14 DAY TRIAL // It was a miracle when 3D printing technology managed to cut the price of prosthetic hands to a thousandth of what they used to be, but in the end it still takes a bit more care and engineering genius to make truly nimble artificial limbs.
Sure, all those E-NABLE robotic hands made from plastic and tied with wire to the arm stump are good enough to grip things, but other than that, they can't do much.
In order for a prosthetic to really be considered a viable replacement for the natural thing, it needs to have at least 70-80% the same range of motion and strength as the original limb.
As it happens, Baoding balls can become the ultimate test as to whether or not a prosthetic hand qualifies as such. A new project by Rii Lab shows a mechanical hand capable of rotating two of those balls repeatedly.
The new mechanical hand
The Research Laboratory of Robotics Innovation and Intervention has created an “underactuated prosthetic hand based on postural synergies” with the help of the Chinese National Program on Key Basic Research Projects.
The researchers started by creating a dummy hand, which they used to track and measure six different poses of the hand.
They then made it so that the mechanical prosthetic could switch seamlessly from one pose to the other, thus performing the needed cycle that resulted in the rotation of the meditation balls.
The specific transmission system to control the prosthetic took a bit of time and effort to pin down, but the designers managed it in due time.
The transmission system maps two synergy inputs to 13 outputs to drive the hand. The scientists describe it as “a mechanical implementation of the postural synergies.”
At one point during development, the team considered using a hydraulic system, but they eventually decided on the mechanical implementation because it provided greater accuracy. Flexible shafts proved key, as they would not be affected by wrist motions.
Availability
Since this is still a proof of concept, you shouldn't expect some new, incredible masterpiece of mechanics any time soon. The automail from Fullmetal Alchemist is still ages away, alas.
