Sensor Technology for Anti-Submarine Warfare

Proposed is an underwater surveillance system for operation in denied littoral areas using autonomous underwater gliders.The approach is particularly suitable for extended surveillance prior to actual conflict and is capable of remote or off-shore deployment of multiple gliders which will patrol over distances of 1000 km or more with an endurance of 30 days.Gliders, which operate by changing buoyancy and gliding in a vertical saw-tooth profile, bring some unique advantages to this challenging problem: silent operation (no propeller), ability to surface or equilibrate at equilibrium depth, hover as required,long range and extended endurance. The principal disadvantage of gliders is: slow speed, approximately 0.4 m/s.An important potential advance is creating a vehicle able to rest on the bottom. Most AUVs must remain in motion, or possibly equilibrium in neutral buoyancy mode at controlled depth with little or no propulsion. The ability to be both mobile and rest onthe bottom creates many opportunities. In particular, advantages include: much longer missions; operating during certain hours with quiescent periods; avoidance of bioluminescent trail; remaining quiescent until triggered by events; accurate observationof local tides and currents; etc. There are difficulties with bottom resting. The principle difficulty is that all AUVs, (especially propeller driven designs) have modest negative buoyancy capability. A design optimized for both mobility and bottomresting is proposedTwo-way, real-time communication by satellite and GPS navigation are current glider capabilities. Air deployment capability is proposed. The Navy will benefit from the development of a new class of patrol and surveillance AUVs . Their unique capability is remote deployment and extended missions of observation and communication in any littoral area. A special benefit is the proposal tobreak new ground in AUV design and operate both in the propelled and bottom resting mode. Bottoming is a novelty in AUV operations, the combination increases endurance and allows deployment of an enhanced suite of sensors.There are benefits for the academic and environmental research community, especially for investigations of sporadic events or observations during specific parts of the daily or tidal cycle or, alternatively, for avoiding unfavorable events. Currentlyavailable gliders are commercially viable and the enhanced capability proposed will substantially increase their utility.