Myoelectric Signal Monitoring System

The Electromyography (EMG) is an important tool for gait analyzes and disorders diagnoses. Traditional methods involve equipment that can disturb the analyses, being gradually substituted by different approaches, like wearable and wireless systems. The cable replacement for autonomous systems demands for technologies capable of meeting the power constraints. This work presents the development of an EMG and kinematic data capture wireless module, designed taking into account power consumption issues. This module captures and converts the analog myoeletric signal to digital, synchronously with the capture of kinetic information. Both data are time multiplexed and sent to a PC via Bluetooth link. The work carried out comprised the development of the hardware, the firmware and a graphical interface running in an external PC. The hardware was developed using the PIC18F14K22, a low power family of microcontrollers. The link was established via Bluetooth, a protocol designed for low power communication. An application was also developed to recover and trace the signal to a Graphic User Interface (GUI), coordinating the message exchange with the firmware. Results were obtained which allowed validating the conceived system in static and with the subject performing short movements. Although it was not possible to perform the tests within more dynamic movements, it is shown that it is possible to capture, transmit and display the captured data as expected. Some suggestions to improve the system performance also were made.

Conceção e Análise de um Demonstrador para a Monitorização Estrutural

Os sistemas de monitorização de estruturas fornecem diversas vantagens, não só no que diz respeito à durabilidade da obra, ao aumento da segurança e do conhecimento relativamente ao comportamento das estruturas ao longo do tempo, à otimização do aspeto estrutural, bem como aos aspetos económicos do processo de construção e manutenção. A monitorização deve realizar-se durante a fase de construção e/ou de exploração da obra para permitir o registo integral do seu comportamento no meio externo. Deve efetuar-se de forma contínua e automática, executando intervenções de rotina para que se possa detetar precocemente sinais de alterações, respetivamente à segurança, integridade e desempenho funcional. Assim se poderá manter a estrutura dentro de parâmetros aceitáveis de segurança. Assim, na presente dissertação será concebido um demonstrador experimental, para ser estudado em laboratório, no qual será implementado um sistema de monitorização contínuo e automático. Sobre este demonstrador será feita uma análise de diferentes grandezas em medição, tais como: deslocamentos, extensões, temperatura, rotações e acelerações. Com carácter inovador, pretende-se ainda incluir neste modelo em sintonia de medição de coordenadas GNSS com o qual se torna possível medir deslocamentos absolutos. Os resultados experimentais alcançados serão analisados e comparados com modelos numéricos. Conferem-se os resultados experimentais de natureza estática e dinâmica, com os resultados numéricos de dois modelos de elementos finitos: um de barras e outro de casca. Realizaram-se diferentes abordagens tendo em conta as características identificadas por via experimental e calculadas nos modelos numéricos para melhor ajuste e calibração dos modelos numéricos Por fim, recorre-se a algoritmos de processamento e tratamento do respetivo sinal com aplicação de filtros, que revelam melhorar com rigor o sinal, de forma a potenciar as técnicas de fusão multisensor. Pretende-se integrar o sinal GNSS com os demais sensores presentes no sistema de monitorização. As técnicas de fusão multisensor visam melhor o desempenho deste potencial sistema de medição, demonstrando as suas valências no domínio da monitorização estrutural.

Avaliação da integridade estrutural de uma prótese cimentada por emissão acústica

Mestrado em Engenharia Electrotécnica e de Computadores

I2S - MBO Management Buy-Out

Com o presente trabalho pretende-se dar a conhecer algumas das ações mais relevantes desenvolvidas pelo seu autor junto de um conjunto de empresas ao longo dos últimos vinte e cinco anos, como especialista de domínio na área da Gestão e Administração, e em particular na área da Gestão Financeira. Pretende-se também, ainda que de uma forma breve, dar a conhecer e fazer o relato das tarefas que foram desenvolvidas no âmbito de uma operação de investimento/financiamento, vulgarmente designada de MBO – Management Buy-Out, que, pelas suas particularidades, poderá ser do interesse geral a sua divulgação. As especificidades desta operação, bem como a abrangência das ações necessárias ao seu sucesso, constituíram para os seus responsáveis um desafio e uma oportunidade de crescimento intelectual, quer pela necessidade de aquisição e aprofundamento de conhecimentos técnicos, quer pelo exercício da gestão pura (negociação, avaliação de cenários, gestão de expectativas, tomada de decisão, comunicação).

Estudo e desenvolvimento de eléctrodos de superfície para electrocardiografia

Mestrado em Engenharia Electrotécnica e de Computadores – Ramo Automação e Sistemas.

ECG denoising based on adaptive signal processing technique

An Electrocardiogram (ECG) monitoring system deals with several challenges related with noise sources. The main goal of this text was the study of Adaptive Signal Processing Algorithms for ECG noise reduction when applied to real signals. This document presents an adaptive ltering technique based on Least Mean Square (LMS) algorithm to remove the artefacts caused by electromyography (EMG) and power line noise into ECG signal. For this experiments it was used real noise signals, mainly to observe the di erence between real noise and simulated noise sources. It was obtained very good results due to the ability of noise removing that can be reached with this technique. A recolha de sinais electrocardiogr a cos (ECG) sofre de diversos problemas relacionados com ru dos. O objectivo deste trabalho foi o estudo de algoritmos adaptativos para processamento digital de sinal, para redu c~ao de ru do em sinais ECG reais. Este texto apresenta uma t ecnica de redu c~ao de ru do baseada no algoritmo Least Mean Square (LMS) para remo c~ao de ru dos causados quer pela actividade muscular (EMG) quer por ru dos causados pela rede de energia el ectrica. Para as experiencias foram utilizados ru dos reais, principalmente para aferir a diferen ca de performance do algoritmo entre os sinais reais e os simulados. Foram conseguidos bons resultados, essencialmente devido as excelentes caracter sticas que esta t ecnica tem para remover ru dos.

Can ERASMUS mobility really help crossing borders? the in and out of a case-study

As lectures, but above all, as Erasmus....

Diagnóstico de máquinas elétricas pela análise de vibração

O diagnóstico de máquinas elétricas pela análise de vibração é utilizado num plano de manutenção, onde é dado a conhecer a “real condição do equipamento”, e surgiu da necessidade de detetar vibrações indesejáveis nas máquinas elétricas, de uma forma simples e com custos acessíveis. Numa fase inicial é obtido um sinal correspondente á vibração da máquina, recorrendo a um acelerômetro, que dependendo da aceleração da máquina, constrói uma forma de onda correspondente. A forma de onda fica guardada em formato de áudio *.wav. Posteriormente, em software Matlab o ficheiro *.wav irá ser carregado, e comparado com o ficheiro *.wav original da máquina. Ao comparar os ficheiros o software analisa o espectro original da máquina através da transformada de Fourier, com o espectro atual. Se este espectro sair do intervalo de segurança, o software deteta nesse espectro a origem da vibração, pois cada vibração tem uma frequência associada. Percorridos os passos descritos, o software disponibiliza ao utilizador as respetivas formas de onda e todo o restante diagnóstico de forma a uma possível intervenção antecipada da avaria.

Multiplexed electrochemical immunosensor for detection of celiac disease serological markers

Celiac disease (CD) is a gluten-induced autoimmune enteropathy characterized by the presence of antibodies against gliadin (AGA) and anti-tissue transglutaminase (anti-tTG) antibodies. A disposable electrochemical dual immunosensor for the simultaneous detection of IgA and IgG type AGA and antitTG antibodies in real patient’s samples is presented. The proposed immunosensor is based on a dual screen-printed carbon electrode, with two working electrodes, nanostructured with a carbon–metal hybrid system that worked as the transducer surface. The immunosensing strategy consisted of the immobilization of gliadin and tTG (i.e. CD specific antigens) on the nanostructured electrode surface. The electrochemical detection of the human antibodies present in the assayed serum samples was carried out through the antigen–antibody interaction and recorded using alkaline phosphatase labelled anti-human antibodies and a mixture of 3-indoxyl phosphate with silver ions was used as the substrate. The analytical signal was based on the anodic redissolution of enzymatically generated silver by cyclic voltammetry. The results obtained were corroborated with commercial ELISA kits indicating that the developed sensor can be a good alternative to the traditional methods allowing a decentralization of the analyses towards a point-of-care strategy.

BANMAC: an opportunistic MAC protocol for reliable communications in body area networks

We consider reliable communications in Body Area Networks (BAN), where a set of nodes placed on human body are connected using wireless links. In order to keep the Specific Absorption Rate (SAR) as low as possible for health safety reasons, these networks operate in low transmit power regime, which however, is known to be error prone. It has been observed that the fluctuations of the Received Signal Strength (RSS) at the nodes of a BAN on a moving person show certain regularities and that the magnitude of these fluctuations are significant (5 - 20 dB). In this paper, we present BANMAC, a MAC protocol that monitors and predicts the channel fluctuations and schedules transmissions opportunistically when the RSS is likely to be higher. The MAC protocol is capable of providing differentiated service and resolves co-channel interference in the event of multiple co-located BANs in a vicinity. We report the design and implementation details of BANMAC integrated with the IEEE 802.15.4 protocol stack. We present experimental data which show that the packet loss rate (PLR) of BANMAC is significantly lower as compared to that of the IEEE 802.15.4 MAC. For comparable PLR, the power consumption of BANMAC is also significantly lower than that of the IEEE 802.15.4. For co-located networks, the convergence time to find a conflict-free channel allocation was approximately 1 s for the centralized coordination mechanism and was approximately 4 s for the distributed coordination mechanism.

Analysis of UV spectral bands using multidimensional scaling

This study describes the change of the ultraviolet spectral bands starting from 0.1 to 5.0 nm slit width in the spectral range of 200–400 nm. The analysis of the spectral bands is carried out by using the multidimensional scaling (MDS) approach to reach the latent spectral background. This approach indicates that 0.1 nm slit width gives higher-order noise together with better spectral details. Thus, 5.0 nm slit width possesses the higher peak amplitude and lower-order noise together with poor spectral details. In the above-mentioned conditions, the main problem is to find the relationship between the spectral band properties and the slit width. For this aim, the MDS tool is to used recognize the hidden information of the ultraviolet spectra of sildenafil citrate by using a ShimadzuUV–VIS 2550, which is in theworld the best double monochromator instrument. In this study, the proposed mathematical approach gives the rich findings for the efficient use of the spectrophotometer in the qualitative and quantitative studies.

Projeto de ensino de Inglês articulado/integrado no 1º Ciclo do Ensino Básico

Mestrado em Ensino Precoce do Inglês

Collision-free prioritized medium access in the presence of hidden nodes without relying on out-of-band signaling

Consider the problem of sharing a wireless channel between a set of computer nodes. Hidden nodes exist and there is no base station. Each computer node hosts a set of sporadic message streams where a message stream releases messages with real-time deadlines. We propose a collision-free wireless medium access control (MAC) protocol which implements staticpriority scheduling. The MAC protocol allows multiple masters and is fully distributed. It neither relies on synchronized clocks nor out-of-band signaling; it is an adaptation to a wireless channel of the dominance protocol used in the CAN bus. But unlike that protocol, our protocol does not require a node having the ability to receive an incoming bit from the channel while transmitting to the channel. Our protocol has the key feature of not only being prioritized and collision-free but also dealing successfully with hidden nodes. This key feature enables schedulability analysis of sporadic message streams in multihop networks.

A sensor classification strategy for robotic manipulators

In practice the robotic manipulators present some degree of unwanted vibrations. The advent of lightweight arm manipulators, mainly in the aerospace industry, where weight is an important issue, leads to the problem of intense vibrations. On the other hand, robots interacting with the environment often generate impacts that propagate through the mechanical structure and produce also vibrations. In order to analyze these phenomena a robot signal acquisition system was developed. The manipulator motion produces vibrations, either from the structural modes or from endeffector impacts. The instrumentation system acquires signals from several sensors that capture the joint positions, mass accelerations, forces and moments, and electrical currents in the motors. Afterwards, an analysis package, running off-line, reads the data recorded by the acquisition system and extracts the signal characteristics. Due to the multiplicity of sensors, the data obtained can be redundant because the same type of information may be seen by two or more sensors. Because of the price of the sensors, this aspect can be considered in order to reduce the cost of the system. On the other hand, the placement of the sensors is an important issue in order to obtain the suitable signals of the vibration phenomenon. Moreover, the study of these issues can help in the design optimization of the acquisition system. In this line of thought a sensor classification scheme is presented. Several authors have addressed the subject of the sensor classification scheme. White (White, 1987) presents a flexible and comprehensive categorizing scheme that is useful for describing and comparing sensors. The author organizes the sensors according to several aspects: measurands, technological aspects, detection means, conversion phenomena, sensor materials and fields of application. Michahelles and Schiele (Michahelles & Schiele, 2003) systematize the use of sensor technology. They identified several dimensions of sensing that represent the sensing goals for physical interaction. A conceptual framework is introduced that allows categorizing existing sensors and evaluates their utility in various applications. This framework not only guides application designers for choosing meaningful sensor subsets, but also can inspire new systems and leads to the evaluation of existing applications. Today’s technology offers a wide variety of sensors. In order to use all the data from the diversity of sensors a framework of integration is needed. Sensor fusion, fuzzy logic, and neural networks are often mentioned when dealing with problem of combing information from several sensors to get a more general picture of a given situation. The study of data fusion has been receiving considerable attention (Esteban et al., 2005; Luo & Kay, 1990). A survey of the state of the art in sensor fusion for robotics can be found in (Hackett & Shah, 1990). Henderson and Shilcrat (Henderson & Shilcrat, 1984) introduced the concept of logic sensor that defines an abstract specification of the sensors to integrate in a multisensor system. The recent developments of micro electro mechanical sensors (MEMS) with unwired communication capabilities allow a sensor network with interesting capacity. This technology was applied in several applications (Arampatzis & Manesis, 2005), including robotics. Cheekiralla and Engels (Cheekiralla & Engels, 2005) propose a classification of the unwired sensor networks according to its functionalities and properties. This paper presents a development of a sensor classification scheme based on the frequency spectrum of the signals and on a statistical metrics. Bearing these ideas in mind, this paper is organized as follows. Section 2 describes briefly the robotic system enhanced with the instrumentation setup. Section 3 presents the experimental results. Finally, section 4 draws the main conclusions and points out future work.

An embedded 1149.4 extension to support mixed-signal debugging

Debugging electronic circuits is traditionally done with bench equipment directly connected to the circuit under debug. In the digital domain, the difficulties associated with the direct physical access to circuit nodes led to the inclusion of resources providing support to that activity, first at the printed circuit level, and then at the integrated circuit level. The experience acquired with those solutions led to the emergence of dedicated infrastructures for debugging cores at the system-on-chip level. However, all these developments had a small impact in the analog and mixed-signal domain, where debugging still depends, to a large extent, on direct physical access to circuit nodes. As a consequence, when analog and mixed-signal circuits are integrated as cores inside a system-on-chip, the difficulties associated with debugging increase, which cause the time-to-market and the prototype verification costs to also increase. The present work considers the IEEE1149.4 infrastructure as a means to support the debugging of mixed-signal circuits, namely to access the circuit nodes and also an embedded debug mechanism named mixed-signal condition detector, necessary for watch-/breakpoints and real-time analysis operations. One of the main advantages associated with the proposed solution is the seamless migration to the system-on-chip level, as the access is done through electronic means, thus easing debugging operations at different hierarchical levels.