The low frequency (0-500 Hz) automotive noise and vibration behavior is influenced by the rolling dynamics of the tire. Driven by pressing environmental concerns, the automotive industry has strived to innovate fuel-efficient and quieter powertrain systems over the last decade. This has eventually led to the prevalence of hybrid and electric vehicles. With the noise masking effect of the engine orders being absent, the interior structure-borne noise is dominated by the tire pavement interaction under 500 Hz. This necessitates an accurate estimation of rolling tire dynamics. To this date, there is no direct procedure available for modal analysis of rolling tires with tread patterns under realistic operating conditions. The present start-of-art laser vibrometer based non-contact measurements are limited to tread vibration measurement of smooth tires only in a lab environment. This study focuses on devising an innovative strategy to use a wireless Tire Cavity Accelerometer (TCA) and two optical sensors in a tire on drum setup with cleat excitation to characterize dynamics of tread vibration in an appreciably easier, time and cost-effective approach. In this approach, First, the TCA vibration signal in a single test run is clustered into several groups representing an array of virtual sensor position at different circumferential positions. Then modal identification has been performed using both parametric and non-parametric operational modal identification procedures. Furthermore, relevant conclusions are drawn about the observed modal properties of the tire under rolling including the limitations of the proposed method. The method proposed here, as is, can be applied to a treaded tire and can also be implemented in an on-road test setup. / Master of Science / The low frequency(0-500 Hz) interior noise and vibration of an automobile is primarily influenced by the dynamics of the rolling tire. In recent studies, the laser vibrometer with moving mirrors for measurement of vibration on the tread of a rotating tire has been used. However, these are limited to tires without tread pattern. In this study, an innovative experimental way of performing operational modal analysis using the Tire cavity Accelerometer (TCA) and optical sensors is presented. The proposed method is simpler in terms of instrumentation and cost and time-effective. This method, as is, can also be implemented in case of a treaded tire

This work addresses the problem of localizing an impact in a dispersive medium (waveguide) using a network of vibration sensors (accelerometers), distributed at various locations in the waveguide, measuring (and detecting the arrival of) the impact-generated seismic wave. In particular, the last part of this document focuses on the problem of localizing footsteps using underfloor accelerometers. The author believes the outcomes of this work pave the way for realizing real-time indoor occupant tracking using underfloor accelerometers; a system that is tamper-proof and non-intrusive compared to occupant tracking systems that rely on video image processing. A dispersive waveguide (e.g., a floor) causes the impact-generated wave to distort with the traveled distance and renders conventional time of flight localization methods inaccurate. Therefore, this work focuses on laying the foundation of a new alternative approach to impact localization in dispersive waveguides. In this document, localization algorithms, including wave-signal detection and signal processing, are developed utilizing the fact that the generated wave's energy is attenuated with the traveled distance. The proposed localization algorithms were evaluated using simulations and experiments of hammer impacts, in addition to occupant tracking experiments. The experiments were carried out on an instrumented floor section inside a smart building. As will be explained in this document, energy-based localization will turn out to be computationally cheap and more accurate than conventional time of flight techniques. / PHD / When a person walks, each footstep impact generates a tiny floor-quake. The floor-quake sends a shock wave traveling along the floor, and causes the floor to vibrate. If these vibrations are sensed/measured at different locations in the floor, then the measurements can be used to estimate the individual footstep impact locations. Estimating the location of each footstep impact can then be utilized to track the walking path of the person. This dissertation proposes a novel footstep location estimation approach. The localization approach uses a group of underfloor vibration sensors, called accelerometers, to measure the footstep-generated floor vibration. Then, the sensor measurements are used to estimate footstep locations. Footstep location estimates are generated using the fact that the strength/energy of the generated wave is absorbed by the floor, and consequently the wave energy is attenuated with the traveled distance. The proposed footstep localization approach can be used to track occupants inside buildings, providing a tracking system that is non-intrusive compared to tracking occupants using a system of cameras and a video image-processing software.

From 2000 to 2015, the cost of operation and maintenance (including reinvestment) and traffic control has increased from approximately three billion to over nine billion Swedish kronor annually. By making more frequent measurements of track irregularities and identifying trends earlier, accurate and effective maintenance can be performed. Therefore, in the industry and academy, different measurement solutions are tested to measure the state of railroad tracks in a simple and more frequent manner. One of the solutions is to use measuring systems mounted on trains in regular traffic. By using regular scheduled services, a higher cost effectiveness regarding inspection frequency can be achieved. When the measuring equipment is mounted on freight trains, a measurement with considerably higher axle load can also be performed. In the course of this work, a literature study have been conducted and a number of scientific articles and reports have been studied at depth. There is a number of different systems that have been manufactured to be mounted on rolling stock in regular service. Different solutions are applied to perform the measurements. Acceleration sensors are robust and reliable, which is necessary because they will be mounted in an exposed environment. A difference that has been identified is the installation of accelerometer sensors that are either mounted before or after the primary suspension. Before suspension the sensors are mounted on the axle box and, after suspension the sensors are mounted on the train bogie. The engineering company Damill is working within monitoring solutions and has developed equipment for mounting on trains in regular traffic called Tracklogger. Earlier evaluations of the equipment have been made with focus on comparison with machine inspections. There is a difference between the technology used in track recording vehicles and the technology that Tracklogger uses, such comparison is not entirely appropriate. In discussion with Damill the focus of this work has been to see if recordings of switches can be linked to maintenance actions. Since the equipment is in the development stage it is important that the measurement data collected is critically reviewed with regard to what information it delivers. The measurements have been carried out on switches in the main train track on track number 119 between Luleå and Boden and the mining company LKAB's ore wagon has been a tool carrier.  Five out of eight cases, a maintenance action can be linked to reduced measured values of switches with fixed crossing points. In one case, maintenance action has increased the measured value. In two cases, there is no signifcant difference in the measured value associated with maintenance actions. In previous evaluation, it was determined that it is good repeatability in the measured position, but not as high repeatability in the measured size. A number of switches have been studied to check the repeatability of the measurement. As the train runs in acircle run in Luleå harbor, there will be a limited number of occasions the equipment is running in the same direction in combination with the sensors on the same axle in the bogie, which may effect the measurement results. When analyzing the repeatability of five passages where the direction of travel is not taken into account, it is determined that three out of five passages show a good repeatability. The repeatability of the measurement is suspected of being related to the condition, as significantly greater differences in the measured signal are obtained just before a maintenance action has been taken.

<p><p>Objective:</p><p>This study aimed to investigate the correlation between physical activity level (PAL), measured with activity diary and accelerometer, among overweight and obese children and adolescents. The aim was also to study differences in PAL between girls and boys.</p><p>Design:</p><p>55 children and adolescents, whom been subjected to a physical activity registration with a physical activity diary and accelerometer during three or four days, were included in this study. From the data received from the children’s journal records PAL was calculated and compiled for statistic analysis.</p><p>Results:</p><p>The results of the study showed that the children underestimated their physical activity level when measured with activity diary, in comparison with the physical activity level measured with accelerometer. Differences between girl and boys PAL values were not statistically significant, although the girls PAL values from the accelerometer, but not from the activity diary, reached a moderate activity level according to Nordic nutrition recommendation. No correlation between the activity diary and accelerometer was found.</p><p>Conclusions:</p><p>The Activity diary can not be used as solitary instrument to mesure physical activity in obese or overweight children.</p><p>There is no validated way to measure physical activity in overweight or obese children.</p><p>Before studies can be conducted with reliable results, physical activity level scales and calculated BMR must be designed for overweight and obese children.</p></p>

Aim: The aim with the current study was to examine the physical activity levels (PAL) in a group of children and adolescents with cystic fibrosis (CF) and compare PAL-values between boys and girls. Further, the aim was to look at the total energy expenditure (TEE) estimated with an activity diary and measured with the accelerometer and compare values between these two measurement methods. Method: The sample consisted of 29 children and adolescents diagnosed with CF where PAL and TEE was measured during a three-day registration with activity diary and the ActiCal© accelerometer. The data was analyzed with the Mann-Whitney U-test. Results: The results indicated that the girls had a slightly higher median PAL-value than the boys. In addition, the range between the lowest and highest PAL-value was larger among the boys. The lowest PAL-value was lower among the boys than among the girls and the highest value was similar to the girls’ highest PAL-value. Overall, the subjective estimation of the PAL-values were slightly higher than what was objectively measured by the accelerometer. There was a slight difference between TEE estimated with the activity diary compared to the TEE measured by the accelerometer. There was no significant difference in PAL-values between boys and girls. Conclusion: There was no significant difference in PAL-value between boys and girls and that there was a slight difference in TEE estimated with the activity diary and measured with the accelerometer. Both methods of data collection are reliable enough when used together to produce a valid estimation of CF- children’s activity levels and TEE. The fact that both PAL and TEE values were higher in the activity diary may be because the participants perceived a higher level of physical activity then what was objectively measured with the accelerometer.

Det här rapporten är en del av mitt examensarbete för högskoleingenjörsexamen i elektroteknik vid Växjö Universitet, MSI. Arbetet är en del av ett större projekt kallat Kranstyrningsprojektet som bedrivs av Växjö Universitet, Rottne Industri med flera, vars syfte är att underlätta för förare att kontrollera den kran som finns på Rottnes skotare. För projektet har det använts en laborationskran och nu har önskemålet varit att det till kranen ska installeras ett nytt styrsystem från dSPACE. Dessutom vill man att nya givare ska sättas på kranen och kopplas till dSPACE. Man vill även ha en manual för att nya studenter ska kunna använda systemet. Det nya dSPACE-systemet består av en datorlåda med processor- och I/O-kort. Man kommunicerar med dSPACE från en PC. Arbetet med installationen har stött på flera problem och arbetet har dragit ut på tiden. När systemet till slut gick att använda utfördes ett par tester och sen implementerades det på kranen. Arbete med att ta fram underlag för installation av accelerometrar på kranen pågick samtidigt och en jämförelse mellan olika alternativ gjordes. Arbetet resulterade i att laborationskranen nu går att styra med det nyinköpta systemet från dSPACE och en manual skapades för att underlätta användandet av systemet. / This document is a part of my bachelor degree thesis in electronic engineering was done at Växjö University, MSI. This work is a part of a bigger project called Crane Tip Control which is pursued by Växjö University, Rottne Industri and others, whose purpose is to facilitate for drivers to control the crane used on forwarders from Rottne. For this project, a laboratory crane has been used and they requested that a new control system from dSPACE was installed to the crane. Also they want new sensors to be placed on the crane and connected to dSPACE. A manual should also be created for new students who want to use the system. The new dSPACE-system consists of a computer box with processor- and I/O-boards. Communication with dSPACE is done via a PC. The work with the installation has encountered many problems and the work has been overrun. When the system finally was working, some tests were performed and then the system was installed at the crane. A task to assemble data for installation of accelerometers, was done during the same time and a comparison between different alternatives was made. The work resulted in the laboratory crane is now able to be controled by the new dSPACE-system and a manual was created to facilitate the usage of the system.

<p>Det här rapporten är en del av mitt examensarbete för högskoleingenjörsexamen i elektroteknik vid Växjö Universitet, MSI. Arbetet är en del av ett större projekt kallat Kranstyrningsprojektet som bedrivs av Växjö Universitet, Rottne Industri med flera, vars syfte är att underlätta för förare att kontrollera den kran som finns på Rottnes skotare. För projektet har det använts en laborationskran och nu har önskemålet varit att det till kranen ska installeras ett nytt styrsystem från dSPACE. Dessutom vill man att nya givare ska sättas på kranen och kopplas till dSPACE. Man vill även ha en manual för att nya studenter ska kunna använda systemet. Det nya dSPACE-systemet består av en datorlåda med processor- och I/O-kort. Man kommunicerar med dSPACE från en PC. Arbetet med installationen har stött på flera problem och arbetet har dragit ut på tiden. När systemet till slut gick att använda utfördes ett par tester och sen implementerades det på kranen. Arbete med att ta fram underlag för installation av accelerometrar på kranen pågick samtidigt och en jämförelse mellan olika alternativ gjordes. Arbetet resulterade i att laborationskranen nu går att styra med det nyinköpta systemet från dSPACE och en manual skapades för att underlätta användandet av systemet.</p> / <p>This document is a part of my bachelor degree thesis in electronic engineering was done at Växjö University, MSI. This work is a part of a bigger project called Crane Tip Control which is pursued by Växjö University, Rottne Industri and others, whose purpose is to facilitate for drivers to control the crane used on forwarders from Rottne. For this project, a laboratory crane has been used and they requested that a new control system from dSPACE was installed to the crane. Also they want new sensors to be placed on the crane and connected to dSPACE. A manual should also be created for new students who want to use the system. The new dSPACE-system consists of a computer box with processor- and I/O-boards. Communication with dSPACE is done via a PC. The work with the installation has encountered many problems and the work has been overrun. When the system finally was working, some tests were performed and then the system was installed at the crane. A task to assemble data for installation of accelerometers, was done during the same time and a comparison between different alternatives was made. The work resulted in the laboratory crane is now able to be controled by the new dSPACE-system and a manual was created to facilitate the usage of the system.</p>

Objective: This study aimed to investigate the correlation between physical activity level (PAL), measured with activity diary and accelerometer, among overweight and obese children and adolescents. The aim was also to study differences in PAL between girls and boys. Design: 55 children and adolescents, whom been subjected to a physical activity registration with a physical activity diary and accelerometer during three or four days, were included in this study. From the data received from the children’s journal records PAL was calculated and compiled for statistic analysis. Results: The results of the study showed that the children underestimated their physical activity level when measured with activity diary, in comparison with the physical activity level measured with accelerometer. Differences between girl and boys PAL values were not statistically significant, although the girls PAL values from the accelerometer, but not from the activity diary, reached a moderate activity level according to Nordic nutrition recommendation. No correlation between the activity diary and accelerometer was found. Conclusions: The Activity diary can not be used as solitary instrument to mesure physical activity in obese or overweight children. There is no validated way to measure physical activity in overweight or obese children. Before studies can be conducted with reliable results, physical activity level scales and calculated BMR must be designed for overweight and obese children.

In the production industry, quality control is of importance. Even though today's tools provide a lot of functionality and safety to help the operators in their job, the operators still is responsible for the final quality of the parts. Today the nutrunners manufactured by Atlas Copco use their driver to detect the tightening angle. There- fore the operator can influence the tightening by turning the tool clockwise or counterclockwise during a tightening and quality cannot be assured that the bolt is tightened with a certain torque angle. The function of orientation tracking was de- sired to be evaluated for the Tensor STB angle and STB pistol tools manufactured by Atlas Copco. To be able to study the orientation of a nutrunner, practical exper- iments were introduced where an IMU sensor was fixed on a battery powered nutrunner. Sensor fusion in the form of a complementary filter was evaluated. The result states that the accelerometer could not be used to estimate the angular dis- placement of tightening due to vibration and gimbal lock and therefore a sensor fusion is not possible. The gyroscope by itself can be used to provide the angular displacement around every axis with high accuracy without taking into account the gimbal lock phenomena or external forces in the form of vibration of the tool. The gyroscope provided data with a probability to measure ±1° in future tightenings by 69,76%. The gyroscope provided data with high accuracy and stability and can be used in real world application and production for true angle functionality of the tools. / I produktionsindustrin är kvalitetskontroll av stor betydelse. Även om dagens verk- tyg innehåller mycket funktionalitet och säkerhet för att hjälpa operatörer i jobbet, är operatören fortfarande ansvarig för den slutliga kvaliteten. Idag använder Atlas Copcos skruvdragare motorns vridmoment för att göra den slutliga åtdragningen. Därav kan operatören påverka åtdragningen genom att vrida verktyget medurs el- ler moturs under en åtdragning och kvaliteten kan inte säkerställas att bulten dras med ett visst vridmoment. Funktion för rörelseavläsning var önskvärd att utvärde- ras för Tensor STB-vinkel- och STB-pistolverktygen tillverkade av Atlas Copco. För att kunna studera orienteringen hos en skruvdragare introducerades praktiska ex- periment där en IMU-sensor fixerades på en batteridriven skruvdragare. En Sen- sorfusion i form av ett komplementärt filter utvärderades. Resultaten visar att acce- lerometern inte kunde användas för att uppskatta vinkelförskjutningen av en åt- dragning på grund av vibration och gimballås och därav kan inte fusionen heller nyttjas. Gyroskopet i sig kan användas för att ge vinkelförskjutningen runt varje axel med hög noggrannhet utan att ta hänsyn till gimballåsfenomen eller yttre kraf- ter i form av vibration från verktyget. Gyroskopet gav data med en sannolikhet att mäta ± 1° i avvikelse från ett förbestämt värde i framtida åtdragningar med 69,76%. Vidare utvärdering av gyroskop och implementation av detta borde göras innan detta skulle anses kunna användas i en riktig applikation för rörelseavläsning un- der en åtdragning.

This project aimed to use accelerometer data and KPIs to predict the oxygen consumption of runners’ during exercises on flat terrain. Based on many studies researching the relationship between oxygen consumption and running economy and a small set of data, a model was constructed which had a prediction accuracy of 81.1% on one individual. Problems encountered during the research include issues with comparing data from different systems, model nonlinearity and data noise. These problems were solved using transformation of data in the R software, model re-specification and identifying outlying observations that could be viewed as noise. The results from this project should be seen as a proof of concept for further studies, showing that it is possible to predict oxygen consumption using a set of accelerometer data and KPIs. With a larger sample set this model can be validated and furthermore implemented in Racefox’s current service as a calibration method of individual results and an early warning system to avoid running economy deficiency. / Detta projekts målsättning var att använda accelerometerdata och KPI-värden för att prediktera syrekonsumtion för löpare på plan mark. Baserat på ett urval av studier om korrelationen mellan syrekonsumtion och löpekonomi samt en liten mängd data så konstruerades en modell med en förklaringsgrad på 81.1% på en individ. Svårigheter under arbetet inkluderar datajämförelser, icke-linjäriteter och databrus. Detta hanterades genom datatransformationer i mjukvaran R, modell-modifikationer och identifikation av avvikande data som kunde klassificeras som brus. Resultaten kan ses som en förstudie som indikerar att det är möjligt att prediktera syrekonsumtion genom accelerometerdata och KPI-värden. En fortsatt större studie med fler individer och mätningar som underlag kan validera denna slutsats samt då implementeras i Racefoxs nuvarande tjänst som en kalibreringsmetod för individuella resultat och som ett varningssystem för att undvika försämrad löpekonomi.