Researchers Create Insect-Inspired Robotic Grippers
Many soft robotic grippers are inspired by the bending of a fish fin. They include triangular components that curve around an object to grip it. These components have cross beams arranged at 90-degree angles, which help the gripper wrap around the object.
Such traditional grippers require a lot of force to lift an object and cannot always handle fragile objects without crushing them. Researchers from five different universities, led by Poramate Manoonpong of the University of Southern Denmark in Odense, draw inspiration from how insects walk and grab objects to develop a new way of making robotic grippers.
Instead of cross beams arranged at 90-degree angles, the international research group in Odense placed the beams at angles of 10 or 30 degrees, similar to the adhesive pads of insects. By changing the tilt angle of these beams, the researchers found that their grippers could bend objects more and lift them using 20% less force.
“We know that many animals can cling or attach to surfaces using flexible pads or paws. We could see that the angle of the pads in insects was different. Previous work has already explored changing the gripping angle, but none of it conducted detailed studies of the effects of different cross beam angles within its frame”
Using less force to grip an object allows the gripper to handle more delicate items, such as food, without crushing them. When researchers tested grippers with beams at 90 or 120 degrees, the gripper needed far more force to lift the object.
The new grippers also improved the robots' walking. When faced with uneven surfaces, such as rocks, or round ones, such as pipes to walk across, the robots could adapt to the situation without complex control. The grippers resemble flippers that easily wrap around the surface the robot walks on.
Manoonpong's team was inspired by insect adhesive pads, but they are not the only researchers turning to nature to advance robotics.
In December 2020, researchers from the College of Engineering at the University of Georgia developed a robotic gripper inspired by bean tendrils. These soft grippers require only one pneumatic control, which simplifies operation. The gripper also had a fiber-optic sensor in the flexible stem of the robot that could detect the object being lifted and any external interference.
“We tried different design options, but the results did not satisfy us, and I remembered the beans I grew in our garden a few years ago. This plant can hold very tightly to other plants or a rope. So I conducted a small study of climbing plants and thought this was a good design from nature that we could explore”
In November 2020, researchers from UNSW Sydney (University of New South Wales) created a gripper inspired by the elephant trunk. This soft-tissue gripper was designed to handle heavy and fragile objects.
The researchers argued that the versatile technology could be widely applied in sectors that handle fragile items, such as agriculture and the food industry, as well as in science and resource exploration, even for人 rescue operations or personal assistive devices.
Dr. Thanh Nho Do said: "Our new soft-tissue gripper is thin, flat, lightweight, and can grasp and retrieve various objects, even from confined cavities, such as a pen inside a tube. The device also has an advanced real-time force sensor that is 15 times more sensitive than traditional designs and determines the gripping force needed to prevent damage to the objects it works with. There is also a thermally activated mechanism that can change the gripper body from flexible to rigid and back, allowing it to grasp and hold items of different shapes and weights — up to 220 times heavier than the gripper's own mass."
The Odense team tested its gripper model using only soft grippers. Their next task is to make it strong enough to cope with harsher conditions.
"Robot foot and gripper designs compatible with various mechanical solutions were developed to improve proper contact formation and grip on different substrates. The Fin Ray structure is one of the solutions. Although the Fin Ray effect has already been proposed and used, no detailed studies of the effects of different crossbar angles within its frame have been conducted," the study says.
According to the scientists, considering factors such as a large contact area, high energy efficiency, and better durability, the Fin Ray model with non-standard crossbars tilted at 10 degrees offers the best compromise compared to other models within the constraints of certain geometric parameters.
