Review of Autonomous Undersea Vehicle (AUV) Developments 
ENVIRONMENTAL AWARENESS 
On November 28, 1995, the Chief of Naval Operations requested that the National Research 
Council initiate, through its Naval Studies Board (NSB), a thorough examination of the impact of 
advancing technology on the form and capability of naval forces to the year 2035. One panel 
focused on future naval forces and the operating environment. In their 1997 report [2], the 
Panel emphasized the importance of highly accurate and timely knowledge of the operating 
environment. 
"Effective Navy and Marine Corps operations of all types require a comprehensive knowledge of the 
operating environment and, in-turn, an understanding of the impact of those operations on the 
environment. The tools for characterizing the operating environment include long- and short-term 
weather forecasting and mapping and modeling of ocean and littoral waters, including positions of 
submarines, ships, and mines. 
Readily available supercomputing-scale computational power, combined with high-resolution, pervasive 
sensor information, increasingly sophisticated sensor fusion and filtering of data, and improved data 
display and assimilation tools, will provide Navy and Marine Corps decision makers with access to 
accurate and predictive battle-space environment information. 
Recent advances in remotely acquired data, mainly from satellites, are providing a wealth of information 
about the ocean and atmospheric environment not previously available. The Navy complements such 
remote sensing with ship-based measurements of ocean depths, temperatures, salinities, and other 
parameters and has good historical data sets derived from more than 100 ship-years of dedicated time. 
New distributed sensors will provide real-time data at high resolution representing large areas, with 
deployment possible in remote or otherwise inaccessible regions as needed. 
A major thrust for the future will be the enhancement of environmental data through the use of 
increasingly sophisticated models of the ocean/atmosphere system. Assimilation of these data into the 
Coupled Ocean-Atmosphere Dynamic System (COADS) model will be enabled by the rapid advances in 
computational power and modeling and simulation technology. The real-time weather prediction made 
possible by this combination of massive database modeling and computational power will allow tactical 
users to anticipate events in real time and strategic planners to more accurately predict seasonal 
weather. 
NRL is a world leader in modeling the world oceans for aspects critical to naval operations. It routinely 
calculates ocean currents, fronts, and eddy locations (in hindcast mode) using daily surface weather 
fields including those obtained from the European Forecasting Center. Despite this excellent capability, 
naval forces in the future must have real-time access to the output of a global model driven by current 
input data on (1) surface wind fields, (2) surface sea level, and (3) the internal variability of thermal fields. 
Wind data may be obtained from scatterometers on polar-orbiting satellites, such as NSCAT. Two 
satellites are required to give the Navy the coverage needed to monitor all remote areas. Altimeters 
mounted on the Navy GEOSAT and NASA TOPEX-POSIEDON satellite have demonstrated the ability to 
measure the shape of the ocean surface. Given an accurate geoid and tidal model, such data can be 
assimilated into ocean models to provide an estimate of ocean currents, front location, and eddy location. 
Measuring the internal variability of thermal fields is more difficult because the information comes from the 
mid-water (on the order of 500- to 2,000-m) ocean thermal structure. The two technical systems that are 
candidates for future development are acoustic tomography and drifting smart floats that measure current 
and temperature and maintain position in a constant water density. Both systems have been tested by 
the academic community, and both show promise. The global acoustic monitoring of ocean thermometry 
(GAMOT) project, for example, has demonstrated that the feasibility of deploying very inexpensive drifting 
passive sonar buoys capable of measuring deep-water travel time using fixed-sound-source acoustic 
transmission and data up-link to satellites. Such measurements allow the development of models of the 
upper 1,000 m of a 4- to 5-km-deep ocean. The other 80 percent is below the level of most conceivable 
naval operations. Because the ocean is stratified, slow moving, and, consequently, hydrostatic, almost all 
of the fundamental environmental information that is time dependent is transferred to the deep ocean 
through conservation of mass and momentum. 
