Engineers Draw on Nature to Develop Soft Robotic Gripper

Engineers from the University of Georgia have followed the ever-increasing pattern of drawing on nature to develop robotics. While it is often animal features in nature such as octopus arms, this instance involved the team looking to pole beans to develop a soft robotic gripper.

The most inspirational features of the pole beans and other twinning plants for the researchers was their touch-sensitive shoots, which are used to wrap around supports. The robot developed by the UGA team can behave in a similar way, firmly but gently grasping objects all the way down to one millimeter in diameter.

Mable Fok is an associate professor and the study’s lead author.

“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 Fok. “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.”

The new study was published in the journal Optics Express.

The team also included Mei Yang and Ning Liu, Ph.D candidates in engineering; Liam Paul Cooper, who is an undergraduate studying computer systems engineering; and Xianqiao Wang, associate professor in the College of Engineering. 

“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,” Fok continued. “Since we use a unique twining motion, the soft robotic gripper works well in confined areas and needs only a small operational space.”

The Robotic Device

Another unique aspect of the UGA device is an embedded sensor that provides critical real-time feedback, which puts it ahead of other robotics on the market.

“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 soft robotic gripper is slightly over three inches long, and it is constructed of silicone. The researchers believe it could be applied in sectors like agriculture, medicine, and research. Specific applications include packaging agricultural products such as plants that are delicate, surgical robotics, and handling research samples in glass tubes.

The study demonstrated the effectiveness of the soft robotic gripper when gripping objects like pencils and paintbrushes. It was able to work with an item as small as a thin wire on a straightened paperclip. Besides being effective, the device has excellent repeatability, high twinning accuracy, and precise external disturbance detection.

The team will now work on improving the automatic feedback control, which the fiber optic sensor readings will provide insight into. They will also look to miniaturize the design, making it more applicable as a biomedical device.

“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 Fok.