Underwater gliders are autonomous buoyancy-driven vehicles (AUVs) that use small changes in its buoyancy in conjunction with wings to convert vertical motion to horizontal, and thereby propel itself forward with very low power consumption. While not as fast as conventional AUVs, gliders using buoyancy-based propulsion represent a significant increase in range and duration compared to vehicles propelled by jets or electric motor-driven propellers, extending ocean sampling missions from hours to months, and to thousands of kilometers of range, providing useful data on temporal and spatial scales unavailable to previous AUVs, and less costly to sample using traditional shipboard techniques.
A change in volume -generated by filling an external oil bladder or moving a piston- creates positive and negative buoyancy. Because of the wings, the buoyancy force results in forward velocity as well as vertical motion. Then, they move on “a sawtooth” pattern through the water column, gliding downward when denser than surrounding water and upward when buoyant. Pitch can be controlled by modifying the internal mass distribution. Wings are fixed and gliders automatically align the positions of the center of buoyancy and the center of gravity to achieve desired angle of ascent/descent. A rudder is used for the heading / roll control and navigation through a waypoints list. Depth rate is limited (for now) up to 1000 m.for commercial models.
All glider technologies described have a high modular component allowing on-demand payload sensor configurations according to the application and the user needs. However, there are some sensors or parameters to measure more “typical” than others (CTD, Dissolved Oxigen, chlorophyll, CDOM, Hydrocarbons, sea currents, noise, meteorological parameters, PAR, nutrients, turbulence,…among others).
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