Modelo comportamental do capacitor ferroelétrico como unidade básica de neurônios artificiais e sua implementação em FPGA

This work proposes the use of the behavioral model of the hysteresis loop of the ferroelectrics capacitor as a new alternative to the usually costly techniques in the computation of nonlinear functions in artificial neurons implemented on reconfigurable hardware platform, in this case, a FPGA device. Initially the proposal has been validated by the implementation of the boolean logic through the digital models of two artificial neurons: the Perceptron and a variation of the model Integrate and Fire Spiking Neuron, both using the model also digital of the hysteresis loop of the ferroelectric capacitor as it’s basic nonlinear unit for the calculations of the neurons outputs. Finally, it has been used the analog model of the ferroelectric capacitor with the goal of verifying it’s effectiveness and possibly the reduction of the number of necessary logic elements in the case of implementing the artificial neurons on integrated circuit. The implementations has been carried out by Simulink models and the synthesizing has been done through the DSP Builder software from Altera Corporation.

Design, development and control of a new generation high performance linear actuator for parallel robots and other applications

The main focus of this research is to design and develop a high performance linear actuator based on a four bar mechanism. The present work includes the detailed analysis (kinematics and dynamics), design, implementation and experimental validation of the newly designed actuator. High performance is characterized by the acceleration of the actuator end effector. The principle of the newly designed actuator is to network the four bar rhombus configuration (where some bars are extended to form an X shape) to attain high acceleration. Firstly, a detailed kinematic analysis of the actuator is presented and kinematic performance is evaluated through MATLAB simulations. A dynamic equation of the actuator is achieved by using the Lagrangian dynamic formulation. A SIMULINK control model of the actuator is developed using the dynamic equation. In addition, Bond Graph methodology is presented for the dynamic simulation. The Bond Graph model comprises individual component modeling of the actuator along with control. Required torque was simulated using the Bond Graph model. Results indicate that, high acceleration (around 20g) can be achieved with modest (3 N-m or less) torque input. A practical prototype of the actuator is designed using SOLIDWORKS and then produced to verify the proof of concept. The design goal was to achieve the peak acceleration of more than 10g at the middle point of the travel length, when the end effector travels the stroke length (around 1 m). The actuator is primarily designed to operate in standalone condition and later to use it in the 3RPR parallel robot. A DC motor is used to operate the actuator. A quadrature encoder is attached with the DC motor to control the end effector. The associated control scheme of the actuator is analyzed and integrated with the physical prototype. From standalone experimentation of the actuator, around 17g acceleration was achieved by the end effector (stroke length was 0.2m to 0.78m). Results indicate that the developed dynamic model results are in good agreement. Finally, a Design of Experiment (DOE) based statistical approach is also introduced to identify the parametric combination that yields the greatest performance. Data are collected by using the Bond Graph model. This approach is helpful in designing the actuator without much complexity.

Use of active power filter to reduce the effects of harmonics in solid oxide fuel cells

The Solid Oxide Fuel Cell (SOFC) is a class of fuel cells that is capable of generating very high levels of power at high temperatures. SOFCs are used for stationary power generation and as Combined Heat and Power (CHP) systems. In spite of all the beneficial features of the SOFC, the propagation of ripple currents, due to nonlinear loads, is a challenging problem, as it interferes with the physical operation of the fuel cell. The purpose of this thesis is to identify the cause of ripples and attempt to eliminate or reduce the ripple propagation through the use of Active Power Filters (APF). To this end, a systematic approach to modeling the fuel cell to account for its nonlinear behavior in the presence of current ripples is presented. A model of a small fuel cell power system which consists of a fuel cell, a DC-DC converter, a single-phase inverter and a nonlinear load is developed in MATLAB/Simulink environment. The extent of ripple propagation, due to variations in load magnitude and frequency, are identified using frequency spectrum analysis. In order to reduce the effects of ripple propagation, an APF is modeled to remove ripples from the DC fuel cell current. The emphasis of this thesis is based on the idea that small fuel cell systems cannot implement large passive filters to cancel the effects of ripple propagation and hence, the compact APF topology effectively protects the fuel cell from propagating ripples and improves its electrical performance.

Valutazione delle prestazioni di reti ad accesso multiplo basate su visible light communication

Nella società odierna, le telecomunicazioni costituiscono un’esigenza fondamentale della vita quotidiana. Difatti, il mercato della ICT (Information and Communications Technology) è in costante espansione, e viene accompagnato da un rapido sviluppo di nuove tecnologie. In particolare, si assiste a un sempre più rilevante ruolo svolto dalle comunicazioni ottiche, ovvero sfruttanti la luce: in questo contesto, il quale comprende diversi rami ingegneristici, si stanno progressivamente affermando nuove forme di comunicazione basate sulla luce visibile, la cosiddetta Visible Light Communication (VLC). Con questa Tesi ci si propone di implementare con Simulink e stateflow di Matlab il livello MAC (Medium Access Control), basato sullo standard IEEE 802.15.7 per le VLC e valutarne le prestazioni. Prescinde da questa Tesi la parte di implementazione su scheda stessa che è lasciata per sviluppi futuri. Nel capitolo uno si introducono le VLC e si discutono i principali scenari attuali dove possono diffondersi. Nel capitolo 2, si mostrano le principali linee guida afferenti agli standard che sono risultate necessarie per sviluppare lo strato MAC. Nei capitoli 3 e 4 si mostra come il layer sviluppato possa essere utilizzato in due principali situazioni: nel capitolo 3 è descritta la realizzazione di una comunicazione punto-punto, ovvero con un trasmettitore e un ricevitore; nel capitolo 4 è descritta l’implementazione di una rete di nodi, ambito in cui il livello MAC risulta indispensabile. Per ognuna delle situazioni si illustrano scelte e caratteristiche dei sistemi simulati e i risultati ottenuti, cercando di coprire diverse eventualità che intercorrono, più in generale, nella gestione e implementazione di sistemi di telecomunicazione wireless.

Sistema de carga bidirecional para veículo elétrico

As preocupações com o elevado consumo de combustíveis fósseis e a crescente poluição atmosférica conduziram ao desenvolvimento dos veículos elétricos e dos veículos elétricos híbridos. O crescimento do parque automóvel elétrico levou à necessidade de considerar a sua integração na rede eléctrica, ao nível dos impactos estimados, mas também na sua potencial contribuição para uma gestão inteligente do sistema, funcionando como um buffer da energia produzida, permitindo desacoplar a produção do consumo, e assim melhor a eficiência global. Neste trabalho foi efetuado um estudo relacionado com a ligação bidirecional entre os veículos eléctricos e a rede eléctrica que permitirá o uso das baterias instaladas nos veículos participar nesse apoio à rede, debruçando-se primeiramente sobre o desenvolvimento das baterias que permanecem como elos mais fracos. Utilizando diferentes ferramentas de simulação e de análise de resultados foi depois efetuado um estudo sobre dois sistemas alternativos capazes de implementar o conceito V2G respeitando as restrições do ponto de vista normativo. Os resultados obtidos a partir de uma simulação coordenada entre os programas Simulink/Matlab e PSIM permitiram demostram o bom funcionamento dos 2 sistemas propostos, permitindo ficar com a convicção que o conversor multinível será capaz de proporcionar os resultados desejados com um menor tempo de resposta.

Design and implementation of generalized topologies of time-interleaved variable bandpass Σ−Δ modulators

In this thesis, novel analog-to-digital and digital-to-analog generalized time-interleaved variable bandpass sigma-delta modulators are designed, analysed, evaluated and implemented that are suitable for high performance data conversion for a broad-spectrum of applications. These generalized time-interleaved variable bandpass sigma-delta modulators can perform noise-shaping for any centre frequency from DC to Nyquist. The proposed topologies are well-suited for Butterworth, Chebyshev, inverse-Chebyshev and elliptical filters, where designers have the flexibility of specifying the centre frequency, bandwidth as well as the passband and stopband attenuation parameters. The application of the time-interleaving approach, in combination with these bandpass loop-filters, not only overcomes the limitations that are associated with conventional and mid-band resonator-based bandpass sigma-delta modulators, but also offers an elegant means to increase the conversion bandwidth, thereby relaxing the need to use faster or higher-order sigma-delta modulators. A step-by-step design technique has been developed for the design of time-interleaved variable bandpass sigma-delta modulators. Using this technique, an assortment of lower- and higher-order single- and multi-path generalized A/D variable bandpass sigma-delta modulators were designed, evaluated and compared in terms of their signal-to-noise ratios, hardware complexity, stability, tonality and sensitivity for ideal and non-ideal topologies. Extensive behavioural-level simulations verified that one of the proposed topologies not only used fewer coefficients but also exhibited greater robustness to non-idealties. Furthermore, second-, fourth- and sixth-order single- and multi-path digital variable bandpass digital sigma-delta modulators are designed using this technique. The mathematical modelling and evaluation of tones caused by the finite wordlengths of these digital multi-path sigmadelta modulators, when excited by sinusoidal input signals, are also derived from first principles and verified using simulation and experimental results. The fourth-order digital variable-band sigma-delta modulator topologies are implemented in VHDL and synthesized on Xilinx® SpartanTM-3 Development Kit using fixed-point arithmetic. Circuit outputs were taken via RS232 connection provided on the FPGA board and evaluated using MATLAB routines developed by the author. These routines included the decimation process as well. The experiments undertaken by the author further validated the design methodology presented in the work. In addition, a novel tunable and reconfigurable second-order variable bandpass sigma-delta modulator has been designed and evaluated at the behavioural-level. This topology offers a flexible set of choices for designers and can operate either in single- or dual-mode enabling multi-band implementations on a single digital variable bandpass sigma-delta modulator. This work is also supported by a novel user-friendly design and evaluation tool that has been developed in MATLAB/Simulink that can speed-up the design, evaluation and comparison of analog and digital single-stage and time-interleaved variable bandpass sigma-delta modulators. This tool enables the user to specify the conversion type, topology, loop-filter type, path number and oversampling ratio.

Sviluppo di un simulatore di determinazione d’assetto per un CubeSat operante nel sistema binario Didymos

Questa tesi riguarda l'implementazione e la verifica di alcuni algoritmi di determinazione d'assetto, con l'obiettivo di verificarne le prestazioni e valutarne la possibilità di utilizzo sul ADS del satellite DustCube, operante nel sistema binario Didymos. I filtri si basano sulla combinazione delle misure di diversi sensori, tra i quali star tracker, sensori di Sole, camera a infrarossi e giroscopio. I sensori in questione sono stati modellizzati all'interno di un simulatore implementato in MATLAB/Simulink. L'approccio utilizzato per la determinazione dell'assetto è quelllo di impiegare due differenti filtri: il primo per la calibrazione del giroscopio, il secondo che utilizza i parametri di calibrazione calcolati dal primo per correggere la velocità angolare misurata da giroscopio e determinare l'assetto con un maggiore accuratezza. Le prestazioni dei vari filtri sono state caratterizzate attraverso un'analisi statistica: le simulazioni Monte Carlo. I risultati, nei limiti delle ipotesi fatte, hanno confermato la validità dell'approccio. Per la determinazione effettiva delle prestazioni di questo sistema sull'ADS del DustCube si rimanda ad uno studio di maggior dettaglio.

Sistema avanzado de alarmas para el reactor RA6.

Los sistemas de alarmas constituyen un elemento clave en las plantas modernas de procesos industriales. A lo largo de los años, los mismos han ido evolucionando de la mano del importante desarrollo en la industria del software, para pasar de ser simples paneles de anunciación y lámparas cableadas hasta complejos sistemas inteligentes que asisten al operador en sus funciones de operación. En el desarrollo de este trabajo se planteó diseñar un Sistema Avanzado de Alarmas para el Reactor Nuclear de Investigación RA6 contemplando las nuevas tecnologías existentes para incorporar mejoras a la actual sala de control. Para ello se trabajó siguiendo la metodología propuesta por la guía de diseño de sistemas de alarmas ANSI / ISA- SP-18. Para asistir al diseño y la verificación del sistema se utilizó un modelo termohidráulico de la planta desarrollado en Matlab/Simulink. Entre las nuevas herramientas incorporadas en el prototipo final obtenido se pueden mencionar: creación de archivos históricos, asignación de prioridades, supresiones de alarmas según estado operativo, filtrado y agrupamiento de alarmas.

Modellistica e controllo di attuatori idraulici

La tesi tratta della modellistica e del controllo di un attuatore idraulico con valvola a quattro vie. Inizialmente si definiscono le grandezze e le formule fondamentali per descrivere un sistema idraulico e costruirne il modello matematico. Successivamente si ricava il modello non lineare del sistema nello spazio degli stati, quindi lo si linearizza per poterlo descrivere e studiare anche tramite funzioni di trasferimento. Si ricava quindi, utilizzando anche Matlab e Simulink, il controllo da applicare al modello linearizzato e si testa il comportamento del sistema in risposta a diversi segnali di ingresso. Infine si applica lo stesso controllore al sistema non lineare e si confrontano i due diversi comportamenti.

Modeling and control algorithms for product phasing using smart belts

Nella seguente tesi è descritto il principio di sviluppo di una macchina industriale di alimentazione. Il suddetto sistema dovrà essere installato fra due macchine industriali. L’apparato dovrà mettere al passo e sincronizzare con la macchina a valle i prodotti che arriveranno in input. La macchina ordina gli oggetti usando una serie di nastri trasportatori a velocità regolabile.
Lo sviluppo è stato effettuato al Laboratorio Liam dopo la richiesta dell’azienda Sitma. Sitma produceva già un tipo di sistema come quello descritto in questa tesi. Il deisderio di Sitma è quindi quello di modernizzare la precedente applicazione poiché il dispositivo che le permetteva di effettuare la messa al passo di prodotti era un PLC Siemens che non è più commercializzato. La tesi verterà sullo studio dell’applicazione e la modellazione tramite Matlab-Simulink per poi proseguire ad una applicazione, seppure non risolutiva, in TwinCAT 3.

Traktorin sähköistysanalyysi virtuaalisimulaatiomallilla

Tämä diplomityö on tehty Lappeenrannan teknilliselle yliopistolle osana yliopiston sähköisen liikkumisen tutkimusta. Työssä on jatkokehitetty ja dokumentoitu Drive!-projektin hybriditraktorin simulaatiomallia, joka toimii Mevea- ja Simulink-ohjelmistoissa. Mevean simulaatioalustalla on mallinnettu traktorin mekaniikkaa ja ympäristöä, kun taas Simulinkillä on simuloitu hybriditraktorin sähkötekniikkaa, dieselgeneraattoria, energiavarastoa ja apulait-teita. Työssä on tarkasteltu traktorin erilaisia maatalouden työtehtäviä ja tämän jälkeen tarkasteltu simulaatiomallin ja simulaatioiden avulla minkälaisella hybriditraktorilla näitä töitä olisi mahdollista suorittaa. Lopuksi tarkastellaan vielä simulaatiomallilla noin 75 kW:n hybriditraktorin toimintaa maatalon pihapiirin työtehtävissä ja lasketaan hybridisoinnin lisäinvestoinnille takaisinmaksuaika. Virtuaalimallilla tehtyjen simulaatioiden ja laskelmien perusteella saatiin tulokseksi, että tämän hetken komponentti- ja energiahinnoilla maataloustraktorin hybridisointi ei ole taloudellisesti kannattavaa. Kuitenkin on huomionarvoista, että ajettaessa pelkällä akkusähköllä käytetyn energian hinta on noin kolmannes verrattaessa perinteiseen dieseltraktoriin.

Sistema avanzado de alarmas para el reactor RA6.

Los sistemas de alarmas constituyen un elemento clave en las plantas modernas de procesos industriales. A lo largo de los años, los mismos han ido evolucionando de la mano del importante desarrollo en la industria del software, para pasar de ser simples paneles de anunciación y lámparas cableadas hasta complejos sistemas inteligentes que asisten al operador en sus funciones de operación. En el desarrollo de este trabajo se planteó diseñar un Sistema Avanzado de Alarmas para el Reactor Nuclear de Investigación RA6 contemplando las nuevas tecnologías existentes para incorporar mejoras a la actual sala de control. Para ello se trabajó siguiendo la metodología propuesta por la guía de diseño de sistemas de alarmas ANSI / ISA- SP-18. Para asistir al diseño y la verificación del sistema se utilizó un modelo termohidráulico de la planta desarrollado en Matlab/Simulink. Entre las nuevas herramientas incorporadas en el prototipo final obtenido se pueden mencionar: creación de archivos históricos, asignación de prioridades, supresiones de alarmas según estado operativo, filtrado y agrupamiento de alarmas.

Hajautetun automaation käyttö osana simulaatiota

Työssä perehdytään simulaatiotekniikkaan, jossa käytetään osana fyysistä laitteistoa, ja siihen tarvittaviin komponentteihin, kuten ohjelmistorajapintoihin sekä kenttäväylään. Työssä tutustutaan myös IEC 61131-3 ja IEC 61499 -standardien mukaisiin toimintolohkomalleihin, joita käytetään automaatiossa. Näiden perusteella kehitetään järjestelmä, jonka avulla Simulink-ympäristössä voidaan oman toimintolohkon avulla käyttää taajuusmuuttajaa osana simulaatiota. Tällaisen reaaliaikaisen systeemin eri osien väliseen synkronointiin kiinnitetään myös huomiota. Järjestelmää testataan simulaatiomallilla, jossa syötetään vääntömomenttiohje taajuusmuuttajalle, joka mittaa siihen kytketyn moottorin pyörimisnopeuden. Mallilla voidaan esimerkiksi arvioida kuorman hitausmomentti. Työssä tutustutaan myös taajuusmuuttajien ohjelmallisiin ominaisuuksiin ja niiden perusteella pohditaan esitetyn kaltaisten järjestelmien käyttöä hajautettuna automaatiojärjestelmänä. Kokeellinen työ tehtiin säätö- ja digitaalitekniikan laboratoriossa vuoden 2010 aikana.

An iterative analytical design framework for the optimal designing of an off-grid renewable energy based hybrid smart micro-grid

Creative ways of utilising renewable energy sources in electricity generation especially in remote areas and particularly in countries depending on imported energy, while increasing energy security and reducing cost of such isolated off-grid systems, is becoming an urgently needed necessity for the effective strategic planning of Energy Systems. The aim of this research project was to design and implement a new decision support framework for the optimal design of hybrid micro grids considering different types of different technologies, where the design objective is to minimize the total cost of the hybrid micro grid while at the same time satisfying the required electric demand. Results of a comprehensive literature review, of existing analytical, decision support tools and literature on HPS, has identified the gaps and the necessary conceptual parts of an analytical decision support framework. As a result this research proposes and reports an Iterative Analytical Design Framework (IADF) and its implementation for the optimal design of an Off-grid renewable energy based hybrid smart micro-grid (OGREH-SμG) with intra and inter-grid (μG2μG & μG2G) synchronization capabilities and a novel storage technique. The modelling design and simulations were based on simulations conducted using HOMER Energy and MatLab/SIMULINK, Energy Planning and Design software platforms. The design, experimental proof of concept, verification and simulation of a new storage concept incorporating Hydrogen Peroxide (H2O2) fuel cell is also reported. The implementation of the smart components consisting Raspberry Pi that is devised and programmed for the semi-smart energy management framework (a novel control strategy, including synchronization capabilities) of the OGREH-SμG are also detailed and reported. The hybrid μG was designed and implemented as a case study for the Bayir/Jordan area. This research has provided an alternative decision support tool to solve Renewable Energy Integration for the optimal number, type and size of components to configure the hybrid μG. In addition this research has formulated and reported a linear cost function to mathematically verify computer based simulations and fine tune the solutions in the iterative framework and concluded that such solutions converge to a correct optimal approximation when considering the properties of the problem. As a result of this investigation it has been demonstrated that, the implemented and reported OGREH-SμG design incorporates wind and sun powered generation complemented with batteries, two fuel cell units and a diesel generator is a unique approach to Utilizing indigenous renewable energy with a capability of being able to synchronize with other μ-grids is the most effective and optimal way of electrifying developing countries with fewer resources in a sustainable way, with minimum impact on the environment while also achieving reductions in GHG. The dissertation concludes with suggested extensions to this work in the future.

Error correcting codes for visible light communication systems

Over the past few years, the number of wireless networks users has been increasing. Until now, Radio-Frequency (RF) used to be the dominant technology. However, the electromagnetic spectrum in these region is being saturated, demanding for alternative wireless technologies. Recently, with the growing market of LED lighting, the Visible Light Communications has been drawing attentions from the research community. First, it is an eficient device for illumination. Second, because of its easy modulation and high bandwidth. Finally, it can combine illumination and communication in the same device, in other words, it allows to implement highly eficient wireless communication systems. One of the most important aspects in a communication system is its reliability when working in noisy channels. In these scenarios, the received data can be afected by errors. In order to proper system working, it is usually employed a Channel Encoder in the system. Its function is to code the data to be transmitted in order to increase system performance. It commonly uses ECC, which appends redundant information to the original data. At the receiver side, the redundant information is used to recover the erroneous data. This dissertation presents the implementation steps of a Channel Encoder for VLC. It was consider several techniques such as Reed-Solomon and Convolutional codes, Block and Convolutional Interleaving, CRC and Puncturing. A detailed analysis of each technique characteristics was made in order to choose the most appropriate ones. Simulink models were created in order to simulate how diferent codes behave in diferent scenarios. Later, the models were implemented in a FPGA and simulations were performed. Hardware co-simulations were also implemented to faster simulation results. At the end, diferent techniques were combined to create a complete Channel Encoder capable of detect and correct random and burst errors, due to the usage of a RS(255,213) code with a Block Interleaver. Furthermore, after the decoding process, the proposed system can identify uncorrectable errors in the decoded data due to the CRC-32 algorithm.