the individual pieces.
Dave Freeman — the owner of
Advanced Computer Products in Santa
Ana, CA — gave me a Novag chess
robot. A customer had broken the
robot arm, and I tried to fix the
broken casting to no avail. I still have
it. The arm’s two segments covered
the board and the forearm segment
swiveled up and down to raise and
lower the gripper, much as a human
arm moving objects about a board.
The gripper had three pieces arranged
120° apart to close in on or release a
chess piece. It was amazing to watch
a robot playing a game back in 1982
when robots were becoming popular.
Our Amazing Human
Hand
I would like to present a few
scenarios and discuss just how
uniquely functional the human hand
really is as compared to the very best
robot hands and grippers. Before
delving into a robot’s gripper, just sit
back in your chair right now and look
at your own hand. Wiggle all of your
fingers and thumb. Hold it up in the
Vulcan sign shown in Figure 3 that
Spock always used to, and then would
say, “Live long and prosper.” Notice
the two fingers separated, as well as
the thumb. You can begin to see just
how versatile our hands are.
The fingers just don’t curl
inward to hold something and
neither does our opposing thumb that
can move in several directions. We can
wrap the thumb around a baseball bat
and then place it in another position
to press a button atop a gaming
joystick. We can curl just the tops of
each finger or curl them all the way.
We can separate individual fingers like
the Vulcan hand sign. Feel the
tendons below your wrist stiffen when
you make a fist. We are talking about
some amazing mechanics here.
I won’t delve into the physiology
of the human hand and its phalanges
and metacarpals as I did a bit over a
year ago. I want to discuss ‘end
effectors’ in a more robotic way.
Typical Robot
Grippers and End
Ef fec tors
The earliest industrial robots were
designed for specific duties and had
their end effectors optimized for the
task at hand. (Pun intended.) The site,
WhatIs.com described an end
effector thusly:
“In robotics, an end effector is a
device or tool that’s connected to the
end of a robot arm where the hand
would be. The end effector is the part
of the robot that interacts with the
environment. The structure of an end
effector and the nature of the
programming and hardware that
drives it depend on the task the robot
will be performing. In manufacturing,
a robot arm can accommodate only
certain tasks without changes to its
end effector’s ancillary hardware
and/or programming. If a robot needs
to pick something up, a type of robot
hand called a gripper is the most
functional end effector. If a robot
needs to be able to tighten screws,
however, then the robot must be
fitted with an end effector that can
spin.”
As you can realize from above,
the end effector can be a special tool
such as a wrench or screwdriver, or it
can be a type of gripper to pick up or
maneuver an object. If you remember,
little R2D2 in Star Wars had a series of
tools or probes (one of which is
shown in Figure 4) that he could
insert into a computer data interface
on the Death Star to download all
sorts of things. It looked more
mechanical than digital to me, but our
heroes were able to determine the
Death Star’s weaknesses with the
retrieved data, and also avoid being
squashed in a garbage compactor.
However, it is the basic gripper that is
most used in industrial applications as
well as personal robotics.
Robot Gripper Types
To delve into a robot’s capability
to handle objects, I am going to
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Figure 4. Star War's R2D2 uses tool to access Death Star's database.
Figure 3. Star Trek's Spock gives Vulcan
welcome sign.