Review of Autonomous Undersea Vehicle (AUV) Developments 
System tradeoff studies and analysis showed that an untethered search vehicle with supervisory 
control outperformed all other tethered, towed, and untethered options. Concurrently 
development of an underwater acoustic communications capability allowed supervised control 
without a tethered cable. 
Potential strengths of properly designed untethered systems are agility, stability, ability to hover 
in three dimensions, high forward speeds, rapid turns, combined with low risk of loss. 
Untethered systems, however, will not have enough self-intelligence in the foreseeable future to 
replace the human decision making capability afforded by vehicle/operator communications. 
The human operator, when allowed to supervise the operation of an untethered system, fills in 
where the untethered system is deficient: complex decision making. The human plans the 
mission and decides how to alter the mission based upon information obtained from both the 
support ship systems and the vehicle itself. The human analyzes vehicle sensor data and 
decides which anomalies in the data are of interest to the mission and therefore deserve further 
investigation, and which are not. The human operator can also alter the tactics pursued by the 
vehicle based upon environmental changes indicated in sensor data. Finally, the human 
operator is uniquely qualified to declare when the mission is completed. 
Autonomous systems can profit by the inclusion of a real-time (cable or fiber optic) or near-real- 
time (acoustic) communications capability during development testing. With this approach, the 
developers/operators have an opportunity to interact with the system and monitor system 
performance in real time while they work out system bugs. 
The evolution toward more autonomy with an untethered system can be carried to completion if 
the mission permits. Increases in AUSS vehicle autonomy have enhanced the human 
operator's capability to supervise by eliminating pilot and navigation burdens, and even allowed 
the matured AUSS vehicle to be used for certain complex, fully autonomous functions. These 
included performing sonar search patterns covering several square nautical miles and transiting 
long distances without operator commands being sent for hours. 
The prototype was a product more of evolution than of its original system engineering. Post- 
design breadboard-level implementations existed throughout, resulting in an unaccountable 
signal-to-noise ratio in the acoustic link system. Transmissions of high-quality images through 
the acoustic link required so much time that the rate at which the system could search was 
below optimal. The vehicle buoyancy system consisted of a pressure vessel providing less than 
adequate displacement supplemented by ad hoc, oddly shaped pieces of syntactic foam. The 
vehicle fiberglass fairings suffered from extensive modifications including holing, sawing, and 
gluing. 
The improved system’s ground-up design was based upon the prototype lessons. The electrical 
and acoustic signal-to-noise ratios were excellent. The vehicle computer systems were 
expanded and upgraded to the best available technology. Contractor-supplied surface console 
software was rewritten and ported to a network of off-the-shelf industrial computers. Original 
image compression algorithms were developed so the optical and sonar images were seen by 
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