Torch-Hand: a humanoid hand with 21 degrees of freedom that reproduces the joint of the human hand, only by wirettes

Without tendons, all its motors housed in the palm, Torch-Hand aims to reconcile anatomical fidelity, gripping force and control simplicity for fine manipulation.

Robotic hands for humanoids must arbitrate between anatomical complexity, robustness, load capacity and ease of control. Torch-Hand attempts to overcome this compromise: it reproduces the joint structure of the human hand with 21 degrees of freedom, including five for the thumb, capable of multi-axis movement at its base to largely oppose the other fingers, and four for each of the other fingers.

Unlike tendon or hybrid hands, the entire drive is driven via screw-operated connecting rods, which provides high gripping force and payload in a human-like format. All actuators are integrated into the palm and arranged so that each motor corresponds directly to a joint, which limits parasitic movements between fingers and simplifies steering.

The tests cover workspace, thumb opposition, force and load, as well as 33 types of sockets of the reference taxonomy and complete manipulation tasks. The authors present it as a robust hardware basis for the dextral manipulation of robots.