Navigation and manipulation for autonomous underwater dismantling of offshore structures
Welch, Christian L.
MetadataShow full item record
LocationGulf of Mexico
The dismantling of offshore structures, known as decommissioning, is a complex task in the oil and gas industry, driven by strict environmental standards. As the environments in which decommissioning is necessary become more challenging, autonomy presents itself as a solution to conduct this work as cost-effectively and safely as possible, namely by taking Remotely Operated Vehicles (ROVs) and divers out of the equation. In this thesis, three avenues are researched in support of Autonomous Underwater Vehicles (AUVs) for decommissioning: navigation, attachment, and manipulation. First, the Iterative Closest Point method (ICP) is investigated as a means to correct position drift of an inertial navigation system, by using a previously obtained coarse map. Using real sonar data from a current decommissioning site in the Gulf of Mexico, the algorithm is able to reconcile the internally dead-reckoned pose of the vehicle with that calculated via ICP, to an accuracy of 7cm from a 100kpoint sonar scan. Second, to attach lifting points to subsea scrap without bracing onto it, a single mechanism was designed to both drill and affix anchors in a single penetration, from a vehicle in free flight. A prototype was fabricated and its functionality verified. Third, to promote robust and stable robotic interactions using an industry standard non-backdrivable manipulator, a control law was developed to have the vehicle-manipulator system passively interact with its environment, by mimicking an arrangement of masses, springs, and dashpots. This control law was tested and analyzed in a simple experiment that achieved a 90% reduction in settling time.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2015
Showing items related by title, author, creator and subject.
Briggs, Michael Jeffrey (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1981-06)The multichannel Maximum Entropy Method (MEM) of spectral analysis is developed and applied in the dynamic analysis of offshore structures. Two different algorithms are implemented and compared with the conventional ...
Vandiver, J. Kim (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1975-01)In fixed offshore structures, damage incurred below the waterline is often difficult to detect, but significant enough to be the source of a subsequent massive failure. A technique is described that can be used to detect ...
Van Avendonk, Harm J. A.; Holbrook, W. Steven; Lizarralde, Daniel; Denyer, P. (American Geophysical Union, 2011-06-22)The Cocos plate experiences extensional faulting as it bends into the Middle American Trench (MAT) west of Nicaragua, which may lead to hydration of the subducting mantle. To estimate the along strike variations of volatile ...