system and its associated manpower and shipboard storage require- 

 ments. There is also no need for stationkeeping during an operation. 



If communications requirements for the free-swimming vehicle were reduced 

 to zero, a totally autonomous submersible could be produced and the support 

 ship itself could be eliminated. Although certain totally autonomous opera- 

 tions are practical, even with today's technology there are several major 

 areas where development is required before untethered RCVs can approach the 

 usefulness of their tethered counterparts. One of these areas is that of 

 adapting a manipulator arm to the free-swimming submersible and developing a 

 reasonable and efficient means of remotely controlling that manipulator by 

 means of a low-bandwidth acoustic channel. For additional discussion 

 concerning the differences between a truly autonomous vehicle and a remotely 

 controlled vehicle, see ref 2. 



1.1 THE NOSC FREE-SWIMMING SUBMERSIBLE 



For the last several years, the Naval Ocean Systems Center (NOSC) has been 

 involved with the development of small, unmanned vehicle systems. The list of 

 these submersibles includes the first hydraulic Snoopy, Submerged Cable 

 Actuated Teleoperator (SCAT), Electric Snoopy, NAVFAC Snoopy, and the Mine 

 Neutralization Vehicle (MNV). (For details of these systems, see ref 3.) 



The development of control systems for these vehicles has proceeded from 

 completely manual control, through heavy, multiwire cable, to automatic con- 

 trol circuits directed by a lightweight, low-drag cable with multiplexed data 

 and control signals. New technological advances in solid-state electronics 

 and microprocessor technology permit a simplification of the hardware required 

 for small unmanned vehicles by allowing the designer to replace much of the 

 hardware with flexible software to meet the changing needs of various mission 

 requirements. With funding from the U.S. Geological Survey, NOSC has devel- 

 oped a free-swimming (untethered) submersible testbed (EAVE WEST) for pipeline 

 and undersea structures inspection as well as Navy search and inspection 

 tasks. The basic development requirements in the design of the vehicle were 

 as follows: 



- Operate with and without a communication link. 



- Demonstrate speeds greater than those of a tethered submersible having 

 the same thruster power. 



- Hover and maneuver at zero and low-to-medium speeds. 



- Operate relatively inexpensively for several test operations and 

 experiments at sea. 



- Be mechanically modular to lend itself to the addition of appendages 

 such as TV cameras, side-looking sonars, and other inspection sensors 

 and effectors. 



- Contain a modular, easily updated, and expandable software structure 

 that allows expansion from a simple single computer system to a more 

 sophisticated supervisory-controlled configuration for autonomous 

 operations. 



