Acoustic Minimization of Ocean Twilight Zone Vehicle, Mesobot
Name
davis-cjodavis-sm-meche-2023-thesis.pdf
Description
Thesis PDF
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5.49 MB
Format
Adobe PDF
Checksum (MD5)
0ef7b322662c52407fe7f62a333e4b50
Author(s)
Davis, Cameron J.
Advisor(s)
Yoerger, Dana
Date Issued
September 2023
Publisher
Massachusetts Institute of Technology
Abstract
The ocean’s twilight zone (OTZ) is one of the most unexplored regions of the Earth’s oceans.
The OTZ is defined as the region of the water column between 200 and 1,000 meters in
depth. It plays a vital role in the global carbon cycle, pushing carbon from the surface layer
into the deep ocean. It has a very diverse population of fauna, known and unknown, that
migrate up and down the water column to feed and reproduce. The migration pattern occurs
based on the amount of radiated sunlight into the water column. The mid-water column
vehicle, Mesobot, was designed to mimic the migration patterns of mesopelagic organisms.
Unmanned Underwater Vehicles (UUVs) have become a staple of ocean exploration for years,
going where man is not able to. Although much quieter than noise from shipping traffic,
the noise radiated from Mesobot could present potential for error in observation, tracking,
and sampling. In this thesis, I have analyzed the effect of commutation methods and
propeller design on the acoustic noise radiated from a single BlueRobotics T200 thruster.
The propeller design choices are a standard three-blade propeller and a three-blade toroidal
propeller. The commutation methods analyzed are trapezoidal control and field-oriented
control. After analyzing four different alternatives, quantitative evidence was found to
recommend using field-oriented control as the commutation scheme to minimize the radiated
noise from the thrusters on Mesobot. The radiated noise from the thurster was dominated by
motor noise, and no conclusive evidence was found to recommend the three-blade propeller
over the toroidal propeller.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Joint Program in Oceanography/Applied Ocean Science and Engineering
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