manipulating devices within reach of the object to be manipulated. In many 
cases, in addition to methods for moving the entire vehicle about, auxiliary 
locomotion subsystems taking such configurations as telescoping lifts, jack- 
knife booms, or the like, may be employed to enable the operator to position 
his handling arms without requiring him to move the entire vehicle. 
For general-purpose operations, a versatile Mobot may be suspended by 
a cable from a barge or other surface vessel. Gross motions of the Mobot 
are accomplished by maneuvering the surface vessel; fine control may be ac- 
complished by small propellers on the Mobot with which it can locate itself 
precisely. 
A freely-moving Mobot is sometimes preferable. This can be accomplished 
by providing sufficient power to drive propellers which will propel the Mobot 
in any desired direction. Depending upon the situation, one may wish to fur- 
nish Mobots which travel mainly horizontally (like unmanned submarines) or, 
in contrast, Mobots which travel mainly vertically (like an underwater ver- 
sion of a helicopter). 
For maneuvering heavy objects or for detailed exploration of the sea 
bottom or similar applications, bottom-crawling vehicles are desirable. 
These may be adaptations of caterpillar tractors or tanks or, alternatively, 
may use large soft rubber tires; in any case, the familiar techniques which 
may have been developed for off-road vehicles on land can be employed under- 
water as well. 
Command and Data Link. This link is the communication medium between 
the operator and the Mobot. It transmits from the operator to the Mobot the 
command information which directs the Mobot's motions; and it transmits from 
the Mobot to the operator sensory data which inform the operator of the situ- 
ation at the Mobot. Most important of the sensory data is the television 
information which (unless special systems are employed) requires an extremely 
wide band-width. In addition, sonar information and other data such as tem- 
perature, radioactivity level, pH of the water, and the like, may be trans- 
mitted. This link must obviously be capable of providing command information 
at a sufficiently rapid rate to control the Mobot, and of transmitting sen- 
sory data from Mobot to operator, again at an adequate rate. Since a cable 
must be provided to enable the operator to communicate with the Mobot (this 
is necessary since radio energy does not propagate in sea water), this same 
cable can be used to transmit electrical power to the Mobot. Modern multi- 
plexing technique makes it quite feasible to combine the two functions of 
communications and power in a very small number of electrical conductors. 
For very long distances the mechanical problems involved in handling 
the cable and the electrical problems involved in transmitting energy through 
it become quite formidable. It may therefore be necessary in such cases to 
employ repeaters within the cable to facilitate the transmission of command 
and TV information. This obviously implies the necessity for furnishing 
power by other means. In some cases it may be desirable to construct perma- 
nent underwater conduit installations, thus eliminating the necessity for 
carrying the entire length of cable on the Mobot itself. 
Power Subsystems. Power subsystems for remote handling systems are 
based upon standard power technology. In most cases prime power for under- 
water mobile vehicles is best transmitted through the cable which serves 
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