Investigation on one-step integrated positioning method for seafloor control network localization

Abstract

Global Navigation Satellite System-Acoustic (GNSS-A) combined positioning is the main technique for seafloor geodetic control points localization, typically including datum transfer and subsequent positioning adjustment. This conventional step-wise method is time-consuming and accuracy-limited. In this paper, a novel one-step integrated positioning method for seafloor control network localization is proposed, which estimates positions of surveying vessels and seafloor points simultaneously. The effectiveness of new method is verified by computer simulation and comparative analysis. First, the conventional underwater acoustic positioning stepwise adjustment method is introduced and the positioning errors are analyzed. Then, to better constrain positions, the baseline lengths and depth-differences between pair of seafloor transponders are taken into consideration. The novel integrated positioning model based on overall adjustment is established. Furthermore, to deal with rank deficiency problem in overall adjustment, selecting weight fitting (SWF) method is applied in consideration of reliable priori information of surveying vessel coordinates. Finally, the regulating parameter determination for SWF method is discussed. Tests demonstrate that depth-differences constraint performs better than baseline length constraint in light of vertical geometry weakness. The novel method is notably superior to the conventional method in terms of positioning accuracy according to rms (Root Mean Square) statistics.