Robots still have trouble gripping and manipulating objects. It’s one of the biggest challenges that
needs to be solved.
However, it appears the University of Washington
(UW) has found a way to help robots get a better
grip. UW built a five-fingered robot hand that teaches
itself how to grasp and manipulate objects on its own,
and it gets better with more practice.
The robot hand uses machine learning algorithms
to model both the physics involved and to plan its
course of action. As the robot hand performs different
tasks, the system collects data from various sensors
and motion capture cameras, using machine learning
algorithms to continually refine and develop more realistic
“A lot of robots today have pretty capable arms, but the
hand is as simple as a suction cup or maybe a claw or a
gripper,” said lead author Vikash Kumar, a UW doctoral
student in computer science and engineering.
UW’s hand is quite expensive at roughly $300,000, so
don’t expect to see it in real world applications anytime
soon. It uses a Shadow Hand skeleton actuated with a
custom pneumatic system and can move faster than a human
hand. The UW team plans to use the robot hand “to push
core technologies and test innovative control strategies.”
The team emphasized how different its autonomous
learning approach is to dexterous manipulation. “Usually
people look at a motion and try to determine what exactly
needs to happen — the pinky needs to move that way, so
we’ll put some rules in and try it and if something doesn’t
work, oh the middle finger moved too much and the pen
tilted, so we’ll try another rule,” said senior author and lab
director, Emo Todorov, a UW Associate Professor of
Computer Science and Engineering, and Applied Mathematics.
At this point, UW has tested the robot hand’s ability to
improve its manipulation of the same object. The next step
will tackle global learning — its ability “to manipulate an
unfamiliar object or a new scenario it hasn’t encountered
“There are a lot of chaotic things going on and collisions
happening when you touch an object with different fingers,
which is difficult for control algorithms to deal with,” said coauthor Sergey Levine, UW Assistant Professor of Computer
Science and Engineering who worked on the project as a
postdoctoral fellow at University of California, Berkeley.
“The approach we took was quite different from a traditional
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unfold. Through a design process that Guitron describes as
“mostly trial and error,” the researchers arrived at a
rectangular robot with accordion folds perpendicular to its
long axis and pinched corners that act as points of traction.
In the center of one of the forward accordion folds is a
permanent magnet that responds to changing magnetic fields
outside the body, which control the robot’s motion. The
forces applied to the robot are principally rotational. A quick
rotation will make it spin in place, but a slower rotation will
cause it to pivot around one of its fixed feet. In the
researcher’s experiments, the robot uses the same magnet to
pick up the button battery.
The researchers tested about a dozen different
possibilities for the structural material before settling on the
type of dried pig intestine used in sausage casings. “We spent
a lot of time at Asian markets and the Chinatown market
looking for materials,” Li says. The shrinking layer is a
biodegradable shrink wrap called Biolefin.
To design their synthetic stomach, the researchers
bought a pig stomach and tested its mechanical properties.
Their model is an open cross-section of the stomach and
esophagus molded from a silicone rubber with the same
mechanical profile. A mixture of water and lemon juice
simulates the acidic fluids in the stomach.
Every year, 3,500 swallowed button batteries are
reported in the US alone. Frequently, the batteries are
digested normally, but if they come into prolonged contact
with the tissue of the esophagus or stomach, they can cause
an electric current that produces hydroxide which burns the
tissue. Miyashita employed a clever strategy to convince Rus
that the removal of swallowed button batteries and the
treatment of consequent wounds was a compelling
application of their origami robot.
“Shuhei bought a piece of ham, and he put the battery
on the ham,” Rus says. “Within half an hour, the battery was
fully submerged in the ham. So, that made me realize that,
yes, this is important. If you have a battery in your body, you
really want it out as soon as possible.”
UW’s robot hand has 40 tendons, 24 joints, and more than 130 sensors.
(Credit: University of Washington)