Building A Cheap, Dexterous Robot Hand

Most of the time, assuming nothing’s gone wrong with them, we take our hands so much for granted that it’s easy to forget what remarkable pieces of engineering they are: not only are they precise and sensitive enough to crack an egg or write a signature, but also strong enough to lift a weight or swing a hammer. Such performance has thus far eluded robot hands, but fortunately few tasks require it; the main challenge is dexterity, which is where [Vittorio Lumare]’s low-cost Yeah Hand could help.

The Yeah Hand is mostly 3D-printed and uses five servo motors per hand; like a human hand, it has no actuators within the fingers themselves, instead using fishing-line tendons to transfer motion from the motors. To reduce friction and keep the motors from overheating, each tendon runs through guides made from PTFE Bowden tubes; in tests, the hand ran 800 cycles of opening and closing without even getting close to overheating. The hand can lift up to eight kilograms and apply a maximum grasping force of five kg. For better grip, each finger has silicone grips along the inner surface, which let it hold smooth objects quite steady; to pick up fine objects, the thumbs have thumbnails.

The hand comes in two versions: robotic and experimental prosthetic, with the main difference being in mounting: the robotic version comes with a wide variety of mounting flanges and has an ROS driver. To control the hand more intuitively, [Vittorio] made a glove with built-in flex sensors to detect the position of his hand and mirror it. For some demonstrations of the hand’s abilities, check out the video below.

We’ve seen a number of human-like robot hands here, though most aren’t nearly as accessible for the average hacker. If you have a more bespoke need in mind, though, designing a purpose-built hand is quick.