May 4, 2017

UK Engineers Design a Prosthetic Hand That Sees

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Image courtesy of Newcastle University.

A new generation of prosthetic hands, which allows the wearer to reach for objects automatically and intuitively, like a natural hand, have been designed by biomedical engineers at Newcastle University, England. The bionic hand is fitted with a camera that instantaneously takes a picture of the object in front of it, assesses its shape and size, and triggers a series of movements in the hand. Bypassing the usual processes that require the user to see the object, physically stimulate the muscles in the arm, and trigger a movement in the prosthetic limb, the hand “sees” and reacts in one fluid movement. Two people with transradial amputations trialed the new technology for the study; the findings were published May 3 in the Journal of Neural Engineering.

Using neural networks, the basis for artificial intelligence, lead author on the study Ghazal Ghazaei, a postgraduate research student in the School of Electrical and Electronic Engineering at Newcastle University, showed the computer numerous images of objects from different angles and orientations, in different light, and against different backgrounds, and taught it to recognize the grip needed for different objects. The computer isn’t just matching an image, it’s learning to recognize objects and group them according to the grasp type the hand must perform to successfully pick it up.

Grouping objects by size, shape, and orientation, according to the type of grasp that would be needed to pick them up, the team programmed the hand to perform four different grasps: palm wrist neutral (such as when you pick up a cup); palm wrist pronated (such as picking up the TV remote); tripod (thumb and two fingers); and pinch (thumb and first finger). Using an inexpensive camera fitted to the prosthesis, the hand sees an object, picks the most appropriate grasp, and sends a signal to the hand—all within a matter of milliseconds and ten times faster than any other limb on the market.

“One way would have been to create a photo database of every single object, but clearly that would be a massive task and you would literally need every make of pen, toothbrush, shape of cup—the list is endless,” said Kianoush Nazarpour, PhD, a senior lecturer in biomedical engineering at Newcastle University and a co-author on the study. “The beauty of this system is that it’s much more flexible and the hand is able to pick up novel objects—which is crucial since in everyday life people effortlessly pick up a variety of objects that they have never seen before.”

The work is part of a larger, multi-university research project to develop a bionic hand that can sense pressure and temperature and transmit the information back to the brain. The aim is to develop an electronic device that connects to the forearm neural networks to allow two-way communications with the brain.

The hand that sees is an interim solution that will bridge the gap between current designs and the future, said Nazarpour. “It’s a stepping stone towards our ultimate goal,” he said. “But importantly, it’s cheap and it can be implemented soon because it doesn’t require new prosthetics—we can just adapt the ones we have.”

Editor’s note: This story was adapted from materials provided by Newcastle University.

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