SO-101 Teleop Arm

SO-101 is the current-generation open-source 6-DOF teleoperated robotic arm from The Robot Studio, designed in collaboration with Hugging Face's LeRobot project. It is the successor to the SO-100 and is one of the most widely built low-cost research arms in the world, used by hundreds of researchers and hobbyists as a platform for imitation learning, robot learning datasets, and end-to-end AI for manipulation.

The design is a leader/follower pair: the human operator back-drives the leader arm by hand, and the follower mirrors the motion to manipulate objects. Both arms share the same 6-DOF serial kinematic structure (base rotation, shoulder, elbow, wrist pitch, wrist roll, gripper) with one STS3215 smart servo per joint. The total bill of materials is under $120 per arm including the parallel-jaw gripper, making it dramatically more accessible than conventional research arms.

SO-101 improves on SO-100 with cleaner wiring channels, easier assembly (no gear disassembly required for installation), and updated motors on the leader arm for improved back-driveability. The design is fully parametric with print-orientation guides provided for both Ender and Prusa workflows. All CAD, STLs, firmware, and assembly instructions are Apache 2.0 licensed.

The arm plugs directly into the Hugging Face LeRobot library for data collection, policy training (ACT, diffusion policy, VQ-BeT), and rollout — you can record teleop demonstrations, train a neural policy, and run autonomous manipulation on the same hardware. This program exposes cloud-side endpoints for homing, gripper control, recorded trajectory replay, and a mirror-leader hook for live teleop relay.

Credit to The Robot Studio (therobotstudio.com) and the Hugging Face LeRobot team — upstream repository at https://github.com/TheRobotStudio/SO-ARM100 under Apache 2.0. Assembly guide at https://huggingface.co/docs/lerobot/so101.

Printing

The Print All set builds the complete leader + follower pair (print one of each file). The two arms share most parts but differ at the wrist/gripper — both variants are included on purpose:

Shared by both arms: Base_SO101, Base_motor_holder_SO101, Motor_holder_SO101_Base, Motor_holder_SO101_Wrist, Upper_arm_SO101, Under_arm_SO101, Rotation_Pitch_SO101, Wrist_Roll_Pitch_SO101.

Follower-only (the gripper): Wrist_Roll_Follower_SO101, Moving_Jaw_SO101.

Leader-only (the hand-drive handle): Wrist_Roll_SO101, Handle_SO101, Trigger_SO101.

Every arm uses one STS3215 smart servo per joint (6 per arm, 12 total). No optional or alternate parts — nothing to deselect.

Build Guide

Official SO-101 / SO-ARM100 assembly guide (covers both leader and follower): huggingface.co/docs/lerobot/so101