The artificial muscles that will power robots of the future Christoph Keplinger
Transcriber: Joseph Geni
Reviewer: Joanna Pietrulewicz
In 2015, 25 teams from around the world
competed to build robots
for disaster response
that could perform a number of tasks,
such as using a power tool,
working on uneven terrain
and driving a car.
That all sounds impressive, and it is,
but look at the body
of the winning robot, HUBO.
Here, HUBO is trying to get out of a car,
and keep in mind,
the video is sped up three times.
(Laughter)
HUBO, from team KAIST out of Korea,
is a state-of-the-art robot
with impressive capabilities,
but this body doesn’t look
all that different
from robots we’ve seen a few decades ago.
If you look at the other robots
in the competition,
their movements also still look,
well, very robotic.
Their bodies are complex
mechanical structures
using rigid materials
such as metal and traditional
rigid electric motors.
They certainly weren’t designed
to be low-cost, safe near people
and adaptable to unpredictable challenges.
We’ve made good progress
with the brains of robots,
but their bodies are still primitive.
This is my daughter Nadia.
She’s only five years old
and she can get out of the car
way faster than HUBO.
(Laughter)
She can also swing around
on monkey bars with ease,
much better than any current
human-like robot could do.
In contrast to HUBO,
the human body makes extensive use
of soft and deformable materials
such as muscle and skin.
We need a new generation of robot bodies
that is inspired by the elegance,
efficiency and by the soft materials
of the designs found in nature.
And indeed, this has become
the key idea of a new field of research
called soft robotics.
My research group
and collaborators around the world
are using soft components
inspired by muscle and skin
to build robots with agility and dexterity
that comes closer and closer
to the astonishing capabilities
of the organisms found in nature.
I’ve always been particularly inspired
by biological muscle.
Now, that’s not surprising.
I’m also Austrian, and I know that I sound
a bit like Arnie, the Terminator.
(Laughter)
Biological muscle
is a true masterpiece of evolution.
It can heal after damage
and it’s tightly integrated
with sensory neurons
for feedback on motion
and the environment.
It can contract fast enough
to power the high-speed wings
of a hummingbird;
it can grow strong enough
to move an elephant;
and it’s adaptable enough
to be used in the extremely versatile arms
of an octopus,
an animal that can squeeze
its entire body through tiny holes.
Actuators are for robots
what muscles are for animals:
key components of the body
that enable movement
and interaction with the world.
So if we could build soft actuators,
or artificial muscles,
that are as versatile, adaptable
and could have the same performance
as the real thing,
we could build almost any type of robot
for almost any type of use.
Not surprisingly,
people have tried for many decades
to replicate the astonishing
capabilities of muscle,
but it’s been really hard.
About 10 years ago,
when I did my PhD back in Austria,
my colleagues and I rediscovered
what is likely one of the very first
publications on artificial muscle,
published in 1880.
“On the shape and volume changes
of dielectric bodies
caused by electricity,”
published by German physicist
Wilhelm Röntgen.
Most of you know him
as the discoverer of the X-ray.
Following his instructions,
we used a pair of needles.
We connected it to a high-voltage source,
and we placed it near
a transparent piece of rubber
that was prestretched
onto a plastic frame.
When we switched on the voltage,
the rubber deformed,
and just like our biceps flexes our arm,
the rubber flexed the plastic frame.
It looks like magic.
The needles don’t even touch the rubber.
Now, having two such needles
is not a practical way
of operating artificial muscles,
but this amazing experiment
got me hooked on the topic.
I wanted to create new ways
to build artificial muscles
that would work well
for real-world applications.
For the next years, I worked
on a number of different technologies
that all showed promise,
but they all had remaining challenges
that are hard to overcome.
In 2015,
when I started my own lab at CU Boulder,
I wanted to try an entirely new idea.
I wanted to combine
the high speed and efficiency
of electrically driven actuators
with the versatility
of soft, fluidic actuators.
Therefore, I thought,
maybe I can try using
really old science in a new way.
The diagram you see here
shows an effect called Maxwell stress.
When you take two metal plates
and place them in a container
filled with oil,
and then switch on a voltage,
the Maxwell stress forces the oil
up in between the two plates,
and that’s what you see here.
So the key idea was,
can we use this effect to push around oil
contained in soft stretchy structures?
And indeed, this worked surprisingly well,
quite honestly,
much better than I expected.
Together with my
outstanding team of students,
we used this idea as a starting point
to develop a new technology
called HASEL artificial muscles.
HASELs are gentle enough
to pick up a raspberry
without damaging it.
They can expand and contract
like real muscle.
And they can be operated
faster than the real thing.
They can also be scaled up
to deliver large forces.
Here you see them lifting
a gallon filled with water.
They can be used to drive a robotic arm,
and they can even
self-sense their position.
HASELs can be used
for very precise movement,
but they can also deliver
very fluidic, muscle-like movement
and bursts of power
to shoot up a ball into the air.
When submerged in oil,
HASEL artificial muscles
can be made invisible.
So how do HASEL artificial muscles work?
You might be surprised.
They’re based on very inexpensive,
easily available materials.
You can even try, and I recommend it,
the main principle at home.
Take a few Ziploc bags
and fill them with olive oil.
Try to push out air bubbles
as much as you can.
Now take a glass plate
and place it on one side of the bag.
When you press down,
you see the bag contract.
Now the amount of contraction
is easy to control.
When you take a small weight,
you get a small contraction.
With a medium weight,
we get a medium contraction.
And with a large weight,
you get a large contraction.
Now for HASELs, the only change
is to replace the force of your hand
or the weight with an electrical force.
HASEL stands for “hydraulically amplified
self-healing electrostatic actuators.”
Here you see a geometry
called Peano-HASEL actuators,
one of many possible designs.
Again, you take a flexible polymer
such as our Ziploc bag,
you fill it with an insulating liquid,
such as olive oil,
and now, instead of the glass plate,
you place an electrical conductor
on one side of the pouch.
To create something
that looks more like a muscle fiber,
you can connect a few pouches together
and attached a weight on one side.
Next, we apply voltage.
Now, the electric field
starts acting on the liquid.
It displaces the liquid,
and it forces the muscle to contract.
Here you see a completed
Peano-HASEL actuator
and how it expands and contracts
when voltage is applied.
Viewed from the side,
you can really see those pouches
take a more cylindrical shape,
such as we saw with the Ziploc bags.
We can also place a few
such muscle fibers next to each other
to create something that looks
even more like a muscle
that also contracts and expands
in cross section.
These HASELs here are lifting a weight
that’s about 200 times heavier
than their own weight.
Here you see one of our newest designs,
called quadrant donut HASELs
and how they expand and contract.
They can be operated incredibly fast,
reaching superhuman speeds.
They are even powerful enough
to jump off the ground.
(Laughter)
Overall, HASELs show promise
to become the first technology
that matches or exceeds the performance
of biological muscle
while being compatible
with large-scale manufacturing.
This is also a very young technology.
We are just getting started.
We have many ideas how to
drastically improve performance,
using new materials and new designs
to reach a level of performance
beyond biological muscle and also beyond
traditional rigid electric motors.
Moving towards more complex designs
of HASEL for bio-inspired robotics,
here you see our artificial scorpion
that can use its tail to hunt prey,
in this case, a rubber balloon.
(Laughter)
Going back to our initial inspiration,
the versatility of octopus arms
and elephant trunks,
we are now able to build
soft continuum actuators
that come closer and closer
to the capabilities of the real thing.
I am most excited
about the practical applications
of HASEL artificial muscles.
They’ll enable soft robotic devices
that can improve the quality of life.
Soft robotics will enable a new generation
of more lifelike prosthetics
for people who have lost
parts of their bodies.
Here you see some HASELs in my lab,
early testing,
driving a prosthetic finger.
One day, we may even merge
our bodies with robotic parts.
I know that sounds very scary at first.
But when I think about my grandparents
and the way they become
more dependent on others
to perform simple everyday tasks
such as using the restroom alone,
they often feel like
they’re becoming a burden.
With soft robotics, we will be able
to enhance and restore
agility and dexterity,
and thereby help older people
maintain autonomy
for longer parts of their lives.
Maybe we can call that
“robotics for antiaging”
or even a next stage of human evolution.
Unlike their traditional
rigid counterparts,
soft life-like robots will safely operate
near people and help us at home.
Soft robotics is a very young field.
We’re just getting started.
I hope that many young people
from many different backgrounds
join us on this exciting journey
and help shape the future of robotics
by introducing new concepts
inspired by nature.
If we do this right,
we can improve the quality of life
for all of us.
Thank you.
(Applause)