Water filled caverns and crevasses in glaciers are miraculous habitats, which can accommodate highly specialized and adapted microbes and bacteria. The challenge for scientists is to obtain a sample of this water without contaminating it with surface bacteria, as well as to protect the sample from oxygen and sunlight. To fulfill these requirements a combined melting and drilling probe called "IceMole" has been developed. It is a semi-automatic probe which can drill a hole into the ice with a flexible trajectory of up to 80 m. Thus, a complex navigation system is needed to pinpoint the target. Navigation inside of glaciers is sophisticated due to the special conditions of a slow motion, long mission durations and high relative accuracy requirements. The "Ice Mole" probe is designed as a long tube with a heated head and an ice screw at the front, and additional heated plates at the side and rear panels. Combination of a reliable navigation system and an ultrasonic environment analysis the IceMole will find its way to the sub glacial water reservoirs of Arctic, Antarctic and extraterrestrial glaciers. This paper focuses on the development of a fault-tolerant navigation system based on magnetometers, which allows precise probe navigation through the ice. This system uses inertial sensors, magnetometers and axial speed information for Dead Reckoning (DR) and sensor fusion. In addition to the built-in sensors, an ultrasonic pinger positioning system is developed to update the combined position. The DR system propagates the current probe position. The Attitude used in DR is initially determined from an inertial measurement unit (IMU) and a modified attitude and heading reference system (AHRS). Enhancement of performance and accuracy is done by a differential magnetometer system. In this setup, one magnetometer is placed inside the IceMole, the other one is placed at the glacier's surface. However, reliable magnetometer measurement takes an extensive modeling of possible disturbances. Modeling and correction algorithms yield an overall heading accuracy below 1°. The difference between magnetic reference and rover magnetic field is recorded and analyzed for further research on differential magnetic navigation. . The required data for testing and validating was collected at three field test campaigns which took place at Morteratsch Glacier, Switzerland and Commonwealth Glacier, East Antarctica.


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    Titel :

    Icemole as Platform for Magnetometer and IMU Aided Positioning w/o External Reference


    Beteiligte:
    Wulfen, B. von (Autor:in) / Kohn, B. (Autor:in) / Macht, S. (Autor:in) / Hecker, P. (Autor:in) / Niedermeier, H. (Autor:in) / Ameres, G. (Autor:in) / Clemens, J. (Autor:in)


    Erscheinungsdatum :

    2014


    Format / Umfang :

    11 Seiten, Bilder, 17 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




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