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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Inomhuspositionering med tre olika tekniker – Bluetooth Low Energy, Wi-Fi och GPS : En jämförelsestudie av positioneringsverktyg vid inomhuspositionering / A comparison study of positioning tools in indoor positioning

Rasch, Kevin, Lipponen, Dennis January 2018 (has links)
Olika navigeringstekniker är något som människan använder sig av dagligen. Det är och har varit en viktig del genom tiderna, i början handlade det om att kunna navigera till havs med hjälp av stjärnorna och idag har många människor i världen någon form av smarttelefon som kan användas som navigeringsverktyg. Inomhuspositionering är något som har blivit ett hett ämne den senaste tiden och eftersom GPS fungerar sämre inomhus har nya tekniker utvecklats för att navigera och positionera sig inomhus. De tekniker som ligger i framkant nu är bland annat Bluetooth Low Energy (BLE) och Wi-Fi där man med hjälp av triangulering kan positionera ut en användare inomhus. Frågan återstår då, vilket positioneringsverktyg är då lämpligt för inomhuspositionering. Detta examensarbete har utförts med en kombination av strategier. Som börjar med en jämförelsestudie av tre olika positioneringstekniker, BLE Wi-Fi och GPS, för att ta fram en lämplig positioneringsteknik för utvärdering i form av ett experiment där flera faktorer, främst precisionen, testas. I denna studie användes BLE beacons som positioneringsverktyg dels för att den var lätt att implementera men även för att den skulle uppnå hög precision. För att testa BLE beacon utvecklades en lätt applikationsprototyp som hade som huvudsyfte att kunna positionera ut en användare i ett koordinatsystem med hjälp av XYvärden. Genom att triangulering användes för att kunna positionera ut en användare uppnådde studien en medelmarginal på ungefär 76 centimeter när fem stycken beacons användes i ett område på 4 x 3 meter, vilket vi ansåg som godkänt för att kunna dra slutsatsen att BLE beacon är ett lämpligt verktyg när det kommer till en inomhuspositionering. Slutsatsen blev även att det skiljer sig avsevärt mycket i precision om man använder sig av för få eller helt enkelt dåligt placerade beacons. / Different navigation techniques are something that people uses on a daily basis. It has been and still is an important part in the history of mankind, initially navigation was about being able to navigate at sea using the stars, and today many people around the world have some kind of smartphone that can be used as a navigation tool. Indoor positioning is something that has become a hot topic in the last decade and since GPS has bad precision indoors new technologies has been developed to navigate and position objects indoors. Some leading technologies now includes Bluetooth Low Energy beacons and Wi-Fi, where you can position a user indoors using triangulation-techniques. The question still remains, which technique is viable for indoor positioning. This study has been conducted as a combination of two strategies, starting with a comparison study of three different positioning techniques, BLE, Wi-Fi and GPS, to come to a conclusion which positioning technique is suitable for indoor positioning. After the conclusion we evaluated the technique in the form of an experiment in which several factors, mainly the precision, are tested. In this study, BLE beacon were used as the positioning tool because it was easy to implement but also to able to achieve high precision in the right environment. To test the beacons, a light application prototype was developed that had the main purpose of positioning a user in a coordinate system using XY values. By using triangulation to position the user. The study achieved a mean margin of approximately 76 centimeters when five beacons were used in a 4 x 3 meter area. The conclusion was BLE beacons is a suitable tool when it comes to indoor positioning and that there is a lot of difference in precision when using too few or poorly placed beacons.
2

ON-MACHINE MEASUREMENT OF WORKPIECE FORM ERRORS IN ULTRAPRECISION MACHINING

Gomersall, Fiona January 2016 (has links)
Ultraprecision single point diamond turning is required to produce parts with sub-nanometer surface roughness and sub-micrometer surface profiles tolerances. These parts have applications in the optics industry, where tight form accuracy is required while achieving high surface finish quality. Generally, parts can be polished to achieve the desired finish, but then the form accuracy can easily be lost in the process rendering the part unusable. Currently, most mid to low spatial frequency surface finish errors are inspected offline. This is done by physically removing the workpiece from the machining fixture and mounting the part in a laser interferometer. This action introduces errors in itself through minute differences in the support conditions of the over constrained part on a machine as compared to the mounting conditions used for part measurement. Once removed, the fixture induced stresses and the part’s internal residual stresses relax and change the shape of the generally thin parts machined in these applications. Thereby, the offline inspection provides an erroneous description of the performance of the machine. This research explores the use of a single, high resolution, capacitance sensor to quickly and qualitatively measure the low to mid spatial frequencies on the workpiece surface, while it is mounted in a fixture on a standard ultraprecision single point diamond turning machine after a standard facing operation. Following initial testing, a strong qualitative correlation exists between the surface profiling on a standard offline system and this online measuring system. Despite environmental effects and the effects of the machine on the measurement system, the capacitive system with some modifications and awareness of its measurement method is a viable option for measuring mid to low spatial frequencies on a workpiece surface mounted on an ultraprecision machine with a resolution of 1nm with an error band of ±5nm with a 20kHz bandwidth. / Thesis / Master of Applied Science (MASc)

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