Calibrating SO-101 leader and follower arms for LeRobot

Define what calibration establishes

Leader-follower teleoperation depends on a consistent relationship between physical joint positions and the values sent through software. Calibration helps establish that relationship. It is different from camera calibration, tool-centre-point measurement or identifying a robot's dynamic model. Begin by writing which two physical arms will be paired and which software representation their demonstrations will use.

The official SO-101 guide describes calibration as aligning position values for comparable physical poses. Its broader suggestion of transfer between robots should be treated as a capability motivation, not a guarantee that a policy trained on one installation will work on another. Mounting, cameras, joint configuration, tooling and task geometry still affect observations and behaviour. The useful output here is a traceable joint mapping for the identified pair.

参考资料： SO-101 setup documentation at LeRobot v0.6.1

Review the setup before connection

Have the responsible competent person confirm assembly, secure mounting, wiring, communication hardware and a controlled workspace against the supplied equipment documentation. Arrange support for any component that can move when motor torque is disabled. The tagged follower implementation explicitly assumes a rest condition where disabling torque is safe; that assumption must be satisfied physically before the software is connected.

Identify the hazards of manual positioning, pinch points, unexpected motion and resets in the local procedure. Establish who can initiate a step and how the operation is stopped. HSE guidance supports competent planning and control of hazardous movement during equipment work, but it is not an SO-101-specific certification. No universal force, load or speed limit is supplied here. Do not improvise those limits from the size of a desktop arm.

参考资料： SO follower calibration implementation at LeRobot v0.6.1 · Maintenance of work equipment

Record arm and port identity

Give the leader and follower distinct persistent names, and associate each name with its physical label, controller connection and calibration record. A port path identifies the current communication route; it should not be treated as the equipment's permanent identity. Verify the route again after reconnection. An apparently sensible file associated with the wrong arm can create a confusing mismatch.

The tagged tutorial uses separate robot and teleoperator arguments and reuses the device id across later operations. Record the software release with those ids. If an arm has been repaired, rebuilt or reassigned, review whether its earlier calibration still describes it before selecting an existing file. Keep the previous record as evidence of the earlier configuration rather than silently relabelling it as current.

参考资料： SO-101 setup documentation at LeRobot v0.6.1 · Imitation learning tutorial at LeRobot v0.6.1 · SO leader calibration implementation at LeRobot v0.6.1

Follow the matching calibration prompts

In a prepared v0.6.1 environment, the documented follower invocation takes this form: lerobot-calibrate --robot.type=so101_follower --robot.port=YOUR_FOLLOWER_PORT --robot.id=YOUR_FOLLOWER_ID. The corresponding leader form is lerobot-calibrate --teleop.type=so101_leader --teleop.port=YOUR_LEADER_PORT --teleop.id=YOUR_LEADER_ID. Replace every uppercase placeholder with the verified value. These commands initiate a hardware procedure and are not offline diagnostics.

The tagged implementation establishes homing offsets from the prompted mid-range condition, records ranges for selected joints, and saves calibration information. It handles wrist_roll separately from the range-recording sweep. Follow the exact software prompts and equipment guidance; do not extrapolate a generic instruction to rotate every joint through arbitrary travel. Stop and investigate binding, unexpected movement or a prompt that does not match the selected hardware instead of forcing completion.

参考资料： SO-101 setup documentation at LeRobot v0.6.1 · SO follower calibration implementation at LeRobot v0.6.1 · SO leader calibration implementation at LeRobot v0.6.1

Verify joint meaning and scaling

Review the recorded joint names and position representation before comparing leader and follower traces. In the tagged SO implementations, body joints can use degree-based or normalised representations depending on configuration, while the gripper has its own normalised range. A number such as fifty therefore has no useful physical interpretation without the feature name and configured units.

Under the approved verification procedure, compare corresponding poses and small, controlled changes in one joint at a time. Record direction, offset, usable range and return behaviour. If a shoulder change appears under a wrist feature, investigate identity or mapping. If direction is wrong, stop the pairing test. Do not compensate for an unexplained mismatch by adding ad hoc offsets to a training dataset; that would preserve an unidentified hardware or configuration error.

参考资料： SO follower calibration implementation at LeRobot v0.6.1 · SO leader calibration implementation at LeRobot v0.6.1

Use a pose verification record

Choose a few non-contact poses relevant to the task and document how the competent person will reach and compare them. The table is an evidence template, not a movement sequence or a required travel range. Describe physical landmarks so another operator can recognise the intended pose, and record actual values rather than relying solely on photographs.

Worked hypothetical example: a pair appears aligned at a central pose, but the follower approaches its useful endpoint while the leader is still mid-travel. That observation suggests a range or representation problem worth isolating. It does not establish which arm is wrong. Compare configuration, calibration identity and recorded endpoints before collecting demonstrations. A dataset gathered now could consistently teach a distorted relationship, making later policy errors difficult to interpret.

参考资料： SO follower calibration implementation at LeRobot v0.6.1 · SO leader calibration implementation at LeRobot v0.6.1 · SO-101 setup documentation at LeRobot v0.6.1

Preserve calibration with demonstrations

Record the calibration file path reported by the procedure and preserve its contents with the equipment identity, date and software version. Include the verification observations and the person responsible for acceptance. Keep a copy with the collection session's configuration record so a later model review can identify which mapping produced its actions.

Treat a calibration change as a dataset provenance event. If a repaired arm requires recalibration, identify the last session using the old configuration and the first using the new one. Before pooling those recordings, compare their action and observation meanings explicitly. Similar numeric ranges do not establish equivalent physical poses. For a private simulation, document any mapping from physical demonstration coordinates into simulator actions as a separate transformation.

参考资料： Imitation learning tutorial at LeRobot v0.6.1 · LeRobotDataset v3.0 documentation at v0.6.1

Diagnose drift before releasing teleoperation

When previously accepted behaviour changes, check the physical and software identities first: arm, port, selected id, calibration file, representation and mechanical changes. Recalibrating immediately can hide the evidence needed to distinguish a loose assembly from a changed configuration. Preserve the symptom and previous record, then let the competent person decide which checks and corrective work are appropriate.

Release the pair for demonstration collection only after the intended task range and stop arrangements have been reviewed. Record the scope of acceptance, including any areas excluded from the task. Learning quality and operational safety remain separate decisions: matching joint values cannot show that a camera sees contact, a gripper holds the part or an autonomous policy will remain within approved conditions. Carry the calibration identity into the next stage so those investigations start from known equipment.

参考资料： SO-101 setup documentation at LeRobot v0.6.1 · Maintenance of work equipment

检查清单

• Identify the SO-101 leader, follower and LeRobot v0.6.1 environment.
• Have a competent person review support, mounting and controlled positioning.
• Verify each port against its physical arm and persistent id.
• Follow the matching prompts, including wrist-roll treatment.
• Check names, units, direction, offset and useful range.
• Preserve calibration files and pose-verification observations.
• Associate each demonstration session with its calibration revision.
• Investigate changed behaviour before replacing accepted calibration evidence.

常见问题