Thank you.

OK.

Our next presentation is by two students.

One is an undergraduate great Koskie who
was interested in working in clinical

biomechanics in our labs interested in
foot and ankle and he's volunteered.

He's actually volunteered his
time just for his enthusiasm for

research interest and he's been
partnered with another undergraduate

Benjamin Adams who's just joined our
team as this research progresses and

then Brian saw great who's a doctoral
student who did a rotation and it's been

a very much a team effort and maybe I'll
preface their their work a little bit.

You've seen some interlinking
with how the projects and

lines of sort of research are that
we're progressing so a horse.

Not earlier presented the door
selection resist A.F.O.

instrumented A.F.O. and
that is actually linked to this project.

It's answering one specific question for
us.

Designing and in G. harvesting A.F.O.
and that is what this project is about and

we're just going in kind of small steps
with regards to this design project.

So there is specific discussion will

be on the development of a mechanism that
harvests power from Dorsett flexion and

planar flexion ankle motion and
that will be Gradkowski and Brian so

great presenting Thank

you

Chris.

Hi I'm Brian so great.

This is Greg.

We're presenting today on our ongoing
research and development of passive

ankle for the first is that this is
a player flexion this case a said.

So there's plenty of selection is
a significant clinical issue here player

flexors as you may have heard earlier
will or what propels your foot forward

at the end of stance phase and
actually be difficult if you have for

example an Achilles tendon injury of which
there are two hundred thirty thousand

each year just in the U.S.
and most were so sees

that you find will limit or
world assist Dorsey flexion but

there's not a lot of good options out
there for powerplay or flexion assistance.

So that's what we're hoping so
that's avoid we're hoping that still

we think we can do this without any
kind of external energy source because

there's a lot of energy
wasted during look in motion.

This is a plot of power and
you can see here zero.

This is real strike all of this

negative very area under
the curve this energy this wast.

This is energy that you get from
the forward momentum of the body and

your muscles in your ankle actually
slow down slow down ankle motion.

During these phases so not only are we
losing energy we're actually using

force our muscles to
dissipate energy energy.

So our idea is to use
a spring to store this energy

and release the energy here in
plentiful action where you need

a large spike power to

one of the animals that we've looked at as
inspiration for this project is a bullfrog

bullfrog based on its
anatomy is able to supply

peak power when it jumps and so it was
an initial inspiration for this project.

Hence the name though so

the first prototype did provide
clear folk flexion assistance but

it was perturbed that other parts of gate
or other other sections of the gate cycle.

So another animal that we've looked
at more recently with regard

to the specific design is
the excuse me the mantis shrimp and

the magistrate has a clause that it
sort of winds up and then releases and

uses to smash its prey basically of the
we're interested in the wind up procedure

or wind of section of that which you to
diagram that here from here to the end of

the claw that has a sort of a clump of
the end of it when the cause cuts back.

It creates a little bit
of the forms the shape of

this paraboloid tendon here.

And so that it acts as a spring.

Now while it's going back.

It has flex for
muscles which are sort of held in place by

by a by a protrusion from
the exoskeleton and so that provides a.

Patch release.

So you can continue birth of
the shrimp can continue to form

this spring like tendon until
those muscles are released

in which point you get a very quick
power release and over a thousand units

of force which is pretty impressive for
a shrimp that weighs less than one Newton.

So as we are going through this design
process we want to answer three

main questions as days ahead noted.

Basically we're trying to
harvest some power here through

the stance phase of the gate cycle and
with this energy harvesting

that we're doing we want to be able
to take that power to store it and

then after a period of time we want to
be able to release that stored energy

into a peak power output that we can
use for our player flexion systems.

So when we're looking at
the stats face on basically we

we need to segment the the motion of

the of the stance face into the strictly
planar flexion of rotations and

the doors flexion rotations for
our purposes.

We're going to design
a curing mechanism and

which we can capture this energy
throughout this entire cycle.

So for planar flexion we're going to
designate a counterclockwise rotation of

a gear and for flexion we're going
to assign a clockwise direction.

So in this diagram here kind
of put out the the stance face

showing how much degree of rotation we
can gather through this stance face.

So first when we make.

So we're looking at the the lateral
view of the right leg right here and

let's place of year at this ankle
joint with the central axis.

As there as we begin the initial
contact with the ground this right here

we get about five degrees of rotation
through the loading response stage

and as we continue through the mid stance
stage we get about fifteen degrees

of course flexion rotation and
then another twenty five degrees.

After we've gone through mid stance and

we've gone to the terminal
stance to the toe off.

We've got that last twenty five degrees
of plentiful action for Taishan So

summing all that together we have about
forty five degrees of rotation and

which we can harvest this energy through
the gate cycle that's continuous

which we now want to be able to store.

So looking at energy storage a catch
release mechanism is possible for

us to use using this catch release we can
hold this power that we've gathered and

then release it with a quick release and
getting a peak power output at the end.

So looking at back it kind of the medics
are looking at this this chameleon's Tom.

So what a chameleon does
is it has a six or eight or

muscle at the back of its tongue
it contracts and it pulls

back these connective tissues that are
also in the tongue creating a strain and

this strain is the elastic energy that it
uses to project its tongue forward when

it's catching flies whatever
whatever prey is trying to eat.

So as it's doing this on
the accelerator muscle is pulled back

at time zero in this graph here and at
about two Hundreds of a second after this.

This Excel or
in a muscle is pulled back the tissues

of gathered this elastic energy and
then releases it instantaneously giving

this peak power output here about
two kilowatts per kilogram of this.

Tongue mass and
that this is a per mass power output

that this study head head
on has gone through so

basically we want to take
our gearing mechanism and

make it analogous to something
that this can be done.

So we have these gears that
are gathering energy and

then we want to be able to stretch a
spring as Brian had mentioned that will be

storing this energy will hold that spring
and then according to whatever mechanism

under the control of our mechanism will
release this this power that we've

gathered to get some
sort of output like this.

Hopefully for
our plentiful excellent systems.

So Brian had mentioned the mantis shrimp

it has this hyperbolic paraboloid
shape and it's anatomy and

basically what it does is allow
us to amplify some of that power

that shrimp gets when it's using its claws
to basically club its prey to death.

So we want to use this

kind of this kind of theory to say
OK well we have this this spring

that we're stretching and we're stretching
it in either a horizontal vertical

direction to get this this load in which
we can store the energy at well what if we

use this this hyperbolic paraboloid that
that could help what could that help us.

Maybe get a little bit more elastic energy
so doing a little bit of a let searching

found this article where they had loaded
a flat plate on a cylindrical shell and

a sphere full shell with a range
of forces and kill Newtons and

basically they they test these loads and
to see what kind of the flexion they get

from applying that to the center of
the plate the shell whatever it may be so

you can see the best of the flat plate
gets about pretty much a linear.

Linear curve as you're applying
more force you're going to get

a linear train of of the flexion now
the sphere go on cylindrical shells for

that same amount of force applied
you get three times more deflection.

So theoretically if we were to use a shape
to say this hyperbolic paraboloid or

some sphere cool shape
first legible shape too and

place of our traditional stretching
spring if we can get a little bit more

deflection with the same amount of force
that we gathering through the gate cycle.

Well maybe we'll have some more elastic
energy that we can use to amplify

the power that we get from this
catch release mechanism so

basically we want to address.

OK well what kind of shape.

Should we use maybe even
the make material properties

that will give us more elastic energy.

So as we progress.

We want to continue
addressing these questions

we have this energy collecting and
anger two different directions.

We need to make this repeatable Big eight
cycles a continuous thing we want to be

able to do this for
the planar flexion systems at each off

and then we want to look at
what's the best placement for

all these mechanisms that we're looking
at where should we put the catch.

Where should we.

What size issue we make the gears how are
we going to put all that together to get

the OPs optimum OP our output and
then again what shape and

what material should we use for the spring
will provide us with some powerful

occasion to optimize this plane
reflection systems so through the summer

we'll be working on this we would like to
prototype this and then eventually test it

to get these people our outputs
with some various iterations and

variations of of these different
these different categories to see.

How we can improve by flexion assistance
and I would like to thank America

north out of and prosthetics initiation
and I H. for providing the funds for

this research project as well as
Mark Johnston Mark Jacobson and

Ben Adams as is it mentioned he's
done a lot of the a lot of work for

us and these guys have helped with working
with models and things and we appreciate

their help and will thank you for
your time in the floor for questions.

And he questions I'll just make a couple
comments on behalf of the team.

So the objective here is that what we
would like to do is try to harvest this

energy during walking and
then perhaps actually

use it to provide a function
rebuilt a view used

at a later point in the gate cycle but
that energy could be used for

a lot of different things driving
driving a motor storing energy for

many different purposes even
outside our facts and prosthetics.

So we've we've got a big
task ahead of us but

we are we feel like are making some
huge gains along this direction.

So as as you've seen there's been
a couple of the other projects

that are answering part of
the questions towards this project.

So OK thanks very much.