A 110-year-old patent has inspired a new robotic hand that can securely grip objects of any shape without the need for complex motorised joints.
The inspiration for the device dates back to 1913, when a now-expired US was granted on an invention for 鈥渙btaining intimate contact with, engaging, or clamping bodies of any shape鈥�. The original design consists of a nested arrangement of pivoting semi-circles in diminishing sizes, each of which could individually rotate to form a contour that securely grasps any shape.
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at the California Institute of Technology in Pasadena happened to see a YouTube video where a tool like this, called a fractal vice, was restored to a working condition, and he immediately recognised that it would work 鈥� with some updates 鈥� on a robot.
The fractal vice can give robots 鈥渁 third hand for oddball shapes鈥�, says Burdick. 鈥淎t the time that it was invented, both applications and manufacturing technology limited it, but we live in a different world today, so we can use the same principle but with new technology and new applications,鈥� he says.
He and his colleague , also at Caltech, redesigned the mechanism to do away with the curved dovetail joints of the original, which would clog with detritus and require regular maintenance. They 3D printed the entire mechanism in one go using a combination of rigid and flexible plastics, and topped each 鈥渇ingertip鈥� with two soft domes to provide friction.
The gripper requires just one motor, which moves its two sides towards each other and traps objects. More complex robotic hands designed to do the same job would need several jointed fingers, all with their own motors.
at the University of Bristol, UK, who wasn鈥檛 involved in the research, says a drawback of the fractal gripper is that it can securely grab objects, but not manipulate them.
鈥淥ur fingers are quite slim, so that they can kind of poke into little spaces to get something, but this is bulky,鈥� says Lepora. 鈥淎nd then once you鈥檝e held onto something, that鈥檚 all it does. It just holds it. We use our hands to manipulate and handle tools, but this is completely passive. Apart from being squeezed together, it doesn鈥檛 have any actuation itself. It鈥檚 a purely passive mechanism.鈥�
arXiv
