Dissertations/Thesis

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2021
Dissertations
1
  • SAMUEL SIMÕES BRITO DE AZEVEDO
  • Evaluation of Fault-Induced Traveling Waves in a Transmission Line Experimental Test Bench

  • Advisor : FLAVIO BEZERRA COSTA
  • BANKING MEMBERS :
  • FLAVIO BEZERRA COSTA
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • RODRIGO PRADO DE MEDEIROS
  • WASHINGTON LUIZ ARAUJO NEVES
  • Data: Jan 28, 2021


  • Show Abstract
  • Traveling-wave detection methods have been widely studied in recent years due to
    the implementation of traveling-wave-based protection and fault location schemes applied to transmission systems since they are faster and more accurate than traditional
    schemes employed by power companies. Researchers have been developed travelingwave detection methods by using the most varied digital signal processing techniques.
    This work provides a traveling wave-based detection methods analysis with the main
    focus on real-time boundary stationary wavelet transform, by using experimental data,
    which is extracted from a three-phase transmission line test platform. This research intends to develop a method that utilizes high-sampling frequency to detect the first incident
    wavefront, as well as the subsequent ones due to reflections at line terminals and at fault
    point. The experimental test bench is composed of a three-phase alternate current source,
    a one kilometer long four-wire polypropylene-type flexible copper cable, which enables
    the traveling-wave propagation phenomenon, a load resistance, and fault resistance. The
    fault switching is realized by pressing a push-button. Currents and voltages are measured
    by means of transducers connected to one of the line terminals, the fault point, and an
    oscilloscope. Therefore, fault transient signals are acquired, stored, and can be offline
    analyzed. Handling this setup, it is possible to control the distance that fault occurs, the
    fault type, as well as the fault resistance and the fault incidence angle.


2020
Dissertations
1
  • VITOR GABOARDI DOS SANTOS
  • Step and ramp detection and modeling system for a lower limb exoskeleton

  • Advisor : PABLO JAVIER ALSINA
  • BANKING MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • PABLO JAVIER ALSINA
  • TANIA LUNA LAURA
  • Data: Feb 28, 2020


  • Show Abstract
  • In recent years, many studies have been carried out on the topic of exoskeletons related to locomotion assistance. The main goal of these devices is to assist the elderly and physically challenged persons in daily activities, replacing or increasing the movement of body articulations. Although significant progress has been achieved, many challenges still remain. A desirable feature for exoskeletons is the planning of autonomous movements, so that the movements are automatically adapted according to the environment that the user is facing. Therefore, it is indispensable the use of a computer vision system to provide information about the environment where the user is located, classifying the structures of the scene as walkable or not. In this sense, we propose a new strategy for ramp and step detection which are in accordance with technical standards and can be climbed for exoskeleton users. Initially, we use a RGB-D sensor to acquire depth information of the environment. Next, we perform plane segmentation using a hypothesis and verification methodology. Through the plane normal analysis, it is possible to establish ramps and steps candidates. Finally, plane dimensions are verified in order to decide whether the ramps and steps are qualified to be climbed. Results were obtained applying the method considering different environments, where it was possible to detect and model ramps and steps satisfactorily for the presented scenarios.

2
  • IGOR CABRAL MACHADO LOPES
  • Decoupled controller for three degrees of freedom articulated robotic manipulator 

  • Advisor : SAMAHERNI MORAIS DIAS
  • BANKING MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • PABLO JAVIER ALSINA
  • SAMAHERNI MORAIS DIAS
  • TIAGO ROUX DE OLIVEIRA
  • Data: Dec 23, 2020


  • Show Abstract
  • This work proposes a control technique to an articulated robotic manipulator, classified in the literature as anthropomorphic (RRR), which is formed by three rotary joints, three degrees of freedom, and spatial movement. Articulated manipulators (RRR) have freedom of movement inside their workspace and are a type of manipulator widely used. The proposed control will use an inversion technique to decouples the dynamic of each joint of the RRR manipulator and apply to each decoupled joint two control strategies. The first strategy is the variable structure model adaptive control, and the second is a linear proportional derivative controller. In the end, simulation results are shown, and some analyses about them are done. 

2019
Dissertations
1
  • FRANCISVAL GUEDES SOARES
  • Attitude and angular velocity estimation using a Luenberger observer for nonlinear systems

  • Advisor : KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • BANKING MEMBERS :
  • ALDAYR DANTAS DE ARAUJO
  • ERICO CADINELI BRAZ
  • JOILSON BATISTA DE ALMEIDA REGO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • SAMAHERNI MORAIS DIAS
  • Data: Apr 30, 2019


  • Show Abstract
  • The technological advances of the last decades, together with the standardization of the CubeSats, have made viable the use of nanosatellites for commercial and institutional purposes. Taking advantage of this trend, the National Institute of Space Research is developing the CONASAT project, which consists of a constellation of nanossatellites for the collection of environmental data. Constellation interaction requires reasonable accuracy of the satellite attitude determination and control system (ADCS), despite the limitations of the CubeSat platform and cost of the project. In this context, the present work proposes a less complex alternative to the extended Kalman filter (EKF), with an implementation of the Luenberger state observer for nonlinear systems in order to estimate the attitude and angular velocity of the satellite, considering the use of the QUEST algorithm to obtain attitude from measured vectors. The estimation scheme adopts a kinematic model of the system with parameterization of the rotation matrix by quaternion, and a dynamic model considering the object as a rigid body, with the presence of torque due to magnetic disturbances. The attitude sensor system consists of a magnetometer and a sun sensor, simulated from the ideal model with additional white noise. The implemented estimator is evaluated using simulations, together with an approach from the EKF. Finally, some conclusions and final considerations are presented.

2
  • NELSON JOSÉ BONFIM DANTAS
  • Control Design for Second-Order Systems with Time-Delay via Frequency Response Methods

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • BANKING MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • JOSÉ MÁRIO ARAÚJO
  • THIAGO ANTONIO MELO EUZÉBIO
  • Data: May 3, 2019


  • Show Abstract
  • Solving control problems for delayed second order systems is one of the engineering challenges. Phenomena such as mechanical vibrations,  resonance and others can be described mathematically by this type of system. This work has as main objective to propose a solution to a problem of design of a state feedback controller for second order systems with time-delay using frequency response approach. Differently from many approaches available in the literature, ou rapproach does not require either the use of approximations for the delay, or a posteriori analysis of the solution. By mathematically defining the control problem as an optimization problem, a search for controller gains is carried out using a genetic algorithm, with the goal of ensuring that the Nyquist curve of the system remains at a safe distance from the instability region . The computed control gains then result in a robust closed-loop system, in the sense that it remains stable in spite of small changes un the system parameters.
    The simulation results obtained at the end of the work proved satisfactory within the desired specifications.

3
  • ÁLVARO PINTO FERNANDES DE NEGREIROS
  • N-Boat: Design and Development of an Autonomous Robotic Sailboat

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • BANKING MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • Data: Jul 1, 2019


  • Show Abstract
  • We propose the design and development of an autonomous sailboat, the N-Boat II, which is being built by the associated laboratories Natalnet (UFRN) and LAICA (IFRN). We introduce the electromechanical design, from design and construction to the control phase. Its great differential is distributed hardware by affinity along isolated watertight compartments. With the premise of being a prototype capable of replication and have complete open source, this robotic model will be used, in principle, to monitor water quality. However, this platform can be used in numerous tasks of various natures. Thus, it is expected at the end of this work, provide the community a complete infrastructure, with potential to be used scientifically, commercially or militarily, in proposals that require a robotic water surface vehicle with sufficient autonomy for medium and long missions.

4
  • ALEX CARLOS RODRIGUES ALVES
  • On-Board Control for Nanosatellites: Development and Application to the CONASAT Project

  • Advisor : SAMAHERNI MORAIS DIAS
  • BANKING MEMBERS :
  • FRANCISCO JOSE TARGINO VIDAL
  • JOSÉ MARCELO LIMA DUARTE
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • SAMAHERNI MORAIS DIAS
  • Data: Sep 26, 2019


  • Show Abstract
  • Since the launch of Sputnik I in 1957, the satellite industry has experienced great te- chnological advances. Initially, the resources for satellite missions were concentrated on large commercial entities and government organizations. However, by offering a low-cost solution with a shorter development time, the CubeSat standard allowed several institu- tions and organizations to be able to develop missions with nanosatellites. In Brazil, the Northeast Regional Center (CRN) of the National Institute of Space Research (INPE) has developed, along with the Federal University of Rio Grande do Norte (UFRN), the CO- NASAT project with the objective of developing a constellation of nanossatellites to the Brazilian Environmental Data Collection System (SBCDA). Currently, it has been deve- loped the CubeSat called CONASAT-0 (first of the constellation), for which is necessary the implementation of an on-board control system capable of meeting requirements of the CONASAT project. In this context, this work presents the first version of the on-board control system for CONASAT-0. Moreover, in this dissertation are presented the tests performed with the developed system and the results obtained. Finally, propositions for future works are presented.

5
  • DANIEL HENRIQUE SILVA FERNANDES
  • Vision System for Plane Detection in Active Orthosis Application

     

  • Advisor : PABLO JAVIER ALSINA
  • BANKING MEMBERS :
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • AGOSTINHO DE MEDEIROS BRITO JUNIOR
  • PABLO JAVIER ALSINA
  • RAQUEL ESPERANZA PATIÑO ESCARCINA
  • Data: Nov 27, 2019


  • Show Abstract
  • In this work, it is proposed the creation of a computer vision system for an active
    orthosis with the objetive of guaranteeing greater autonomy in its movements. This equipments
    are generally present means of understanding the work environment, which makes
    difficult the Orthosis to organize such environments and predict actions of their users,
    for example. In this context, a strategy is presented which, through an RGB-D camera,
    obtain a point cloud scenery to detect planar regions of the environment. Starting from
    the principle that most walking sites are flat regions, we can classify regions transposable
    to the base with no set of points that can be classified as ground, for example. To verify
    the quantify and refinery are an classification for an update, is necessary that has been
    the testing and filtering with specific date of data to processing. The preliminary results
    were obtained in simulation environments and in real environment, to which the indicators
    were satisfactory with the considerable reduction of the set of points, but keeping the
    shape of the plane close to the original.

2018
Dissertations
1
  • FELIPE DE SOUZA PINHEIRO
  • Real Time Hand Gesture Recognition Using Surface Electromyography Signals

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • BANKING MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • JOILSON BATISTA DE ALMEIDA REGO
  • ALUISIO IGOR REGO FONTES
  • Data: Jan 31, 2018


  • Show Abstract
  • The control of prostheses, orthoses and other mechanisms based on the electrical response of a specific region's musculature represents the integrations between user and application. This work presents the results of three promising techniques for feature extraction, and its implementation as well, with the intention of identifying different gestures performed by the right hand based on four surface electromyography signals from de forearm's musculature. After that will be presented the results of the final implementation on the hardware using the techniques with the previous best performances.
2
  • JEAN MARIO MOREIRA DE LIMA
  • Soft Sensor applied to Natural Gas Process Units

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • BANKING MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • Data: May 28, 2018


  • Show Abstract
  • In NGPU (Natural Gas Processing Units), one of the most profitable products is LPG (Liquefied Petroleum Gas) which is composed mostly of propane (C3) and butane (C4). In addition, pentane (C5) and ethane (C2) may also be present in the gas as contaminants. Measurement of the molar fraction of the components of the GLP has been done by gas chromatographs. However, chromatography is a slow process, making it impossible to monitor the quality of the product in real time. In this work, it is proposed a soft sensor, using artificial neural networks, with the objective of inferring the molar fractions of C3, C4, C5 and C2. In this way, it would be possible to estimate the molar fractions of these LPG components once per minute, considerably faster than chromatographers. The results obtained are promising, showing that the virtual sensor can infer the molar fractions of C3, C4, C5 and C2 and thus enable improvement in the monitoring of LPG quality and, consequently, profitability.

3
  • PEDRO ANDRÉ NOGUEIRA SOUZA DE OLIVEIRA VALE
  • Control of a debutanizer column using GS-PID

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • BANKING MEMBERS :
  • ADEMAR GONÇALVES DA COSTA JÚNIOR
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • Data: Jul 9, 2018


  • Show Abstract
  • Nowadays, where there is a continuous increase in competition, it is necessary to have an increasingly efficient control of the process, in order to seek a better product quality, lower costs and greater safety. In the petrochemical industry it is no different, and one of the most important processes in this industry is distillation. In order to carry out the distillation, a set of equipment, valves, controllers, vessels, distillation columns, in an interconnected way, is necessary in order to allow a control to obtain the product (LPG, gasoline etc) with quality within a specification. However, even with a high degree of mesh non-linearity, in practice, PID controllers are still used to control these complex plants. In this work the GS-PID method will be used to improve the control of a debranching column in a larger operational region, thus increasing the profitability and safety of the process.
4
  • EDUARDO LACERDA CAMPOS
  • Attitude Control for Nanosatellites

  • Advisor : KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • BANKING MEMBERS :
  • JOILSON BATISTA DE ALMEIDA REGO
  • JOSÉ MARCELO LIMA DUARTE
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • SAMAHERNI MORAIS DIAS
  • Data: Sep 13, 2018


  • Show Abstract
  • With advances in nanosatellite research, as an alternative to space exploration, the Instituto Nacional de Pesquisas Espaciais (INPE) is interested in using this new nanosatellite technology in its future missions. This makes it necessary to have a platform on which to study nanosatellite behavior in space. In this context, the following thesis implemented a simulator, composed with a navigation system and a proportional and derivative controller (PD). The sensors used to estimate the attitude were composed of a magnetometer and a solar sensor, simulated by using an ideal model with white noise. To represent the kinematics, the quaternion was adopted and the nanosatellite was a rigid body. In the navigation system, the norm-constrained Extended Kalman Filter had shown itself to be adequate to work with the sensors embedded in the nanosatellite. Thus allowing the estimate of the angular velocity and the quaternion that represents the attitude. For the controller, the values estimated by the Filter were directly used as a control signal, which has the advantage of dealing with the nonlinearities. Different tests were performed to assess the simulator and evaluate the stability of the navigation and control system. The results have demonstrated that the set up is able to stabilize and correct the attitude of the nanosatellite, even in the face of different perturbations, large angles and high angular velocities. Hence, the simulator generates adequate results, allowing it to be used in future nanosatellite studies.

5
  • KASSIO JANIELSON DA SILVA EUGENIO
  • Low-cost Wearable Multisensory System for Human Gait Capture applied to the Orthopedic Orthopedic
    Exoskeleton Ortholeg 2.0

  • Advisor : PABLO JAVIER ALSINA
  • BANKING MEMBERS :
  • ARMANDO SANCA SANCA
  • MARCIO VALERIO DE ARAUJO
  • NICHOLAS DE BASTOS MELO
  • PABLO JAVIER ALSINA
  • SAMAHERNI MORAIS DIAS
  • Data: Dec 17, 2018


  • Show Abstract
  • Nowadays, several researches are underway with respect to orthopedic exoskeletons for lower limbs. Nevertheless, the ability of these exoskeletons to carry out anthropomorphic movements is still a problem that researchers confront. However, a recent research developed a statistical method for gait synthesis taking into consideration the individual characteristics and parameters of movement of each individual. Therefore, in order to the orthopedic exoskeletons reproduce the peculiarities of the movements of each user, it is necessary to construct a database that provides all the necessary information, to the statistical model characteristics and parameters of the movements. However, kinematic parameter capture systems are too expensive, and require specific environmental conditions, such as luminosity and precise positioning of the cameras, which often make it difficult to use them. In this context the objective of this work is to present the development of a low cost and wearable multi sensorial system that allows to measure kinematic parameters of the anthropomorphic movements. For this, the Information Filter was used, which is an estimation technique to perform fusion of sensor data that allows to obtain more accurate information of the system. The measured parameters will be stored in a database to be used by the statistical method utilized in Ortholeg 2.0 Orthopedic Exoskeleton. The proposed system composed of four encoder type sensors, five inertial measurement unit sensors and four flex sensors, allowing to measure the kinematic parameters of the anthropomorphic movements.

2017
Dissertations
1
  • RAFAEL CARDOSO PEREIRA
  • Tracking and target pursuit technique using the Haar cascade algorithm applied to ground Robots with movement restrictions

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • BANKING MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • PABLO JAVIER ALSINA
  • ADRIAO DUARTE DORIA NETO
  • TIAGO PEREIRA DO NASCIMENTO
  • Data: Jun 21, 2017


  • Show Abstract
  • The ability to follow or move along with a specified person or object, capable of move, is a necessary skill in several autonomous agents to perform various tasks present in everyday life, and can be applied either in everyday tasks, as in supermarket carts or cleaning environments, as well in high-risk tasks such as in large industries or autonomous cars. The idea presented here is to develop a target tracking and following method applicable to mobile wheeled land robots that have restrictions on their movement, which mean that standard control techniques can not always be applied. The work developed here also takes into account the use of a target detection technique that can be adapted to practically any type of target stipulated by the designer according to the needs of its application. The development of the proposed methods was accomplished by adding standard recognition techniques, used in common RGB cameras, position estimation and orientation techniques, and intelligent control algorithms applicable to robots with movement restrictions, which have a low computational cost.

2
  • ELIZABETH VIVIANA CABRERA AVILA
  • Analysis of metrics to determine similarity between restrict non-rigid objects in real time.

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • BANKING MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • RAFAEL BESERRA GOMES
  • ROSIERY DA SILVA MAIA
  • Data: Jul 5, 2017


  • Show Abstract
  • Within the area of Mechatronics, mainly in CAD and computer vision, many applications are developed that involve the analysis of non-rigid or deformable objects.This master dissertation proposes an approach to measure similarity of deformable objects using as underlying representation clouds of three dimensional points of them. Basically, three point clouds of the analyzed object are considered: one without changes, another representing the degree of maximum deformation and a third  that describes the deformation of interest. Here are presented two alternatives to measure similarity based on Distance measures, with the respective accuracy and time checks. The first method is based on the Mahalanobis distance computation and in the second the Hausdorff distance is used with a previous registration and alignment steps. The experiments are developed considering some parts of the human body, its evidents that the analysis with  Mahalanobis distance has the shortest execution time. Several applications in the areas initially mentioned and in others as Virtual Reality can rely on the results obtained in this proposal to determine the deformation levels of restricted deformable objects.

3
  • LUIS ENRIQUE ORTIZ FERNANDEZ
  • A generic approach for estimation and modeling of the RMS error in depth data from 3D vision sensors 

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • BANKING MEMBERS :
  • LUIZ MARCOS GARCIA GONCALVES
  • BRUNO MARQUES FERREIRA DA SILVA
  • ANDERSON ABNER DE SANTANA SOUZA
  • Data: Jul 5, 2017


  • Show Abstract
  • Several devices are used in artificial vision, like MS Kinect v1/v2, the stereo cameras PG Bumblebee XB3 and Stereolabs ZED, among others. Since they are all devices that estimate depth data, they may have errors. In this work, we present the design and implementation of a generic method for estimating RMS error in depth data provided by any device capable of generating data of type RGB-D, that is, an image and the depth map, to the same time. To verify the method, an embedded system was built based on the NVIDIA Jetson TK1 and three sensors, the two versions of the MS Kinect and the ZED stereo camera. At the moment of data collection, the mathematical models of the RMS error were established for each device and, at the end, an analysis was made of the accuracy of each one. It is intended that the proposed method be the basis for other future works, such as p. ex. achieve a 3D reconstruction using the mix of depth data captured by various 3D sensors, with the lowest possible RMS error. In addition, it is sought that the error information obtained through the method can be used in any application to obtain more accurate results.

4
  • ALCEMY GABRIEL VITOR SEVERINO
  • Meta-heuristics applied to system identification

  • Advisor : FABIO MENEGHETTI UGULINO DE ARAUJO
  • BANKING MEMBERS :
  • FABIO MENEGHETTI UGULINO DE ARAUJO
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • CARLOS EDUARDO TRABUCO DOREA
  • LEANDRO LUTTIANE DA SILVA LINHARES
  • TAKASHI YONEYAMA
  • Data: Dec 8, 2017


  • Show Abstract
  • The systems identification have the goal to determine mathematical models to describe the dynamic characteristics of systems from observations. The identification process is generally divided into the following steps: i) experimental data collection, ii) determination of model structure, iii) parameter estimation and iv) model validation. In this work, the problem of the determination of structures is investigated. An algorithm was developed to determine the structure of polynomial NARX models from the optimization techniques known as meta-heuristics. Unlike traditional methods, metaheuristics use a set of possible solutions and strategies, usually based on nature, to find the solution of the case applied. Among the techniques studied are the genetic algorithm, the particle swarm optimization, and the bat algorithm. The methodology proposed in this work was applied to identify three experimental examples: an electric heater, a buck converter and a pneumatic valve. The results demonstrate that metaheuristics can be applied to the problem of the selection of polynomial NARX model structures.

5
  • FRANKELENE PINHEIRO DE SOUZA
  • High Impedance Fault Identification by Cyclostationary Feature Analysis

  • Advisor : LUIZ FELIPE DE QUEIROZ SILVEIRA
  • BANKING MEMBERS :
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ALLAN DE MEDEIROS MARTINS
  • FLAVIO BEZERRA COSTA
  • FELIPE VIGOLVINO LOPES
  • GEORGE ROSSANY SOARES DE LIRA
  • Data: Dec 20, 2017


  • Show Abstract
  • Conventional overcurrent protection systems are often not sensitized to the occurrence of high impedance faults, because they have a low amplitude. This type of disturbance causes damages to the concessionaires, as well as can cause damages to the lives of people and/ or animals. Therefore, different identification methods of high impedance faults in electric power distribution systems have been proposed. The main difficulty found by these methods is due to noise interference on the signal, as well as the low fault overcurrent level. Therefore the search for efficient and reliable method to identify high impedance faults, which does not present the drawbacks found in the methods proposed in the literature, an innovative method is proposed that minimizes the noise interference on the signal, and uses characteristics Statistics present on the signals with lack of high impedance to identify them, and thus to differentiate them from other phenomena present in the electrical systems. Specifically, the method uses analysis of cyclostationary processes to extract cyclic autocorrelation information from the samples of the signals of interest by calculating the cyclic spectral density function. From this information, we can obtain descriptors that allow to classify at a later stage the faults of high impedance. Preliminary results indicate that the method is robust to noise and efficient in terms of correct classification rate of high impedance events. 

2016
Dissertations
1
  • PHILIPPE EDUARDO DE MEDEIROS
  • Controle ativo de vibração em estruturas inteligentes utilizando um controlador por modos deslizantes com compensação difusa

  • Advisor : WALLACE MOREIRA BESSA
  • BANKING MEMBERS :
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • MARCELO AMORIM SAVI
  • SAMAHERNI MORAIS DIAS
  • WALLACE MOREIRA BESSA
  • Data: Mar 1, 2016


  • Show Abstract
  • Estruturas e sistemas inteligentes tem como principal característica a capacidade de emular o comportamento de organismos vivos, os quais possuem comportamento autorregulado. Deste modo, devido a presença de um mecanismo de estímulo-resposta, este tipo de estrutura possui propriedades adaptativas. O termo estrutura inteligente vem sendo usado para identificar sistemas estruturais capazes de modificar sua geometria e/ou propriedades físicas no intuito de executar determinada tarefa. Neste trabalho, um controlador por modos deslizantes com compensação difusa é empregado para o controle ativo de vibrações em uma treliça de Von Mises feita de liga com memória de forma. Este sistema possui uma dinâmica bastante rica e complexa, podendo apresentar comportamento caótico mesmo quando submetido a carregamentos de frequências moderadas. Simulações numéricas são apresentadas para comprovar a eficácia da estratégia utilizada.

2
  • TALES VINICIUS RODRIGUES DE OLIVEIRA CAMARA
  • Aplicação da Função Densidade Espectral de Correntropia Cíclica em uma Arquitetura de Sensoriamento Espectral

  • Advisor : ALLAN DE MEDEIROS MARTINS
  • BANKING MEMBERS :
  • ALLAN DE MEDEIROS MARTINS
  • ADRIAO DUARTE DORIA NETO
  • LUIZ FELIPE DE QUEIROZ SILVEIRA
  • ALUISIO IGOR REGO FONTES
  • Data: Apr 25, 2016


  • Show Abstract
  • Técnicas de Classificação Automática de Modulação (AMC) têm sido utilizadas por sistemas modernos de comunicação para otimizar o uso do espectro e com isso aumen- tar as taxas de transmissão de dados. No processo de AMC, várias arquiteturas podem ser utilizadas para retirar informação e avaliar características do sinal modulado em um canal. Uma grande parte dessas arquiteturas são construídas utilizando como base a ci- cloestacionariedade. A análise cicloestacionária é realizada por meio das ferramentas: Função de Autocorrelação Cíclica (CAF) e Função Densidade Espectral Cíclica (SCD). Esta ultima particularmente, é utilizada para observar as características cicloestacionárias de diferentes sinais, as quais são chamadas de assinaturas. Embora tenha várias aplica- ções bem sucedidas no âmbito de AMC, a cicloestacionariedade possui restrições pois a CAF e SCD são limitadas à análise estatística de segunda ordem, devido ao uso da correlação com cerne de sua expressão. Com o objetivo de generalizar a avaliação da cicloestacionariedade sobre infinitos momentos estatísticos de um sinal, surgem Função de Autocorrentropia Cíclica (CCAF) e a Função Densidade Espectral de Correntropia Cíclica (CCSD). Tais funções são fundamentadas no cálculo da correntropia. Neste tra- balho a CCSD será investigada quanto capacidade de gerar assinaturas para diferentes modulações e seu potencial de uso em AMC será avaliado. 

3
  • JOÃO GUTEMBERG BARBOSA DE FARIAS FILHO
  • Model Predictive Control with Compensation of Nonlinearities for Quadcopter Control

  • Advisor : CARLOS EDUARDO TRABUCO DOREA
  • BANKING MEMBERS :
  • CARLOS EDUARDO TRABUCO DOREA
  • KURIOS IURI PINHEIRO DE MELO QUEIROZ
  • PABLO JAVIER ALSINA
  • WALLACE MOREIRA BESSA
  • ANDRE GUSTAVO SCOLARI CONCEICAO
  • Data: Sep 30, 2016


  • Show Abstract
  • This study analises the application of Model Predictive Control (MPC) with the proposed Nonlinear Compensation Method in order to control a quadcopter. This method is based on the use of the system nonlinear model to predict and insert nonlinearities in the predictive control formulation by means of an affine structure. With respect to the control of a quadcopter, the proposed controller is compared, using numerical simulations, to the traditional linear predictive controller. After that, experiments were made with a real quadcopter mounted in a test bench. As a result, the use of the proposed method brought a considerable perfomance improvement when the system state were farther apart from the operation point in which it was linearized.


4
  • GEORGE OLIVEIRA DE ARAUJO AZEVEDO
  • Controle de sistemas eletro-hidráulicos via linearização por realimentação com compensação inteligente de incertezas.

  • Advisor : WALLACE MOREIRA BESSA
  • BANKING MEMBERS :
  • ALESSANDRO ROSA LOPES ZACHI
  • CARLOS EDUARDO TRABUCO DOREA
  • MARCIO VALERIO DE ARAUJO
  • WALLACE MOREIRA BESSA
  • Data: Nov 25, 2016


  • Show Abstract
  • Com o surgimento de técnicas de controle que utilizam estratégias não lineares combinadas com algoritmos da inteligência artificial, tem sido possível em diversas área da engenharia o controle eficaz de sistemas não lineares, mesmo na presença de elevado grau de incertezas. A lógica difusa (fuzzy) se destaca dentre as técnicas de inteligência artificial tanto pela facilidade de sua implementação quanto pela semelhança entre o seu processo de inferência e o raciocínio humano. Outra vantagem reside no fato da lógica difusa não necessitar de conhecimento prévio do modelo do sistema, quando aplicada ao controle de sistemas dinâmicos. No que tange às estratégias de controle não linear, a principal limitação da técnica de linearização por realimentação, por exemplo, está na necessidade do conhecimento do modelo do sistema. Os sistemas eletro-hidráulicos, por sua vez, possuem modelo não linear de difícil controle pelas técnicas tradicionais e são utilizados em diversas áreas da engenharia, como por exemplo nos setores industrial e aeroespacial. Desta forma, mostra-se extremamente importante que seu controle seja realizado de maneira eficiente, tanto por questões de economia quanto de segurança. Partindo das dificuldades apresentadas ao tentar controlar esse tipo de sistema, são apresentadas propostas de utilização da técnica de controle de linearização por realimentação em conjunto com a lógica difusa para compensar a não linearidade de zona morta e demais incertezas inerentes a este tipo de sistema. Para avaliar o desempenho das estratégias de controle propostas são realizadas simulações numéricas utilizando um modelo não linear simplificado desse sistema e também são desenvolvidos testes experimentais em um atuador eletro-hidráulico de bancada.

5
  • YURI SARMENTO SILVEIRA
  • A New Robot Path Planning Method Based on Probabilistic Foam

  • Advisor : PABLO JAVIER ALSINA
  • BANKING MEMBERS :
  • PABLO JAVIER ALSINA
  • ADELARDO ADELINO DANTAS DE MEDEIROS
  • ALLAN DE MEDEIROS MARTINS
  • EDUARDO OLIVEIRA FREIRE
  • Data: Dec 16, 2016


  • Show Abstract
  • Path planning is a well studied problem in robotics. The capability of analyzing the environment and defining a sequence of actions that lead a robot from an initial location to a final desired location, without colliding with obstacles, is an fundamental ability when creating autonomous robotic systems that can run various functions.  

    In order to contextualize the theme addressed in this work, a succinct study of the state-of-the-art on path planning for autonomous robotic systems is presented.

    Each planning method has its own strategy to explore the ambient and plan the path. In this dissertation, a new robot path planning method is proposed. In the proposed method, the ambient free space is partially covered by a set called Probabilistic Foam, composed of the union of overlapping convex subsets called Bubbles.

    Starting from the initial robot localization, new bubbles are randomly created on the surface of the foam, that propagates through the free space, with a behavior similar to a wave front propagation, generating a search tree that grows until reaching the desired final robot localization. In this way, it is possible to find a sequence of concatenated bubbles, called Rosary, connecting the desired final localization to the initial localization of the robot. A valid path contained in the maneuvering space defined by the rosary can be easily found.

    In the proposed method, the search process is guided by only two parameters. Tuning criteria for these parameters are studied and presented in this work.

    In order to validate the proposed path planning method, its performance was evaluated through computer simulations of different case studies.

2015
Dissertations
1
  • ANDOUGLAS GONÇALVES DA SILVA JÚNIOR
  • Sistema Mecatrônico de Tempo Real para Monitoramento da Qualidade da Água Embarcado em Veleiro Robótico Autônomo

  • Advisor : LUIZ MARCOS GARCIA GONCALVES
  • BANKING MEMBERS :
  • JOAO MORENO VILAS BOAS DE SOUZA SILVA
  • LUIZ MARCOS GARCIA GONCALVES
  • PABLO JAVIER ALSINA
  • RAFAEL VIDAL AROCA
  • Data: Oct 8, 2015


  • Show Abstract
  • Propomos um sistema mecatrônico completo para monitoramento da qualidade da água em rios, lagoas (e represas) e no mar, capaz de realizar a coleta, processamento e apresentação dos dados na web, em tempo real, com o intuito de facilitar a sua análise, de forma rápida e precisa pelas comunidades interessadas. A título de aplicação, o sistema está sendo embarcado em um veleiro robótico autônomo, que será a plataforma responsável por coletar os dados em vários pontos pré-definidos em um sistema de planejamento de navegação. Este projeto une as vantagens da autonomia de um veleiro robótico com a necessidade de monitoramento rápido e preciso da qualidade da água. Introduzimos a arquitetura de hardware e software de um sistema de monitoramento genérico que dá suporte a diferente aplicações, focando sua utilização em um veleiro robótico autônomo não tripulado, facilitando o desenvolvimento de pesquisas nessa área. 

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