Scientists often look to nature for cues when designing robots — some robots mimic human hands while others simulate the actions of octopus arms or inchworms. Now, researchers have designed a 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 new robot is designed to firmly but gently grasp objects as small as 1 millimeter in diameter.

The soft robotic spiral gripper offers several advantages over existing robotic devices. The 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. With the twining motion, the soft robotic gripper works well in confined areas and needs only a small operational space. A fiber optic sensor is embedded 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.

The researchers believe the 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 like plants and flowers that require a soft touch, surgical robotics, or selecting and holding research samples in fragile glass tubes during experiments.

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.

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.

For more information, contact Michael Terrazas at This email address is being protected from spambots. You need JavaScript enabled to view it.; 706-542-5941.


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This article first appeared in the August, 2021 issue of Tech Briefs Magazine.

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