Open-Source Dexterous Hand
Orca Hand Specifications
Full technical specifications for the Orca Hand dexterous hand platform from ETH Zurich's Soft Robotics Lab.
Mechanical
| Total DOF | 17 (fingers + abduction axes + wrist) |
| Fingers | 5 — thumb, index, middle, ring, pinky |
| Thumb joints | 4 — MCP, abduction, PIP, DIP |
| Per finger (index–pinky) | 3 each — abduction, MCP, PIP |
| Wrist | 1 — flex/extend (±60°) |
| Actuators | Feetech STS3215 serial bus servos (×17) |
| Motor IDs | 1 – 17 (all on one bus) |
| Wrist mount | Standard robot arm flange (ISO 9283 compatible) |
| Build type | Open-source — design files and BOM publicly available |
Joint Range of Motion — All 17 DOF
Source: orca_core/models/orcahand_v1/config.yaml
All values in degrees. The thumb has 4 DOF including a distal interphalangeal (DIP) joint. Fingers 2–5 each have 3 DOF (abduction, MCP, PIP). Motor IDs are not sequential by anatomy — always command by joint name.
| Joint | Min (°) | Max (°) | Description |
|---|---|---|---|
| thumb_mcp | −45 | +45 | Thumb metacarpophalangeal flex/extend |
| thumb_abd | −65 | +65 | Thumb abduction / adduction |
| thumb_pip | −20 | +140 | Thumb proximal interphalangeal |
| thumb_dip | −20 | +120 | Thumb distal interphalangeal |
| index_abd | −40 | +40 | Index finger abduction / adduction |
| index_mcp | −20 | +120 | Index metacarpophalangeal |
| index_pip | −20 | +140 | Index proximal interphalangeal |
| middle_abd | −40 | +40 | Middle finger abduction / adduction |
| middle_mcp | −20 | +120 | Middle metacarpophalangeal |
| middle_pip | −20 | +140 | Middle proximal interphalangeal |
| ring_abd | −40 | +40 | Ring finger abduction / adduction |
| ring_mcp | −20 | +120 | Ring metacarpophalangeal |
| ring_pip | −20 | +140 | Ring proximal interphalangeal |
| pinky_abd | −40 | +40 | Pinky abduction / adduction |
| pinky_mcp | −20 | +120 | Pinky metacarpophalangeal |
| pinky_pip | −20 | +140 | Pinky proximal interphalangeal |
| wrist | −60 | +60 | Wrist flexion / extension |
Motor-to-Joint Map
| Motor ID | Joint | Finger / Group |
|---|---|---|
| 1 | ring_mcp | Ring finger |
| 2 | middle_abd | Middle finger |
| 3 | pinky_mcp | Pinky finger |
| 4 | pinky_pip | Pinky finger |
| 5 | index_mcp | Index finger |
| 6 | middle_mcp | Middle finger |
| 7 | thumb_dip | Thumb |
| 8 | thumb_mcp | Thumb |
| 9 | ring_pip | Ring finger |
| 10 | pinky_abd | Pinky finger |
| 11 | ring_abd | Ring finger |
| 12 | index_abd | Index finger |
| 13 | thumb_abd | Thumb |
| 14 | thumb_pip | Thumb |
| 15 | index_pip | Index finger |
| 16 | middle_pip | Middle finger |
| 17 | wrist | Wrist |
Control & Communication
| Baudrate | 3,000,000 bps (3 Mbps) |
| Protocol | Dynamixel (Feetech compatible) |
| USB port (Linux) | /dev/ttyUSB0 |
| USB port (macOS) | /dev/tty.usbserial-FT4TFV01 |
| Control mode | current_based_position (default) |
| Max current | 500 (raw unit) |
| Calibration current | 450 (raw unit, low-force homing) |
| SDK | orca_core — Python, installed via Poetry or pip |
| Python requirement | Python 3.9+ |
| Calibration file | models/orcahand_v1/calibration.yaml (auto-saved) |
Simulation (MuJoCo)
| Format | MuJoCo MJCF (orcahand_description repo) |
| Single-hand models | orcahand_left.xml, orcahand_right.xml |
| Bimanual scene | scene_combined.xml (left + right mounted together) |
| Extended variant | orcahand_*_extended.xml — camera mount, U2D2, inertial bodies |
| Mesh assets | Visual STL + simplified collision meshes in meshes/ |
Build & License
| Origin | Orcahand Team |
| License | MIT |
| Website | orcahand.com |
| Design files & docs | docs.orcahand.com |
| SDK source | github.com/orcahand/orca_core |
| MJCF models | github.com/orcahand/orcahand_description |