Review of Autonomous Undersea Vehicle (AUV) Developments 
AUTONOMOUS BENTHIC EXPLORER (ABE) [1,38] 
The Autonomous Benthic Explorer (ABE) (figures 22 and 23) was designed to address the need 
for long-term monitoring of the sea floor which is very expensive using a surface ship for 
repeated visits with ALVIN or Jason. While manned submersibles and ROVs allow intensive 
study of an area, they can remain on station for only hours, days, or weeks. Consequently, a 
system that can remain in an area gathering data to fill the time voids between submersible and 
ROV visits would provide another level of more detailed information on temporal variations. 
Cameras and other fixed instruments may not always be the best solution to this problem 
because they have limited spatial coverage and are vulnerable to fouling from bacterial growth 
or mineral deposits. 
After discussions with many scientists studying hydrothermal systems, the concept of a roving 
robot that could remain working on station for up to a year was developed. The robot would 
spend most of its time "sleeping" in a safe location, then, at pre-programmed intervals, undock, 
perform a survey with video cameras and other sensors, then redock and go back to "sleep." 
From these ideas, the ABE was created and built at Woods Hole. 
ABE is a true robot, able to move on its own with no pilot or tether to a ship, and designed to 
perform a predetermined set of maneuvers to take photographs and collect data and samples 
within an area about the size of a city block. During long deployments, ABE will “sleep” at a 
docking station between data excursions, conserving power for months of extended operation. 
ABE was developed by a team of engineers, who assembled what might be called the robot's 
body, muscles (thrusters), nerves (cabling and power to operate the motors, cameras, and 
sensors), and brain (computer systems for powering up and down and for determining where to 
go and when to make measurements). Each of these components presented a complex design 
challenge. 
Currently, ABE follows a set of instructions placed in its memory before deployment and is 
recovered for data download following an excursion. However, its developers envision the not- 
too-distant day when underwater acoustic transmission systems now being developed will allow 
scientists anywhere in the world to receive video and data from ABE and to control its 
movement and measurements from their home laboratories. 
To minimize cost, ABE is a three-body, open-frame vehicle. This allows glass balls to be used 
for flotation (there are three in each of the two free-flooded, upper pods), and all the batteries 
and electronics to be placed in a single, lower housing. This separation of buoyancy and 
payload gives a large righting moment that simplifies control and allows the propellers to be 
located inside the protected space between the three faired bodies. ABE has seven thrusters 
and can move in any direction. It can travel forward at 1m/sec on about 50 watts to its motors. 
Navigation and control take only about 12 additional watts. 
50 
