by David Geer
Contact the author at geercom@alltel.net
Kuka Robot Plays Air Hockey
Students from the Department of Technological Studies at Ohio Northern University
found a fun, creative way to solve an industrial robotics problem: How can a robot pick
parts from a bin if the parts are in motion? Answer: The same way it can play air hockey.
Enabling an industrial robot — in
this case, the KUKA KR3 — to
play air hockey solves some of
the same problems faced when trying
to make it pick up moving parts. The
robot has to identify the moving puck
and direct its arm to meet it where it
is before it moves again.
The project team used an
industrial KUKA KR3 six-axis articulated
robot, which they inverted above one
side of an air hockey table, according
to Dr. Adam Stienecker, assistant
professor, Technological Studies, Ohio
Northern University. The robot can
move up to 3 kilograms at a time
while maintaining its maximum speed
of movement.
Air Hockey Table
Side Rails, Puck
Return System
Medium Density Fiberboard (MDF)
Air hockey robot with Kuka robot, table, and
system, built by the Department of Technological
Studies at Ohio Northern University.
Puck Striker
The robot moves its arm at
speeds up to two meters per second.
This is still not fast enough to
compete with a human opponent,
who strikes the puck at a faster
rate. In order for the robot to strike
the puck with equal speed, the
team engineered a mechanical
puck striker and added that to the
robotic arm.
The team designed the puck
striker in CATIA V5, an advanced 3D
CAD modeling program. Then, they
printed (formed) the striker in a rapid
prototype 3D printer. This kind of
printer forms the actual part out of
ABS plastic. To do this, it melts narrow
strings of the plastic and layers them
one at a time, similar to how a 2D
printer puts ink on paper, according
to Dr. Stienecker. The machine adds
layer after layer to the part
using the printer until the
part is formed.
The striker moves four
spring-loaded disc quarters
out in all four directions
by striking them with a
cam. The cam attaches
to a motor powered
shaft. According to Dr.
Stienecker, the cam
(protrusion) sticks out
from the shaft and hits a
mating piece on each disc
quarter, pushing it outward
as the shaft rotates. A
spring return brings each
disc quarter quickly back
to its original position so
that the cam can strike it
again. The cam pushes
each disc quarter out
about three to five times
per second.
The diameter of the
striker is 100 mm, like
the striker in the human
opponent’s hand. This is to
ensure that the robot gains
no special advantage.
SERVO 06.2008 11
