Features
Move the leader arm by hand — the follower mirrors every motion in real time.
Six degrees of freedom per arm for reaching, rotating, and stacking tasks.
Plug in any USB webcam and train vision-based pick-and-place policies.
Python-first SDK — record demonstrations, train policies, and replay them.
Fully open-source, 3D-printable design. Build it, remix it, share it.
Connects over USB-serial. No proprietary dongle, no cloud lock-in.
Specifications
- Reach
- ~45 cm
- Weight
- ~1.1 kg per arm
- Degrees of freedom
- 6 per arm
- Servos
- 6x Feetech STS3215 smart serial
- Payload
- ~250 g at full reach
- Gripper
- Parallel-jaw, interchangeable
- Materials
- 3D-printed frame + machined brackets
- Connectivity
- USB-C (serial)
Specifications are approximate and may vary by build — confirm against the latest LeRobot hardware documentation.
In the box
Getting started
Secure the base of each arm to your desk clamp or the included mounting plate.
Plug both the leader and follower arms into your computer via USB-C.
Run the one-time calibration script so each servo's zero position is registered.
Launch the LeRobot teleoperate script, move the leader, and watch the follower mirror it live.
Want to train your own policies?
Learn how to record demonstrations, train imitation-learning policies with LeRobot, and deploy them back onto the arm.
Go to Training GuideFAQ
How long does assembly usually take?
Most builders finish assembling both arms in 3-4 hours once parts are printed. Printing the parts takes longer than the assembly itself.
Are any of the assembly steps difficult?
The trickiest part is threading and tensioning the servo horns evenly so both arms move smoothly — everything else is standard screwdriver work.
Do I need a 3D printer?
No — SO-101 is available as a pre-printed kit, or as STL files if you'd rather print the parts yourself.
My follower arm doesn't move when I move the leader. What should I check?
Confirm both arms are powered and connected via USB, then re-run the calibration script — an uncalibrated servo is the most common cause.
Do I have to calibrate every time I power on?
No, calibration is saved to a config file on your computer. You only need to recalibrate if a servo horn slips or you swap a motor.
Can I use my own camera?
Yes — any USB webcam works. Vision-based tasks in LeRobot expect a standard video stream, no proprietary hardware required.
Is the hardware open source?
Yes. SO-101's STL files, bill of materials, and firmware are fully open source, maintained by TheRobotStudio and the Hugging Face LeRobot community.
Where can I get help if I get stuck?
Check the LeRobot documentation and join the Hugging Face Discord — the community is active and quick to help with build and calibration issues.
Bring the SO-101 Arm home.
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