Year: 2015
Type: dissertation
Abstract: The exploration of arctic seas for offshore oil- and gas resources has received increasing\ninterest the past few years. Despite the recent dramatic fall in oil prices,\nestimates indicate that as much as 22% of the worlds remaining hydrocarbons are\nlocated in arctic areas. Thus it is unlikely that the arctic areas will go largely\nuntouched the following decades. One of the main challenges of extracting hydrocarbons\nin arctic areas is the abundance of sea ice that can cause damaging loads on\ninstallations. An important part of oil exploration in these areas is thus the ability\nto manage potentially damaging sea ice. The current methods for ice management\ninclude manned helicopters and other aircraft for detection together with ships to\nbreak up or drag away dangerous ice. The main objective of this thesis is to assess\nthe use of Unmanned Aerial Systems (UAS) to perform ice monitoring. An autonomous\nUnmanned Aerial System for ice detection and mapping using a thermal\nimaging sensor on a small fixed wing aircraft is proposed. The main contributions\nof this thesis is a real-time Bayesian recursive algorithm for occupancy grid map\nestimation representing sea ice. An expedition to Svalbard with several PhD and\nmaster students from NTNU was originally planned in April 2015, but this was\ncanceled in March due to time constraints among the participants. The expedition\nwas a major source of inspiration for the methods developed, and an indoor\nlaboratory environment for on-board computer vision was developed\nusing the Robot Operating System (ROS) software framework. The setup included\na quadcopter with an on-board camera, and a motion capture system capable of\ntracking the pose of the quadcopter at 120 Hz. The laboratory setup was used to\ntest much of the planned functionality for the Svalbard expedition. The developed\ncomputer vision based map estimation algorithm is capable of running in real time on an on-board computer. As a part of\nthe preparation for the Svalbard excursion, a path planning framework developed\nby PhD student Anders Albert was successfully tested in the laboratory setup.\nThe experimental results of the mapping algorithm were visually appealing, but\ncloser investigation revealed unsatisfactory accuracy. Using on-board navigational\nsystems alone to perform real-time mapping did not yield sucient accuracy for\npractical use. Sources of error and means to improve the results in further work\nwere investigated.
Source: BIBSYS Brage (BIBSYS (Norway))
Author: Andreas L. Flåten
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2492938122