A gravitational torque energy harvesting system for rotational motion

This thesis describes a novel, single point-of-attachment, gravitational torque energy harvesting system powered from rotational motion. The primary aim of such a system is to scavenge energy from a continuously rotating host in order to power a wireless sensor node. In this thesis, a wireless tachometer was prototyped. Most published work on motion-driven energy harvesters has used ambient vibrations in the environment as the energy source. However, none of the reported devices have been designed to harvest energy directly from continuous ambient rotation. There are important applications such as tire pressure sensing and condition monitoring of machinery where the host structure experiences continuous rotation. In this work, it is shown that in many applications, a rotational energy harvester can offer significant improvements in power density over its vibration-driven counterparts. A prototype single point-of-attachment rotational energy harvester was conceived using a simple direct-current generator. The rotational source was coupled to the stator and an offset mass was anchored on the rotor to create a counteractive gravitational torque. This produces a relative angular speed between rotor and stator which causes power to be generated. Power transfer from the generator to a load was maximised by enforcing an input impedance match between the generator’s armature resistance and the input impedance of a boost converter which in this case, functioned as a resistance emulator. Energy storage and output voltage regulation were implemented using supercapacitors and a wide-input buck regulator respectively. When excess power was generated, it was stored in the supercapacitors and during low source rotation speeds, i.e. insufficient harvested power, the supercapacitors will discharge to maintain operation of the interface electronics. A detailed optimisation procedure of a boost converter was conducted in Matlab in order to minimise the power loss, resulting in a maximum voltage gain of 11.1 and measured circuit efficiency of 96 %. A state-space control model of the harvester electronics was developed in the analogue domain using classical control techniques and this showed the system to be closed-loop stable. A final prototype of the rotational energy harvesting system was built and this comprised an input impedance controller, wireless transmitter and tachometer. The entire system has a measured end-to-end efficiency which peaked at 58 % from a source rotation of 1400 RPM with the generator producing 1.45 W under matched load conditions

Autonomous Vehicle and Smart Traffic

Long-term forecasting of technology has become extremely difficult due to the rapid realization of any suggested idea. Communication and software technologies can compensate for the problems that may arise during the transition period between idea generation and realization. However, this rapid process can cause problems for the automotive industry and transportation systems.Autonomous vehicles are currently a hot topic within the transportation sector. This development is related to the compatibility of vehicles of the near future with the development of the infrastructure on which these vehicles will be based. There are certain problems regarding the solutions that are currently being worked on, such as how autonomous should vehicles be, their control mechanisms, driving safety, energy requirements, and environmental use. The problem is not just about the design of autonomous vehicles. The user transportation systems of these vehicles also need problem-free solutions. The problem should not only be seen as financial because sociological effects are an important part of this feature.In this book, valuable research on the modeling, systems, transportation, technological necessity, and logistics of autonomous vehicles is presented. The content of the book will help researchers to create ideas for their future studies and to open up the discussion of autonomous vehicles

Energy harvesting from body motion using rotational micro-generation

Autonomous system applications are typically limited by the power supply operational lifetime when battery replacement is difficult or costly. A trade-off between battery size and battery life is usually calculated to determine the device capability and lifespan. As a result, energy harvesting research has gained importance as society searches for alternative energy sources for power generation. For instance, energy harvesting has been a proven alternative for powering solar-based calculators and self-winding wristwatches. Thus, the use of energy harvesting technology can make it possible to assist or replace batteries for portable, wearable, or surgically-implantable autonomous systems. Applications such as cardiac pacemakers or electrical stimulation applications can benefit from this approach since the number of surgeries for battery replacement can be reduced or eliminated. Research on energy scavenging from body motion has been investigated to evaluate the feasibility of powering wearable or implantable systems. Energy from walking has been previously extracted using generators placed on shoes, backpacks, and knee braces while producing power levels ranging from milliwatts to watts. The research presented in this paper examines the available power from walking and running at several body locations. The ankle, knee, hip, chest, wrist, elbow, upper arm, side of the head, and back of the head were the chosen target localizations. Joints were preferred since they experience the most drastic acceleration changes. For this, a motor-driven treadmill test was performed on 11 healthy individuals at several walking (1-4 mph) and running (2-5 mph) speeds. The treadmill test provided the acceleration magnitudes from the listed body locations. Power can be estimated from the treadmill evaluation since it is proportional to the acceleration and frequency of occurrence. Available power output from walking was determined to be greater than 1mW/cm³ for most body locations while being over 10mW/cm³ at the foot and ankle locations. Available power from running was found to be almost 10 times higher than that from walking. Most energy harvester topologies use linear generator approaches that are well suited to fixed-frequency vibrations with sub-millimeter amplitude oscillations. In contrast, body motion is characterized with a wide frequency spectrum and larger amplitudes. A generator prototype based on self-winding wristwatches is deemed to be appropriate for harvesting body motion since it is not limited to operate at fixed-frequencies or restricted displacements. Electromagnetic generation is typically favored because of its slightly higher power output per unit volume. Then, a nonharmonic oscillating rotational energy scavenger prototype is proposed to harness body motion. The electromagnetic generator follows the approach from small wind turbine designs that overcome the lack of a gearbox by using a larger number of coil and magnets arrangements. The device presented here is composed of a rotor with multiple-pole permanent magnets having an eccentric weight and a stator composed of stacked planar coils. The rotor oscillations induce a voltage on the planar coil due to the eccentric mass unbalance produced by body motion. A meso-scale prototype device was then built and evaluated for energy generation. The meso-scale casing and rotor were constructed on PMMA with the help of a CNC mill machine. Commercially available discrete magnets were encased in a 25mm rotor. Commercial copper-coated polyimide film was employed to manufacture the planar coils using MEMS fabrication processes. Jewel bearings were used to finalize the arrangement. The prototypes were also tested at the listed body locations. A meso-scale generator with a 2-layer coil was capable to extract up to 234 µW of power at the ankle while walking at 3mph with a 2cm³ prototype for a power density of 117 µW/cm³. This dissertation presents the analysis of available power from walking and running at different speeds and the development of an unobtrusive miniature energy harvesting generator for body motion. Power generation indicates the possibility of powering devices by extracting energy from body motion

Miniaturized Thin-Film Piezoelectric Traveling Wave Ultrasonic Motor

For many small-scale systems, compact rotary actuators are highly attractive. Many current millimeter-scale motor technologies, such as electrostatic motors and electromagnetic motors, operate at high speeds (on the order of 105 RPM) but low torque, usually pico- or nano-newton-meters. In order to drive large loads at speeds closer to 100 to 1000 RPM, gearing would be required, which drastically increases system complexity and size. Electromagnetic motors, which are effective at the macro-scale, become less practical at the millimeter-scale due to unfavorable scaling of energy density and complex fabrication. Electrostatic micro-motors require approximately 100 V for operation and produce limited torque. Traveling wave ultrasonic motors (TWUM) can provide micro- to milli-newton-meters of torque at low speeds and fill a necessary place within the millimeter-scale rotary motor landscape. Using recent developments in high quality piezoelectric film deposition and microfabrication techniques, TWUM can be made an order of magnitude smaller than currently possible. The fabrication process for the TWUM is described within, with a focus on stator fabrication and the enabling fabrication methods developed for the manufacture of TWUM, including backside vapor-HF release, deep reactive ion etch footing release, and photoresist deep-trench refill. Design and characterization of the traveling wave stator component, both disc and ring are described. Disc stators, 1 to 3 mm in diameter, exhibited traveling waves up to 1 μm in out-of-plane amplitude with quality factors in air of 95. The design process for ring stators with mechanical impedance transformer tethers is presented. The tethers are designed to allow large motion at the stator perimeter, while tethering the stator to the anchored substrate. This mechanical impedance transformer tether allowed for an in increase in standing wave amplitude by over 100% compared to straight tethers. TWUM were demonstrated and characterized, and represent the smallest TWUM currently reported, at 2 to 3 mm in diameter and less than 1 mm thick. Motor performance characteristics are presented, with speeds exceeding 2000 RPM while consuming 4 mW of power at 10 V. These millimeter-scale motors have potential applications in fields such as fuzing, medical imaging, micro-robotics, and sensor steering and calibration

Hardware-software design of embedded systems for intelligent sensing applications

This Thesis wants to highlight the importance of ad-hoc designed and developed embedded systems in the implementation of intelligent sensor networks. As evidence four areas of application are presented: Precision Agriculture, Bioengineering, Automotive and Structural Health Monitoring. For each field is reported one, or more, smart device design and developing, in addition to on-board elaborations, experimental validation and in field tests. In particular, it is presented the design and development of a fruit meter. In the bioengineering field, three different projects are reported, detailing the architectures implemented and the validation tests conducted. Two prototype realizations of an inner temperature measurement system in electric motors for an automotive application are then discussed. Lastly, the HW/SW design of a Smart Sensor Network is analyzed: the network features on-board data management and processing, integration in an IoT toolchain, Wireless Sensor Network developments and an AI framework for vibration-based structural assessment

Short Distance Telemetry for Piston Monitoring. Design and Development of Short Distance Telemetry for Engine Condition Monitoring.

Piston telemetry research involves monitoring the temperatures at specific internal location points within a combustion engine piston. The temperatures are detected with type K thermocouples as voltages and processed to convert them into temperatures using cold junction compensation methods. The present system uses a specific sensor designed to operate in the high temperature environment within the piston, reading multiple thermocouples. Because of the reciprocating motion of the piston, power generation is intermittent and available only when the piston reaches near bottom dead centre, using inductive coupling to power the sensors and transmit data to an evaluation unit for data processing. The planned system involves designing and building a prototype telemetry unit using ¿off the shelf¿ components that integrate the reading of thermocouple outputs, signal processing and cold junction compensation. Wireless telemetry is adopted for data transmission with an integrated Bluetooth and microcontroller module. The data acquisition module can be adapted for other sensors by adapting the firmware uploaded to the microcontroller. The hardware electronics are envisaged to be encased in thermal insulation to enable operation in high temperature environments. The considered system requires a power supply for the integrated components in the form of a power generator and that it should meet two criteria: to be located within confined spaces and to be permanently available, without having to dismantle systems to change batteries. The selected method is an induction generator constructed from a coil stator connected to the piston connection rod big end and a permanent magnet rotor connected to the crankshaft. The suggested mechatronic system is validated against the present system by comparing both systems to determine whether wireless telemetry can perform within acceptable tolerances and limits for the specified task. Then, for acceptable performances, reduce costs and include flexibility to operate in multiple environments. Bench testing shows that the power generator is capable of driving the sensors and the Bluetooth integrated DAQ system.EPSRC and University of Bradfor

Fault detection system for internal combustion engines

Dissertação de mestrado, Engenharia Eléctrica e Electrónica, Instituto Superior de Engenharia, Universidade do Algarve, 2017O desenvolvimento de dispositivos para Internet das Coisas abre novas oportunidades na área de manutenção preditiva. A ideia geral da Internet das Coisas é ligar tudo à Internet, permitindo criar assim sistemas escaláveis suportados pelo processamento remoto, centralizado ou decentralizado. Com a utilização de módulos de baixa potência e de baixo custo, esses sistemas são também eficazes em termos de custo. Alguns estudos indicam que nos próximos anos a manutenção preditiva das máquinas será a principal aplicação da análise de dados na indústria, baseada em Internet das Coisas. Apesar de existirem vários tipos de máquinas, as mais importantes são os motores elétricos e os de combustão interna. Os motores elétricos são amplamente utilizados em diversos setores. Já os motores de combustão interna, por sua vez, são principalmente utilizados nas indústrias automóvel e marítima. Tipicamente, os motores modernos de combustão interna têm uma unidade de controlo computadorizado com capacidade de autodiagnóstico. Contudo, ao contrario da indústria automóvel que utiliza o sistema de On-board diagnostics, a indústria marítima não possui uma norma definida, ou pelo menos uma norma dominante. Isso acarreta a utilização de equipamentos de preço elevado para extrair informação sobre o estado do motor da unidade de controlo. Além disso, a monitorização é intermitente, obrigando ao proprietário de uma embarcação a efetuar a extração dos dados periodicamente para posterior análise. A monitorização das características de operação de um motor um processo fundamental numa manutenção preditiva, sendo que, pela monitorização de um ou mais parâmetros de uma máquina (incluindo a vibração, temperatura, etc.), tenta identificar uma mudança significativa na mesma, que, por sua vez, possa indicar o aparecimento de uma falha. A estratégia de monitorização preditiva assegura que as atividades de manutenção são executadas apenas quando são realmente necessárias, mas para tal é necessário monitorizar periodicamente ou constantemente o equipamento, processar os dados e analisar os resultados. Este método tem, no entanto, as suas desvantagens. O custo do equipamento portátil de monitorização, ou de um sistema estacionário que esteja permanentemente instalado, depende do tipo de variáveis monitorizadas, da precisão de medida, do ambiente de trabalho, ou até do nível de desenvolvimento do sistema. Para além disso, o defeito pode não ser detetado, ou então ser detetado um defeito não existente (um falso positivo, ou uma falsa detecção). Para efectuar uma monitorização preditiva, podem ser utilizados um ou mais métodos de monitorização. Os métodos principais são: análise de vibração, análise de óleo, análise de desempenho, termografia, ferrografia ou análise dos sinais acústicos. De entre todos, a análise de vibração é particularmente interessante, por ser um método não intrusivo e por permitir não só detetar as falhas, mas também classificá-las. Para monitorizar as vibrações de uma máquina utilizam-se transdutores de deslocamento, de velocidade ou de aceleração (acelerómetros). Os transdutores de deslocamento utilizados na indústria permitem medir apenas o deslocamento relativo, o que nem sempre é conveniente. Os preços dos transdutores industriais de velocidade são relativamente altos. Os acelerómetros piezoelétricos industrias também têm um preço elevado. Se as condições ambientais não forem exageradas (por exemplo, temperaturas elevadas) podem ser utilizados acelerómetros MEMS (Microelectromechanical system). Os acelerómetros do tipo MEMS não têm a resposta em frequência tão ampla como os piezoelétricos, no entanto a diferença de preço em relação às restantes opções é muito significativa, e os acelerómetros MEMS, hoje em dia, são praticamente todos digitais, o que simplifica o sistema. Outra alternativa é a película piezoelétrica feita a partir de polyvinylidene difluoride (PVDF). A resposta em frequência desta pelicula é por vezes melhor do que a dos acelerómetros piezoelétricos, com frequências de ressonância acima de 10 MHz. O preço de uma película PVDF depende das dimensões da película, mas é normalmente maior do que o preço de um acelerómetro MEMS, sendo ainda assim muito menor do que um acelerómetro piezoelétrico. É importante referir que há modelos de acelerômetros piezoelétricos que incluem amplificador, mas no caso da película PVDF requerem um circuito de condicionamento do sinal. Para além disso, no caso da película PVDF, tem que ser considerada a sensibilidade à interferência eletromagnética. Dado este contexto, o trabalho realizado nesta Tese resulta de uma proposta feita por uma empresa interessada em automatizar este processo, que entrou em contato com universidade para encontrar uma possível solução. O sistema desenvolvido baseia-se no conceito Internet das Coisas, efetuando a monitorização autónoma da condição do motor, de forma independente do sistema de autodiagnóstico que possa existir. Este trabalho tem, genericamente, três objetivos: (i) desenvolver um módulo de contabilização do número de horas de funcionamento do motor; (ii) desenvolver um módulo de monitorização de ocorrência de falhas num motor de combustão interna através da medição e análise de vibrações; (iii) investigar e analisar os resultados de monitorização, para identificar desvios de parâmetros de funcionamento e detetar de forma preditiva a ocorrência de falhas (antes que as mesmas ocorram realmente). O sistema, que compreende os módulos (i) e (ii), será montado no motor, comunicando com um dispositivo do cliente (por exemplo, um smartphone ou tablet) através de uma interface sem fios. Neste caso optou-se por utilizar uma ligação sem fios baseada na tecnologia Bluetooth Low Energy. Para implementação do módulo de contabilização do número de horas de funcionamento, recorreu-se a um sensor do tipo MEMS, por ter um consumo muito baixo. Já o módulo de módulo de monitorização de ocorrência de falhas recorre a um sensor do tipo PVDF, por permitir elevadas definições temporais na captura do sinal de vibração. Para efectuar a análise de dados que permite a identificação da ocorrência de falhas, foram testados e comparados um conjunto de 16 algoritmos de análise conjunta de dados no tempo e na frequência, suportando a identificação de falhas e a diferenciação entre tipos de falhas. Os algoritmos foram avaliados com base em dados reais, obtidos por falhas induzidas num motor de combustão interna, permitindo por essa via encontrar os algoritmos que melhor servem o objetivo proposto

Desenvolvimento de um robô quadrotor autónomo

Mestrado em Engenharia Electrónica e TelecomunicaçõesExiste actualmente um interesse visível por parte de grupos de investigação e entusiastas em veículos aéreos não tripulados de descolagem e aterragem vertical, especialmente numa aeronave denominada de quadrotor. Este interesse surge, em grande parte, devido _a capacidade destes veículos desempenharem funções em ambientes de difícil acesso ao homem. O Grupo de Actividade Transversal em Robótica Inteligente (ATRI) do Instituto de Engenharia Eletrónica e Telemática de Aveiro (IEETA) com experiência em diversos tipos de plataformas robóticas terrestres, pretende iniciar o estudo neste tipo de aeronaves com o objectivo de, a prazo, as tornar totalmente autónomas. Esta dissertação consiste, consequentemente, no estudo da dinâmica neste tipo de veículos, assim como na construção de um primeiro protótipo de testes. São descritas as varias etapas de construção, desde a escolha dos componentes, desenvolvimento de uma placa de controlo e estabilização _a assemblagem final da aeronave. São explicados quais os sensores necessários para efectuar a estimativa da orientação do veiculo, assim como a implementação de filtros de fusão sensorial para uma estimativa mais precisa. Alem disso, e descrito do algoritmo de controlo PID aplicado para controlo e estabilização do quadrotor. No final são expostos os testes realizados e os resultados experimentais, retirando conclusões para trabalhos futuros.Nowadays, many research groups and enthusiasts developed an interest in Vertical Take Of and Landing (VTOL) vehicles due to the ability to perform tasks in hazardous environments for human beings. The Transverse Activity on Intelligent Robotics (ATRI) research group, part of the Institute of Electronics and Telematics Engineering of Aveiro (IEETA), which has a lot of experience in terrestrial robots, wants to start the research in these kind of aircrafts, setting the future goal of developing a fully autonomous quadrotor. Therefore, this dissertation overviews the study of the quadrotor dynamics and the developing of a rst version of a VTOL prototype. Several stages of research are discussed, since the components selection, the required sensors to estimate the quadrotor attitude and the implemented fusion lters to improve that estimation. The implemented control algorithms( PID) necessary to perform control and stabilization are also discussed. Finally, the experimental results are presented, followed by the conclusions and future work