Calibration Procedure for ETH Calibration Using the TCP Touch Method

This section will guide you through the ETH calibration using the TCP touch method.

Calibration Preset

1. Open Mech-Vision, click the Camera Calibration (Standard) button. The Calibration Preset window will be prompted.

2. In the Please select calibration mode window, select the Start a new calibration process radio button, and then click the Next button.

   

3. In the Please select a calibration setup window, select the Eye to Hand radio button, and then click the Next button.

   

4. In the Select a method to add calibration points window, select the TCP touch radio button, and then click the Start calibration button.

   

Till now, the calibration preset work is completed and you will enter the calibration procedure.

Calibration Procedure

Note

The following part introduces the calibration steps by taking a connected robot as an example. If you use a special robot, please refer to Manual Calibration Procedure.

Connect to the Camera

1. In the Connect to Camera window, find the camera to connect in the Detected Cameras list, and click the Connect button.

   

2. After the camera is connected, click the Capture Live or Capture Once button.

   

3. In the right panel of the calibration interface, ensure that the captured image meets the calibration requirements and click the Next button.

   Note

   If the captured image does not meet the calibration requirements, you need to open the Mech-Eye Viewer software to adjust the 2D and 3D scanning parameters and re-capture images.

Mount the Calibration Board

1. In the Mount Calibration Board window, specify the calibration board type according to its model nameplate and click the Confirm button.

2. Make sure that the calibration board has been placed to the plane of the workobject, and then click the Confirm button.

3. Confirm that the calibration board is in the center of the camera’s field of view (the red rectangle in the 2D image), and then click the Confirm button.

4. After all operations are completed, click the Next button.

Check Camera Intrinsic Parameters

1. In the Check Camera Intrinsic Parameters window, click the Check Camera Intrinsic Parameters button.

2. Confirm the results of the camera intrinsic parameters check.

   • If the camera intrinsic parameters check passes, click the Next button.

   • If the camera intrinsic parameters check fails, adjust detecting parameters by drawing aid circles or manually adjusting the detecting parameters, and then click the Check Camera Intrinsic Parameters button again.

Generally, when the lighting conditions are good and the camera parameters are appropriate, the intrinsic parameter check will pass by simply keeping the default values. The following figure shows a successful detection of the feature points.

• Draw aid circle

To draw an aid circle, click the Start Drawing Aid Circle button, draw a circle coinciding with a circle in the calibration board. After that, the detecting parameters of the circles should change.

Tip

If the calibration circles are too small to be selected easily, the user could right click the 2D image, clear the Fit to Window check box, and select Normal Size. Start drawing aid circles after adjusting the size of the image.

• Manually adjust the detecting parameters

To manually adjust the detecting parameters, click Edit Detecting Parameters and change the values of detecting parameters accordingly.

• Adjust camera parameters

If the feature points are still not detected, please adjust the camera settings according to the on-site operating conditions. Detailed information can be found in Mech-Eye Viewer.

Set the TCP Value

Note

In order to accurately measure the pose of the calibration board in the robot base reference frame, it is necessary to obtain the position of TCP relative to the origin of flange (default direction) first.

• If the TCP value is known, in the the Set TCP Value window, select the Known TCP Value radio button, input the TCP value, and click the Confirm TCP values button.

  Note

  Make sure that the TCP value is set to 0 in the teach pendant when selecting the Known TCP Value radio button.

• If the TCP value is unknown, calculate the TCP value by referring to Calculate the TCP Value.

Calculate the TCP Value

1. In the the Set TCP Value window, select the Known TCP Value radio button, and then click the Calibrate TCP button.

   

2. Fix a sharp point in the robot work space. Use Mech-Viz or teach pendant to move the robot to touch this point from 4 different directions (namely 4 different poses). Click the Add Pose button every time the robot touches the point and the pose will be shown in the list.

   Tip

   If an error pose needs to be deleted, select the entry to delete, and click the Delete Pose button.

3. After adding 4 poses, click Calculate TCP to obtain the position of TCP. The TCP value will automatically filled and the the precision information will be prompted, as shown in the following figure.

   

4. After confirming that the TCP position is correct, click Confirm TCP Value, and then click the Next button.

Tip

Some robots, such as ABB, cannot be controlled by the teach pendant after connecting to Mech-Center. The solution is to disconnect the robot from Mech-Center, move robot to touch the sharp point with the teach pendant, click Add Pose, and manually input the pose which is shown on the teach pendant.

Add Marker-Images and Poses

1. Use Mech-Viz or teach pendant to move the robot touch P1, P2 and P3 on the calibration board. Everytime the robot touches a point, click Add Pose to add the pose into the list. After all three points are touched, the three poses will be shown in the Touch Poses Viewer, as shown in the following figure.

   

   The real TCP touch for ETH is shown in the following figure.

   

2. Move the robot to a pose where the camera could capture the entire calibration board. Click the Add Single Board Image And Record Pose button to make the camera take a photo and detect the circles on the calibration board.

3. Click the Next button, as shown in the following figure.

   

Attention

Make sure the calibration board is stationary in the whole process.

Calculate Camera Parameters

1. In the Calculate Camera Parameters window, click the Calculate Camera Parameters Results button to confirm and save the calibration data accordingly, as shown in the following figure.

   

2. Click the Display Point Cloud in Mech-Viz button.

   

3. Enter Mech-Viz, select the Robot tab. Click the Configure Robot button, and in the pop-up that appears, choose the correct robot type, as shown in the following figure.

   

4. In Mech-Viz, select the Scene tab, and adjust the ground height accordingly, as shown in the following figure.

   

5. In the simulation interface of Mech-Viz, confirm that the point cloud of the calibration board are qualified, as shown in the following figure.

   

6. Return to Mech-Vision, click the Save button to save the calibration results to a specified project’s directory.

(Conditional) Adjust Camera Parameters

Note

For 4-axis robots or other rotation-constrained robots, extrinsic parameters at Z axis cannot be calibrated and need to be modified manually.

In the Adjust Camera Parameters window, select the Adjust Z-axis Translation radio button, set the Z-axis Translation parameter and then click the Save button to save the calibration results to a specified project’s directory.

Alternatively, in the Adjust Camera Parameters window, select the Adjust All Extrinsic Parameters radio button, adjust extrinsic parameters, and then click the Save button to save the calibration results to a specified project’s directory.

Till now, the calibration procedure is completed.