Dissertations / Theses on the topic 'Sensor'

The aim of the diploma thesis is to get acquainted with possibilities of realization of a multifunctional sensor for agricultural purposes. The theoretical work deals with the principles of measurement of environmental variables. Subsequently, sensors are selected which can measure the environmental variables. The thesis discusses the possibilities of wireless communication. Attention is paid to the communication modules of the DIGI® manufacturer. The main part describes the physical implementation of the multifunctional sensor. Here is a detailed breakdown of what components are selected for implementation with adherence to general implementation requirements. At the end of the work is described a program serving multifunctional sensor.

A context-aware computing system is one that can deduce the state of its surroundings using input from sensors and can change its behaviour accordingly. Context-aware devices might personalise themselves to their current user, alter their functionality based on where they were being used, or take advantage of nearby computing and communications resources. Location-aware systems, whose behaviour is determined by the positions of objects in the environment, represent a practical subset of the context-aware computing paradigm, and several systems of this nature have already been demonstrated. The location sensors used by those systems, however, report the positions of objects to only a room-scale granularity, limiting the extent to which devices and applications can adapt to their surroundings. Sensor technologies that can provide more detailed information about the locations of objects must therefore be investigated. This dissertation describes a new ultrasonic location sensor, which may be deployed in indoor environments such as offices and homes. The sensor can provide fine-grain , three-dimensional position and orientation information, and its characteristics are well suited to the demands of location-aware computing- the sensor is simple, low-powered and unobtrusive. Furthermore, the location system is scalable, in both the number of objects that it can track and the volume within which they may be monitored. A thorough assessment of the sensor's performance is presented in the dissertation, so that location-aware applications can be tailored to its properties. Subsequently, a software architecture that can efficiently distribute finegrain location information to applications is described. The software system provides support for the types of query that will be made frequently by location-aware applications, such as those concerning the spatial relationships between objects and their proximity to one another. The dissertation concludes by examining the use of the ultrasonic location sensor and software architecture to implement a set of novel location-aware applications.

In recent years wireless sensor network (WSN) is introduced in the fresh food tracking area as a promising solution to monitor the food transportation process. The widely applications of WSN are demanding a Universal Sensor Interface (USI) that is able to support large numbers of sensors, including gas sensors, force sensors, temperature sensors, water quality sensors, etc. In this thesis, the Universal Sensor Interface (USI) based on Programmable System on Chip (PSoC) from Cypress is presented and discussed. Multiple sensor interfaces are implemented in PSoC therefore a "sensor interface design library" is established. The dynamic reconfiguration, which is a key feature of USI, is also demonstrated. It allows USI to support multiple sensors in a time division fashion by in-circuit and run-time reconfiguration. Part of the sensor interfaces are tested and evaluated, proving both the hardware and software design. Finally the conclusion is made and future work is discussed as a guidance of the follow up work.

Pre-feasibility analysis on the optimization of the performance of the indirect tyre pressure monitoring system through a sensor fusion with a new generation of ultrasound parking sensors: from the idea to the development of macro project specifications and macro business case, with definition of the possible new scenario in terms of performance, costs and perceived quality

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California
This paper explains the development of a wireless network system implemented to streamline grocery store checkout procedures. The design employs a wireless telemetry network consisting of a base station and wireless motes (Micaz MPR2400) that will be located on certain aisles, and attached to shopping carts. This system allows customers to scan items while they shop and uses cashiers for payment purposes only. The objective is to minimize the amount of processing performed by cashiers in order to reduce waiting times in line. The system was tested in a simulation environment and waiting times were reduced by 65%.

U disertaciji je prikazano teorijsko i praktično istraživanje koje se odnosi na projektovanje, fabrikaciju i karakterizaciju heterogeno integrisanih induktivnih senzora za mjerenje sile, pritiska i pomjeraja. Cilj istraživanja doktorske disertacije je kombinovanje različitih tehnologija izrade i materijala, kako bi se projektovali senzori koji će biti konkurentni aktuelnim rešenjima, i koji bi se mogli koristiti za konkretne primjene. U okviru istraživanja, heterogenom integracijom su kombinovane prednosti tehnologije štampanih ploča (Printed Circuit Board - PCB), fleksibilne tehnologije i tehnologije niskotemperaturne zajedno-pečene keramike (Low Temperature Co-fired Ceramics – LTCC). Razvijena su tri prototipa senzora za mjerenje sile, pritiska i pomjeraja korišćenjem struktura sa induktorom i feritom u njegovoj blizini. Mjerenje realizovanih prototipova senzora vrši se bežično pomoću spregnutog antenskog namotaja. Na osnovu početnih rezultata ispitivanja, senzori su modifikovani u cilju poboljšanja i optimizovanja performansi. Projektovani senzori omogućavaju bežično mjerenje, jeftini su, kompaktni i jednostavni. Na osnovu teorijske analize, simulacija, eksperimetnalnih mjerenja, ustanovljena je ispravnost rada i primjenljivost realizovanih senzora.
In doctoral thesis theoretical and practical investigation on design, fabrication and characterisation of heterogenous integrated inductive sensors for measuring force, pressure and displacement are shown. The aim of the thesis is to investige the usage of different technologies and materials in order to design sensors which will be competitive to actual solutions and usable for specific aplications. Using heterogenous integraton, advantages of Printed Circuit Board technology (PCB), flexible and Low Temperature Co-fired Ceramics (LTCC) technologies are used. Three sensor prototypes for measuring force, pressure and displacement are developed using inductor and ferrite in its near proximity. Measurements of the realised sensor prototypes are wirelessly done using an external surrounding coil as an antenna. Based on the initial measuring results, sensors are redesigned in order to improve and optimize their performance. Projected sensors are low-cost, compact, simple, and enable wireless measurement. The proper operation and applicability of realized sensors are confirmed using theoretical analysis, simulation and experimental testing with presented results.

This thesis describes the design and implementation of mobile robot IEEE Micromouse category. The aim is to build a functional design of robot usable to testing methods of mapping and localization. The thesis also deals with the design of electronics for motion control. Electronic design of optical sensors operating on the principle of reflection of infrared light and the signal processing.

There has been an enormous growth in the usage of smartphones in recent times. Smartphones are not limited to communication purposes. It has various applications designed as per the daily requirements of humans such as web-searching, online shopping, bank transactions, games, etc. With the increase in the usage of the smartphone, the more useful information is captured and stored by it, which raises the question of security. The goal of this research is to develop two android applications. One is a sensor detector application and the second is a screen lock application. The first application will help the user to identify all the hidden sensors and working sensors on the mobile phone. This application even describes the features and usage of every sensor in detail. Using a graphical description of each sensor which depicts the behaviour of each sensor as per environment/movement. The second application is designed using a combination of two sensors. Screen lock applications contain two main factors. One is to work properly in all cases and efficiently do the functions that are required to do. The second is to maintain a smooth inner system interaction because in addition to locking the screen this application should make sure to hide the display of all the other applications without closing the process of these applications. With the increase in the usage of the smartphone, it becomes difficult for older generations to memorize the security pattern techniques and use them. This thesis develops a simple technique in the mobile authentication android application. The thesis is developed on the Android studio platform. The background functionality of the app is coded in java using android SDK tool and frontend of the application is designed using XML files. The GENYMOTION emulator and a mobile phone are used to test the output.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (leaves 97-101).
Modern sensor environments often attempt to combine several sensors into a single sensor network. The nodes of this network are generally heterogeneous and may vary with respect to sensor complexity, sensor operational modes, power costs and other salient features. Optimization in this environment requires considering all possible sensor modalities and combinations. Additionally, in many cases there may be a time critical objective, requiring sensor plans to be developed and refined in real-time. This research will examine and expand on previous work in multi-sensor dynamic scheduling, focusing on the issue of near optimal sensor-scheduling for real-time detection in highly heterogeneous networks. First, the issue of minimum time inference is formulated as a constrained optimization problem. The principles of dynamic programming are applied to the problem. A network model is adopted in which a single "leader" node makes a sensor measurement. After the measurement is made, the leader node chooses a successor (or chooses to retain network leadership). This model leads to an index rule for leader/action selection under which the leader is the sensor node with maximum expected rate of information acquisition. In effect, the sensor and modality with the maximum ratio of expected entropic decrease to measurement time is shown to be an optimal choice for leader.
(cont.) The model is then generalized to include networks with simultaneously active sensors. In this case the corresponding optimization problem becomes prohibitively difficult to solve, and so a game theoretic approach is adopted in order to balance the preferences of the several sensors in the network. A novel algorithm for multiplayer coordination is developed that uses iterative partial utility revelation to achieve bounded Pareto inefficiency of the solution.
by Peter Jones.
S.M.

The objective of this thesis is to formulate and solve the sensor placement problem for damage localization in a sensor network. A Bayesian estimation problem is formulated with the time-of-flight (ToF) measurements. In this model, ToF of lamb waves, which are generated and received by piezoelectric sensors, is the total time for each wave to be transmitted, reflected by the target, and received by the sensor. The ToF of the scattered lamb wave has characteristic information about the target location. By using the measurement model and prior information, the target location is estimated in a centralized sensor network with a Monte Carlo approach. Then we derive the Bayesian Fisher information matrix (B-FIM) and based on that posterior Cramer-Rao lower bound (PCRLB), which sets a limit on the mean squared error (MSE) of any Bayesian estimator. In addition, we develop an optimal sensor placement approach to achieve more accurate damage localization, which is based on minimizing the PCRLB. Simulation results show that the optimal sensor placement solutions lead to much lower estimation errors than some sub-optimal sensor placement solutions.

Methods to improve performance of sensors with regard to sensor nonlinearity, sensor noise and sensor bandwidths are investigated and new algorithms are developed. The necessity of the proposed research has evolved from the ever-increasing need for greater precision and improved reliability in sensor measurements. After describing the current state of the art of sensor related issues like nonlinearity and bandwidth, research goals are set to create a new trend on the usage of sensors. We begin the investigation with a detailed distortion analysis of nonlinear sensors. A need for efficient distortion compensation procedures is further justified by showing how a slight deviation from the linearity assumption leads to a very severe distortion in time and in frequency domains. It is argued that with a suitable distortion compensation technique the danger of having an infinite bandwidth nonlinear sensory operation, which is dictated by nonlinear distortion, can be avoided. Several distortion compensation techniques are developed and their performance is validated by simulation and experimental results. Like any other model-based technique, modeling errors or model uncertainty affects performance of the proposed scheme, this leads to the innovation of robust signal reconstruction. A treatment for this problem is given and a novel technique, which uses a nominal model instead of an accurate model and produces the results that are robust to model uncertainty, is developed. The means to attain a high operating bandwidth are developed by utilizing several low bandwidth pass-band sensors. It is pointed out that instead of using a single sensor to measure a high bandwidth signal, there are many advantages of using an array of several pass-band sensors. Having shown that employment of sensor arrays is an economic incentive and practical, several multi-sensor fusion schemes are developed to facilitate their implementation. Another aspect of this dissertation is to develop means to deal with outliers in sensor measurements. As fault sensor data detection is an essential element of multi-sensor network implementation, which is used to improve system reliability and robustness, several sensor scheduling configurations are derived to identify and to remove outliers.

The task is to build an intelligent sensor that can instruct a Lego robot to perform certain tasks. The sensor is mounted on the Lego robot and it contains a digital camera which takes continuous images of the front view of the robot. These images are received by an FPGA which simultaneously saves them in an external storage device (SDRAM). At one time only one image is saved and during the time it is being saved, FPGA processes the image to extract some meaningful information. In front of digital camera there are different objects. The sensor is made to classify various objects on the basis of their color. For the classification, the requirement is to implement color image segmentation based object tracking algorithm on a small Field Programmable Gate array (FPGA). For the color segmentation in the images, we are using RGB values of the pixels and with the comparison of their relative values we get the binary image which is processed to determine the shape of the object. A histogram is used to retrieve object‟s features and saves results inside the memory of FPGA which can be read by an external microcontroller with the help of serial port (RS-232).

Fear of the dentist can be a very serious issue for many children and adolescents. According to academic researches into Dental Fear and Anxiety, some young people hate dentist visits so much that they often refuse to co-operate, or worse - they don’t even go to the dentist. Scientists at Princeton and Tufts have been working a thin tooth sensor that may limit the amount of times we will need to get our teeth checked. The sensor will alert you when it detects any bacteria that could cause cavities, plaque buildup, or any other infections. The scientists say that the new sensor can recognize human oral activities, such as chewing, drinking, speaking and coughing. It also can help to better understand people’s habits and identify potential health problems, such as if a person is smoking or drinking too much. The sensor is so small that it can either fit inside an artificial tooth or straddle a real one.

When developing algorithms for autonomous vehicles it is important to test several different scenarios many times. New and untested algorithms are prone to make errors which results in accidents. It is therefore preferred to use a simulation environment instead. Sensors used to determine the vehicle’s position must then be modelled. This thesis answers the question whether adding sensor simulation to an existing simulation platform (AGXUnity) is viable, or if using other existing options is preferred. To reach the goal, a function-based sensor is developed and its accuracy tested. Its performance is determined by simulation in a standard scene. Tests showed that the sensor had acceptable accuracy and performance. The conclusion is that AGXUnity is a viable platform for sensor simulation.

Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of such methods require a priori knowledge of the characteristics of the defects under consideration. This makes the whole enterprise of detecting structural defects logically circular, as there is usually limited a priori information about the characteristics and the locations of defects that are yet to be detected. Furthermore, the majority of SHM techniques rely on sensors for response collection, with the very same sensors also prone to structural damage. The Surface Response to Excitation (SuRE) method is a broadband frequency method that has high sensitivity to different types of defects, but it requires a baseline. In this study, initially, theoretical justification was provided for the validity of the SuRE method and it was implemented for detection of internal and external defects in pipes. Then, the Comprehensive Heterodyne Effect Based Inspection (CHEBI) method was developed based on the SuRE method to eliminate the need for any baseline. Unlike traditional approaches, the CHEBI method requires no a priori knowledge of defect characteristics for the selection of the excitation frequency. In addition, the proposed heterodyne effect-based approach constitutes the very first sensor-less smart monitoring technique, in which the emergence of mechanical defect(s) triggers an audible alarm in the structure with the defect. Finally, a novel compact phased array (CPA) method was developed for locating defects using only three transducers. The CPA approach provides an image of most probable defected areas in the structure in three steps. The techniques developed in this study were used to detect and/or locate different types of mechanical damages in structures with various geometries.

La rapida diffusione e la grande popolaritá di laptops, smartphones,PDAs, dispositivi GPS e altri apparecchi elettronici nell'era post-PC, hanno alimentato la tendenza di produrre apparecchi elettronici sempre piú portatili, versatili e a buon mercato, con capacitá di calcolo sempre piú elevate. I continui progressi tecnologici hanno condotto ad un'abbondante disponibilitá di microprocessori e microcontrollori sempre piú piccoli ed economici, equipaggiati con sensori sempre piú avanzati, storage e dotati di connessione wireless. In quest' ottica si colloca l'emergere di una nuova tipologia di reti di telecomunicazioni: le Wireless Sensor Networks (WSNs), le quali rappresentano pienamente l'ultima tendenza della famosa legge di Moore nei confronti della miniaturizzazione e dell'ubiquitá dei dispositivi elettronici. L'integrazione di capacitá di calcolo, memorizzazione e comunicazione in dispositivi di dimensioni ridotte e a basso costo ha portato alla de finizione delle WSNs. Le reti di sensori sono state pensate come possibili strumenti per l'activity recognition in campo biomedico, i risultati di tale applicazione mostrano come questa essa sia molto e fficace nel monitoraggio della azioni di pazienti. Viene inoltre presentata un applicazione realizzata attraverso una WSN. Si tratta di un un applicazione per HRV (Heart Rate Variability). L'HRV é basata sull'analisi tempo-frequenza degli intervalli R-peak raccolti da un segnale ECG. Tale studio propone un toolkit realizzato attraverso una rete di sensori wireless per l'analisi temporale dell'HRV, chiamata SPINE-HRV (Signal Processing In Node Environment SPINE). SPINE-HRV é composto da un sistema indossabile per il monitoring dell'attivitá cardiaca in grado di raccogliere continuamente gli R-peak e un applicazione in grado di processare cosí i dati raccolti. L'analisi fatta attaverso lo SPINEHRV toolkit fornisce sette parametri ben noti in letteratura medica in grado di aiutare i cardiologi nella diagnosi relativa a diverse problematiche. Inoltre tale toolkit fornisce uno strumento automatico per rilevazione di stati di stress acuti rilevabili durante tutte le attivitá svolte quotidianamente. Nella seconda parte verrá presentata una panoramica sui media gateway in particolare sui transcoder video per gli standard di codi ca video H.263+ e H.264. L'eterogeneitá sempre piú diffusa dei dispositivi presenti all'interno della rete Internet, rende necessaria lo sviluppo di dispositivi hardware o software in grado da permettere una a dabile intercomunicazione tra tali diversi dispositivi. In particolare si mostrerá come é possibile riutilizzare i modi Intra estratti durante il processo di decodi fica per aumentare l'efficienza della codifi ca in altro standard di codi ca video. Sono stati sviluppati due algoritmi in grado di selezionare attraverso una decisore a soglia, utilizzato sia per i modi 4x4 che 16x16. Verranno presentati le prestazioni in termini di PSNR e tempi di elaborazione confrontati con quelle relative l'approccio full transcoding. Tali risultati mostrano come siano stati ottenuti signi ficativi riduzioni dei tempi computazionali pur mantenendo un livello di PSNR confrontabile con quello relativo al processo di full transcoding.
With the wide diffusion and popularity of laptops, cell-phones, Personal Digital Assistants (PDAs), GPS devices and other intelligent electronic in the post-PC era, computing devices have become more portable, mobile and cheap. Nowadays the electronic in uences the daily life of each man and many tasks hard to do in the past now have become reality and easy to perform thanks to the signi cant advances in technology. From this viewpoint the emergence of wireless sensor networks (WSNs) is essentially the latest trend of Moore's Law toward the miniaturization and ubiquity of computing devices. Wireless sensor networks are used in order to perform activity recognition in heath care eld, the results of this application show how that it is effective in patient's actions monitoring. Moreover an application regarding Heart Rate Variability (HRV)will be presented. This work is based on the analysis of the Rpeak to R-peak intervals (RR-intervals) of the ECG signal in the time and/or frequency domains. Doctors and psychologists are increasingly recognizing the importance of HRV; in fact, a number of studies have demonstrated that patients with anxiety, phobias and posttraumatic stress disorder consistently show lower HRV,even when not exposed to a trauma related prompt. Importantly,this relationship existed independently of age, gender, trait anxiety, cardio-respiratory tness, heart rate, blood pressure and respiration rate. The SPINE-HRV is composed of a wearable heart activity monitoring system to continuously acquire the RR-intervals, and a processing application developed using the SPINE framework. The RR-intervals are processed using the SPINE framework at the base station side through a time-domain analysis of HRV. The analysis provides seven common parameters known in medical literature to help cardiologists in the diagnosis related to several heart diseases. In particular, SPINE-HRV is applied for stress detection of people during activities in their everyday life. Experimentations carried out by monitoring subjects in speci c activities have shown the effectiveness of SPINE-HRV in detecting stress. Currently few research prototypes based on BSNs exist that allow for HRV analysis. However SPINE-HRV represents the fi rst prototype using a wireless chest belt so making the system more comfortable than systems using wired electrodes or handheld devices. Furthermore, because the chest belt is a commercial product for sport and tness activities, it has been designed to be robust against body movements. SPINE-HRV is currently applied to stress detection that is computed through an effective threshold based algorithm. The experimentation of such an application has been carried out on different subjects performing different activities of the everyday life: walking, working at the PC, watching TV, sleeping, and driving. The obtained result are interesting as they show that SPINE-HRV is able to detect stress by performing only a time-domain analysis of HRV with respect to more complex computational methods based on the frequency-domain analysis. Thus, SPINE-HRV can be actually used to detect stress of human beings in real-time. Currently, we are focusing our research efforts in improving the stress analysis algorithm by introducing frequency domain features as well as comparing the obtained results to the clinical blood test for the stress hormone, which has been identi ed by the medical community as the quantitative measurement of the emotional stress level. In the second part of this thesis will be described two smart video transcoder processes in order to develop a media gateway. The aim of this network device is to bring about a conversion of the input bitstream into another one characterized by a different video codec. The codecs involved in the transcoding algorithm are the H.263+ (Annex I) and the H.264 baseline pro le. The scope of this study focuses on the possibility of reusing the Intra modes extracted from the input bitstream. Regarding H.263+ to H.264 transcoding, two different thresholds are evaluated for 4x4 blocks and 16x16 macroblocks: all the incoming modes that lead to costs over threshold are rejected and a re-estimation is performed. Otherwise, the incoming Intra mode is directly passed to the H.264 encoder. On the other hand, all the H.264 Intra modes are mapped into the H.263+ Intra modes and passed to the H.263+ encoder skipping the Intra prediction stage. Performance in terms of PSNR and elaboration time of our algorithms are compared to that of the full transcoding approach. A high correlation with PSNR scores is obtained and a significant reduction of computational burden for both transcoding processes is also achieved. The two video transcoder architectures are proposed in order to perform the H.263+ to H.264 conversion and vice versa. Referring to the rst transcoder, two adaptive thresholds are implemented. Both thresholds, used for 4x4 Intra block mode decision and 16x16 Intra block mode decision, vary according to the overall macroblock cost in order to consider the level of detail of the under-study macroblock. This solution is an innovation relating to the approaches proposed in literature based on the usage of a single xed threshold. We can assert that these algorithms represent a basis for the implementation of a low complexity fast transcoder for real-time applications thanks to the low complexity of the modi cation introduced, and also for the reduced computational burden of the entire trancoding process. In fact, we demonstrate a decrease of about 32% in the overall elaboration procedure using an arbitrary QP. The proposed platform also shows high reliability in terms of perceived quality. This is confi rmed by PSNR evaluations for fast transcoding output. PSNR differences are limited to 0.1 dB for all sequences used in the tests. So, the quality of the full transcoding output is very close to the one obtained by the fast transcoding technique. In addition, the overall increase in the bitrate is less than 12%. The H.264 to H.263+ transcoder uses a mapping between the incoming H.264 modes that is rather different to the one proposed in literature. The obtained results, using several standard sequences and QP, show that the overall quality is the same for the output bitstream obtained by the full transcoder and the proposed smart transcoder algorithm, and the bitrate increase is limited to 9% in the worst case. With this mapping it is possible to cancel the computational burden of the Intra mode prediction process. All these considerations allow us to assert that the proposed algorithm can be used in real-time transcoding architectures. Similar analysis concerning Inter frame pictures are actually under study by the authors in order to reduce the complexity of motion estimation procedure in transcoding architectures.

This thesis describes utilization of a nanotechnology in new pressure sensors. Detailed analysis of individual principles are carrying on. And simulations and experimental models of sensors are developed. More detailed description is provided for new capacitive pressure sensor, which is manufactured using nanotechnology, including its model and analysis in order to improve its properties. The work deals with the emission pressure sensor which uses the principle of cold emissions, including analysis comparison of the measured values of the emission current from the applied nanotubes field and analysis to improve emissions performance.

First part of this work is focused on the description exist methods for measuring refraction index of air. Second part deal with concrete problem realization measurement unit for monitoring of refraction index of air. Refraction index of air is measured indirect method which is based on a modified Edlen formula.

The main goal of this diploma thesis is to get familiar with organic sensors developed at the Faculty of Chemistry at Brno University of Technology. The outcome is the implementation of smart hydrogen detector which is based on use of these sensors. This device will allow to test and use relevant sensors outside the test apparatus placed in the laboratory of the Faculty of Chemistry at Brno University of technology.

Exploitation of wireless sensor networks (WSNs) in ubiquitous computing environments is continuously increasing for gathering data. Contemporary distributed software systems on WSNs for pragmatic business applications have become extremely adaptive, dynamic, heterogeneous and large scaled. Management of such system is not trivial to fulfil these features, leading to more and more complex management and configuration. Along with encompassing state of art and novel techniques for such diversely dynamic system, in this thesis two alternative techniques namely “task initiation by command” and “run-time task deployment and processing” are compared, for such system’s setup and configuration. Both techniques have their own pros and cons which makes them suitable according to the requirements and contextual situations. A lot of effort has been put to make WSNs more and more efficient in terms of computations and power consumption. Hence comparative analysis of both techniques used in this report to setup and configure WSN can be a benchmark to lead towards most appropriate solution to compensate the need of efficient energy and resource consumption.Both alternative schemes are implemented to setup WSN on Sun Microsystems sunSPOT (Small Programmable Object Technology) sensor nodes which are embedded microcontrollers and programmed them in java (j2me). It performs radio communication between wireless sensors and host via sink node also called base station, along with over the air run-time management of sensors. SunSPOTs built in libraries and KSN libraries are used to implement these alternatives and compare the memory footprint, communication pattern and energy consumption.Exploitation of wireless sensor networks (WSNs) in ubiquitous computing environments is continuously increasing for gathering data. Contemporary distributed software systems on WSNs for pragmatic business applications have become extremely adaptive, dynamic, heterogeneous and large scaled. Management of such system is not trivial to fulfil these features, leading to more and more complex management and configuration. Along with encompassing state of art and novel techniques for such diversely dynamic system, in this thesis two alternative techniques namely “task initiation by command” and “run-time task deployment and processing” are compared, for such system’s setup and configuration. Both techniques have their own pros and cons which makes them suitable according to the requirements and contextual situations. A lot of effort has been put to make WSNs more and more efficient in terms of computations and power consumption. Hence comparative analysis of both techniques used in this report to setup and configure WSN can be a benchmark to lead towards most appropriate solution to compensate the need of efficient energy and resource consumption.Both alternative schemes are implemented to setup WSN on Sun Microsystems sunSPOT (Small Programmable Object Technology) sensor nodes which are embedded microcontrollers and programmed them in java (j2me). It performs radio communication between wireless sensors and host via sink node also called base station, along with over the air run-time management of sensors. SunSPOTs built in libraries and KSN libraries are used to implement these alternatives and compare the memory footprint, communication pattern and energy consumption.

The rapid developments in the sensor and its related technology have made automation possible in many processes in diverse fields. Also sensor-based fault diagnosis and quality improvements have been made possible. These tasks depend highly on the sensor network for the accurate measurements. The two major problems that affect the reliability of the sensor system/network are sensor failures and sensor anomalies. The usage of redundant sensors offers some tolerance against these two problems. Hence the redundancy analysis of the sensor system is essential in order to clearly know the robustness of the system against these two problems. The degree of sensor redundancy defined in this thesis is closely tied with the fault-tolerance of the sensor network and can be viewed as a parameter related to the effectiveness of the sensor system design. In this thesis, an efficient algorithm to determine the degree of sensor redundancy for linear sensor systems is developed. First the redundancy structure is linked with the matroid structure, developed from the design matrix, using the matroid theory. The matroid problem equivalent to the degree of sensor redundancy is developed and the mathematical formulation for it is established. The solution is obtained by solving a series of l1-norm minimization problems. For many problems tested, the proposed algorithm is more efficient than other known alternatives such as basic exhaustive search and bound and decomposition method. The proposed algorithm is tested on problem instances from the literature and wide range of simulated problems. The results show that the algorithm determines the degree of redundancy more accurately when the design matrix is dense than when it is sparse. The algorithm provided accurate results for most problems in relatively short computation times.

Wireless sensor networks (WSNs) have gained attention in recent years with the proliferation of the micro-electro-mechanical systems, which has led to the development of smart sensors. Smart sensors has brought WSNs under the spotlight and has created numerous different areas of research such as; energy consumption, convergence, network structures, deployment methods, time delay, and communication protocols. Convergence rates associated with information propagations of the networks will be questioned in this thesis. Mobility is an expensive process in terms of the associated energy costs. In a sensor network, mobility has significant overhead in terms of closing old connections and creating new connections as mobile sensor nodes move from one location to another. Despite these drawbacks, mobility helps a sensor network reach an agreement more quickly. Adding few mobile nodes to an otherwise static network will significantly improve the network’s ability to reach consensus. This paper shows the effect of the mobility on convergence rate of the wireless sensor networks, through Eigenvalue analysis, modeling and simulation.

This thesis has investigated how the energy consumption can be reduced in a mobile sensor unit by using a dynamic measurement scheme. This was done by developing a scheme based on inspiration from existing works in related areas and on techniques found in literature. The developed scheme was then implemented on a mobile sensor unit and tests were conducted where the energy consumed by the scheme was measured. This was compared to a static baseline approach in order to evaluate the efficiency of the scheme. The results showed that on the platform used in this thesis the developed scheme can reduce the energy consumption in a typical scenario by 4.7% or 6.7% depending on which sensors are used. A conclusion drawn is that the platform has a major impact on how effective the scheme can be.

Many machines in these days have sensors to collect information from the world they inhabit. The correctness of this information is crucial for the correct operation. However, at times sensors are not so reliable since they are sometimes affected of some type of noise and thus give incorrect information. Another drawback might be lack of information due to shortage of existing sensors. Sensor fusion is trying to overcome these drawbacks by integrating or combining information from multiple sensors. The heating of a building is a slow and time consuming process, i.e. either the flow or energy consumption are object to drastically changes. On the other hand, the tap water system, i.e. the heating of tap water can be the source to severe changes in both flow and energy consumption. This because of that the flow is stochastic in the tap water system, at any given time a tap may be opened or closed and therefore drastically change the flow. The purpose of this thesis is to investigate if is it possible to use sensor fusion to get accurate continuous flow values from a district heating substation. This is done by integrating different sensor fusion algorithms in a district heating substation simulator.

Wireless sensor networks (WSNs) can provide new methods for information gathering for a variety of applications. In order to ensure the network quality of service, the quality of the measurements has to be guaranteed. Distributed fault detection and isolation schemes are preferred to centralized solutions to diagnose faulty sensors in WSNs. Indeed the first approach avoids the need for a central node that collects information from every sensor node, and hence it limits complexity and energy cost while improving reliability.In the case of state estimation over distributed architectures, the sensor faults can be propagated in the network during the information exchanging process. To build a reliable state estimate one has to make sure that the measurements issued by the different sensors are fault free. That is one of the motivations to build a distributed fault detection and isolation (FDI) system that generates an alarm as soon as a measurement is subject to a fault (has drift, cdots ). In order to diagnose faults with small magnitude in wireless sensor networks, a systematic methodology to design and implement a distributed FDI system is proposed. It resorts to distinguishability measures to indicate the performance of the FDI system and to select the most suitable node(s) for information exchange in the network with a view to FDI. It allows one to determine the minimum amount of data to be exchanged between the different nodes for a given FDI performance. In this way, the specifications for FDI can be achieved while the communication and computation cost are kept as small as possible. The distributed FDI systems are designed both in deterministic and stochastic frameworks. They are based on the parity space approach that exploits spacial redundancy as well as temporal redundancy in the context of distributed schemes. The decision systems with the deterministic method and the stochastic method are designed not only to detect a fault but also to distinguish which fault is occurring in the network. A case study with a WSN is conducted to verify the proposed method. The network is used to monitor the temperature and humidity in a computer room. The distributed FDI system is validated both with simulated data and recorded data.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

Les progrès de la robotique mobile nous permettent aujourd'hui d'ajouter la notion de mobilité dans plusieurs classes de réseaux de capteurs sans fil. Le déploiement de capteurs mobiles est possible et utile dans de nombreuses applications, comme la surveillance de l'environnement, les applications dans l'industrie, dans la santé et le domaine militaire. Le terme robot mobile peut représenter n'importe quel type de robot avec la capacité de modifier sa position. Cette notion inclut une vaste gamme de robots industriels utilisés dans les lignes de production. Dans le contexte spécifique de cette thèse, l'attention se focalise uniquement sur les robots mobiles et plus particulièrement les véhicules autonomes dont les mouvements ne sont pas limités par leur taille physique. Ainsi, un robot ou un groupe de robots mobiles peuvent être utilisés pour explorer des environnements inconnus et effectuer une variété de fonctions. La mobilité du robot dans le contexte des réseaux de capteurs, nous permet de résoudre les problèmes qui ne pourraient pas être résolues dans un cas statique. Les robots mobiles permettent d'augmenter la robustesse du réseau en remplaçant des nœuds de capteurs et de s'adapter aux environnements inconnus ou dynamiques. Deux thèmes sont abordées dans cette thèse : la conception d'un intergiciels pour les réseaux de robots mobiles et un ensemble d'approches pour le déploiement de robots mobiles dans le cadre de réseaux de capteurs sans fil. L'intergiciel proposé et décrit dans cette thèse permet à l'utilisateur de facilement mettre en œuvre différents types d'algorithmes de déploiement pour les robots mobiles. Il permet de déployer une application sur la station de base centrale qui permet à un utilisateur de rassembler toutes les informations captées par la flotte de robots. L'application de la station de base permet à un utilisateur d'envoyer des commandes à un groupe ou à un robot, introduisant ainsi la commande manuelle en option dans le réseau robotique. L'intergiciel présenté dans ce travail est dédié à être utilisé avec des robots mobiles Wifibot. Il permet réaliser plusieurs tâches. Tout d'abord, il interagit avec le microgiciel du robot pour piloter les moteurs des roues et recueille les informations concernant la sortie du capteur et de l'état de la batterie. Deuxièmement, il gère la communication avec d'autres robots et les stations de base du réseau. Troisièmement, il traite les informations sur l'environnement et les messages reçus des voisins dans le réseau. Enfin, il réagit et il s'adapte de manière rapide et fiable pour aux événements de l'environnement. Dans la deuxième partie de la thèse, trois problèmes sont présentés et analysés : le problème de l'amélioration de la qualité de service avec l'utilisation des réseaux robotiques mobiles, la couverture du point d'intérêt avec des robots mobiles et la découverte de points d'intérêt et leur couverture avec l'utilisation des robots mobiles. Le premier problème est résolu avec l'utilisation de l'algorithme de déploiement qui améliore les performances de la transmission multimédia. Cet algorithme utilise une méthode intrusive pour réunir les métriques de qualité de service. Ensuite, l'attention est focalisé sur l'application des réseaux de capteurs sans fil est la surveillance de l'environnement. Au lieu de surveiller toute la région, couvrir seulement un ensemble de points d'intérêt spécifiques accroît les performances du réseau et réduit le coût de déploiement. Nous faison l'hypothèse que la station de base fixe est placé à l'intérieur du domaine d'intérêt, tandis que les robots mobiles disponibles couvrent le point d'intérêt et relayent l'information vers la station de base. L'approche pour résoudre le dernier problème est basée sur le mouvement continu et à vitesse variable de capteurs mobiles, qui suivent des trajectoires circulaires concentriques afin d'explorer et de couvrir le domaine d'intérêt. En se déplaçant constamment, les capteurs exécutent la tâche de découverte de l'environnement et, en ajustant la vitesse de déplacement, ils répondent aux contraintes de la couverture et la connectivité avec la station de base. L'algorithme installé sur tous les capteurs mobiles est distribué et introduit une nouvelle technique de calcul de la vitesse en fonction des informations disponibles à partir des capteurs dans le voisinage à un-saut. Ces algorithmes de déploiement de robots mobiles ont prouvé leur faisabilité à travers de nom- breuses simulations ainsi que dans la mise en pratique en s'appuyant sur l'intergiciel proposé.

Wireless Sensor Networks (WSN) have an important role to play in applications involving surveillance, security and autonomous systems. Furthermore, recent technological advances have allowed wireless sensor networks to be applied to a plethora of areas such as environment monitoring, traffic control, health, agriculture, medical, home applications, as well as fire fighting, and object tracking. One of the main, generic WSN requirements is the collection of large amounts of data which can be afterwards used in classification and decision making processes. Within such a general WSN framework, this dissertation studies sensor node positioning strategies. Thus given a fixed number of sensors operating in a completely unknown environment, work is focussed on the development of efficient sensor positioning techniques. Efficiency here relates to i) collection of data in order to characterize (for a given accuracy) the environment, with a minimum number of sensor moving steps i.e. as quickly as possible, and ii) the location and tracking of major features of the environment, for example the maxima of data distributions used to form in simulations the data profile of a given environment. Furthermore, the above WSN movement/positioning methodologies are applied to both data static and data dynamic environments. Note that these methodologies contain two key processes: i) data interpolation; and data prediction as applied to trajectories of moving environment features. Thus WSN data is interpolated using a form of Kriging interpolation whereas prediction is performed using a polynomial based approach. Experimentation has been performed using computer simulation of proposed methods and experimental results are presented in the thesis which allows proposed schemes to be compared in terms of different criteria. Results associated to systems employing ground truth data, as a substitute for ideal interpolation and prediction processes, are also presented and are taken as providing bounds of system performance.

A long operational lifetime is one of ultimate goals of wireless sensor networks (WSNs) due to the limited energy resources of sensors. As sensors are often randomly deployed in vast and inaccessible areas, it is impractical to recharge or replace their energy resources such as batteries. Thus, energy efficiency is likely to be a highly important issue for the WSNs. A key approach to enhancing energy efficiency is sensor scheduling. Sensor scheduling means that in each operational round certain sensors are selected to be active, whilst others are pushed into sleep mode. However, the required quality of sensing coverage and network connectivity must be guaranteed. The former is that the entire monitored area must be fully covered at a given level called a desired coverage degree (k). Meanwhile, the latter is that every active sensor must be connected with others. Both properties together are known as the connected coverage assurance. This thesis proposes a series of sensor scheduling methods, namely 6-Triangle (6-Tri), 4-Square (4-Sqr), 3-Symmetrical area (3-Sym) and Optimum-Symmetrical area (O-Sym). The 6-Tri method uses a hexagon tessellation as a virtual partition in order to group sensors into hexagonal cells. This method activates 6 sensors from each cell. Otherwise, the 4-Sqr method uses a virtual square partition instead in order to divide the sensors into square cells. A cell consists of 4 sub-squares, within each of which a sensor is activated. Similar to the 6-Tri method, the 3-Sym method has a hexagon tessellation as its virtual partition. As only three sensors whose position is symmetrical with each other are selected in each cell, the 3-Sym method can significantly reduce the number of active sensors, compared to both the 6-Tri and 4-Sqr methods. The O-Sym method enhances the 3-Sym method by optimising coverage efficiency. It firstly investigates coverage redundancy, which is produced by the 3-Sym method, and then tries to minimise the redundancy to the desired coverage degree. This method achieves both energy efficiency and coverage efficiency, which are the main objectives of this thesis.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical and Computer Engineering, 2008.
Includes bibliographical references.

The usage of inertial sensors has traditionally been confined primarily to the aviation and marine industry due to their associated cost and bulkiness. During the last decade, however, inertial sensors have undergone a rather dramatic reduction in both size and cost with the introduction of MEMS technology. As a result of this trend, inertial sensors have become commonplace for many applications and can even be found in many consumer products, for instance smart phones, cameras and game consoles. Due to the drift inherent in inertial technology, inertial sensors are typically used in combination with aiding sensors to stabilize andimprove the estimates. The need for aiding sensors becomes even more apparent due to the reduced accuracy of MEMS inertial sensors. This thesis discusses two problems related to using inertial sensors in combination with aiding sensors. The first is the problem of sensor fusion: how to combine the information obtained from the different sensors and obtain a good estimate of position and orientation. The second problem, a prerequisite for sensor fusion, is that of calibration: the sensors themselves have to be calibrated and provide measurement in known units. Furthermore, whenever multiple sensors are combined additional calibration issues arise, since the measurements are seldom acquired in the same physical location and expressed in a common coordinate frame. Sensor fusion and calibration are discussed for the combination of inertial sensors with cameras, UWB or GPS. Two setups for estimating position and orientation in real-time are presented in this thesis. The first uses inertial sensors in combination with a camera; the second combines inertial sensors with UWB. Tightly coupled sensor fusion algorithms and experiments with performance evaluation are provided. Furthermore, this thesis contains ideas on using an optimization based sensor fusion method for a multi-segment inertial tracking system used for human motion capture as well as a sensor fusion method for combining inertial sensors with a dual GPS receiver. The above sensor fusion applications give rise to a number of calibration problems. Novel and easy-to-use calibration algorithms have been developed and tested to determine the following parameters: the magnetic field distortion when an IMU containing magnetometers is mounted close to a ferro-magnetic object, the relative position and orientation of a rigidly connected camera and IMU, as well as the clock parameters and receiver positions of an indoor UWB positioning system.
MATRIS (Markerless real-time Tracking for Augmented Reality Image), a sixth framework programme funded by the European Union
CADICS (Control, Autonomy, and Decision-making in Complex Systems), a Linneaus Center funded by the Swedish Research Council (VR)
Strategic Research Center MOVIII, funded by the Swedish Foundation for Strategic Research (SSF)

Inexpensive instruments that measure concentrations of airborne particles in workplaces have grown to become an efficient way to estimate personal aerosol exposure of workers. This study evaluates the performance of two types of inexpensive instruments: an “active” version which pulls particle-laden air into a sensing zone for measurement, and a “passive” version which does not. The response of these instruments to clean air over time was evaluated as an indicator of contamination in laboratory and factory settings. Additionally, the effect cleaning of the instruments had on performance was evaluated. After exposure to high concentrations of particles in the laboratory, the active and passive versions of the instruments lost partial to full ability to detect particle concentrations. In the factory, this change was only seen in the active version, and occurred over a longer amount of time. Cleaning of the instruments returned some ability to detect particles, but not to the ability a new instrument. The accumulation of particles within instruments used to estimate aerosol exposures can affect the output of and overall performance of the instruments. Cleaning of the instruments after accumulation results a lessening of the effect, but not completely. Cleaning can be a way to extend the lifetime of these instruments. However, the time and financial costs related to cleaning several sensors within a workplace should be considered.

This is the final documentation of the basis that can be the foundation of how to solve the

problem with leaking hydraulic oil in a shoe press at the company Albany International

AB in Halmstad, Sweden.

The project has been performed at Halmstad University as a degree project commissioned

by Albany International AB. The purpose of the degree project was to find a way of

detecting the hydraulic leak of a shoe press. The reason is that the shoe press runs

unattended during nights and weekends, this can cause an extensive decontamination

work and production stop if leak. The hydraulic oil could be leaking in large amounts or

slowly as a fine mist. The development of a working system that can detect a hydraulic

oil leak and stop the machine before a large amount of hydraulic oil leaks out would

considerably reduce the cost of the decontamination work. It would also reduce the

interruption time of the production. When the hydraulic oil is leaking as a fine mist and

spreading in the facility, the risk of fire is much higher and will be reduced if detected in

time.

The outcome of the degree project is this document containing results of investigations

and a suggestion on how to make a prototype. In benefit of investigations, inquiry and

tests the project group has been able to choose a suitable method of how to detect a

hydraulic leak. The prototype has been tested in laboratory environment and showed a

god ability to detect hydraulic oil.

This thesis presents an experimental smart tactile sensor system based on a 16-by-16 array of Force Sensing Resistor (FSR) elements. The tactile image data are acquired, memorized, and then transferred to a PC by an electronic interface using a PICmicro microcontroller. A user-friendly graphical user interface, integrates all the functions needed to acquire, process, display and save the tactile measurement data. Experiments on a set of 3D geometric symbols illustrate the functionality of the tactile sensor system. Finally, an application of the smart tactile sensor for robotic tactile object recognition is presented.

Most approaches to spatial image management involve GPS or image processing. In this thesis, a sensor-focused alternative is explored. It requires user and camera tracking, particularly challenging in indoor environments. Possible indoor tracking methods are evaluated and pedestrian dead reckoning is selected. A study is conducted to evaluate sensors and choose a combination for pedestrian and camera tracking. Gyroscope and accelerometer offer comparable step detection performance, with gyroscope and tilt compensated compass providing heading data. Images taken from the same viewpoint are successfully arranged using panorama stitching without any image processing. The results compare favourably to conventional methods. While lacking visual definition of image processing methods, they can complement them if used in tandem. Sensor compositing and pedestrian tracking are implemented in a unified system. Several methods for fusing compass and gyroscope data are compared, but do not produce statistically significant improvement over using just the compass. The system achieves loop closure accuracy of 91% of path length and performs consistently across multiple participants. The final system can be used in GPS-denied locations and presents an image content independent way of managing photographs. It contributes to pedestrian tracking and image composting fields and has potential commercial uses (illustrated by an example Android app).

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada
The scope of this document is the description of design and implementation of the wireless sensor network realized as a part of our Senior Design Capstone Project. The various components and sub-systems that comprise the final product are discussed, followed by the implementation procedures and results.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California
The yawsonde is a device used at the U.S. Army Research Laboratory (ARL) to investigate the in-flight behavior of spinning projectiles. The standard yawsonde consists of a pair of solar cells and slits that respond to solar rays. The sun is used as an inertial reference to measure the pitching and yawing motions of the projectile. An FM telemetry package transmits the sensor data to a ground receiving station for analysis. The standard yawsonde package is housed in an M577-type artillery fuse body. The spinning motion of the projectile serves as the sampling rate for the measurements. When the spin rate is not significantly higher than the yaw rate, multiple sets of sensors must be used to effectively increase the sampling rate. The pinhole yawsonde sensor was developed for projectiles that require multiple sets of sensors in a very limited space. This pinhole yawsonde consists of a number of sensors located behind pinholes placed around the projectile's circumference. Since each pinhole makes a yaw measurement, many measurements, or samples, are taken with each projectile spin revolution. More pinhole sensors may be added to increase the measurement sampling rate. One application of this yawsonde is to aid in evaluating the performance of tactical devices and inertial systems onboard projectiles with limited space for instrumentation.

Den här uppsatsen beskriver processen av att skapa en plattformsoberoende mobilapplikation för att koppla upp mobila enheter mot trådlösa sensorer med hjälp av Bluetooth Low Energy, samla in data från uppkopplade sensorer och ladda upp den insamlade datan till en molnlagringstjänst. Allt eftersom konsumenter och forskare använder fler sensorer och andra Bluetooth-enheter, [1] ökar behovet av simplare och standardiserade lösningar för att arbeta med dessa. En litteraturstudie har genomförts där information om närliggande forskning insamlats och viktig information om de nödvändiga mjukvarukomponenter som krävs har utvärderats. I kombination med litteraturstudien har en IT-artefakt utvecklats i form av en mobilapplikation som har testats utefter insamlade krav för att säkerställa applikationens funktionalitet. Syftet med det här arbetet är att tydliggöra och konkretisera en mjukvaruutvecklingsprocess som kan användas för att skapa en mobilapplikation av det här slaget, samt vilka potentiella svårigheter som finns i dagsläget med att utforma den här typen av applikationer. Resultaten visar att en del tillverkare inte följer standarden för Bluetooth-kommunikation, detta gör det svårt att skriva generaliserade metoder för att hämta data från sensorer av alla typer och från samtliga tillverkare.
This thesis describes the process of creating a platform-independent mobile application for connecting mobile devices to wireless sensors using Bluetooth Low Energy, collecting data from connected sensors and uploading the collected data to a cloud storage service. As consumers and researchers use more sensors and other Bluetooth-devices, [1] one could argue that there is a need for simpler and standardised solutions to working with these. A literature study has been conducted where information on related research has been collected and important information about the necessary software components has been evaluated. In combination with the literature study, an IT artefact has been developed in the form of a mobile application that has been tested according to collected requirements to ensure the application's functionality. The purpose of this work is to contribute with a clear scientific process over what is required to create a mobile application of this kind and what potential difficulties exist in present-day design of this type of applications. The results show that some manufacturers may not be following the standards for Bluetooth data communication, thus making it hard to write generalized methods for retrieving data from sensors of any type or manufacturer.

Mestrado em Engenharia Electrónica e Telecomunicações
Neste trabalho foi desenvolvido um sensor para medição do ângulo de flexão do cotovelo de um indivíduo. Este sensor é uma ajuda na aferição da recuperação de uma pessoa que sofreu um acidente cardiovascular e que tenha perdido mobilidade no conjunto ombro-braço. Embora o sensor por si só não desempenhe uma função vital na recuperação de um paciente com as características referidas, espera-se que se torne uma ajuda na motivação da pessoa bem como uma maneira de quantificar o desenvolvimento por parte do profissional de saúde. Para este efeito, foi usada uma fibra óptica de plástico uma vez que reúne algumas características importantes para o trabalho a realizar, como é o caso do seu reduzido tamanho, peso e custo de produção, a sensibilidade a flexões macroscópicas e, devido ao diâmetro consideravelmente largo, facilidade em ser manuseada. Foram ainda investigados alguns métodos para tornar a referida fibra verdadeiramente sensível sendo também apresentados os resultados obtidos. Com o intuito de inovar, foi apresentado um novo método para a realização desta medição sendo o seu comportamento comparado com os procedimentos anteriores. No âmbito desta dissertação, o sensor foi também integrado num sistema inteligente que permite o envio dos valores obtidos para um computador, sendo possível posteriormente a sua representação numa aplicação gráfica para uma melhor visualização. Este sistema possui um módulo de comunicações sem fios que visa aumentar a liberdade de movimentos do utilizador durante a execução do teste bem como diminuir ao máximo o incómodo causado pelo sensor. ABSTRACT: In this work a sensor to measure the bending angle of the elbow of an individual was developed. This sensor is a helping tool to ascertain the degree of recovery of a person who suffered a cerebral vascular accident resulting in a loss of mobility of the shoulder-arm set. Although the sensor itself plays no vital role in recovery of a patient with the mentioned damages it is expected that it will become a mean of motivation of the patient and also a way of measuring the progress by the health professional. For this purpose a polymer optical fibre was used because it gathers some important features for the aim of this work such as being small and of little weight and not costly to develop, sensitive to macroscopic bendings and, due to its considerably large diameter, of easy handling. One has also investigated some methods to make the mentioned fibre truly sensitive to bending and the achieved results are also displayed. With the view to innovate a new method to perform this measurement is introduced and its behaviour compared to the previous procedures. Within the frame of this thesis, the sensor has also been integrated in a smart system that allows capture and transmission of the achieved results to a computer to enable their posterior graphical representation for a better vision. This system has a unit of wireless communication aiming the increase freedom of movement of the user during tests and also to reduce as far as possible the discomfort caused by wearing the sensor.

As far as the Printed Circuit Boards (PCB) manufacture industry is concerned, for high production volumes, solder paste is applied on the connection pads through customized stencils. This is a very productive method, yet if the design has to be updated, cost is increasing as the stencil should be changed. For higher exibility, such as in rapid prototyping, jet-printing machines similar to Mycronic MY500 are used. In these equipments, solder paste is jet-printed on the circuit board. The shooting is done by a piston moving on the vertical axis at high speed, hence projecting solder paste onto the connection pads of the PCB. In order to improve the understanding of the jetting process, it is important to collect data on pressure uctuations in the jetting head. To do so, this project is using a strain gauge to sense the strain applied by the piston on the nozzle. The gauge is connected in a Wheatstone bridge, and the differential signal is extracted and amplified a first time with an instrumentation amplifier. The remaining amplification is then performed with the help of an operational amplifier so that the signal matches the Analog to Digital Converter (ADC) levels. Finally, the converted results are transmitted to a personal computer for further analysis.