This study proposed a numerical algorithm for estimating the angular misalignments between sensors of an ultra short baseline (USBL) positioning system. The algorithm is based on positioning a seabed transponder by moving a vessel along a predetermined straight-line path. Under the scheme of straight-line survey, mathematical representations of positioning error arising from heading, pitch, and roll misalignments were derived, respectively. The effect of each misalignment angle and how the differences can be used to calibrate each misalignment angle in turn are presented. A USBL calibration procedure that takes advantage of the geometry of position errors resulting from angular misalignments is then developed. During the USBL measurement, temporal and spatial variations of sound speed structure in water column are the major error sources. Therefore, this study used the sound speed profile together with a ray tracing method to correct observations of the USBL measurement. In addition, this study developed a method to compensate the effects of cross-track error on the estimation of alignment errors, and this makes the proposed algorithm applicable for using a vessel without dynamic positioning (DP) systems to collect USBL observations. The performance of the algorithm is evaluated through simulation and field experiment. The simulation and experimental results have demonstrated the effectiveness and robustness of the iterative scheme in finding alignment errors. The proposed algorithm yields a very rapid convergence of the solution series; usually the estimates obtained in the first iteration approximate to true values, and only a few iterations are necessary to achieve fairly accurate solutions.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0809109-233755 |
| Date | 09 August 2009 |
| Creators | Chang, Hsu-Kuang |
| Contributors | Shiahn-Wern Shyue, Hsin-Hung Chen, Chau-Chang Wang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0809109-233755 |
| Rights | withheld, Copyright information available at source archive |
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