Document version: 1.2

Valid for: MiR100, MiR200, MiR500, MiR1000, MiR Hook 100, and MiR Hook 200 with D435 3D cameras

Valid for software version: N/A

Valid for hardware version: N/A

This guide describes how to calibrate a D435 3D camera—see Camera type to check if your robot has a D435 3D camera. If a 3D camera either detects nonexistent objects or fails to detect objects, it is possible that the camera needs to be calibrated. If you have a robot with two cameras, you may need to calibrate both.

Things you will need

• USB cable that supports USB 3.0 (you can also use the one inside the robot)

• A computer with:

  • USB 3.0 port

  • Intel Dynamic calibration tool installed

  • Intel Realsense Viewer program installed

• A smartphone with Intel’s Dynamic Target tool app

Before calibrating the camera

Before calibrating the camera, you need to first check if your robot has a D435 3D camera, see Camera type, and then the following (explained in depth in the following sections):

• The camera is able to detect objects

• Data frequency is around 15 Hz

• Camera output and depth quality are acceptable

If any of the above are not satisfactory, you need to calibrate the camera.

Lastly, you should create a backup of your current calibration before calibrating the camera—see Create backup.

Camera type

To check which camera type your robot is using, go to System > Settings > 3D cameras in the robot interface. Under Floor camera type, the camera type is displayed.

Obstacle detection

Hold an obstacle in front of the robot above the scanners' plane of view (200 mm from the ground). Check in the robot interface whether the object appears on the active map as a purple cloud. If the cloud does not accurately represent where the object is relative to the robot, the camera must be calibrated.

The 3D cameras used in MiR robots are not always reliable at detecting objects that are smooth and transparent, have repeating structures, or are highly reflective. Do not use any object matching these descriptions when testing the 3D camera.

Data frequency

In the robot interface, go to Monitoring > Hardware health > Sensors > 3D camera. Check if the Data frequency is around 15 Hz. If it is below or occasionally dips below 12 Hz, it is likely that the camera is losing frames due to poor calibration.

Camera output and depth quality

To check the camera output and depth quality, follow these steps:

1. Turn off the robot, and switch the Battery disconnect switch to Off.

2. Remove the necessary covers or hatches to access the 3D cameras. Refer to your robot's user guide or operating guide for help gaining access to the 3D cameras.

     

3. Connect one of the 3D cameras to your computer using a USB 3.0 cable. For the camera to communicate with the robot, it is important that the cable supports data transfer, and that it is plugged into a USB 3.0 port. These ports can be identified by the following symbol .

   You can use the cable that connects the camera to the robot computer. Unplug the cable from the robot computer, and plug it into the USB 3.0 port on your computer.

    

4. Launch the Realsense Viewer program, and check the camera output for flickering data or large areas of missing data. The following images are examples of output from a well-calibrated camera and a poorly calibrated camera. The data that indicates a poor calibration is circled.
   

   Good calibration	Poor calibration

5. The Realsense Viewer program includes a Depth quality tool that can be used to evaluate how well the camera determines depth. To use the tool, follow these steps:

   1. Place the camera approximately two meters from a large flat surface, and measure the distance between the camera and surface as accurately as possible.

   2. Launch the Depth quality tool.

   3. Enable Ground truth, and enter the exact distance between the camera and the flat surface in the displayed text field.

   4. Read the error under Z Accuracy. If it is larger than 2%, the camera needs to be calibrated.
      

Create backup

To create a backup of the current camera calibration, follow these steps:

1. Open Command prompt, and run the following command:

   Intel.Realsense.CustomRW -r -f cam_calib.xml

   The camera calibration is now saved in the cam_calib.xml file.

2. To restore the camera calibration you just saved, run the command:

   Intel.Realsense.CustomRW -w -f cam_calib.xml
   

Calibrating the camera

The calibration takes approximately 45 minutes.

1. Launch the Intel Dynamic calibration tool. When the program starts, you can verify that it has connected to the camera device in the menu to the left.

   If you want to see a demonstration of the calibration process, select Show demo, and a short video will play. We recommend watching this video to make sure you calibrate the camera correctly.

   

2. Select Start Calibration. The message Preparing camera... is displayed.

3. Start the Dynamic Target tool on your phone, and follow the instructions on the screen. In the following steps you will be facing the screen of your phone towards the camera while your phone displays a calibration pattern.

4. Make sure you face the screen of your phone so the calibration pattern is vertical, not horizontal.

   

5. Complete the first calibration by attempting to clear all the blue squares from the screen.

   

6. Complete the second calibration by moving the phone around until the green progress bar on the bottom has reached the end of the screen. The blue rectangles show where the calibration tool has registered the calibration pattern.

   

7. Complete the third calibration by moving the phone around until the green progress bar on the bottom has reached the end of the screen. Once you have completed this step, the camera is finished calibrating.

   

8. Unplug the camera from your computer, and reassemble the robot. This includes plugging the robot's USB cable into the 3D camera, reattaching any covers or hatches removed to access the camera, reconnecting the battery, and turning on the robot.