Teach a £100 robot arm a task by showing it (Hugging Face LeRobot)
Move a leader arm with your hand while a second arm copies you and a webcam watches. Do that 50 times, train for a few hours on a rented GPU, and the arm picks up the cube on its own. It runs on the open-source SO-101 arm and LeRobot 0.6.1, with about £195 of parts for the pair plus printed parts and a webcam.
- An ACT policy trained on a rented GPU, then run on the arm to do the task by itself
- A kit: parts list, a command sheet for every stage, the GPU training script and a demonstration checklist
- SO-101 parts for two arms: 12 Feetech STS3215 servos, 2 driver boards, 2 power supplies (about £195 at the official bill of materials), or a ready kit
- The printed parts: your own 3D printer, or a kit that includes them
- A USB webcam (around £20 to £30) and a desk you can clamp to
- A computer with Python 3.12 (Linux or macOS is smoothest; Windows works with conda)
- A few hours of rented GPU time: Rent a cloud GPU
How imitation learning works, and what to buy
Understand the loop (show, record, train, run) and get the right parts first time.
Imitation learning in one paragraphYou demonstrate a task by moving the leader arm. The follower arm copies it, and LeRobot records, 30 times a second, what the camera sees, where every joint is, and what you told the arm to do. A policy called ACT (Action Chunking with Transformers) learns to map "what the camera sees plus where the joints are" to "the next second of movements". Run it, and the arm repeats the task from what it sees, even with the object in a slightly different place.
The armThe SO-101 is an open-source design by The Robot Studio and Hugging Face. Each arm has six Feetech STS3215 serial bus servos and a small driver board. The follower uses six identical 1/345 geared servos. The leader uses a mix of gear ratios (1/191, 1/345 and 1/147) so it's light to move by hand. Use the leader-specific servos, or the leader will fight you.
- Build it yourself: the official bill of materials ↗ totals about €226 for both arms (about €124 for a single follower), plus the 3D printed parts from the same repo. That's roughly £100 an arm in parts.
- Buy a kit: Seeed Studio, WowRobo and others sell parts kits with printed parts, or fully assembled arms, for more money and less time. The repo's Kits section lists current sellers.
- Camera: a USB webcam that does 640x480 at 30 frames a second. A second camera (wrist or top-down) helps once the first task works.
- Power: the 7.4V servos run from the 5V supplies in the bill of materials. Only the 12V follower servo option needs a 12V 5A supply.
The parts list, the command sheet and the training script are in the kit: Download the kit.
If it breaksCan I use SO-100 parts?
Can I use SO-100 parts?
so100_follower), so stick to SO-101 if you're buying new.