The Michigan Daily - michigandaily.com

Thursday, January 16, 2014 - 5'

LEFT: Fruneer 'ig graduate students Brent Grif
RIGHT:b -fixes the loose jrts of the robot

Fr P . ': n 1v Sne rbot w k i during an experiment.

One step for robot-kind...

ROBOT
From Page IA
humans in to," Grizzle said.
The team began their work
with MABF.iL an earlier and
slightly more primitive version
of MARLO - whose hips only
moved forwards and backwards.
This version of the robot could not
provide its own lateral stabiliza-
tion and was confined to walking
or running in circle, irrsil the lab
attached to a boom.
MARLO, however, can walk in
all directions attached only to a
safety cable that prevents it from
toppling over and breaking when
it loses balance. This improved
ability to balance allowed the
tearm to take MARLO for a test
run outside the lab. On one chilly
day in early December, MARLO
firrally saw the light of day.
"We'd done the length of the
lab 25 or 30 times, but these
robots are eventually supposed to
be able to go outside and handle
real walking situations," Grizzle
said. "lie Saturday morning we
took a siot at it, and it almost

worked. '
MAIILIO valk'nd arind for
about two hours until a knee
broke. I trook rough l an hur
of sanding and gluing to put the
pieces tack together, and another
day for the glue to dry
tWe re still rookies at working
on this robot, but we'll lick that
problem soon," Grizzle said.
Engineering graduate sttudent
Brian Buss said ie was attracted
to the project because of the way
it atttc l such a complex pi oblerm,
and he appreciates the potential it
has to help people.
He r elated programming
MAR O t'r'hing a child how
to walk.
"A child is born with limbs and
muscles, but can't walk until it
learns how," he said. "The pro-
grarnming part we've done con-
sists of figuring out what to do
with six motors and sensors that
measures angles if' the robot is
leaningover."
Buss said balance is a trickier
thing to accomplish than most
people realize. It's not as simple as
sore tay think; when compared
to M A R LO. humans have the

advantage of nerves that detect
pressure and tipping angles, eyes
to see where they're going and
flexible ankles that can correct
balance issues.
The team plans to install high-
performance internal measuring
units on MARLO to give the robot
an even better sense of balance.
Currently, devices at the ankles
measure forces on the ground
while others calculate the angle of
the body. However, these devices
aren't foolproof and MARLO still
trips over itself from time to time.
Jill Petkash, an orthotic and
prosthetic technician at Universi-
ty Hospital, started working with
the team last September to select
prosthetic feet that would pro-
vide the robot with more stability.
She ultimately helped fit MARLO
with College Park's Tribute model
prosthetic. The company agreed
to donate the feet to the project
free of charge.
The 'Tribute Foot is designed
for human amputees, giving
MARLO a more human-like gait.
in addition, a series of clamps
and tubes that attach the feet to
the end of the robot's legs act as a

sort of shin bone, and provide an
increased range of motion even
though the ankle is fixed with
respect to the rest of the leg.
These clamps and tubes will
also simplify the process of
switching out prosthetic feet,
should the team choose to do so.
"MARLO is astandard produc-
tion prosthetic item, so if they
wanted lighter weight or more
high performance materials, they
could easily do that by just using
standard componentry," Petkash
said.
MARLO is a completely cus-
tomized machine, and its creators
are still working to come up with
better designs. But even when the
programming team works until
the early hours of the morning,
getting to test and perfect their
ideas is just one enjoyable part of
the job.
"The really fun days are when
we have a particular design that
we want to try, like a new idea
for controlling or improving con-
trol of the robot," Buss said. "It's
excitingto see the robot work andr
get people excited about it."

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