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. You may refer to the links below.

Pre-calibration Configuration

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

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

  3. 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.

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

  5. In the Calibration method and robot control window, select Automatic and Standard Interface, and then click the Next button.

  6. In the Communication mode window, keep the default value of Protocol. Click the Start interface service button in the Connect the robot area, and the message on this button will change to Waiting for the robot to connect....

    • The port number for the Host IP address parameter is 50000 by default. If the port number determined in the communication solution is not 50000, please change it as required.

    • After finishing the previous steps, do not close the Configuration before Calibration window.

    wait for robot connection

Teach Calibration Start Point

Record 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

Modify Calibration Program

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

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 before Calibration window in Mech-Vision, the current status changes to Connected and the button Waiting for the robot to connect…​ changes to Disconnect robot in the Connect the robot section, click Calibrate. The calibration window will be prompted.

    start calilbration1

    If the robot is connected successfully, the Console tab of Mech-Vision Log panel will display a log.

    start calilbration2

Calibration Procedure

Conduct calibration according to the camera mounting method. You may refer to the links below.

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 Camera Calibration Parameters 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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