controls engineer Brandon Peterson explains that the soft-
ware and mechanics in the exo are similar to what’s used in
IHMC’s humanoid robots.
“Mark directs the exoskeleton, but he’s actually sort of
riding the device,” Peterson says. “The exo weighs about 75
pounds, but the user doesn’t feel like they’re carrying that
extra weight. Like a car or motorcycle, the exo is grounded
and supports its own weight. Mark is along for the ride, but
still relies on his crutches for balance.”
Peterson is designing one of the key upgrades for the
suit that Daniel will wear for the 2020 competition: sensors
embedded in the soles of the exo’s feet that send pressure data
to the computer housed in the suit’s backpack. The computer
then transmits vibrations to pads in Daniel’s vest, alert-
ing him if he’s off-balance and ensuring that he’s in a safe
position to take another step. “Able-bodied people do that
naturally, using proprioception in the lower body to gain an
understanding of their joint positions without having to look
down at their legs,” Peterson says. “Mark can’t do that. He
has no sensory feedback in his legs, and the messages to and
from his brain stop at the break in
his spinal cord.”
There will be other updates
as well: The team has added two
actuators that will allow Daniel to
move side to side without having
to pivot the entire suit. They’ve
also shifted the transmission
system in the DC motors from a
harmonic drive, whose high gear
ratio produces higher friction,
to a ball-screw linkage system
that reduces friction. New cop-
per tubing will drain heat from
the actuators. The challenge is to
make everything as cool, small,
lightweight, and user-friendly as
possible.
Peterson pauses, running his
hand along the blue aluminum-
anodyne actuator machined
to match the length of Daniel’s
right thigh. “Programming bal-
ance in an autonomous humanoid
robot is relatively easy,” he says.
“Achieving autonomous balance
control on a device to which a
human attached is another story.
When off-balance, the exo will
make a correction based on the
software algorithm and the user will instinctively correct
with their crutches. The two actions can end up fighting
each other, resulting in a dangerous tug-of-war between
the robot and user.”
So having a human being in an exoskeleton makes the job
of balancing a lot harder. But of course, the human being is
the whole point.ark Daniel was 5 years old when he started riding
dirt bikes through the pine woods around Pensa-
cola. He was 15 when his mom and dad insisted he
quit after a crash ruptured his spleen and nearly
killed him. Daniel redirected his restless energy into
cocaine and small-scale street crime. He was 17 when his
parents confronted him with a choice: continue on a path of
self-destruction or deal with his addiction by enrolling in
the Job Corps. Daniel picked Job Corps.
He arrived at the Muhlenberg Job Corps Center in Green-
ville, Kentucky, strung out, weighing 130 pounds, and notM
COURTESYETH^ ZÜRICH/NICOLAPITARO(CYBATHLON2016)◀ Peter Neuhaus works on the
exoskeleton at IHMC's headquarters
in Pensacola, Florida.34 May/June 2020