UGA engineers develop soft robotic gripper

Professor Mable Fok. (Photo by Andrew Davis Tucker/UGA)

Scientists often look to nature for cues when designing
– some robots mimic human hands while others
simulate the actions of octopus arms or inchworms. Now, researchers
in the University of Georgia College of Engineering have designed a
new soft robotic gripper that draws inspiration from an unusual
source: pole beans.

While pole beans and other twining plants use their
touch-sensitive shoots to wrap themselves around supports like
ropes and rods to grow upward, the UGA team’s robot is designed
to firmly but gently grasp objects as small as 1 millimeter in

“We had tried different designs but we were not happy with the
results, then I recalled the pole beans I grew in our garden few
years ago,” said Mable Fok, an associate professor and the
study’s lead author. “This plant can hold onto other plants or
rope so tightly. So, I did some research on twining plants and
thought it was a good design from nature for us to explore.”

In a
new study published in the journal Optics Express
, the
researchers say their soft robotic spiral gripper offers several
advantages over existing robotic devices.

Only needs a small space

“Our robot’s twining action only requires a single pneumatic
control, which greatly simplifies its operation by eliminating the
need for complex coordination between multiple pneumatic
controls,” said Fok. “Since we use a unique twining motion, the
soft robotic gripper works well in confined areas and needs only a
small operational space.”

The UGA device offers another advancement over many existing
robotics: an embedded sensor to provide critical real-time

“We have embedded a fiber optic sensor in the middle of the
robot’s elastic spine that can sense the twining angle, the
physical parameters of the target, and any external disturbances
that might cause the target to come loose,” said Fok.

The researchers believe their soft robotic gripper – a little
more than 3 inches long and fashioned from silicone – could be
useful in many settings, including agriculture, medicine and
research. Applications might include selecting and packaging
agricultural products that require a soft touch such as plants and
flowers, surgical robotics, or selecting and holding research
samples in fragile glass tubes during experiments.

Highly accurate and precise

In their study, the research team says the spiral gripper proved
effective in gripping objects such as pencils and paintbrushes –
even an item as small as the thin wire of a straightened paperclip.
The device also demonstrated excellent repeatability, high twining
sensing accuracy and precise external disturbance detection.

In addition to Fok, the research team includes Mei Yang and Ning
Liu, both Ph.D. candidates in engineering; Liam Paul Cooper, an
undergraduate studying computer systems engineering; and Xianqiao
Wang, an associate professor in the College of Engineering.

The team plans to continue its work with an eye on improving the
automatic feedback control based on the readings of the fiber optic
sensor. They also want to explore miniaturizing the design to serve
as the foundation of a biomedical robot.

“This twining soft robot with its embedded fiber optic sensor
forms a building block for a more comprehensive soft robot. Having
a simpler design and control is definitely an advantage,” said

Originally published by
Mike Wooten
| December 15, 2020
University of Georgia