September 12, 1996. Copyright, 1996, Graphic News. All rights reserved

ARTIFICIAL LIMBS WITH A MIND OF THEIR OWN
By Laura Spinney, Science Editor

EMBARGOED UNTIL 16.45 THURSDAY 12 SEPTEMBER

LONDON, September 12, Graphic News - A new generation of artificial limbs that can learn precise movements and improve their own dexterity could be on trial within a year, a British researcher announced at the British Association's annual science meeting in Birmingham today.

Professor Roland Burns of the University of Plymouth realised his work with intelligent machines could be applied to prosthetic limbs when he saw the limited movement that a conventional artificial arm gave one of his students. By jerking his shoulder, the student could make pincer movements with his claw-like prosthetic hand, but the hand was incapable of performing small manoeuvres that required precision.

The first step towards developing a thinking prosthetic hand was to investigate the patterns of electrical activity in the muscles that accompany different hand movements. By digitally sampling the electrical signals produced by muscles in the arm, Burns and his team discovered that each action of the fingers or wrist has a characteristic signal pattern. When this pattern, or frequency signature, is fed into an artificial neural network, the network gradually learns to recognise the different signatures and their corresponding muscle actions. 

An artificial neural network is a representation of the human brain in a computer. Just as humans learn through the reinforcing of neural pathways in the brain, an artificial neural network learns when software links are reinforced mathematically as a result of data being fed in. In Burns's prototype prosthetic hand, a sensor would detect the frequency signature generated by the amputee's remaining muscles, the neural network would then recognise the desired movement from that signature and command one or more small, battery-driven motors built into the artificial arm to execute the movement.

Burns believes that the different stages of this intelligent system will be assembled within a year, by which time the smart prosthetic hand will be ready for clinical trials. In his opinion, prosthetics will never be the same again. 'The quality of life with these artifical limbs would be tremendous,' he says.

Sources: British Association Annual Festival of Science