← Back to 09Home · The FourAll Dossiers
A3 · DOSSIERPrehensile Hand System

Hands.

Twenty-two degrees of freedom, tendon-driven, with a silicone fingertip pad that reads pressure and shear in real time. Strong enough to carry; soft enough to never pinch.

Hands. — engineering reference
01Prehensile Hand System

Anatomy

Anatomy

Four long fingers and a shorter opposable thumb — the chimpanzee precision-grip pattern. Phalanges are machined aluminium with carbon-fibre tendons routed through PTFE sheaths to the forearm, where 22 brushless micro-actuators sit out of the way of the impact envelope.

Read full subsection →
02Prehensile Hand System

Tactile fingertip

Tactile fingertip

Each fingertip carries a 6 × 6 array of capacitive tactels under a 2 mm silicone pad, plus a 3-axis MEMS force cell at the bone. The control loop resolves both normal pressure and incipient slip — the moment an object starts to slide, grip force rises before the object falls.

Spatial resolution is 1.2 mm; refresh is 2 kHz.

Read full subsection →
03Prehensile Hand System

Grip regulation

Grip regulation

Three firmware modes:

  • Carry: up to 180 N total grip — a bag of shopping, a watering can.
  • Hold-hand: capped at 8 N — a child or an elder can pull away at any moment.
  • Fragile: capped at 2 N with active slip-arrest — a wine glass, an egg, a phone.
Read full subsection →
SPSpecifications
Degrees of freedom
22 per hand
Tactile resolution
1.2 mm @ 2 kHz
Grip force — carry
≤ 180 N
Grip force — hold-hand
≤ 8 N
Grip force — fragile
≤ 2 N
Closing time (full fist)
180 ms
← All DossiersHead →