MEDICAL DEVICES
Both Mate and EksoVest
transfer the weight of
the arms to the pelvis
down again, adduction).
For example, the Mate does not
increase the strength of workers, points
out Giuseppe Colombina, head of the next
generation business platform at Comau
(an industrial automation company owned
by FCA). He is also CEO of IUVO, a spinout
of the Sant’Anna School of Advanced
Studies in Pisa, Italy that helped designed
it. “What it does is help compensate the
weight of your arm by a mechanical chain
that discharges the weight of your arm: not
to the shoulder, but directly to your pelvis
bones.”
THREE ELEMENTS
The device, which weighs less than 4kg,
consists of three elements, Colombina
explains: a passive mechanism called
the ‘active box’ to provide adjustable
gravity compensation; a mechanical chain
including linear and rotational guides to
naturally follow the body’s motion; the
surfaces of the device that actually attach
to the body.
The Mate team included input from
Icelandic design company Össur, which
designed the carbon fibre prostheses
(‘blades’) made famous by South African
athlete Oscar Pistorius. Mate comes in
two sizes: small/medium and large. Each
can be adjusted in width at the shoulder,
in height, and at the belly. Since product
launch in December 2018, some 350
have been sold.
Although the ExoVest development
process at Ekso Bionics was similar, it
actually came about in reaction to a kind
of failure of an overly-ambitious project,
confesses senior product manager Zach
Haas. Formed in 2005, the company’s
first device was the EksoGT, an
exoskeleton device for assisting people
with rehabilitation after stroke or spinal
cord injury. But the company harboured
ambitions to expand into general industry,
and launched a new division in 2015. The
first idea was to develop a mechanical
arm that would support the weight of a
heavy tool (and a user’s arm). He says:
“We had a whole chassis suit
that an operator/worker could
wear and we bolted that arm
to the suit, but it transferred
all of the weight to the ground,
so the operator would not
feel the weight of the suit, or
the weight of the arm or the
weight of the tool that the
suit was holding. And while it
worked well in concept, it was
just a little too cumbersome
for people to adopt, so that’s why we
took a step back and the exoskeleton
with the super arm, and turned it into a
non-wearable device.” That became the
EksoZeroG tool support arm that mounts
to fixed equipment.
But separating the arm from the suit
resulted in the idea for the ExoVest: “Hey,
the reason why this is so cumbersome is
that you have to attach all of this stuff to
our legs, which is critical to transfer all the
weight to the ground. Could you just give
us a device for our arms?”
What has resulted is a device that
uses compressed gas springs to provide
5-15lbs (2.3-6.8kg) of force per arm.
When adjusting the device, which only
comes in one size, users can set the level
of assistance by swapping out the spring;
there are four. The spine post
adjusts to accommodate different
torso heights. In addition to
shoulder straps and a hip belt,
this device also includes arm
cuffs, important to make sure
the device is properly taking
the load. To make it easier to
take on and off, the ExoVest
includes a button to immobilise
the spring actuators. Also, the
parts of the ExoVest that make
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