Marine Observation Using a Hybrid Glider

Abstract

Observations of marine physical (chemical) or biological phenomena have been evolving considerably within the last 20 years. Advances in underwater robotics have made it possible to take measurements in situ automatically. These techniques include Yoyo profilers (automatic vertical profile generation using ballast), autonomous underwater vehicles (AUVs, short-terms missions using an autonomous submarine), and more recently underwater gliders (long-range buoyancy driven vehicles). The above-mentioned solutions have advantages and drawbacks that can be considered to create a more optimized vehicle. AUVs allow precise navigation in shallow coastal areas, bottom following, and horizontal transits, but is limited to a few days of endurance. Contrarily, the glider's endurance extends to months, but its maneuverability, efficiency in shallow waters, and payload volume are limited, and its wings are fragile. In addition, most existing vehicles rely on hazardous surface position fixes and/or very expensive inertial navigation systems with poor accuracy after hours of a mission. In order to avoid collisions, an acoustic system allowing underwater position fixes using a single buoy may be used. This paper describes how the advantages of the two types of platforms can be merged into an "hybrid glider," capable of gliding but also of being propelled at low speed and high efficiency.