Page 39 - Sensing, Intelligence, Motion : How Robots and Humans Move in an Unstructured World

14 MOTION PLANNING—INTRODUCTION

The Robotics Institute of America adds some engineering jargon and empha-
sizes the robot’s ability to shift from one task to another:

A robot is a reprogrammable multifunctional manipulator designed to move mate-
rial, parts, tools, or specialized devices through variable programmed motions for
the performance of a variety of tasks.
Somehow this definition also leaves a sense of dissatisfaction. Insisting solely on
“manipulators” is probably an omission: Who doubts that mobile vehicles like
Mars rovers are robots? But “multifunctional”? Can’t a robot be designed solely
for welding of automobile parts? And then, is it good that the definition easily
qualifies our familiar home dishwasher as a robot? It “moves material” “through
variable programmed motions,” and the user reprograms it when choosing an
appropriate cycle.
These and other definitions of a robot point to dangers that the business of
definitions entails: Appealing definition candidates will likely invite undesired
corollaries.
In desperation, some robotics professionals have embraced the following def-
inition:

I don’t know what a robot is but will recognize it when I see one.

This one is certainly crisp and stops further discussion, but it suffers from the lack
of specificity. (Try, for example, to replace “robot” by “grizzly bear”—it works.)
A good definition tends to avoid explicitly citing material components neces-
sary to make the device work. That should be implicit and should leave enough
room for innovation within the defined function. Implicit in the definitions above
is that a robot must include mechanics (body and motors) and a computing device.
Combining mechanics and computing helps distinguish a robot from a computer:
Both carry out large amounts of calculations, but a computer has information
at its input and information at its output, whereas a robot has information at its
input and motion at its output.
Explicitly or implicitly, it is clear that sensing should be added as the third
necessary component. Here one may want to distinguish external sensing that the
machine uses to acquire information about the surrounding world (say, vision,
touch, proximity sensing, force sensing) from internal sensing used to acquire
information about the machine’s own well-being (temperature sensors, pressure
sensors, etc.). This addition would help disqualify automobiles and dishwashers
as robots (though even that is not entirely foolproof).
Perhaps more ominously, adding “external” sensing as a necessary component
may cause devastation in the ranks of robots. If the robot uses sensing to obtain
information about its surroundings, it would be logical to suggest that it must
be using it to react to changes in the surrounding world. The trouble is that this
innocent logic disqualifies a good 95–98% of today’s robots as robots, for the
simple reason that all those robots are designed to work in a highly structured
environment of a factory floor, which assumes no unpredictable changes.