Calibration Topic

1. Importance

Calibration is critical for the Huenit robotic arm to ensure consistent pen pressure and accurate drawing within the 125mm x 125mm area. Without calibration, the pen may drag or fail to reach the paper.

2. Process

• Tool: huenit_draw.py calibrate
• Steps:

1. Manually jog the arm to the home position.
2. The arm touches several points on the surface to determine the plane and tilt.
3. The Z-height for pen-up (Z_UP=6.0mm) and pen-down is established.

• Output: Writes calibration.json which is consumed by all hardware control scripts.

3. Operations

Calibration must be run after every physical restart of the arm. It is triggered by the operator using a desktop shortcut: Calibrate Robot Ross.command.

4. Notes and Open Points

• Surface Leveling: Software calibration can compensate for some tilt (TILT_SLOPE), but physical documentation emphasizes that the table should be as level as possible. The limit of software-based tilt compensation is not explicitly documented.
• Auto-Calibration: There is no mention of a "re-calibration" trigger during long-running sessions, which might be necessary if the arm drifts or the surface shifts.

Sources:

• ~/.openclaw/workspace/skills/huenit/huenit_draw.py
• AGENTS/CONTEXT/robot_ross_artist.md