Welcome to DOFBOT-Ultra repository

Calibration Offset (Depth Camera)

Please confirm that the currently selected camera is DABAI_DCW2.

Make sure the calibration board is flat. Even slight unevenness may cause a calibration error of more than 10 mm.

1. Preparation Before Calibration

1. Ensure the robotic arm and depth camera are properly connected.
2. Place the AprilTag calibration board on the table.
3. Prepare a 30 mm high wood block with an AprilTag (used for the second stage: plane/height calibration).
4. Do not move the robotic arm body during calibration; only move the Tag or the Tag on the spacer block.

Placeholder image:

2. Start the Calibration Wizard

Run the following command in the terminal:

ros2 run dofbot_ultra_driver calibration_wizard

The program will display a menu:

1. Vision & Plane Calibration
2. Mechanical Bias & Height Comp Tuning
3. Run Grasp Test Q. Quit

This tutorial covers depth camera offset calibration. Please select 1.

3. Step 1: Center Point Offset Calibration (X/Y)

After entering vision calibration, the calibration window (Rotation Calibration) will open.

Follow the on-screen instructions:

1. Place the Tag flat on the table reference position (the interface will show Place Tag flat on table at X=18.1cm).
2. Ensure the Tag is stably recognized in the frame.
3. Press the SPACEBAR (or ENTER) to start sampling.

After this step, x_offset and y_offset in offset_value.yaml will be written or updated.

4. Step 2: Plane and Height Calibration (Slope/Z)

This calibration addresses the issue of inconsistent height readings when the block moves across different positions on the screen.

Continue following the on-screen instructions:

1. Place the Tag on a 30 mm spacer block, or use a 30 mm high block with an AprilTag on its surface. Place the block at different positions on the table.

   1. (It is recommended to place the first point at the AprilTag position on the calibration paper.) Press SPACEBAR to complete one sample.
   2. Ensure there is only one AprilTag in the frame during each sample.

2. Collect points at different positions on the table. Press SPACE at each new position.

3. After collecting at least 3 points, press ENTER (or C) to calculate and save the result.

This step will update the following configurations:

• planar_correction.yaml (slope correction)
• offset_value.yaml (updates z_offset, and may recalculate x_offset)
• arm_bias.yaml (updates z_comp_x, z_comp_z)

After calibration, the window will display completion and exit automatically.

5. Configuration File Locations

The program will automatically search and save configurations in the following directories (in order of existence):

Raspberry Pi paths:

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/home/yahboom/dofbot_ultra/src/core/dofbot_ultra_driver/config
/home/yahboom/dofbot_ultra/core/dofbot_ultra_driver/config
/home/yahboom/dofbot_ultra_ws/src/dofbot_ultra_driver/config

RDK X5 paths:

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/home/sunrise/dofbot_ultra_ws/src/core/dofbot_ultra_driver/config

Common file example:

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x_offset: 0.0
y_offset: 0.0
z_offset: 0.0

6. Important Notes

1. Press ESC in the calibration window to exit the current calibration.
2. If the Tag is not recognized or the depth data is invalid during sampling, a failure prompt will appear. Adjust and retry.
3. Important: After calibration is complete, return to the main menu and select option 3 to test grasping. If there is still an offset, this offset is a fixed mechanical error and can be adjusted through option 2 in the main menu.

7. Grasp Test

Close the calibration program and run the grasp test to verify whether the calibration was successful.

Restart the calibration wizard program and select option 3 from the menu to enter the grasp test:

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ros2 run dofbot_ultra_driver calibration_wizard

Press the SPACEBAR to grasp. If the gripper can grasp the middle-lower part of the block, the calibration is successful.

You can also move the block to different positions and press SPACEBAR to test grasping.