Mestrado em Engenharia Elétrica

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http://repositorio.ufes.br/handle/10/17619

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Agora exibindo 1 - 20 de 370

Analise comparativa de algumas estruturas de filtros digitais de segunda ordem imunes a ciclos limite
(Universidade Federal do Espírito Santo, 1994-08-19) Simmer, Ana Cristina Staut; Orientador1; Sarcinelli Filho, Mário
This work is a comparative study of the relative output roundoff noise variance performance for some second-order state-space structures, as a function of the filter bandwidth. The addressed second-order structures are used as building blocks for realizing lowpass, highpass, bandpass and bandreject digital filters. In this sense, this study complements a recent one, which just investigated the lowpass filter case. In both studies only narrow-band digital filters are discussed, regarding the well known good performance of the state-space structures in those cases. In order to compare the output roundoff noise performance for all spectra, new firstorder spectral transformations, derived from the well known transformations due to Constantinides, are developed, for varying the filter bandwidth of a parallel-form prototype filter. All this effort is justified by the importance of knowing the performance of the structures which are suitable for a desired application, what represents a significative contribution to the problem of designing digital filters.
Uma interface gráfica de usuário para projeto e implementação de filtros digitais com processador dedicado
(Universidade Federal do Espírito Santo, 1996-06-19) Machado, Arnaldo Cordeiro; Schneebeli, Hans Jorg Andreas; Sarcinelli Filho, Mário; Coradine, Luis Claudius; Pequeno, Mauro Cavalcante
This work describes a software platform developed in order to support the design and DSP-based implementation of digital filters. It is a WINDOWS program designed to run on a personal computer containing a DSP board. A card based on the 16-bit fixed point Texas Instruments TMS320C25 chip is used, which is attached to the ISA PC bus. The developed software is specially designed to accomplish three main features: the filter design task, restricted to the PC microprocessor, the real-time synchronous filter algorithm, running exclusively on the DSP, and the necessary information exchanging between both processors, and between the PC computer and the user, in order either to load filter parameters or to check for the filter input/output signals. In addition, the user may edit/view text files containing the filter transfer function or network coefficients, or edit/compile/debug files that contain assembly code for the DSP.
Sobre o projeto de filtros digitais de segunda ordem imunes a ciclos limite
(Universidade Federal do Espírito Santo, 1998-12-30) Camponêz, Marcelo Oliveira; Sarcinelli Filho, Mário; Calmon, Luiz de Calazans; Mota, Francisco das Chagas
A set of three constant-input limit cycle-free state-space second-order digital filtersections were proposed in a paper of 1986, to be used as building blocks for cascade orparallel higher order filter design. They were called structure type I, structure type II (which isentirely identical to the first one) and structure type III, by the authors who proposed them.Those structures are different from other constant-input limit cycle-free second-orderbuilding blocks in the sense that they are computationally less complex. As showed in thepaper that introduced it, the structure type I is also a low roundoff noise one, when comparedto the minimum noise structure designed under L∞ scaling. Unfortunately, because thestructure type III is slightly more complex than the structure type I (its demands three two-input adders more to be computed), its synthesis procedure and noise performance were notaddressed in the initial paper. However, it was demonstrated later, that the structure type IIIpresents relative output roundoff noise variances lower than the structure type I for the case ofL2 scaled lowpass filters.Then, in this work, the structure type III is revised, and new strategies for designing itare proposed. Under proper design, it is showed that the relative output roundoff noisevariance is minimal. Both L2 and L∞ scaling are here discussed. Examples are shown tosupport the results presented.Finally, in order to stress the good noise performance of the structure type III designedaccording to the strategies here discussed, it is compared to the noise performance of someother filter structures known in the literature. The conclusion is that the new structure type IIIhere proposed is a good candidate for being the building block to implement high ordernarrowband filters.
Sistema de visão para robôs móveis: uma aplicação ao reconhecimento de referências geométricas
(Universidade Federal do Espírito Santo, 1999-02-26) Freitas, Roger Alex de Castro; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire; Almeida, Ailson Rosetti de; Rillo, Márcio
The availability of sensorial data is an important issue for the navigation systemof autonomous mobile robots. The robot needs information about its surroundingenvironment in order to make a decision on what to do when it faces an obstacle. Insome cases, it not only does need to detect the presence of the obstacle but also torecognize it. This way, it is necessary that the onboard sensing system be much morespecialized. For an agent-based controlled autonomous mobile robot, a sensing systemthat combines ultrasonic sensors and artificial vision is here addressed. It makesavailable information about the type of obstacle detected in the trajectory of the robot, aswell as the distance from the detected object to the robot. This external sensing systemis also able to avoid the generation of redundant and unnecessary information, besidesnot demanding too much computational effort to process the acquired images onboardthe robot
Inspeção visual automática de mamões
(Universidade Federal do Espírito Santo, 2003-12-17) Simão, Josemar; Orientador1; Schneebeli, Hans Jorg Andreas; Koo, Robert Liang; Loureiro, Getúlio Vargas; Salles, Evandro Ottoni Teatini
This work shows the development of an automatic inspection system for papaya fruits. This system can measure the size and the degree of maturation of the fruits, and classify them accordingly. The regional sector of papaya production and exportation has grown and the use of an automatic visual inspection system can contribute for the production increase and maintenance of the standards of quality demanded by the consuming markets. The automatic visual inspection systems have often been an alternative to the traditional processes of inspection done by trained individuals. The main reasons are costs reduction and the guarantee of the quality standard assured by the inspection of all fruits in a lot. In contrast, human inspectors get tired with repetitive work and present inconsistency in the inspection criteria. The system basic structure is a conveyor belt carrying a continuous flow of fruits and a digital video camera, located above, which gets a sequence of images of the moving fruits. These images are processed and analyzed by a personal computer. The first processing stage is the conversion of color to binary images for fruits dimensions estimation. The maturation is quantified by a hue histogram curve of the fruits in the color images. Comparing with data in a database, that stores the knowledge of experts, the information acquired can be used to classify the fruits and set up a mechanism capable to separates them as necessary. The results had shown that a set of the simple hardware could evaluate the dimensions and the degree of maturation of the fruits despite illumination changes.
Desvio tangencial de obstáculos para um robô móvel navegando em ambientes semi-estruturados
(Universidade Federal do Espírito Santo, 2004-06-28) Ferreira, André; Bastos Filho, Teodiano Freire; Sarcinelli Filho, Mário; Freire, Eduardo Oliveira; Caldeira, Eliete Maria de Oliveira
This thesis proposes a new strategy for a mobile robot to deviate from obstacles while navigating in a semi-structured environment. The proposed control architecture is based on a reactive approach, thus demanding low computational e®ort. It allows the robot to navigate from a starting point to a destination point without colliding to any obstacle in its path. The deviation from an obstacle is performed according to an escape angle calculated so that the new robot orientation is tangent to the obstacle. It is also shown that such strategy generates more e±cient trajectories, in the sense that the destination point is reached in less time while saving energy and reducing the demand on the robot motors. Another interesting aspect of the proposed strategy is that it also allows to implement the behaviors Wall Following and Corridor Following. The proposed methodology is validated through simulated examples and practical experiments as well, which were run in a PIONEER 2-DX mobile robot.
Controle da navegação de um robô móvel em um corredor com redundância de controladores
(Universidade Federal do Espírito Santo, 2004-06-29) Gamarra, Daniel Fernando Tello; Bastos Filho, Teodiano Freire; Sarcinelli Filho, Mário; Freire, Eduardo Oliveira; Caldeira, Eliete Maria de Oliveira
abstract
Comparação das técnicas de modulação multiportadoras aplicadas às comunicações via rede elétrica
(Universidade Federal do Espírito Santo, 2004-07-09) Dezan, Tadeu Leite; Segatto, Marcelo Eduardo Vieira; Salles, Evandro Ottoni Teatini; Almeida, Ailson Rosetti de; Lima, Antônio César de Castro
The use of the low voltage energy grid as high speed communication networks, known as Power Line Communication – PLC, opens up the possibility to establish low cost widespread local area networks services such as internet. In this master thesis dissertation, transmission issues on the power line are investigated and modeling aproaches are investigated. Multi-carrier modulation based on orthogonal transmultiplexer is used, because of its fast algoritms capabilities. Three diferent techniques are compared: Orthogonal Frequency Division Multiplexing, Discrete Wavelet Multitone through Extended Lapped Transform and Wavelet Packet Modulation. The main characteristics of each technique, including their computational cost, are described based on the filter banks theory. The system performance is analysed in terms of the bit-error rate versus signal-tonoise rate in a multipath powerline channel.
Estratégias para deslocamento de cargas através de cooperação entre robôs móveis a rodas
(Universidade Federal do Espírito Santo, 2004-12-22) Bragança, Jaines de Oliveira; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire; Salles, Evandro Ottoni Teatini; Ferasoli Filho, Humberto
This work deals with the control of cooperative robots, using a non linear position controller. The feedback of the control loop is carried out using a camera located over the environment where the robots actuate. After capturing an image, it is processed into a computer, which is responsible for generate the set point to the robots. It was used only a non linear position control and it was possible develop strategies for allowing the displacement of an object using two robots to push it. These strategies consist of analyzing the position and orientation of the object in order to displace it. In addition to these strategies, several tasks were developed by the robots, allowing them reaching a destination point or follow a predefined path. Also, tasks to the robots like formation in a line or side to side were implemented in this work.
Análise de sistemas de multiplexação por subportadora - SCM
(Universidade Federal do Espírito Santo, 2005-03-22) Togneri, Arnaldo Paterline; Orientador1; Segatto, Marcelo Eduardo Vieira; Ribeiro, Moisés Renato Nunes; Pohl, Alexandre de Almeida Prado
abstract
Análise da aplicação de conexão em paralelo de capacitores em circuitos secundários de baixa tensão
(Universidade Federal do Espírito Santo, 2005-05-13) Sarcinelli, Carlos Alberto; Sousa, Gilberto Costa Drumond; Simonetti, Domingos Sávio Lyrio; Aragão Filho, Wilson Correia Pinto de; Pomílio, José Antenor
The objective of this work is to analyze the behavior of a radial low voltage secondary distribution network subject to linear and non-linear loads, with and without magnitude voltage control by the automatic insertion of capacitor banks. The analysis is performed by considering the variations in the secondary distribution network elements. These elements are the loads connected to each pole of the network (power varying from no-load to full load, and displacement factor varying from 0.7 to 1.0), the changes in the ratings of the supply transformers (apparent power in kVA, primary and secondary impedances, and primary and secondary voltages), the number of poles and the distance among them. The harmonic behavior of the rms voltage of the distribution network is also analyzed, with and without the insertion of a capacitor bank at the last pole, since the distribution network might amplify harmonics as a result of resonances in the system, which have influence on the control of the voltage magnitude. Finally, a steady-state frequency domain analysis is performed by using a computer program (MATLAB), whose results are confirmed through time domain simulations performed using SIMULINK. The results concerning the time and frequency analyses are presented as a set of plots, from which some conclusions are highlighted, for a case study consisting in a network having five poles and a 13,800/220 V, 75kVA transformer.
Sintonia do ganho de escorregamento de um servoacionamento por controle vetorial de um motor de indução trifásico
(Universidade Federal do Espírito Santo, 2005-05-25) Massaro, Claudio Menegatti; Sousa, Gilberto Costa Drumond; Fardin, Jussara Farias; Rey, Joost Pieter
Servo drive applications require fast dynamic responses. Modern power electronics and Microcomputers enabled high performance ac drives for this purpose and the induction motor cage type is the most commonly used in adjustable-speed ac drive systems because of its robustness and low-cost. Vector control of an induction motor surpasses the performance of a direct current motor but the control method is inherently complex. The indirect vector control method, used in the present work, has a problem of performance degradation due to parameter variations, mainly rotor time constant, which is used in the slip gain calculation. An adaptive observer of an induction motor with a parameter adaptive scheme is proposed for tuning the slip gain calculation, in the present work. The system simulations were performed using Matlab/Simulink software to demonstrate its effectiveness. An experimental study with assembly software implementation was carried out, by using of a Texas Instruments DSP board.
Análise de dispersão em fibras PCF com o método de elementos finitos
(Universidade Federal do Espírito Santo, 2005-06-29) Ramos, Breno Guimarães; Frasson, Antonio Manoel Ferreira; Calmon, Luiz de Calazans; Figueroa, Hugo Enrique Hernandez
In the present work, the full vectorial, total anisotropic, Finite Element Method was implemented, using second order nodal base functions for the electric field longitudinal component discretization, and Nedelec base functions, quadratic normal and linear tangencial (QNLT), for the discretization of the magnetic field transversal component, applying triangular elements in the domain of solution. Through this implementation, it was studied several configurations of Photonic Cristal Fibers (PCF), making changes in the diameter of the holes and in the distance between then, also called pitch. The intention was to show how feasible and practical is the control of the ultraflattened dispersion profile for this new model of optical fiber, as was reported in recent works. The calculated dispersion results shown that is possible to get dispersion profile completely flat in a range of wavelength of 200 nm, and with the possibility to add offsets in this profiles, making it negative (for applications related to dispersion compensation), or yet, making it flat in a region as close as possible to zero, what is very useful for WDM multiplexing systems. In addition to the dispersion evaluation, the method developed also allows to calculate the effective modal area and also features a graphical presentation of the electric field distribution, or the magnetic field distribution, of the guided modes in the fiber. Concerning the tailoring of the dispersion curve, applying finite element simulation, it was validated the use of empiric equations for dispersion computations from scaling operations in the structure of PCF fibers. These equations can simplify even more the procedure of dispersion tailoring, because the number o simulations by finite element method is reduced considerably. It was also important to analyze the behavior of the propagating wave in the fiber’s interior. For this, it was implemented the Beam Propagation Method (BPM) using two different approaches. Initially, it was applied Crank-Nicholson method, which didn’t show good results because it was not possible to stabilize the propagation process. As a second option, the Newmark method was used, but it was only possible to make the propagation process stable with a simulation step which had the same order of magnitude of the wavelength applied. Thus, unfortunately it was not possible to observe any phenomena of interest during the guiding process.
Estudo do sinal eletroencefalográfico (EEG) aplicado a interfaces cérebro computador com uma abordagem de reconhecimento de padrões
(Universidade Federal do Espírito Santo, 2005-09-06) Azevedo, Anderson Prado; Almeida, Ailson Rosetti de; Salles, Evandro Ottoni Teatini; Bastos Filho, Teodiano Freire; Andreão, Rodrigo Varejão
The conjunction of signal processing, pattern recognition and brain electrical signal acquisition made possible a new communication modality, until now a subject for science fiction movies: the Brain-Computer Interface (BCI). This complex system can acquire and process the brain signals in order to obtain information to be used as a control signal. This innovation can benefit people who have neuromuscular disorders, which cause damages on the volunteer movement. These people would communicate, or even move, using a BCI to control electronic devices. Looking ahead, these systems can be used in other applications, mainly for multimedia purposes. The purpose of this work is study the EEG characteristics, the signal processing and pattern recognition techniques in order to use in a Brain Computer Interface (BCI) For this, will be used a international data base, in order to compare our results with results of other international groups. In this context, this work describes the human brain and the EEG characteristics relevant to BCI understanding. Moreover, it presents the implementation of a pattern recognition system, which is able to classify the motor imagination laterality with accuracy over 85%.
Um método interativo de recuperação de diagramas GRAFCET e de estados a partir de Diagramas Ladder usando diagramas binários de decisão
(Universidade Federal do Espírito Santo, 2005-11-04) Giacomin, Paulo André Sperandio; Schneebeli, Hans Jorg Andreas; Denti Filho, José; Okamoto Junior, Jun; Amaral, Paulo Faria Santos
abstract
Reator eletrônico microcontrolado de alto fator de potência para lâmpadas de alta intensidade de descarga
(Universidade Federal do Espírito Santo, 2005-11-24) Orletti, Renato; Có, Márcio Almeida; Vieira, José Luiz Freitas; 1º membro da banca
This work presents an overview about the High intensity discharge (HID) Lamps, showing its operation, the lamps variety and the peculiarities of this drive. The drive with electromagnetic ballast and electronic ballast are studied to verify advantages and disadvantages. After the analysis of electromagnetic and electronic drives, an electronic ballast is proposed. A prototype was implemented to verify the ballast performance. The experimental results have proved the viability of the electronic ballast proposed, emphasizing the reduced number of components used to make the prototype.
Limitador de corrente de falta supercondutor
(Universidade Federal do Espírito Santo, 2005-12-16) Oliveira, Flávio Duarte Couto; Simonetti, Domingos Sávio Lyrio; Fardin, Jussara Farias; Jota, Patricia Romeiro da Silva; Orlando, Marcos Tadeu D’Azeredo
The goal of this work is to present a resistive superconductor fault current limiter. For this study was used a SFCL based on Hg0.8Re0.2Ba2Ca2 Cu3O8+δ (Hg-1223) ceramic made in High Pressure Lab - UFES. Among all the high Tc superconductor cuprates, the Hg-1223 compound has record transition temperature, i.e., Tc = 135 K under normal pressure.To this aim, the work shows a discussion about fault current limiters and a heuristic review of superconductor theory describing the principal characteristics. Furthermore, sample preparation as well a design methodology for a resestive type limiter are described here. The performance of the device is evaluated under several fault conditions. It has been verified that intense over-current did not cause loss of sample stoichiometry showing the viability of this type of device for future application.
Desenvolvimento de servidores OPC DA e OPC XML DA para sistemas de aquisição de dados via telefonia celular
(Universidade Federal do Espírito Santo, 2005-12-20) Nascimento Filho, Osmar Assis do; Munaro, Celso José; Alvarenga, Arlindo Gomes de; Lüders, Ricardo
This work presents the relevant information for development of OPC data servers in the two more promising ways of this standard: OPC DA and Web Services. A proposal of necessary steps for the development of this type of system is presented, in the context of a real situation of data acquisition using cellular telephony technology as access way. The results of conformity and performance tests are presented and demonstrate the interoperability capacity supplied by the implemented solutions.
Sistema de monitoramento remoto de processos via web e wap
(Universidade Federal do Espírito Santo, 2005-12-21) Oliveira, Aldemar José de; Amaral, Paulo Faria Santos; Munaro, Celso José; Segatto, Marcelo Eduardo Vieira; Rigo, Daniel; Lüders, Ricardo
In this work, a solution for remote process supervision via WEB and WAP is presented. The proposal is composed by a remote terminal unit, based on a microcontroller and a CDMA modem. And for master terminal unit, a computer connected to internet, is used for receiving, processing and distributing collected field data. The solution is applied to a temperature remote supervision problem, and results from tests are presented and discussed, showing its usefulness for remote supervision of processes spread over large areas.
Avaliação do desempenho de redes com foco na aplicação em sistemas de controle digitais
(Universidade Federal do Espírito Santo, 2005-12-22) Souza, Fabio Luiz Vale de; Garcia, Anilton Salles; Denti Filho, José; Martinelli, Fernando José
The continuous evolution of control strategies has lead many manufactures to use networks as the interface between field devices and the logic process controller and also between controllers, e.g., DeviceNet, ControlNet Profibus, Ethernet, DH+, Industrial IP. These systems which use network as part of its loop control are called Networked Control System (NCS). During the engineering phase of industrial plant automation, the knowledge about process controllers and industrial networks are indispensable. Therefore, the necessity of evaluating if the proposed system fits the control system basic specifications considering the fact of using a network is the new challenge. This dissertation has the focus of studying NCS by running simulations using the OPNET IT_GURU software. For Ethernet Network simulation was used the basic library available in the software and the traffic generation patterns and transmission modes used were the ones normally used industrial applications. To simulate ControlNet and DeviceNet was necessary to modify and also create new libraries that could represent these networks behavior and similar to Ethernet different kind of traffic generation and transmission modes were used. By using the obtained results form the simulations many analysis were done which allowed the identification of each network and their applicability in control systems. Additionally comparisons among the networks were done and the differences causes also were discussed. Finally at the end of this dissertation the reader will have an objective fast consulting material that will help the performance evaluation of networks herein studied and will be able to evaluate other networks just by using the concepts and methodology applied in this job.

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