DigiArm Prosthetic Hand
A low-cost, lightweight 3D-printed anthropomorphic prosthetic hand with enhanced dexterity for typing on keyboards and pianos.
- Other
- Open source
- arduino
- 3D printable
Suggested by Robotheca, created by @deanzadok (opens in a new tab), from github.com/deanzadok/digiarm (opens in a new tab). Pinned to commit d16fdb5 (opens in a new tab).
- Hardware license
- Apache-2.0 (opens in a new tab)
- Software license
- Apache-2.0 (opens in a new tab)
- Commercial use
- Allowed
Photo and 3D model
3D preview converted from github.com/deanzadok/digiarm at d16fdb5, under Apache-2.0. View the original files from GitHub (7.7 MB) (opens in a new tab)
- Weight
- 648 g
What it can do
Written by Robotheca from the project's documents.
- Four independently actuated fingers driven by cable mechanisms with underactuated gear linkage
- Active thumb with a single degree of freedom for pressing and grasping
- Manual splay mechanism for finger spacing across five discrete positions, adjusted by hand without a motor
- Dual-axis wrist providing ulnar/radial deviation and pronation/supination
- Seven degrees of freedom in total, controlled through an ESP32 and Teensy 4.1 wireless controller
- Designed for typing on keyboards or piano and general object manipulation
Bill of materials
12 parts12 of 12 parts shown
| # | Component | Quantity | Est. price | Supplier |
|---|---|---|---|---|
| 1 | Micro metal gear DC motor with encoder | 4 | – | – |
| 2 | Micro metal gear DC motor with encoder | 1 | – | – |
| 3 | Micro metal gear DC motor with encoder | 1 | – | – |
| 4 | Micro metal gear DC motor with encoder | 1 | – | – |
| 5 | 6-pin cable for micro metal gear motors | 5 | – | – |
| 6 | 6-pin cable for micro metal gear motors | 2 | – | – |
| 7 | ESP32 development board | 2 | – | – |
| 8 | Teensy 4.1 | 1 | – | – |
| 9 | 74HC154DW 4-to-16 line decoder | 1 | – | – |
| 10 | 3.7V rechargeable Li-ion batteries | 2 | – | – |
| 11 | 6-pin motor connectors | 7 | – | – |
| 12 | DC motor driver | 7 | – | – |
12 of 12 parts have no price in the source, so there is no parts total. Read from README.md at the pinned commit.
Build guide
The guide appears here as you scroll.
Guide by @deanzadok (README.md), under Apache-2.0.
More guides
Wiring and electronics
Notes written by Robotheca from the project's documents.
Main parts
- Seven micro metal gear DC motors with encoders: four 1:75 for fingers, 1:100 for thumb, 1:100 for wrist deviation, 1:210 for wrist rotation
- Two ESP32 development boards: one on the hand receiving commands via ESP-NOW, one as external transmitter
- Teensy 4.1 as main motor controller performing closed-loop position control with SPI encoders and PWM
- 74HC154DW 4-to-16 line decoder as SPI multiplexer selecting between seven encoders
- Seven DC motor drivers, one per motor
- Two 3.7V rechargeable Li-ion batteries providing 7.4V total
Connections
- Each motor uses a 6-pin connector carrying PWM, direction, and encoder signals
- Motor cables are 25 cm for fingers and thumb and 16 cm for wrist motors in the authors' setup
- Motors must not receive more than 6V, as higher input can burn them out
- The decoder multiplexes SPI so the Teensy reads seven encoders over shared lines
- Finger motor wiring is routed through the bridge and wrist sleeve to the controller
Cables and connectors
From the parts list.
- 6-pin cable for micro metal gear motors × 5
- 6-pin cable for micro metal gear motors × 2
- 6-pin motor connectors × 7