Robot hand that plays Jingle Bells could help us make better limbs.
By Douglas Heaven
It’s not the best version of Jingle Bells you’ll hear this year but has some festive cheer – it’s being played by a rubber robot hand that can’t move by itself. What’s more, the piano could point the way to better designs for robot limbs.
Most artificial limbs require complex mechanisms to control all their moving parts, but that might be overkill. When we use our hands to play piano or pick something up, a lot of the movement comes from the way their physical structure interacts with the environment. “Hands have intelligence in themselves,” says Josie Hughes at the University of Cambridge, UK.
To explore how much of a hand’s movement comes from its shape – rather than how the brain controls it – Hughes and her colleagues 3D-printed a life-size replica with plastic bones and rubber-like ligaments but no muscles. Looking like a Halloween accessory, the skeletal digits were then attached to a mechanical arm that moved up and down to play a keyboard.
The team was surprised at how many different movements the rigid hand was able to make simply by being pressed against the keys in different ways. For example, it could use the thumb to slide between notes – a technique known as a glissando. “The variety of playing was very exciting,” says Hughes.
Learning which movements come for free will help us make better robot hands. The team plans to move on from festive songs to look at how doctors use their hands to perform examinations. The way a doctor palpates a patient – pressing the torso with hands and fingers – is mechanically simple but can be used to diagnose tumors, for example.
We use our hands for a lot of things, from a light touch with a single finger to a heavy punch with the whole fist. If we understand the mechanics of each movement we could design and print a specific hand to do that task in a matter of hours, says Hughes.
It would also be interesting to experiment with different hand designs, she says. “We could look at a hand with two thumbs.”