Human hands are really complicated, and roboticists have put a lot of effort into replicating that complexity. But, while a huge amount of research has been devoted to the mechanical dexterity of those robots, the actual surface characteristics of the artificial “skin” are often overlooked. This new robot hand from Yale’s GRAB Lab puts that at the forefront of with a variable friction gripper.
The robot is designed to mimic how you actually manipulate objects, not just the physical form of your hand. You may not even notice it, but when you handle something like a pen you often slide your fingertips across the surface. The friction ridges of your fingerprint allow you to firmly grip the pen, while also giving you the ability to reduce that friction with less pressure. This design recreates that with a dual-surface gripper mechanism.
The 3D-printed gripper itself is simple, and only has two fingers that pivot on a single axis. One of those fingers has a friction pad with ridges that’s made from a rubbery elastomer. The other finger has a similar pad, but with the addition of a retractable insert. The insert is made from rigid ABS, which has a much lower coefficient of friction than the primary pad. By retracting or extending the insert, the robot hand can vary the friction of its grip. As the researchers demonstrate, that makes it adept at more sophisticated manipulation than we’re used to seeing. And, because it’s mechanically simple, it could be easily integrated into other robot grippers.