Johann, Felix (2023)
Magnetic Calibration and GNSS Processing in Strapdown Dynamic Gravimetry.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00024342
Ph.D. Thesis, Primary publication, Publisher's Version
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Magnetic Calibration and GNSS Processing in Strapdown Dynamic Gravimetry | ||||
Language: | English | ||||
Referees: | Becker, Prof. Dr. Matthias ; Forsberg, Prof. Dr. René ; Eichhorn, Prof. Dr. Andreas | ||||
Date: | 2023 | ||||
Place of Publication: | Darmstadt | ||||
Collation: | xii, 153, VIII Seiten | ||||
Date of oral examination: | 20 April 2023 | ||||
DOI: | 10.26083/tuprints-00024342 | ||||
Abstract: | Dynamic gravimetry means the determination of the gravity acceleration with observations conducted on a moving platform. In strapdown gravimetry, gravity is obtained as the difference between the kinematic acceleration due to vehicle movement and the specific force observed by the accelerometers of an Inertial Measurement Unit (IMU). This thesis analyses potential improvements in both summands. Strategies for kinematic acceleration determination using GNSS observations are reviewed, categorised and promising methods are implemented with slight adaptions. The methods are either based on the numerical differentiation of GNSS-derived position solutions or on GNSS phase range observations followed by least-squares estimation. In static and dynamic experiments, both approaches were found to be suited for dynamic gravimetry with accuracies being approximately on par. Recommendations for the selection of a method are made based on available data and tolerable processing delay due to waiting time for required precise satellite products. For Q-Flex QA-2000 accelerometers, reading errors of several mGal (1 mGal = 10^-5 m/s²) were observed for a magnetic field intensity in the order of the Earth's field. A calibration based on the magnetic field is developed based on static experiments inside of a 3-D Helmholtz coil in addition to thermal calibration. The calibration functions were applied to several airborne and shipborne campaigns using the direct method of strapdown gravimetry. For almost all campaigns, the magnetic calibration resulted in precision improvements between 8 and 82% depending on the observation region, the intersection angle between crossover point lines and the carrier vehicle type. The high number of campaigns allows for an evaluation of possible relations between the observation conditions and the obtained gravity precision. A line-wise upward continuation approach is introduced for comparing repeated lines of a shipborne and an airborne campaign. The strapdown gravimetry approach proved to reliably deliver a precision around the 1 mGal level. Based on crossover residual analysis, without any crossover adjustment, the best precision estimates obtained for airborne and shipborne campaigns were 0.50 and 0.27 mGal, respectively. |
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Uncontrolled Keywords: | gravimetry, IMU, strapdown, kinematic acceleration, magnetic field | ||||
Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-243426 | ||||
Classification DDC: | 500 Science and mathematics > 550 Earth sciences and geology 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering |
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Divisions: | 13 Department of Civil and Environmental Engineering Sciences > Institute of Geodesy 13 Department of Civil and Environmental Engineering Sciences > Institute of Geodesy > Physical and Satellite Geodesy |
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Date Deposited: | 26 Jul 2023 12:20 | ||||
Last Modified: | 27 Jul 2023 10:52 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/24342 | ||||
PPN: | 509944396 | ||||
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