Researchers at the Korea Institute of Machinery and Materials (KIMM) were inspired by how elephants can pick up small objects by pinching them with the tip of their trunks, and pick up large objects by sucking in air. They developed a gripper with a soft structure and thin walls, and wires enabling it to change its shape, which is capable of performing both actions.
The soft structure of the gripper has a number of micro-channels that create a vacuum inside, helping it attach to an object. Each of these micro-channels is flexible, so the gripper can modify its shape to match that of objects it comes into contact with. Therefore, the soft structure itself functions as a suction gripper by generating adhesive force to the surface of objects.
By pulling the wires that control the shape of the gripper, located in the centre of the soft structure, the gripper can fold in half on itself, which allows for it to be used like a claw gripper, pinching and grasping the objects. When used in this way, the stretchable-thin wall located outside the gripper wraps around and seals the target object. By creating a vacuum inside the gripper after pinching and wrapping around the object, the gripping force can be greatly increased as needed.
It solves problems with the two main types of gripper currently available: claw-type grippers which can’t pick up anything larger than the size of the claw, and suction-type grippers which struggle with very thin or air-permeable objects.
The gripper newly developed by KIMM can grip objects of various sizes and materials by simultaneously applying the claw-type and suction-type gripping mechanisms. It is not only capable of gripping small objects, such as acupuncture needles (0.25mm in diameter) from the floor, which are smaller than one hundredth the size of the gripper, but it also can grip large objects such as boxes that are 10 times its size.
Also, this gripper can pinch and grasp various objects in claw-gripping mode by simply turning on and off the pneumatic cylinder that moves the shape-modifying wires, without any complicated sensors or controls. “After contacting the soft gripper to the floor and then creating a vacuum while conducting a pinching motion, the gripper can grip objects as if you were strongly pinching the floor with your fingers,” says Dr Sung-Hyuk Song, a senior researcher at KIMM’s AI Robot Research Division. “In this way, even very thin objects can be easily gripped and lifted from the floor.”
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