Electronics Weekly Electronics Design & Components Tech News
The device is inspired by weaving and can be made at different sizes, always maintaining large ratio between gripping capacity and its own mass.
“Utilising soft, flexible materials such as cloth, paper and silicone, soft robotic grippers acts like a robot’s hand to perform functions such as grasping and releasing objects,” according to the Korea Institute of Science and Technology (KIST). “Unlike conventional rigid material grippers, they are more flexible and safe, and are being researched for household robots that handle fragile objects such as eggs, or for logistics robots that need to carry various types of objects.”
The gripper consists of strips of fabric or flexible polymer, each hanging down, bent around with a half twist back to a central point (colourful diagram left).
At the centre, one end of each loop is connected to the same small disc. All the other ends are connected to a second small disk, immediately behind the first, on the same axis.
By holding one disc still and rotating the other around this axis, the bundle of loops can be made to open and close.
If it is closed around an object, due to the way the loops interact, the object cannot be pulled out axially without physically breaking the loops.
Essentially, pointed out the researchers, the device weaves and unweaves as it operates, with each strip serving as both warp and weft along its length.
To predict performance, the team has created a theoretical model that can be used to design grippers with different numbers of strips and different strip geometries.
Several weight-carrying proof-of-concept grippers were made from suitably-sized strips of PET plastic.
In practice, “the grippers can lift various objects of different shapes and hardness that have a smaller volume compared to the gripper’s capacity”, KIST researcher Kahye Song told Electronics Weekly.
They can also handle objects with knobs on top – the 300mm version in the top photo, shown lifting 90kg, can also lift a flower from a vase without damaging it.
“Additionally, it can lift coins and small parts like M3 nuts,” said Song. “Since this gripper is scalable, [we] have created both a small version 55mm diameter and a large version 1.2m diameter.”
The 55mm diameter version demonstrated picking up a 500g weight using the top knob designed for human fingers, the 1.2m diameter version has picked up a six-pack of two litre plastic water bottles and, on another occasion, a 5kg cardboard box.
“The manufacturing process can be completed in less than 10 minutes, and it is easy to replace and maintain,” said KIST. “In addition to PET, the gripper can also be made of various materials such as rubber and compounds that possess elasticity, allowing the team to customise and utilise grippers suitable for industrial and logistics sites that require strong gripping performance or various environments that need to withstand extreme conditions.”
KIST worked with KAIST, the Korea Advanced Institute of Science and Technology on this project, which is published in Nature Communications as ‘Grasping through dynamic weaving with entangled closed loops‘ – available in full without payment.
