Robot-Camera Calibration Tool

Robot-Camera Calibration Tool, version: 0.8 beta

Robot-Camera Calibration Tool is used to find the transformation between the camera (PhoXi 3D Scanner) and robot coordinate spaces. Computed matrix transforms points from camera coordinate system to robot coordinate system.

You need a licensed USB Dongle to run the application.

Calibration process

Preparation

1. Mount robot and camera so as their mutual position is fixed.
2. Get calibration ball. This might be a table tennis ball or a bearing ball. (When using bearing ball make sure it is not too shiny so the scanner can locate it with high accuracy.)
3. Put the calibration ball into the robot's gripper at the gripping point.
4. Start PhoXi Control Application.
5. Plug in your licensed USB Dongle.
6. Start Robot-Camera Calibration Tool, select desired 3D PhoXi Scanner and hit Connect button.
7. Set the radius of calibration ball in the application. This value is used for locating the calibration ball in captured 3D scans.

Collecting calibration points

1. Move the gripper with the ball in front of the camera.
   • Choose a representative location, e.g. when calibrating for bin-picking application, the locations should cover the area where desired objects will be picked.
2. Type the position of calibration ball in robot coordinate system into the application.
   • Tip: If you use a program to position the robot, it is useful to save all planned positions into a file and load it into calibrations table. Values in a row should be separated by white space, each row on the new line.
3. Type the rotation of gripper into the application [optional].
   • This step is not necessary, but might improve the calibration accuracy. When the ball is not exactly at the gripping point, the actual position of calibration ball slightly differs from the position reported by the robot. This error can be eliminated knowing the gripper rotation.
   • Pick the right rotation formalism from the rotation combo box. This format is used for all points at the time of matrix computation.
4. Use Capture button to trigger new scan and locate the calibration ball.
5. Repeat until sufficient number of calibration points are collected. The minimum is 4 points.

Computation

1. Hit Compute button.
2. The output console shows the process of computation.
3. Computed matrix is displayed in the table. Save it to a file for later use.
4. To see the result of applying the transformation on camera point, hit Test button. This will trigger new scan, locate calibration ball and transforms its position into robot coordinates. The output is shown in output console.