Adapting a Survey-Class AUV for High Resolution Seafloor Imaging

Abstract

Over the past four years, development work at the MIT AUV Lab focused on a vehicle that is now almost a decade old. “Xanthos,” one of the last surviving examples of the venerable Odyssey II series of AUVs (developed at MIT in the early 1990s), is a small, deep-rated, low- drag vehicle originally intended for oceanographic survey work. In this project, the AUV Lab pushed the limits of the Odyssey II platform to bring this aging vehicle up to the state of the art in underwater imaging. Originally designed to carry a CTD and ADCP, Xanthos was refit with DVL and AHRS for navigation, and sidescan sonar, high-resolution digital still camera, and high-powered strobe for seafloor imaging. No part of the original vehicle was left untouched; several subsystems were redesigned and rebuilt from scratch to accommodate the new sensors. The ultimate goal: to turn a simple CTD profiler into a tool for deep-water marine archaeology. Xanthos’ rebirth culminated in a visit to Greece, aboard the Hellenic Center for Marine Research’s R/V “Aegaeo.” This attempt at AUV-based archaeology demonstrated the strengths and weaknesses of the re-design, as Xanthos contended with strong currents, navigation failures, sensor limitations, and mechanical damage. Lessons learned from the development of Xanthos as an imaging platform form the foundation of the MIT AUV Lab’s latest project. The “Odyssey IV,” capable of hovering and holonomic maneuvers at depths of up to 3000m, will carry a stereo camera and sonar as its primary sensor payloads.