DOBOT CR Series Automatic Calibration

This topic introduces the process of automatic calibration via Standard Interface communication between the DOBOT CR Series robot and Mech-Mind Vision System.

Preparation before Calibration

Make preparation before calibration according to the camera mounting method.

Pre-calibration Configuration

  1. Open Mech-Vision, and click the Camera Calibration button in the toolbar. The Configuration before Calibration window will be prompted.

  2. Confirm that the checks are performed, click I’ve finished all checks, and then click Next.

  3. In the Select how to calibrate window, select the New calibration radio button, and then click the Next button.

  4. In the Select calibration task window, select Hand-eye calibration for listed robot from the drop-down list box, click the Select robot model button to select the robot model used by the project, and then click the Next button.

  5. In the Select camera setup window, select the camera mounting method in this project, and then click the Next button.

  6. In the Calibration method and robot control window, select Automatic and Standard Interface, and then click the Calibrate button to go to the Calibration window.

Calibration Procedure

Conduct calibration according to the camera mounting method.

Precautions

  • When you proceed to the third calibration step (connecting the robot) and you click Start interface service button in the Connect the robot window, the button will change to Waiting for the robot to connect.... If the interface service is already started, you do not need to perform this operation.

  • When the button displays Waiting for the robot to connect..., perform the following steps on the robot side. Then, continue the calibration in the software.

1. Teach Calibration Start Point

  1. In the Control interface of DobotStudio Pro, select the Jog mode to move the robot to a proper calibration start position. Set User Frame to 0 and Tool Frame to 0.

  2. In the Points interface of DobotStudio Pro, click Add (⑦) to record the current position of the robot.

    record start position
  3. Return to the script programming interface of DobotStudio Pro, find the mm_auto_calib function in the global.lua file, and then modify the parameter values of P1 in the Go command to the values of the recorded current position.

    modify calibration program

2. Run Calibration Program

  1. Call the mm_auto_calib() function in the src0.lua file and click Start to run the calibration program.

    run calibration program
  2. When, in the Configuration window in Mech-Vision, the current status changes to connected and the button Waiting for the robot to connect changes to Disconnect robot, click Next. Next, proceed to the fourth step of the calibration process (i.e. setting the movement path).

    start calilbration1

Change the Extrinsic Parameter File

If the camera’s extrinsic parameter file has been used by a Mech-Vision project, you need to change the extrinsic parameter file used by the Mech-Vision project to a new one after you finish the hand-eye calibration.

  1. Select the Capture Images from Camera Step.

    change calibration parameter group
  2. In the Step Parameters panel, click change calibration parameter group icon of the Calibration Parameter Group parameter, and select the newly calibrated extrinsic parameter file.

Calibration-Related Status Codes

During automatic calibration via Standard Interface communication, the vision system returns data together with the status code to the robot. Status codes, which are categorized into error codes and normal status codes, indicate the command execution status. Calibration related status codes are listed in the tables below.

Error codes

Error code Description

Calibration: Parameter error

Calibration: No calibration flange pose provided from Mech-Vision

Calibration: No calibration joint angles provided from Mech-Vision

Calibration: Robot failed to reach calibration point

Normal status codes

Normal status code Description

7100

Calibration: Robot moved to the calibration point successfully

7101

Calibration: Pose received from Mech-Vision successfully

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