Cian O'Mathuna

Microfabricated inductors for 20 MHz Dc-Dc converters

This paper presents the design and measured results for micro-fabricated inductors suitable for use in high frequency (> 10 MHz), low power (1 -2 W) dc-dc converters. The design has focused on maximizing inductor efficiency for a given converter specification. Inductors in the range of 100 nH to 300 nH have been fabricated and tested. The small signal measurements show a relatively flat inductance profile, with a 10% drop in inductance at 30 MHz. Inductance vs. dc bias current measurements show less than 15% decrease in inductance at 500 mA current. The performance of the micro-inductors have also been compared to a conventional wire-wound inductor in a 20 MHz dc-dc converter. The converter efficiency is shown to be approximately 4% lower when the micro-inductor is used compared to the when the wire- wound inductor is used. The peak efficiency of the micro-inductor in the converter is estimated to be approximately 93%.

A 3D miniaturised programmable transceiver

Purpose – To describe the development of a three dimensional programmable transceiver system of modular design for use as a development tool for a variety of wireless sensor node applications.Design/methodology/approach – As a stepping‐stone towards the development of wireless nodes, sensor networks programme was put in place to develop a 25 mm cube module, which was modular in construction, programmable and miniaturised in form factor. This was to facilitate the development of wireless sensor networks for a variety of different applications. The nodes are used as a platform for sensing and actuating through various parameters, for use in scalable, reconfigurable distributed autonomous sensing networks in a number of research projects currently underway in the Tyndall Institute, as well as other institutes and in a variety of research programs in the area of wireless sensor networks.Findings – The modular construction enables the heterogeneous implementation of a variety of technologies required in the ar...

Experiences and recommendations in deploying a real-time, water quality monitoring system

Monitoring of water quality at a river basin level to meet the requirements of the Water Framework Directive (WFD) using conventional sampling and laboratory-based techniques poses a significant financial burden. Wireless sensing systems offer the potential to reduce these costs considerably, as well as provide more useful, continuous monitoring capabilities by giving an accurate idea of the changing environmental and water quality in real time. It is unlikely that the traditional spot/grab sampling will provide a reasonable estimate of the true maximum and/or mean concentration for a particular physicochemical variable in a water body with marked temporal variability. When persistent fluctuations occur, it is likely only to be detected through continuous measurements, which have the capability of detecting sporadic peaks of concentration. Thus, in situ sensors capable of continuous sampling of parameters required under the WFD would therefore provide more up-to-date information, cut monitoring costs and provide better coverage representing long-term trends in fluctuations of pollutant concentrations. DEPLOY is a technology demonstration project, which began planning and station selection and design in August 2008 aiming to show how state-of-the-art technology could be implemented for cost-effective, continuous and real-time monitoring of a river catchment. The DEPLOY project is seen as an important building block in the realization of a wide area autonomous network of sensors capable of monitoring the spatial and temporal distribution of important water quality and environmental target parameters. The demonstration sites chosen are based in the River Lee, which flows through Irelands second largest city, Cork, and were designed to include monitoring stations in five zones considered typical of significant river systems-–these monitor water quality parameters such as pH, temperature, depth, conductivity, turbidity and dissolved oxygen. Over one million data points have been collected since the multi-sensor system was deployed in May 2009. Extreme meteorological events have occurred during the period of deployment and the collection of real-time water quality data as well as the knowledge, experience and recommendations for future deployments are discussed.

Towards a wireless sensor platform for energy efficient building operation

Abstract Currently, the IT-support for energy performance rating of buildings is insufficient. So-called IT-platforms often “built” of an ad-hoc, inconsistent combination of off-the-shelf building management components, distributed data metering equipment and several monitoring software tools. A promising approach to achieve consistent, holistic performance data management is the implementation of an integrated, modular wireless sensor platform. This paper presents an approach of how wireless sensors can be seamlessly integrated into existing and future intelligent building management systems supporting improved building performance and diagnostics with an emphasis on energy management.

Thin film micro-transformers for future power conversion

This paper presents an investigation into the use of micro-fabricated transformers for future power conversion in the 5-10 MHz frequency range. The structure of the micro-transformers is described and an analytical model is used to optimize the transformer for maximum efficiency. The optimized devices are based on improved fabrication processes which give 80 /spl mu/m thick copper conductors and a two layer laminated magnetic core. The optimization suggests that an efficiency of 82% at an output power of 3.5 W can be achieved. Initial small signal results are presented for micro-transformers fabricated using the improved processes. The estimated efficiency of the fabricated microtransformer based on these results is 78%.

FPGA implementation of spiking neural networks - an initial step towards building tangible collaborative autonomous agents

This work contains the results of an initial study into the FPGA implementation of a spiking neural network. This work was undertaken as a task in a project that aims to design and develop a new kind of tangible collaborative autonomous agent. The project intends to exploit/investigate methods for engineering emergent collective behaviour in large societies of actual miniature agents that can learn and evolve. Such multi-agent systems could be used to detect and collectively repair faults in a variety of applications where it is difficult for humans to gain access, such as fluidic environments found in critical components of material/industrial systems. The initial achievement of implementation of a spiking neural network on a FPGA hardware platform and results of a robotic wall following task are discussed by comparison with software driven robots and simulations.

Multi-sensor classification of tennis strokes

In this work, we investigate tennis stroke recognition using a single inertial measuring unit attached to a players forearm during a competitive match. This paper evaluates the best approach for stroke detection using either accelerometers, gyroscopes or magnetometers, which are embedded into the inertial measuring unit. This work concludes what is the optimal training data set for stroke classification and proves that classifiers can perform well when tested on players who were not used to train the classifier. This work provides a significant step forward for our overall goal, which is to develop next generation sports coaching tools using both inertial and visual sensors in an instrumented indoor sporting environment.

Thin Film Microtransformer Integrated on Silicon for Signal Isolation

Microtransformers have been fabricated on silicon substrates with the aim of providing isolation for signal and power. Interleaved primary and secondary windings are sandwiched between two electroplated magnetic layers. The transformer has a turn ratio of 4:4. It has a primary inductance of 400 nH at low frequencies and dc resistance of 0.48 Omega. The voltage gain is -1 dB between 1-20 MHz with a 50-Omega load. When compared to previously reported microtransformer characteristics this is the highest reported voltage gain for a microtransformer

Autonomous wireless sensor network based Building Energy and Environment Monitoring system design

Wireless sensor network technology emerged in recent years with numerous potential applications. The building environment and energy monitoring (BEEM) is among the most important ones. The design of such smart wireless sensing system is presented in this paper. The proposed system consists of low power Tyndall wireless sensor node hardware with light energy harvesting featured power supply and energy management system for long-term deployment. Energy consumption, light level, temperature and humidity parameters are measured and transmitted via a 2.4GHz Zigbee wireless network. Evaluations of the system are conducted in a local office building with a total of 62 nodes operating with varying functions. The evaluation results of the system including the measured energy and environmental data are presented. The evaluation results show that this design is worlds first known indoor light energy harvesting powered BEEM system.

Energy harvesting embedded wireless sensor system for building environment applications

For many wireless sensor networks applications, indoor light energy is the only ambient energy source commonly available. Many advantages and constraints co-exist in this technology. However, relatively few indoor light powered harvesters have been presented and much research remains to be carried out on a variety of related design considerations and trade-offs. This work presents a solution using the Tyndall mote and an indoor light powered wireless sensor node. It analyses design considerations on several issues such as indoor light characteristics, solar panel component choice, maximum power point tracking, energy storage elements and the trade-offs and choices between them.