Date of Award
Doctor of Philosophy (PhD)
Global-scale underwater navigation presents challenges that modern technology has not solved. Current technologies drift and accumulate errors over time (inertial measurement), are accurate but short-distance (acoustic), or do not sufficiently penetrate the air-water interface (radio and GPS). To address these issues, I have developed a new mode of underwater navigation based on the passive observation of patterns in the polarization of in-water light. These patterns can be used to infer the sun__s relative position, which enables the use of celestial navigation in the underwater environment. I have developed an underwater polarization video camera based on a bio-inspired polarization image sensor and the image processing and inference algorithms for estimating the sun__s position. My system estimates heading with RMS error of 6.02_ and global position with RMS error of 442 km. Averaging experimental results from a single site yielded a 0.38_ heading error and a 61 km error in global position. The instrument can detect changes in polarization due to a 0.31_ movement of the sun, which corresponds to 35.2 km of ground movement, with 99% confidence. This technique could be used by underwater vehicles for long-distance navigation and suggests additional ways that marine animals with polarization-sensitive vision could perform both local and long-distance navigation.
Mark Anastasio, Shantanu Chakrabarrty, Ron Cytron, Roman Garnett,