due to lack of air, the presence of nuclear radiation, to high temperature, 
or to any other hostile environment which makes it impossible for a man to 
enter. The operations required may be equally broadly considered. Typi- 
cally, it is necessary to translate objects from one position to another, 
to operate tools, such as screw drivers or wrenches, or to operate measur- 
ing equipment of many kinds. Usually, fixed obstacles are contained within 
the hazardous area, limiting the freedom of motion of any equipment con- 
tained therein. 
A typical problem to be handled by a general-purpose underwater remote 
handling system is that of engaging a power-operated wrench with a nut or 
screw. This engagement and the operation of the wrench itself must, of 
course, be done in a manner which is independent of the separation between 
the operator who controls the operations and the equipment, and it must be 
done even in the presence of numerous fixed obstacles. 
In the past, problems of this type have sometimes been attacked by 
the use of long tongs or forceps. Some of these have become extremely com- 
plex and have employed hydraulic or electromechanical actuators to supple- 
ment the physical strength of the operator. All such devices may be con- 
sidered extensions of the man's arms, and the man himself is just outside 
the hazardous area and protected from it by a suitable barrier or shield. 
Let us approach this problem in a more generalized way, and let us 
assume that the separation between the hazardous area and the safe area is 
so great that tong-like tools cannot be used. This requires us squarely 
to face the problem of operating in areas which are inaccessible. This is 
sometimes done by providing the operator with protective clothing suitable 
to the environment. Movable personnel shields may be used in nuclear en- 
vironments, and the space suit of science-fiction is often proposed for the 
space environment. 
In all such cases we find that we have actually not solved the problem. 
We have, on the contrary, merely changed the geometry. The safe area is now 
contained within the hazardous area, but the operator is still separated 
from his work by his protective system and must use tongs rather than his 
own hands for manipulation. 
From the viewpoint of solving the fundamental problem of operating 
within an inaccessible as well as hazardous area, let us analyze a man as 
a handling system. For this purpose we may ignore many of his more inter- 
esting attributes and note that just four interrelated systems are involved. 
These may be identified briefly as his brain, his eyes, his hands, and his 
feet. More seriously, the eyes and the sensory nervous system provide in- 
formation concerning his surroundings. The hands, as controlled by the 
motor nervous system, are able physically to move objects as desired. The 
feet and legs, controlled by their separate motor nervous system, enable 
the entire organism to move about; and finally, the brain assembles and or- 
ganizes all these data and directs the motor systems as required. 
The three functions symbolized by eyes, hands, and feet may readily 
be extended by modern electronic means over any desired distance. In this 
way, aman's senses and his ability to accomplish useful work may be extended 
to any distance, while his brain, which can be duplicated by no existing com- 
puter, remains in safety and comfort at any desired location. 
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