Application of AUV Technology in Seafloor Classification and Submarine Cable Route Design
Date Issued
2015
Date
2015
Author(s)
Chen, Edward
Abstract
This study proposes an automated method for submarine cable route design from sonar scanlines collected by an autonomous underwater vehicle (AUV). Traditionally, the route design is carrying out by experienced surveyors and engineers using seafloor survey data. In the work, an automated classification and route planning method using real time data gathered by an AUV is developed to improve the efficiency for submarine cable construction. Firstly, to improve the accuracy of AUV localization, a linear time-varying equation is applied to describe the motion of an AUV that enables the utilization of observability analysis for maneuvering accuracy. Observability is a property in linear system which related to the initial state and the system outputs. An observability-based maneuvering planner is proposed to enhance the vehicle state estimation. Simulation results demonstrated that unobservable modes can be controlled through maneuvering and will affect the accuracy of vehicle state estimaton. Secondly, a novel idea using sonar scanlines and grid-based maps is introduced to map the seafloor for classification. A probabilistic classifier based on Bayes'' theorem and Naïve assumption is applied to distinguish the types of seafloor. A node map is constructed by probabilistic roadmap and then an A-star algorithm is applied to determine appropriate cable routes on a corridor from the node map. Seafloor classification, bathymetry, steep slope, angle of alter course, and cable length are five factors of the A-star algorithm. A field result of a case of the cable route survey between islands was demonstrated. The planned route using the proposed method is close in range to the one recommend by experts. The proposed cable route design method costs less to the one performed by experienced engineers, and therefore is advantageous for the budget saving of the submarine construction.
Subjects
AUV
observability-based maneuvering
indirect SLAM
sonar scanlines
occupancy grid
Submarine cable route design
probabilistic roadmap
A-star algorithms
SDGs
Type
thesis
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