter contribuições, ou informações, da atividade pulsante da rede em que está inserido. Neste trabalho é apresentado um controlador de posição no eixo Z utilizando fusão de sensores baseado no paradigma de Redes Neurais Recorrentes. O sistema proposto utiliza uma Máquina de Estado Líquido (LSM) para controlar o robô colaborativo BAXTER. O framework foi projetado para trabalhar em paralelo com as LSMs que executam trajetórias em formas fechadas de duas dimensões, com o objetivo de manter uma caneta de feltro em contato com a superfície de desenho, dados de sensores de força e distância são alimentados ao controlador. O sistema foi treinado utilizando dados de um controlador Proporcional Integral Derivativo (PID), fundindo dados de ambos sensores. Resultados mostram que a LSM foi capaz de aprender o comportamento do controlador PID em diferentes situações. / The idea of employing biologically inspired neural networks to perform computation has been widely used over the last decades. The essential fact in this paradigm is that a neuron can integrate and process information, and this information can be revealed by its spiking activity. By describing the dynamics of a single neuron using a mathematical model, a network in which the spiking activity of every single neuron will get contributions, or information, from the spiking activity of the embedded network. A positioning controller based on Spiking Neural Networks for sensor fusion suitable to run on a neuromorphic computer is presented in this work. The proposed framework uses the paradigm of reservoir computing to control the collaborative robot BAXTER. The system was designed to work in parallel with Liquid State Machines that performs trajectories in 2D closed shapes. In order to keep a felt pen touching a drawing surface, data from sensors of force and distance are fed to the controller. The system was trained using data from a Proportional Integral Derivative controller, merging the data from both sensors. The results show that the LSM can learn the behavior of a PID controller on di erent situations.
68

Estrat?gia de escalonamento de controladores PID baseado em regras Fuzzy para redes industriais foundation fieldbus usando blocos padr?es

Lima, F?bio Soares de 15 July 2004 (has links)
Made available in DSpace on 2014-12-17T14:56:03Z (GMT). No. of bitstreams: 1 FabioSL.pdf: 932823 bytes, checksum: c32fee13ca97b70482987a8228b171cd (MD5) Previous issue date: 2004-07-15 / The main objective of work is to show procedures to implement intelligent control strategies. This strategies are based on fuzzy scheduling of PID controllers, by using only standard function blocks of this technology. Then, the standardization of Foundation Fieldbus is kept. It was developed an environment to do the necessary tests, it validates the propose. This environment is hybrid, it has a real module (the fieldbus) and a simulated module (the process), although the control signals and measurement are real. Then, it is possible to develop controllers projects. In this work, a fuzzy supervisor was developed to schedule a network of PID controller for a non-linear plant. Analyzing its performance results to the control and regulation problem / Com o objetivo de se manter a padroniza??o Foundation Fieldbus, neste trabalho s?o apresentados procedimentos para se implementar estrat?gias de controle inteligente, baseadas em escalonamento nebuloso de controladores PID, utilizando-se apenas blocos funcionais padr?es dessa tecnologia. Para validar a proposta, foi desenvolvido um ambiente para realiza??o dos testes necess?rios. Este ambiente ? h?brido, ou seja, possui uma parte real (a rede industrial) e uma parte simulada (o processo), por?m os sinais de controle e medi??o s?o reais. Desta forma, ? poss?vel desenvolver projetos de controladores. Neste trabalho desenvolveu-se um supervisor fuzzy para escalonar uma rede de controladores PID para uma determinada planta n?o-linear, sendo analisados seus resultados de desempenho tanto para o problema de controle quanto de regula??o
69

Controle de posição com múltiplos sensores em um robô colaborativo utilizando liquid state machines

Sala, Davi Alberto January 2017 (has links)
A ideia de usar redes neurais biologicamente inspiradas na computação tem sido amplamente utilizada nas últimas décadas. O fato essencial neste paradigma é que um neurônio pode integrar e processar informações, e esta informação pode ser revelada por sua atividade de pulsos. Ao descrever a dinâmica de um único neurônio usando um modelo matemático, uma rede pode ser implementada utilizando um conjunto desses neurônios, onde a atividade pulsante de cada neurônio irá conter contribuições, ou informações, da atividade pulsante da rede em que está inserido. Neste trabalho é apresentado um controlador de posição no eixo Z utilizando fusão de sensores baseado no paradigma de Redes Neurais Recorrentes. O sistema proposto utiliza uma Máquina de Estado Líquido (LSM) para controlar o robô colaborativo BAXTER. O framework foi projetado para trabalhar em paralelo com as LSMs que executam trajetórias em formas fechadas de duas dimensões, com o objetivo de manter uma caneta de feltro em contato com a superfície de desenho, dados de sensores de força e distância são alimentados ao controlador. O sistema foi treinado utilizando dados de um controlador Proporcional Integral Derivativo (PID), fundindo dados de ambos sensores. Resultados mostram que a LSM foi capaz de aprender o comportamento do controlador PID em diferentes situações. / The idea of employing biologically inspired neural networks to perform computation has been widely used over the last decades. The essential fact in this paradigm is that a neuron can integrate and process information, and this information can be revealed by its spiking activity. By describing the dynamics of a single neuron using a mathematical model, a network in which the spiking activity of every single neuron will get contributions, or information, from the spiking activity of the embedded network. A positioning controller based on Spiking Neural Networks for sensor fusion suitable to run on a neuromorphic computer is presented in this work. The proposed framework uses the paradigm of reservoir computing to control the collaborative robot BAXTER. The system was designed to work in parallel with Liquid State Machines that performs trajectories in 2D closed shapes. In order to keep a felt pen touching a drawing surface, data from sensors of force and distance are fed to the controller. The system was trained using data from a Proportional Integral Derivative controller, merging the data from both sensors. The results show that the LSM can learn the behavior of a PID controller on di erent situations.
70

Análise, desenvolvimento e controle de uma plataforma de movimentos com 6 graus de liberdade / Analysis, development and control of a platform of movements with 6 degrees of freedom

Ricardo Breganon 19 May 2014 (has links)
Nos últimos anos, tem havido grande interesse em estudar manipuladores paralelos, aplicados principalmente em simuladores de voo, com seis graus de liberdade. O interesse em estruturas cinemáticas paralelas é motivado por sua alta rigidez e excelente capacidade de posicionamento em relação às estruturas cinemáticas seriais. Além disso, como os atuadores são posicionados em uma base, eles podem ser aplicados em cargas pesadas e ainda apresentam baixo consumo de energia, tendo em vista que vários atuadores atuam simultaneamente no mesmo corpo. A presente tese apresenta o projeto de três controladores, sendo eles, o controlador H infinito com realimentação de saída, o controlador PID e o controlador Fuzzy, com isto, esta metodologia poderá ser empregada na construção de um futuro simulador de voo. O modelo dos atuadores foi obtido através de uma entrada degrau de tensão nos motores, medindo os seus deslocamentos através dos encoders acoplados, individualmente, a cada um dos respectivos eixos dos motores. Sabendo-se a relação de transmissão do mecanismo de movimento entre o motor e cada haste dos atuadores obtém-se o deslocamento de cada haste a partir da rotação de cada motor medida pelo correspondente encoder e com isso obtém-se o modelo matemático de cada atuador em conjunto com seu sistema de transmissão. Entretanto, na prática, cada atuador é ligeiramente diferente dos outros, o que leva a comportamento e desempenho diferentes entre si. Isso afeta o comportamento da plataforma fazendo com que a trajetória final desejada não possa ser seguida adequadamente, algo que é extremamente necessário em simuladores de voo. Assim, uma das contribuições importantes deste trabalho é, em primeiro lugar, apresentar uma metodologia de padronização das respostas dos atuadores de modo a que todos eles tenham no final, um comportamento igual o mais próximo possível, particularmente em termos de velocidade e de posicionamento. Com os dados da cinemática e da dinâmica da plataforma compondo o modelo completo do sistema foram realizadas várias simulações que aplicadas na plataforma de Stewart real validaram o modelo e mostraram a eficiência das técnicas de controle aplicadas no controle de posição e orientação da plataforma. Para validar o projeto da Plataforma de Stewart como uma possível base de movimento de um simulador de voo, foi implementada a dinâmica longitudinal e lateral de um Boeing 747-100, e com o auxilio de um sensor inercial Xsens® MTi-G, foram realizadas as medições dos ângulos de Euler da Plataforma. Os resultados obtidos pelos três controladores foram satisfatórios e ilustram o desempenho e a robustez da metodologia proposta. / In recent years there has been great interest in studying parallel manipulators, mainly applied in flight simulators, with six degrees of freedom. The interest in parallel kinematic structures is motivated by its high stiffness and excellent positioning capability in relation to serial kinematic structures. Furthermore, since the actuators are positioned on a base, they can handle heavy loads and also have low power consumption, considering that several actuators act on the same platform. This thesis presents the design of three controllers, which are, H-infinity controller with output feedback, PID controller and Fuzzy controller, so that this methodology can be employed in building a future flight simulator. The actuators models were obtained by a step voltage input to the engines and measuring their displacements by the encoders that are coupled to each of the respective axes of the motors. Knowing the relation from the motion transmission mechanism between the motor and the spindle of each actuator, the displacement of each spindle is obtained from the rotation of each motor measured by the corresponding encoder and thus we obtain the mathematical model of each actuator together with its transmission system. However, in practice, each actuator is slightly different from others, which leads to different behavior and performance of each. This affects the behavior of the platform making the final desired trajectory cannot be properly followed something that is extremely necessary in flight simulators. Thus, one of the important contributions of this work is first to present a methodology to standardize the actuators responses so that they all have in the end a behavior equal a close as possible, particularly in terms of velocity and positioning. With the kinematics data and platform dynamics composing the complete system model, several simulations applied to the real Stewart Platform validate the model and show the effectiveness of control techniques applied to control the position and orientation of the platform. In order to validate the Stewart Platform design as a possible base for a motion flight simulator, the longitudinal and lateral dynamics of a Boeing 747-100 model were implemented, and with the aid of an inertial sensor Xsens® MTi-G, measurements of the Euler angles of the platform were performed. The results obtained by the three controllers were satisfactory and illustrate the performance and robustness of the proposed methodology.

Page generated in 0.0445 seconds