Building a human-like hand is one of the most difficult challenges in both robotics and prosthetics. The human hand is a remarkable evolutionary achievement, because it is capable of dexterity, strength, and touch. But, those same factors make it difficult to replicate. A robot gripper may be capable of strength, but might sacrifice the ability to lightly grab a delicate object.
Researchers at MIT have been experimenting with using soft robotics to more closely reproduce the abilities of the human hand. In their Hand Development Kit, they’ve create tendon-actuated silicone fingers. The silicone is cast is a simple 3D-printed mold, with wire tendons running through channels in the casting.
A servo motor, which can be driven by any off-the-shelf controller, is used to tighten or relax the tendons. Just like with a human finger, that causes the prosthetic finger to either grip or release. While the researchers intend this to be used for augmentation purposes, which would give someone extra fingers, it clearly has potential for replacing lost appendages as well.
In cases like that, the biggest challenge is natural control. But, the same solutions that they’re using for augmentation, like mirroring another finger’s movement, could certainly be used in replacement prosthetic cases as well. The real value here is in the compact structure of the prosthetic, and in it’s ability to provide dexterity, as well as usable strength, while still retaining flexibility and softness.