Doutorado em Engenharia Elétrica

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A brain-computer interface architecture based on motor mental tasks and music imagery
(Universidade Federal do Espírito Santo, 2013-08-30) Benevides, Alessandro Botti; Bastos Filho, Teodiano Freire; Sarcinelli Filho, Mário; Ferreira, André; Frizera Neto, Anselmo; Conci, Aura; Tierra Criollo, Carlos Julio
This present research proposes a Brain-Computer Interface (BCI) architecture adapted to motor mental tasks and music imagery. For that purpose the statistical properties of the electroencephalographic signal (EEG) were studied, such as its probability distribution function, stationarity, correlation and signal-to-noise ratio (SNR), in order to obtain a minimal empirical and well-founded parameter system for online classification. Stationarity tests were used to estimate the length of the time windows and a minimum length of 1.28 s was obtained. Four algorithms for artifact reduction were tested: threshold analysis, EEG filtering and two Independent Component Analysis (ICA) algorithms. This analysis concluded that the algorithm fastICA is suitable for online artifact removal. The feature extraction used the Power Spectral Density (PSD) and three methods were tested for automatic selection of features in order to have a training step independent of the mental task paradigm, with the best performance obtained with the Kullback-Leibler symmetric divergence method. For the classification, the Linear Discriminant Analysis (LDA) was used and a step of reclassification is suggested. A study of four motor mental tasks and a non-motor related mental task is performed by comparing their periodograms, Event-Related desynchronization/synchronization (ERD/ERS) and SNR. The mental tasks are the imagination of either movement of right and left hands, both feet, rotation of a cube and sound imagery. The EEG SNR was estimated by a comparison with the correlation between the ongoing average and the final ERD/ERS curve, in which we concluded that the mental task of sound imagery would need approximately five times more epochs than the motor-related mental tasks. The ERD/ERS could be measured even for frequencies near 100 Hz, but in absolute amplitudes, the energy variation at 100 Hz was one thousand times smaller than for 10 Hz, which implies that there is a small probability of online detection for BCI applications in high frequency. Thus, most of the usable information for online processing and BCIs corresponds to the α/µ band (low frequency). Finally, the ERD/ERS scalp maps show that the main difference between the sound imagery task and the motor-related mentaltasks is the absence of ERD at the µ band, in the central electrodes, and the presence of ERD at the αband in the temporal and lateral-frontal electrodes, which correspond tothe auditory cortex, the Wernickes area and the Brocas area.
A fairness-focused spectrum assignment algorithm for elastic optical networks
(Universidade Federal do Espírito Santo, 2016-09-27) Tessinari, Rodrigo Stange; Garcia, Anilton Salles; Waldman, Hélio; Martins, Joberto Sérgio Barbosa; Resendo, Leandro Colombi; Segatto, Marcelo Eduardo Vieira; Paiva, Marcia Helena Moreira
In the past few years, Elastic Optical Networking (EON) emerged as the next generation core network technology, intended to surpass Wavelength-Division Multiplexing (WDM) weaknesses and limitations. WDM is the most successful and widely used technology in the backbone of the optical networks. However, in recent years Internet traffic in the core network has been doubling almost every two years, and predictions indicate that it will continue to exhibit exponential growth due to emerging applications such as high-definition and real-time video communications. To keep pace with the always greater demand for bandwidth, EON relies on Optical Orthogonal Frequency Division Multiplexing (OOFDM) and advanced modulation technologies which enhance spectral efficiency and flexibility. OOFDM allows the aggregation of multiple sub-carriers to form super-channels, thus changing the paradigm of the network from fixed-size WDM channels to variable-sized EON channels that can reduce spectrum waste up to 60%. EON presents several other benefits such as high spectral and energy efficiency and flexible bandwidth adaptation over time. Despite all benefits, no technology is perfect, and the added EON efficiency and flexibility comes at the price of increased complexity and new problems, such as spectrum fragmentation and service unfairness. A considerable amount of work has been done on both fragmentation and unfairness problems, introducing a broad range of solutions, which raises the following question: "how to compare existent solutions and how to identify which one is better suited for the required scenario?" In this context, it is presented the first contribution of this Doctoral Thesis, ElasticO++, an Elastic Optical Network Simulation Framework for OMNeT++. ElasticO++ is a framework created to enable testing a whole range of routing, modulation, spectrum assignment, defragmentation algorithms, parameters, and topologies. At present, the proposed framework is the first software available capable of working with fragmentation and defragmentation in dynamic network scenarios. The flexibility offered on the proposed tool allows both academia and industry to develop new algorithms and techniques for Elastic Optical Networks. The second contribution of this Doctoral Thesis is the Zone-Based Spectrum Assignment Algorithm. The proposed algorithm is an attempt to solve the unfairness and fragmentation problems, taking advantage of the spectrum management concept. In this Doctoral Thesis, it is presented two versions of the technique: the static version and the dynamic version. The static version is intended to be used in cases where the information regarding the nature of the network traffic is known beforehand, whereas the dynamic version was developed as a solution in cases in which absolutely no information is known.
A Human-Machine Interface Based on Eye Tracking for Controlling and Monitoring a Smart Home Using the Internet of Things
(Universidade Federal do Espírito Santo, 2019-02-20) Bissoli, Alexandre Luís Cardoso; Encarnação, Lucas Frizera; Bastos Filho, Teodiano Freire; Adams, Kimberly; Krishnan, Sridhar; Villa Parra, Ana Cecilia; Ferreira, André
People with severe disabilities may have difficulties when interacting with their home devices, due to the limitations inherent to their disability. Simple home activities may be even impossible for this group of people. Although many works have been devoted to proposing new assistive technologies to improve the lives of people with disabilities, some studies have found that the abandonment of such technologies is quite high. In this sense, this work presents a new and useful assistive system based on eye tracking for controlling and monitoring a smart home based on internet of things, which was developed following concepts of user-centered design and usability. With this system, a person with severe disabilities was able to control everyday equipment of her residence, such as lamps, television, fan and radio. In addition, her caregiver was able to monitor remotely, by internet, her use of the system in real time. Additionally, the user interface developed here has some functionalities that allowed improving the usability of the system as a whole. The experiments were divided into two steps. In the first step, the assistive system was assembled in an actual home, where tests were conducted with 29 participants without disabilities (group of able-bodied participants). In the second step, the system was tested with online monitoring, for seven days, by a person with severe disability (end-user), in her own home, not only to increase convenience and comfort, but also so that the system could be tested where it would in fact be used. At the end of both steps, all the participants answered the SUS questionnaire, which showed that both the group of able-bodied participants and the person with severe disabilities evaluated the assistive system with a mean of 89.9 and 92.5, respectively.Keywords:Human-Machine Interface (HMI); Human-Computer Interaction (HCI); Smart Home; Eye Tracking; Assistive Technology; Usability Evaluation; User-Centered Design (UCD); Home Automation; Internet of Things (IoT).
A novel approach of independent brain-computer interface based on SSVEP
(Universidade Federal do Espírito Santo, 2016-09-01) Tello, Richard Junior Manuel Godinez; Ferreira, André; Müller, Sandra Mara Torres; Bastos Filho, Teodiano Freire; Ciarelli, Patrick Marques; Lima, Eduardo Roncon de; Sá, Antônio Maurício Miranda de
Over the past ten years, Brain Computer Interfaces (BCIs) based on Steady- State Visual Evoked Potentials (SSVEP) have attracted the attention of many researchers due to the promissory results and the high accuracy rates achieved. This type of BCI provides to people with severe neuromotor difficulties the possibility to communicate with the world around them using visual attention modulation to blinking lights at a given frequency. This thesis aiming at developing a new approach of Independent BCI, in which users are not required to perform neuromuscular tasks to select visual targets, a feature that distinguishes it from traditional SSVEP-BCIs. Thus, people with severe motor disabilities as Amyotrophic Lateral Sclerosis (ALS) have a new alternative channel to communicate with the world around them using brain signals. Several contributions were done in this thesis, such as: improvement of the feature extractor called Multivariate Synchronization Index (MSI) for detecting evoked potentials; development of a new method for detecting evoked potentials through correlating multidimensional models (tensors); a first study on the influence of colored stimuli in SSVEPs detection using LEDs; the development of the concept of Compressive sensing applied to SSVEPs; and, finally, the development of a novel independent BCI under an approach named Figure-Ground Perception (FGP)
A novel stimulation paradigm for a brain-computer interface based on SSVEP
(Universidade Federal do Espírito Santo, 2015-11-30) Atencio, Anibal Cotrina; Ferreira, André; Bastos Filho,Teodiano Freire; Frizera Neto, Anselmo; Sarcinelli Filho, Mario; Krohling, Renato Antônio; Sá, Antonio Mauricio Ferreira Leite Miranda de
Brain-computer interfaces (BCIs) are systems that provide a direct connection between users’ brain signals and a computer, generating an alternative channel of communication that does not involve the traditional way as muscles and nerves. They help to restore or replace useful functions of people with paralysis. For instance, BCI systems based on SSVEP (SSVEP-BCI) present a set of stimuli flickering at different frequencies to the users, detect which stimulus is being gazed and associate this information to commands that can be used to control a robotic wheelchair, an exoskeleton, or a speller. Nowadays, SSVEP-BCIs are being widely used due to the high SNR of their response that is achieved when the target stimulus is brought to the center of the user’s field of view. Paradoxically, it is their main disadvantage because bringing a stimulus to the center of the field of view demands muscular activity making them not suitably for paralyzed people who cannot control their head, neck and/or eyeball movements for redirecting their gaze. In optical systems, the range of distance near the point of focus where objects are perceived sharp is referred as Depth-of-field; objects outside this region are defocused and blurred. The mechanism of the visual system that adjusts the eye focal length for focusing does not demand neck, head and/or eyeball movements. Furthermore, ophthalmology studies state that the amplitude and the latency of visual evoked potentials are affected by defocusing. In this context, this Thesis proposes a novel SSVEP-BCI paradigm, in which two stimuli are presented together in the center of the user’s field of view but at different distances from him, ensuring that if one stimulus is focused on, the other one is non-focused, and vice versa; with the aim of providing an alternative way of sending commands through a stimuli selection by a focusing mechanism. In this sense, first, a model of VEP generation for two stimuli is introduced and the hypothesis that distinguishable SSVEP can be elicited by the focused stimulus, regardless of the non-focused stimulus is also present, is tested by employing the SFT-based ORD. Next, a demodulation method based in LPF and HPF is proposed for the case in that two stimuli are present in the field of view; and spatial-temporal retinal response for flickering stimuli is described by using PSF and NPSF functions. Finally, CCA, PSDA, LASSO with EEG signals re-referenced at Pz and CAR are employed to detect the SSVEP pattern. Accuracy rate, Kappa coefficient, AUC, and ITR are used to evaluate the detection performance. As a result of the hypothesis test, the absence of evoked potentials due to a focused stimulus, when a non-focused stimulus is also present was rejected in most of the cases. In SSVEP detection experiments, an average accuracy rate of 0.93 was achieved for a time window of 7s and for eight healthy subjects who were asked to focus on just one stimulus at a time.
Admittance control of a robotic knee orthosis based on motion intention through sEMG of trunk muscles
(Universidade Federal do Espírito Santo, 2017-12-04) Parra, Ana Cecilia Villa; Frizera Neto, Anselmo; Bastos Filho, Teodiano Freire; Ferreira, Andre; Caldeira, Eliete Maria de Oliveira; Rocon, Eduardo; Bó, Antonio Padilha Lanari
The population that requires devices for motion improvement has increased considerably, due to aging and neurological impairments. Robotic devices, such as robotic orthosis, have greatly advanced with the objective of improving both the mobility and quality of life of people. Clinical researches remark that these devices, working in constant interaction with the neuromuscular and skeletal human system, improves functional compensation and rehabilitation. Hence, the users become an active part of the training/rehabilitation, facilitating their involvement and improving their neural plasticity. For this purpose, control approaches based on motion intention have been presented as a novel control framework for robotic devices. This work presents the development of a novel robotic knee exoskeleton controlled by motion intention based on sEMG, which uses admittance modulation to assist people with reduced mobility and improve their locomotion. For recognition of the lower-limb motion intention, sEMG signals from trunk are used, which implies a new approach to control robotic assistive devices. The control system developed here includes a stage for human-motion intention recognition (HMIR) system, which is based on techniques to classify motion classes related to knee joint. The motion classes that are taken into account are: stand-up, sit-down, knee flexionextension, walking, rest in stand-up position and rest sit-down position. For translation of the users intention to a desired state for the robotic knee exoskeleton, the system includes a finite state machine, in addition to admittance, velocity and trajectory controllers, which has also the function of stopping the movement according to the users intention. This work also proposes a method for on-line knee impedance modulation, which generates variable gains through the gait cycle for stance control during gait. The proposed HMIR system showed, in off-line analysis, an accuracy between 76% to 83% to recognize motion intention of lower-limb muscles, and 71% to 77% for trunk. Experimental on-line results of the controller showed that the admittance controller proposed here offers knee support in 50% of the gait cycle, and assists correctly the motion classes. A positive effect of the controller on users regarding safety during gait was also found, with a score of 4 in a scale of 5. Thus the robotic knee exoskeleton introduced here is an alternative method to empower knee movements using motion intention based on sEMG signals from lower limb and trunk muscles.
Alternativas de topologias retificadoras para aerogeradores síncronos a ímã permanente de baixa potência
(Universidade Federal do Espírito Santo, 2015-12-11) Freitas, Tiara Rodrigues Smarssaro de; Menegáz, Paulo José Mello; Simonetti, Domingos Sávio Lyrio; Antunes, Fernando Luiz Marcelo; Fardin, Jussara Farias; Encarnação, Lucas Frizera; Pinto Filho, Wilson Aragão Correia
Two controlled rectifier topologies applied to low power wind energy conversion system with permanent magnet synchronous generator are presented. For low power or stand-alone operation systems, where the energy from wind generation is a significant part of the total power system, generators and converters have the role of maintaining the grid’s voltage and frequency constant, despite the fluctuations of the wind turbine. In variable speed permanent magnet synchronous generator (PMSG), the preferred solution has been a conversion on two stages: AC-DC-AC. Several converter topologies have been explored, but kind of this conversion has many controlled elements, most of them with 6 controlled switches in AC-DC conversion, making it difficult and more expensive its control; each new topology introduces new aspects and always looking for a converter that best suits the system with minimally influence to the quality of power generation. The topologies presented in the literature are effective for the high power levels, but when it comes to systems with lower power levels, simpler converters (single or three controlled switches) can serve the purpose of rectification with a lower cost and without the conversion quality been reduced. The contribution of this thesis is the development of a new SEPIC rectifier topology using three controlled switches, and the analysis and new application of an existing resonant buck topology, with a single controlled switch, to wind energy system. They are simpler rectifying solutions, applied to low power wind generation based on permanent magnet synchronous generator, offering simplicity and control facility. The converter’s project, the equations that define them, the simulation and experimental results for each converter are presented. It was verified that both topologies could achieve high power-factor and low harmonic distortion employing only one single gate signal, on a wide range of wind speed with no current’s generator closed loop control.
Amplificadores óticos a fibra sob um ambiente dinâmico
(Universidade Federal do Espírito Santo, 2006-08-18) Freitas, Márcio; Calmon, Luiz de Calazans; Barbero, Andrés Pablo López; Ribeiro, Moisés Renato Nunes; Pontes,Maria José; Segatto, Marcelo Eduardo Vieira; Frasson, Antônio Manoel Ferreira
The recent advance in WDM technologies with the ability of add, drop and in effect construct wavelength-switched and wavelength-routed networks has brought a new dynamic-reconfigurable WDM network. This dynamic environment brings, besides the already well-known transmission impairments (such as chromatic dispersion, nonlinear effects, PMD, ASE, etc), a new set of impairments related to the add-drop possibilities that could severely degrade the system performance. Furthermore, the development of new optical amplifiers that could reach high output power values has also brought an increasing impact of nonlinear effects in the signal propagation at different applications. The optical fiber amplifiers presented in the study are the erbium-doped fiber, the ytterbiumdoped fiber amplifier, the erbium-ytterbium codoped fiber amplifier and the Raman fiber amplifiers. For this study, appropriate numeric models for each amplifier were implemented. This work investigates by numerical simulation how the optical fiber amplifiers and consequently the system performance are affected by the dynamic-reconfigurable traffic. Some contributions about the study of the power transient evolution generated by the optical amplifiers in different transmission bandwidths, under different amplifier configurations and in different applications are presented. It is also presented a contribution for the optimization of control methods to minimize the power transients generated by the optical amplifiers due the add-drop of channels in the system. Moreover, this work also analyzes the impact of high powers generated in the amplification process, and presents some contributions for the study of the nonlinear effects in the signals propagation through the amplifier.
AProSiMA - ambiente de resolução cooperativa de problemas baseado em simulação multiagente
(Universidade Federal do Espírito Santo, 2007-12-21) Azevedo, Lívia Lopes; Menezes, Crediné Silva de; Cury, Davidson; Boeres, Maria Claudia Silva; Tavares, Orivaldo de Lira; Castro Junior, Alberto Nogueira de
The complex systems studies has caught researchers ́ attention in several knowledge areas lately, because of increasing interest in the way of systems ́ organization. Examples of complex systems are presented in a variety of situation which we live and they have been largely studied through model of multiagent simulation. However, there is a gap between environments for complex systems studies and their users. This thesis shows a proposal to an environment named AProSiMA, which allows no experts users in program planning, build up their own model of multiagent simulation. The environment still presents like a general proposal to propose a process of cooperative problem solving. By the way it ́s available to the users: acess to information recover and mechanisms to locate experts who may be geographically distributed and invite them to work in a cooperative system looking for a solution to the problem, shared place to discuss and formalize the problems ́ resolution strategies; mechanisms to direct questions and answers to the experts, cooperated groups formation and communication mechanisms which may support up the cooperative work.
Back Lane Marking Registry: uma abordagem de localização e seguimento de caminho por veículos autônomos em via sinalizada
(Universidade Federal do Espírito Santo, 2017-11-23) Vivacqua, Rafael Peixoto Derenzi; Martins, Felipe Nascimento; Vassallo, Raquel Frizera; Wolf, Denis Fernando; Samatelo, Jorge Leonid Aching; Komati, Karin Satie; Amaral, Paulo Faria Santos
This thesis aimed to contribute with the development of autonomous driving technology. More specifically, the aim of this work was to design, build and test all the hardware and software needed to adapt a commercial vehicle so that it is able to successfully perform a predetermined transport mission repeatedly, as if it was a train traveling on a virtual railway. The issue of dynamic obstacles was not addressed in this research. Three approaches widely used in the literature were studied: (i) direct path tracking by detection of lane markings, (ii) global localization tracking (GNSS), and (iii) path tracking by lane marking maps. A prototype vehicle was built, respecting the low cost philosophy of the project, to carry out the experimental tests. The first two approaches served as the basis for the development of the final approach, based on visual track marker maps. This approach has produced the most positive results of the work and represents the greatest contribution of this thesis: the method called Back Lane Marking Registry or BLMR. The BLMR allows the construction of accurate, reliable and extensive perception of lane markings in the vicinity of the vehicle from low-cost sensors. This extensive perception combined with a fast filtering algorithm and map matching techniques led to localization accuracy which is high enough for autonomous application, as demonstrated in tests conducted in Italy.
Brain-Computer interface based on unsupervised methods to recognize motor intention for command of a robotic exoskeleton
(Universidade Federal do Espírito Santo, 2017-12-01) Rodríguez, Denis Delisle; Frizera Neto, Anselmo; Bastos Filho, Teodiano Freire; Ciarelli, Patrick Marques; Rocon, Eduardo; Bó, Antonio Padilha Lanari
Stroke and road traffic injuries may severely affect movements of lower-limbs in humans, and consequently the locomotion, which plays an important role in daily activities, and the quality of life. Robotic exoskeleton is an emerging alternative, which may be used on patients with motor deficits in the lower extremities to provide motor rehabilitation and gait assistance. However, the effectiveness of robotic exoskeletons may be reduced by the autonomous ability of the robot to complete the movement without the patient involvement. Then, electroencephalography signals (EEG) have been addressed to design brain-computer interfaces (BCIs), in order to provide a communication pathway for patients perform a direct control on the exoskeleton using the motor intention, and thus increase their participation during the rehabilitation. Specially, activations related to motor planning may help to improve the close loop between user and exoskeleton, enhancing the cortical neuroplasticity. Motor planning begins before movement onset, thus, the training stage of BCIs may be affected by the intuitive labeling process, as it is not possible to use reference signals, such as goniometer or footswitch, to select those time periods really related to motor planning. Therefore, the gait planning recognition is a challenge, due to the high uncertainty of selected patterns, However, few BCIs based on unsupervised methods to recognize gait planning/stopping have been explored. This Doctoral Thesis presents unsupervised methods to improve the performance of BCIs during gait planning/ stopping recognition. At this context, an adaptive spatial filter for on-line processing based on the Concordance Correlation Coefficient (CCC) was addressed to preserve the useful information on EEG signals, while rejecting neighbor electrodes around the electrode of interest. Here, two methods for electrode selection were proposed. First, both standard deviation and CCC between target electrodes and their correspondent neighbor electrodes are analyzed on sliding windows to select those neighbors that are highly correlated. Second, Zscore analysis is performed to reject those neighbor electrodes whose amplitude values presented significant difference in relation to other neighbors. Furthermore, another method that uses the representation entropy and the maximal information compression index (MICI) was proposed for feature selection, which may be robust to select patterns, as only it depends on cluster distribution. In addition, a statistical analysis was introduced here to adjust, in the training stage of BCIs, regularized classifiers, such as support vector machine (SVM) and regularized discriminant analysis (RDA). Six subjects were adopted to evaluate the performance of different BCIs based on the proposed methods, during gait planning/stopping recognition. The unsupervised approach for feature selection showed similar performance to other methods based on linear discriminant analysis (LDA), when it was applied in a BCI based on the traditional Weighted Average to recognize gait planning. Additionally, the proposed adaptive filter improved the performance of BCIs based on traditional spatial filters, such as Local Average Reference (LAR) and WAR, as well as others BCIs based on powerful methods, such as Common Spatial Pattern (CSP), Filter Bank Common Spatial Pattern (FBCSP) and Riemannian kernel (RK). RK presented the best performance in comparison to CSP and FBCSP, which agrees with the hypothesis that unsupervised methods may be more appropriate to analyze clusters of high uncertainty, as those formed by motor planning. BCIs using adaptive filter based on Zscore analysis, with an unsupervised approach for feature selection and RDA showed promising results to recognize both gait planning and gait stopping, achieving for three subjects, good values of true positive rate (>70%) and false positive (<16%). Thus, the proposed methods may be used to obtain an optimized BCI that preserves the useful information, enhancing the gait planning/stopping recognition. In addition, the method for feature selection has low computational cost, which may be suitable for applications that demand short time of training, such as clinical application time.
Contribuição à modelagem, simulação, implantação e controle inteligente de sistemas de combustão
(Universidade Federal do Espírito Santo, 2006-12-19) Lopes, Sérgio Leite; Ferreira, Edson de Paula; Salles, Evandro Ottoni Teatini; Amaral, Paulo Faria Santos; Amaral, Paulo Faria Santos; Fardin, Jussara Farias
The energy from combustion process performs na important role on World energy cenary and should be like that for a long time. The ambiental impact due to burn emissions joined to the rising fuel cost, justify new thechnological improvments on projects to control those process increasing energy efficience and emissions reducing. The proposal of this project is to reserch instrumentation technics, actuation and control in pulse and conventional combustion opperation process, applied to prototypes and industrial plants. The use of low cost instrumenatation and actuators on pulse furnace showed to br feasible since the design considerated high integration between fluid dynamics, sensors and actuators. On the traditional combustion issue, yhe use of neural net glue us a significant reduction on digital processing time at fuel burn chemical simulation giving a very good tool to control emissions and energetic efficiency.
Contribuições ao estudo da viabilidade de controle de laminadores de produtos planos : uma proposta Gain Scheduling clássica
(Universidade Federal do Espírito Santo, 2012-12-28) Cavazzana, Erlon; Denti Filho, José; Mattedi,Alessandro; Salles, José Leandro Félix; Caccioppoli, José Maria Ramon; Machado, Marcelo Lucas Pereira
abstract
Contribuições para o projeto de grooming de tráfego sobre redes ópticas WDM
(Universidade Federal do Espírito Santo, 2008-10-10) Resendo, Leandro Colombi; Pires, João José de Oliveira; Ribeiro, Moisés Renato Nunes; Mateus, Geraldo Robson; Almeida, Renato Tannure Rotta de; Garcia, Anilton Salles; Oliveira, Elias Silva de
The Traffic Grooming Problem (TGP) consists in how to arrange low-bandwidth connection requests into high-capacity lightpaths efficiently. TGP solution aims at improving network capacity utilization. The minimal number optoelectronic transceivers that enable accommodating traffic demands is often used as the objec- tive function for solving TGP. However, TGP belongs to a class of NP-hard problems and optimal solutions are only possible to be found within feasible processing time for small networks (e.g., 6 nodes). This work proposes novel Integer Linear Pro- gramming (ILP) models, heuristic and a hybrid solution to TGP for medium-sized (i.e., around 12 nodes) translucent networks. Initially, ILP models using node-link and link-path paradigms are proposed and their solutions are compared. These models lay the foundations for more complex models addressing issues on network design. A hybrid method is then proposed. It makes use of a heuristic for selecting lightpaths (i.e., the virtual topology) and an ILP model to route the traffic demands over both physical and virtual topologies efficiently. The practical implications of such approach is that it allows, for the first time, the quantification of benefits of transparent lightpaths in terms of transceiver count reduction. Moreover, the miti-gation of transit traffic processing in the electronic layer is also analyzed. For large networks the ILP phase in the hybrid approach again becomes the bottleneck for optimal network design and a fully heuristic solution is necessary. This work shows that efficient solutions can be found through a simple and fast tool for network design without the need of complex parameter tuning, as comparisons with results obtained from solving the hybrid model. Finally, the integration of TGP with survivability is proposed. This work puts forward ILP models for an iterative method using two ILP models to design networks with incremental protection with minimal num- ber of transceivers in mesh networks. Dual Node Interconnected (DNI) multi-ring topologies are studied under inter-ring traffic protection using Virtual Ring (VR) and Drop and Continue (D&C) strategies. Results compare optimal solutions that take into account traffic grooming for different network scenarios including opaque vs. translucent configurations and inter vs. intra traffic growth.
Controladores regulatórios auto-sintonizados de distúrbios cíclicos baseados em lógica fuzzy
(Universidade Federal do Espírito Santo, 2022-08-19) Pereira, Rogerio Passos do Amaral; Bastos Filho, Teodiano Freire; Salles, José Leandro Félix; https://orcid.org/0000-0001-9081-0418; Silva Junior, João Manoel Gomes da; Araújo, Rejane de Barros; Caldeira, Eliete Maria de Oliveira; Fardin, Jussara Farias
Some industrial processes have intrinsic cyclic disturbances. In these cases, it is natural to use Iterative Learning Control (ILC) or Repetitive Control (RC), or even combinations of these with other controllers, such as the Repetitive GPC (R-GPC), which integrates the RC with the Generalized Predictive Controller (GPC). One of the main weaknesses of these controllers is when the frequency of the periodic signal varies, as there is a gradual loss in its efficiency. Thus, in this PhD Thesis, a Fuzzy Logic based technique is proposed to estimate the total number of samples contained in a periodic disturbance subject to small and unknown frequency variations. Therefore, the Adaptive Fuzzy ILC (AF-ILC) controller and the Adaptive Fuzzy Repetitive GPC (AFR-GPC) controller are proposed here. In the AF-ILC, the proposed Fuzzy Estimator is applied to the ILC controller, whereas, in the AFR-GPC the Fuzzy Estimator is applied to a structure composed of predictive controllers, allowing these controllers to minimize periodic disturbances with frequency changes over time. Before testing, the controllers are tuned offline via genetic algorithm (AG). To adapt these controllers for frequency change variation, the number of disturbance samples is estimated with the system operating in closed loop (self-tuning adaptive controller) using Fuzzy Logic. As a case study, these controllers are tested in computer simulations in a continuous casting plant to compensate for the bulging disturbance present in the mold level control. In addition to the simulations, the controllers are tested in a didactic plant consisting of a resistive-capacitive circuit where periodic disturbances are present, which, although not having the same structure as the casting system, allows demonstrating that the proposed controllers work for a real plant.
Controle de robôs móveis por fusão de sinais de controle usando filtro de informação descentralizado
(Universidade Federal do Espírito Santo, 2002-08-14) Freire, Eduardo Oliveira; Bastos Filho,Teodiano Freire; Sarcinelli Filho, Mário; Carelli, Ricardo; Schneebeli, Hansjörg Andreas; Nasisi, Oscar; Salles, José Leandro Felix; Bergerman, Marcel
This thesis proposes an alternative approach to deal with the problem of mobile robot navigation, which is called fusion of control signals. The proposed technique has presented good results when a robot has to execute relatively complex tasks, like it is shown in the experiments here presented. The technique is developed with basis on the decentralised information filter, whose equations are here derived from the equations of the decentralised Kalman filter and the information filter. Motion controllers available in the literature and others introduced here for the first time are used to produce the control signals that are fused using a decentralised information filter in order to produce the overall output signal to be sent to the actuators. A stability analysis of the proposed architecture is also addressed.
Controle de sistemas multi-robôs aéreos
(Universidade Federal do Espírito Santo, 2014-12-10) Rosales, Claudio Darío; Scaglia, Gustavo Juan Eduardo; Sarcinelli Filho, Mário; Carelli, Ricardo; Canali, Luis Rafael; Patiño, Hector Daniel; Soria, Carlos Miguel; Altamira, Aníbal Leodegario
abstract
Controle de veículos aéreos não tripulados transportando cargas suspensas
(Universidade Federal do Espírito Santo, 2019-03-08) Pizetta, Igor Henrique Beloti; Brandão, Alexandre Santo; Sarcinelli Filho, Mário; Raffo, Guilherme Vianna; Bastos Filho, Teodiano Freire; Celeste, Wanderley Cardoso; Santana, Lucas Vago
The use of unmanned aerial vehicles (UAVs) to perform tasks is already a reality. These vehicles have great versatility, so that they can be used in several applications, such as in load transportation. In this Doctoral Thesis two load-carrying systems are proposed, with the use of one or two vehicles for transporting a load suspended by cables. As the load is free in the space, limited by the connection with the UAVs, oscillations occur due to its inertia, which affect the flight of the vehicles due to the transmission of forces to the vehicles connected by the cables. Mathematical models are developed starting from the Euler-Lagrange equations, and a nonlinear controller is proposed to guide the systems in the accomplishment of flight tasks, rejecting the disturbance generated by the load. In addition, the developed systems have the ability to avoid obstacles in their path. As an extra feature of the cooperative system, a potential field is proposed to prevent the vehicles of approaching during positioning tasks, thus preserving flight safety. First, the models and controller presented deal with navigation in a plane (PVTOL - Planar Vertical Takeoff and Landing). Next, we present the models and controller for the systems when navigating in three-dimensional space, with flight tasks corresponding to positioning and trajectory tracking, in addition to the combination with obstacle avoidance.
Controle em ambientes interiores de veículos aéreos não tripulados
(Universidade Federal do Espírito Santo, 2017-10-20) Santos, Milton César Paes; Carelli, Ricardo; Brandão, Alexandre Santos; Sarcinelli Filho, Mário; Mut, Vicente Antonio; Gandolfo, Daniel Ceferino; Celeste, Wanderley Cardoso; Santana, Lucas Vago
This thesis proposes nonlinear controllers to be applied to unmanned aerial vehicles (UAVs) in positioning, trajectory-tracking and path-following missions in 3D airspace. In addition, a prototype of a platform conceived to allow using UAVs in indoor environments is shown, with several computational tools that allows using aerial robots in such classic navigation missions. In order to contextualize the developed tools, we highlight the development of algorithms for the detection and localization of objects in the environment and a decentralized sensorial fusion structure that is used to improve the measurement of the posture data (position and orientation) of the UAVs, in addition to detecting obstacles. Subsequently, the same fusion filter is used to combine PVTOL (Planar Vertical Takeoff and Landing) control signals, relaxing the aircraft motion constraints, previously limited to displacement along the Z axis and the XZ and YZ vertical planes. Complementarily, the implementation of navigation and control systems is based on two different dynamic models, one simple and the other detailed. The control systems are designed using classic model inversion techniques, which has shown to be an efficient methodology for the design of controllers for the developed applications, namely positioning, trajectory-tracking and path-following. Additionally, a collision avoidance controller, an adaptive controller, and a controller with maximum speed saturation are designed. The stability of such controllers is demonstrated by the asymptotic convergence of the control variables and by the fulfillment of the control objective during the simulations and experiments performed, as expected from the theoretical analysis.
Controle preditivo sintonizado via algoritmo genético aplicado em processos siderúrgicos
(Universidade Federal do Espírito Santo, 2011-03-04) Almeida, Gustavo Maia de; Denti Filho, José; Salles, José Leandro Félix; Fardin, Jussara Farias; Mattedi, Alessandro; Coelho, Antônio Augusto Rodrigues; Machado, Marcelo Lucas Pereira
Techniques of Model Based Predictive Control (MPC) are increasingly applied in industry because they generally exhibit a good performance and robustness, since the parameters of controller are tuned correctly. This thesis use the Genetic Algorithm (GA) to perform the tuning of parameters of the predictive controller to control mono and multivariable, linear and nonlinear models. The existing technical literature for tuning Predictive Dynamic Matrix Controller (DMC), which use a step response to control systems that are open loop stable will be compared with the tuning by GA. In the event that the process is unstable in open-loop, there is not an analytical method for the tuning. Therefore, it is noted in the literature that the use of MPC in some open-loop unstable systems, linear or not (Such as these to be studied in this thesis) is lacking, because the tuning procedure is based on trial and error and sometimes is impractical. Therefore, this study focuses the application of the MPC tuning by Genetic algorithm for two open-loop unstable processes, which are very important in the Steel Industry. The first is composed by Rolling Mill Stands, where we wish to minimize the variation of strip thickness the last stand due to disturbances that affect the process such as temperature and strip thickness variations in the first stand. In this case we use the linear and multivariable model to develop the Generalized Predictive Controller (GPC) whose parameters are tuned by GA. The second process, unstable in open-loop, is the level of Mold of a Continuous Casting, which has a nonlinear model and is therefore controlled by techniques of nonlinear predictive control using neural networks and Hammerstein model. A comparison is made between these controllers to analyze the stability and robustness when the mold is affected by disturbance of Bulging, Clogging and Argon.

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