3 · Connect and calibrate
Previous: 02 Install and runNext: 04 Teleoperation
Calibration records each joint's zero point and travel range. Do it once per arm; redo it after disassembly or if the calibration file is lost.
Before you start
- Both arms assembled, servos given their IDs.
- Both arms powered.
- One USB cable per arm, into two separate USB ports — a shared hub sometimes enumerates them unreliably.
Linux: serial permissions
sudo usermod -aG dialout $USERThen log out and back in. Without this, LeLab finds the arm but every read fails with a permission error. Windows and macOS need nothing.
Which arm is which
| Arm | LeRobot name | LeLab calls it |
|---|---|---|
| The one you move by hand | so101_leader | teleop |
| The one that follows | so101_follower | robot |
Calibrate the leader first. Mixing the two up is the usual reason a freshly calibrated arm behaves strangely.
The flow
Open the Calibration tab and work through one arm at a time:
- Pick the device — leader (teleop) or follower (robot).
- Pick the serial port. LeLab lists the USB serial devices it sees. To tell them apart, unplug one arm and see which entry disappears. The choice is remembered.
- Pick a calibration profile — an existing one, or a new one. The profile holds the saved zero positions; if this arm was calibrated before, reuse its profile.
- Follow the guided steps. LeLab walks through each joint in turn; move the joint to the position it asks for and confirm. No keyboard prompts.
- Repeat for the other arm — its own profile and port.
Each profile belongs to one physical arm. Swapping the two arms over means recalibrating.
Cameras
Cameras are configured on the same tab. Each camera's name (front, wrist, …) is the key the policy sees, so use names you will recognise in a training log.
Cameras can be mounted before or after calibration; calibration does not depend on them. Keep the binding stable — swapping which physical camera is called wrist between recording and inference makes a trained policy behave nonsensically.
Rotation
If a camera is mounted upside down or sideways, set its Rotation: 0°, 90°, 180° or 270° clockwise. An upside-down wrist camera is 180°.
Rotation is saved per camera and applied to the setup preview, the teleoperation preview, recorded frames and inference. Profiles without a rotation setting are treated as 0°.
- 90° and 270° swap the output dimensions. A 640 × 480 capture becomes 480 × 640.
- Checkpoint image dimensions do not reveal orientation. 0° and 180° produce identical dimensions but opposite images. Before inference, set the rotation used while recording — see page 6.
What gets saved
| File | Contents |
|---|---|
~/.cache/huggingface/lerobot/calibration/teleoperators/so101_leader/*.json | Leader profiles |
~/.cache/huggingface/lerobot/calibration/robots/so101_follower/*.json | Follower profiles |
~/.cache/huggingface/lerobot/ports/leader_port.txt | Leader serial port |
~/.cache/huggingface/lerobot/ports/follower_port.txt | Follower serial port |
These live under ~/.cache/, so cache-cleanup tools can delete them. If a calibrated arm asks to be calibrated again, check here — see Troubleshooting.
Next: 04 Teleoperation