Measuring dynamic signals with direct sensor-to-microcontroller interfaces applied to a magnetoresistive sensor

This paper evaluates the performance of direct interface circuits (DIC), where the sensor is directly connected to a microcontroller, when a resistive sensor subjected to dynamic changes is measured. The theoretical analysis provides guidelines for the selection of the components taking into account both the desired resolution and the bandwidth of the input signal. Such an analysis reveals that there is a trade-off between the sampling frequency and the resolution of the measurement, and this depends on the selected value of the capacitor that forms the RC circuit together with the sensor resistance. This performance is then experimentally proved with a DIC measuring a magnetoresistive sensor exposed to a magnetic field of different frequencies, amplitudes, and waveforms. A sinusoidal magnetic field up to 1 kHz can be monitored with a resolution of eight bits and a sampling frequency of around 10 kSa/s. If a higher resolution is desired, the sampling frequency has to be lower, thus limiting the bandwidth of the dynamic signal under measurement. The DIC is also applied to measure an electrocardiogram-type signal and its QRS complex is well identified, which enables the estimation, for instance, of the heart rate.Postprint (published version

Design criteria for flight evaluation. Monograph 4 - Control system evaluation

Methods and analyses for flight evaluation of control systems for multistage launch vehicle

Smart chemical sensing microsystem : towards a nose-on-a-chip

The electronic nose is a rudimentary replica of the human olfactory system. However there has been considerable commercial interest in the use of electronic nose systems in application areas such as environmental, medical, security and food industry. In many ways the existing electronic nose systems are considerable inferior when compared to their biological counterparts, lacking in terms of discrimination capability, processing time and environmental adaptation. Here, the aim is to extract biological principles from the mammalian olfactory systems to create a new architecture in order to aid the implementation of a nose-on-a-chip system. The primary feature identified in this study was the nasal chromatography phenomena which may provide significant improvement by producing discriminatory spatio-temporal signals for electronic nose systems. In this project, two different but complimentary groups of systems have been designed and fabricated to investigate the feasibility of generating spatio-temporal signals. The first group of systems include the fast-nose (channel 10 cm x 500 μm2), proto-nose I (channel 1.2 m x 500 μm2) and II (channel 2.4 m x 500 μm2) systems that were build using discrete components. The fast-nose system was used to characterise the discrete sensors prior to use. The proto-nose systems, in many ways, resembles gas chromatography systems. Each proto-nose system consists of two microchannels (with and without coating) and 40 polymer-composite sensors of 10 different materials placed along it. The second group of systems include the hybrid-nose and the aVLSI-nose microsensor arrays assembled with microchannel packages of various lengths (5 cm, 32 cm, 7lcm, 240 cm) to form nose-on-a-chip systems. The hybrid-nose sensor array consists of 80 microsensors built on a 10 mm x 10 mm silicon substrate while the aVLSI-nose sensor array consists of 70 microsensors built on a 10 mm x 5 mm silicon substrate using standard CMOS process with smart integrated circuitries. The microchannel packages were fabricated using the Perfactory microstereolithography system. The most advanced microchannel package contains a 2.4 m x 500 J.lm2 microchannel with an external size of only 36 mm x 27 mm x 7 mm. The nose-on-a-chip system achieved miniaturisation and eliminates the need for any external processing circuitries while achieving the same capability of producing spatio-temporal signals. Using a custom-designed vapour test station and data acquisition electronics, these systems were evaluated with simple analytes and complex odours. The experimental results were in-line with the simulation results. On the coated proto-nose II system, a 25 s temporal delay was observed on the toluene vapour pulse compared to ethanol vapour pulse; this is significant compared to the uncoated system where no delay difference was obtained. Further testing with 8 analyte mixtures substantiated that spatio-temporal signals can be extracted from both the coated proto-nose and nose-on-a-chip (hybrid-nose sensor array with 2.4 m long microchannel) systems. This clearly demonstrates that these systems were capable of imitating certain characteristics of the biological olfactory system. Using only the temporal data, classification was performed with principal components analysis. The results reinforced that these additional temporal signals were useful to improve discrimination analysis which is not possible with any existing sensor-based electronic nose system. In addition, fast responding polymer-composite sensors were achieved exhibiting response times of less than 100 ms. Other biological characteristics relating to stereolfaction (two nostrils sniffing at different rates), sniffing rate (flow velocity) and duration (pulse width) were also investigated. The results converge with the biological observations that stereolfaction and sniffing at higher rate and duration improve discrimination. Last but not least, the characterisation of the smart circuitries on the aVLSI-nose show that it is possible to achieve better performance through the use of smart processing circuitries incorporating a novel DC-offset cancellation technique to amplify small sensor response with large baseline voltage. The results and theories presented in this study should provide useful contribution for designing a higher-performance electronic nose incorporating biological principles

Electronics for Sensors

The aim of this Special Issue is to explore new advanced solutions in electronic systems and interfaces to be employed in sensors, describing best practices, implementations, and applications. The selected papers in particular concern photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) interfaces and applications, techniques for monitoring radiation levels, electronics for biomedical applications, design and applications of time-to-digital converters, interfaces for image sensors, and general-purpose theory and topologies for electronic interfaces

Advances in Gas Sensing and Mapping for Mobile Robotics

Esta tesis aborda el problema de la detección, cuantificación y mapeo de sustancias olorosas empleando un robot móvil equipado con una nariz electrónica. En robótica móvil se emplean los sistemas de muestreo abierto (Open Sampling Systems - OSS), los cuales están caracterizados por introducir importantes fuentes de incertidumbre en las medidas de gases obtenidas. Estas fuentes de incertidumbre se deben principalmente a los mecanismos de dispersión de los gases y al comportamiento dinámico de los sensores de gas, los cuales complican en gran medida las tareas de detección de gases con robots móviles. En esta tesis se proponen contribuciones en tres sub-áreas de la robótica móvil olfativa. Referente a la detección de sustancias olorosas en OSS, y especialmente enfocando a paliar el problema de la lenta recuperación de los sensores basados en tecnología de óxido de metal (Metal Oxide Semiconductor - MOX), se proponen dos contribuciones: un nuevo diseño de nariz electrónica (Multi Chamber Electronic Nose - MCE-nose) y un enfoque basado en el modelado dinámico de estos sensores. Referente a la cuantificación de gases, se propone un novedoso enfoque probabilístico el cual permite la estimación de la concentración del gas junto con su incertidumbre asociada, algo imprescindible para aplicaciones de robótica olfativa. Finalmente, relacionado con el estudio de la distribución espacial de los gases, esta tesis contribuye con la propuesta de un método probabilístico para la generación de mapas de gas. Este novedoso método permite, por primera vez, considerar tanto los obstáculos presentes en el entorno, como el envejecimiento (factor temporal) de las medidas de gas

Electronic Noses for Biomedical Applications and Environmental Monitoring

This book, titled “Electronic Noses for Biomedical Applications and Environmental Monitoring”, includes original research works and reviews concerning the use of electronic nose technology in two of the more useful and interesting fields related to chemical compounds detection of gases. Authors have explained their latest research work, including different gas sensors and materials based on nanotechnology and novel applications of electronic noses for the detection of diverse diseases. Some reviews related to disease detection through breath analysis, odor monitoring systems standardization, and seawater quality monitoring are also included

Development of new intelligent autonomous robotic assistant for hospitals

Continuous technological development in modern societies has increased the quality of life and average life-span of people. This imposes an extra burden on the current healthcare infrastructure, which also creates the opportunity for developing new, autonomous, assistive robots to help alleviate this extra workload. The research question explored the extent to which a prototypical robotic platform can be created and how it may be implemented in a hospital environment with the aim to assist the hospital staff with daily tasks, such as guiding patients and visitors, following patients to ensure safety, and making deliveries to and from rooms and workstations. In terms of major contributions, this thesis outlines five domains of the development of an actual robotic assistant prototype. Firstly, a comprehensive schematic design is presented in which mechanical, electrical, motor control and kinematics solutions have been examined in detail. Next, a new method has been proposed for assessing the intrinsic properties of different flooring-types using machine learning to classify mechanical vibrations. Thirdly, the technical challenge of enabling the robot to simultaneously map and localise itself in a dynamic environment has been addressed, whereby leg detection is introduced to ensure that, whilst mapping, the robot is able to distinguish between people and the background. The fourth contribution is geometric collision prediction into stabilised dynamic navigation methods, thus optimising the navigation ability to update real-time path planning in a dynamic environment. Lastly, the problem of detecting gaze at long distances has been addressed by means of a new eye-tracking hardware solution which combines infra-red eye tracking and depth sensing. The research serves both to provide a template for the development of comprehensive mobile assistive-robot solutions, and to address some of the inherent challenges currently present in introducing autonomous assistive robots in hospital environments.Open Acces

Calma Station and a new data acquisition system for Neutron Monitors

Este trabajo de tesis recopila las actividades de investigación llevadas a cabo por el doctorando en el ámbito de la detección de rayos cósmicos con monitores de neutrones, siendo los resultados más relevantes el diseño, construcción y puesta en marcha del Monitor de Neutrones de Castilla-La Mancha (CaLMa), y de un sistema de adquisición de datos para monitores de neutrones basado en la combinación de dispositivos de lógica programable de tipo FPGA con sistemas empotrados con Linux. Los monitores de neutrones son detectores terrestres diseñados para medir partículas de alta energía que llegan a la atmósfera terrestre principalmente desde el exterior del Sistema Solar. Desde su concepción inicial por el profesor A. Simpson, en la Universidad de Chicago en 1948, han sufrido diferentes actualizaciones, no en su concepción básica sino en las nuevas tecnologías disponibles para su construcción, distribución y análisis de sus datos. La combinación de tecnologías de bases de datos y la red Internet ha permitido unificar y centralizar los datos proporcionados por muchas estaciones de todo el planeta en la denominada Base de Datos de Monitores de Neutrones (NMDB). Este proyecto ha abierto un nuevo camino en la investigación de la Física Solar, Partículas Energéticas e Interacción Tierra-Sol y Rayos Cósmicos. El nuevo Monitor de Neutrones de Castilla-La Mancha, CaLMa. es un monitor de neutrones tipo NM64 ubicado en Guadalajara (España), 40º 38’ 32.2’’ N, 3º 9’ 44.4’’ W a 708 m sobre el nivel del mar, y tiene una rigidez de corte vertical calculada de 6.95 GV. Esta estación está integrada en la base de datos de monitores de neutrones y proporciona datos en tiempo real de 1 minuto de alta resolución, disponibles al público a través de los canales de distribución de la NMDB. Junto con el monitor de neutrones CaLMa, también se ha diseñado un nuevo sistema de adquisición de datos desde cero para abordar problemas de obsolescencia y proporcionar nuevas funciones mediante la aplicación de tecnologías basadas en FPGA. Este nuevo sistema ya ha estado funcionando en otras estaciones, por lo que también se ha proporcionado un análisis comparativo de los datos de los sistemas de adquisiciones antiguos y nuevos. Esto nos ha permitido análisis de validación para el nuevo sistema

Application of advanced technology to space automation

Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits