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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

Mobile Indoor Positioning for Augmented Reality Systems

Glass, Robert B 01 January 2014 (has links)
This thesis explores the creation and setup of a prototype that allows users of the device to interact within an indoor real world environment and a virtual environment simultaneously using high-tech common technology. The prototype is comprised of a small mobile device such as a cellular mobile phone, Raspberry Pi computer, a battery powered handheld Pico projector, and software developed for the Android OS. The software can easily be ported to other mobile and non-mobile operating systems. The mobile device must contain accelerometer, magnetometer, and gyroscope embedded sensors as well as 802.11 wireless network chip. The prototype software implements an indoor positioning system to track the current location and orientation of the prototype device in real time. It also displays a virtual world projection upon the surfaces of the real world in relation to the prototype’s physical location and orientation. Three different orientation estimation methods were tested and compared in this thesis. Accelerometer and magnetometer based method, gyroscope based method, and a combined method using a technique called sensor fusion were implemented. A multilateration approach was used for location estimation. Location estimates were calculated from the measured received signal strength of multiple 802.11 wireless network access points. The location of all wireless access points were known and fixed. Received signal strength data was converted to meters using a log distance propagation model, and tests were conducted to compare actual distance with converted distance. Tests were also conducted to compare multilateration estimates from unfiltered or raw RSS and filtered RSS data using a Kalman filter.
2

Evaluation of MEMS accelerometer and gyroscope for orientation tracking nutrunner functionality / Utvärdering av MEMS accelerometer och gyroskop för rörelseavläsning av skruvdragare

Grahn, Erik January 2017 (has links)
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.

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