A novel method for surface to subsea localization utilizing a modified hough transform

A new approach for acoustic localization of a fixed subsea transponder using a surface vessel equipped with a transceiver and global positioning system (GPS) based on a modified Hough transform (MHT) is presented. The MHT developed in this work is used to determine the latitude and longitude coordinates of a transponder utilizing acoustic range and GPS data gathered by the surface vessel while traveling a particular route. Various survey scenarios for a single seabed transponder have been simulated and studied considering both, accurate and inaccurate ranging, as well as realistic conditions such as different route lengths and inexactly geometrical routes (inter alia ellipse-shaped routes). The MHT-based localization approach may particularly find use in the survey of long baseline transponders. The fixed seabed transponders are provided to enable exploration tasks by acoustic networking in various fields, from science and research covering the seas and oceans (e.g. oceanography, marine biology and geology) to industrial use (e.g. exploration of deep-sea resources and minerals, monitoring of offshore constructions). The simulation results demonstrate that the proposed approach can localize the transponder unambiguously and precisely for accurate ranging. Concerning the impact of uniform ranging uncertainties, e.g. arising from spatio-temporally coherent sound speed variations, it can be concluded that full circle and ellipse routes enable a precise estimate while half and quarter circle as well as ellipse routes enable a positioning accuracy within the millimeter range. In the presence of noisy range measurements, e.g. impacted by GPS errors, the approach can provide root mean squared errors from less than 5 mm to 5 m for ranging with a standard deviation of 7.5 mm and 7.5 m, respectively. The proposed positioning approach outperforms the least-squares estimation when shortened survey routes such as half and quarter ellipse are considered. These route forms acceler- te the data gathering process, which are motivated by the reduction of the vessel time and cost for the transponder survey.