Universal Robots CB3 Kinematic Calibration Manual
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Universal Robots CB3 Kinematic Calibration Manual

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Kinematic Calibration Manual for CB3
Copyright c 2009–2020 by Universal Robots A S
Version 3.13

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Summary of Contents for Universal Robots CB3

  • Page 1 Kinematic Calibration Manual for CB3 Copyright c 2009–2020 by Universal Robots A S Version 3.13...

  • Page 2: Table Of Contents

    Contents 1 Plate Calibration 2 Dual Robot Calibration 2.1 Required Equipment ............2.2 Mounting the Robots to the Calibration Horse .

  • Page 3: Plate Calibration

    1. Plate Calibration 1 Plate Calibration NOTE: Plate Calibration will not be available in versions of the Calibration Manual after and including Version 3.10...

  • Page 4: Dual Robot Calibration

    The method requires a Dual Robot Calibration kit from Universal Robots (purchase number: 185500) and one pair of UR3, UR5 or UR10 robots, respectively, with a CB3 control box. The robot bases are connected with the Calibration Horse and the robot tools are connected by the Tool Connector, see Figure 2.1. This creates a closed chain where the distance between the bases and the tools are fixed to known distances.

  • Page 5: Required Equipment

    The method requires a Dual Robot Calibration Kit from Universal Robots (purchase number: 185500) and one pair of UR3, UR5 or UR10 robots with control box CB3. The robot bases are connected with a device and the robot tools are connected by a device (Appendix A). This creates a closed chain where the distance between the bases and the tools are fixed to known distances.

  • Page 6: Mounting The Robots To The Calibration Horse

    2. Dual Robot Calibration 2.2 Mounting the Robots to the Calibration Horse (1) Mount the Calibration Horse to a stand of a height of at least 0.5 m and mount the robots to the Calibration Horse, as in Figure 2.3. (2) Mount two robots of the same type and version on the Calibration Horse, see Figure 2.3.

  • Page 7: Safety Settings Of The Robots

    2. Dual Robot Calibration Figure 2.6: Select Kinematics Calibration in Expert Mode. This takes you to the Calibration screen. It also enables a new button called "Calibrate robot" on the "Welcome screen", should you need to return to the Calibration screen at a later time. Clicking the "Kinematics Calibration"...

  • Page 8: Network Connection Between The Robots

    2. Dual Robot Calibration Figure 2.8: Safety settings 2.5 Network Connection Between the Robots The Dual Robot Calibration screen appears as shown in Figure 2.9. There are a number of options to choose from within connection types which are described below: Master - the robot acts as master of the calibration process.

  • Page 9: Master Slave Connection

    2. Dual Robot Calibration (7) Use either the master slave or manual connection method to establishment network connection between the two robots controllers. Note: Robot 1 is the master robot and Robot 2 is the slave. 2.5.1 Master Slave Connection A Master Slave connection works by connecting two robots via a network cable or over a network switch.

  • Page 10: Before Starting

    2. Dual Robot Calibration Figure 2.13: Manual enter IP address 2.6 Before starting The steps through the calibration are by default done automatically, unless it needs help from an operator. This can be disabled by the Auto step checkbox, see Figure 2.14. Figure 2.14: Calibration options Furthermore, It is optional to save and correct the home position of each robot, which can be relevant if only one of the robots need to be calibrated.

  • Page 11: Mounting The Ur Dual Robot Calibration Connector

    2. Dual Robot Calibration 2.7 Mounting the UR Dual Robot Calibration Connector The robots are now ready to be physically connected if the robots are in their home position, see Figure 2.15. (11) Ensure that the robots are in the Home position. (12) Continue the procedure by pressing Connect Robots, see 2.16.
  • Page 12 2. Dual Robot Calibration (13) Attach the tool connector to the master robot (Robot 1) as in Figure 2.19. (14) When the tool is mounted on the master robot (Robot 1), Press Proceed in the pop-up Figure 2.20. (15) The slave robot (Robot 2) now enters free drive mode. Move the slave towards the connector and attach the screws with washers.

  • Page 13: Measuring Positions And Calibration Statistics

    2. Dual Robot Calibration 2.8 Measuring Positions and Calibration Statistics After step no.: 16, the robot will begin measure and identify the calibration. First a number of initial measure- ments are collected. A preliminary calibration is calculated from those. Second, the final set of measurements will be done and the final calibration will be calculated, see Figure 2.23 and 2.24.

  • Page 14: Applying The Calibration

    2. Dual Robot Calibration Mean deviation: The average deviation in millimeters and in milliradians between the positions mea- sured by the first and second robot Standard deviation: The standard deviation calculated on basis of the above Max deviation: The maximal measured deviation Expected results The calibration is passed successfully if: Mean deviation will be less than 1 mm and 2 mrad...
  • Page 15 2. Dual Robot Calibration (b) Verify that the 3.5 mm No Go tool can not pass in-beween the two robot’s tool flanges (Figure A.4, Appendix A) (20) If the verification is successful in step no. 19, Proceed to the next validation step, see Figure 2.31. Figure 2.29: Proceed to the Verification procedure Figure 2.28: Robots ready for the validation procee- dure...

  • Page 16: Reset Calibration

    2. Dual Robot Calibration Figure 2.34: Kinematic Calibration is done 2.9.2 Reset Calibration The calibration can manually be adjusted or reset by editing the root .urcontrol calibration.conf file placed together with the other configurations. To reset the calibration all decimal and hex numbers is reset to zero like in Listing ?? in page ??.

  • Page 17: Program Correction By Key-Waypoints

    3. Program Correction by Key-waypoints 3 Program Correction by Key-waypoints This tutorial describes how to perform an automatic program correction of key-waypoints, so that a program can be moved from an uncalibrated robot to another and still work. The technique can also be used to make programs work after e.g.

  • Page 18: Accessing The Functionality

    3. Program Correction by Key-waypoints 3.2 Accessing the Functionality The starting point for the tutorial steps is as follows: (1) From Expert Mode on the controller screen enable calibration by toggling the "Kinematics Calibration" button. Figure 3.2: Select "Kinematics Calibration" in Expert Mode to enable the calibration functionality. (2) This takes you to the Calibration screen.

  • Page 19: Redefine Key-Waypoints

    3. Program Correction by Key-waypoints 3.3 Redefine Key-waypoints The program used in this tutorial is a simple pick and place program with two key-waypoints, the waypoint for the pick and place positions. (4) The chosen program can now be loaded by pressing "Load Program": Figure 3.4: Press "Load Program"...

  • Page 20: Corresponding Tool Position

    3. Program Correction by Key-waypoints Figure 3.6: Press "Change this waypoint" to redefine the configuration for this waypoint. (7) This leads to the "Move" tab. Move the robot to the new position and press "OK". 3.3.1 Corresponding Tool Position To help the method, it is important to adjust the Corresponding Tool Position (CTP) which is the offset from the endpoint of the robot with or without e.g.

  • Page 21: Waypoints From Multiple Programs

    3. Program Correction by Key-waypoints Figure 3.8: Change the CTP coordinates and press OK (10) This completes redefining the "pick" key-waypoints. In the program three, the reteached waypoint is no longer displayed in italics and the icon is now the one for a defined waypoint. Continue by repeating step 5 to 9 until all key-waypoints are redefined.

  • Page 22: Correcting A Program

    3. Program Correction by Key-waypoints Each key-waypoint is marked with its name and the program it is coming from as shown in Figure 3.10 and 3.11. It is possible to delete key-waypoints from the model by selecting a waypoint or a group of waypoints and press "Delete".
  • Page 23 3. Program Correction by Key-waypoints Figure 3.12: Load the program which is going to be corrected (14) Another popup tells when the correction is done. As the correction can take some time, please be patient. If the correction failed, please verify your key-waypoints and improve their accuracy. (15) After the program is corrected and before saving, it is recommended that: it is tested by letting the robot move through its waypoints, by playing the program or by selecting waypoints individually and using the "Move robot here"...
  • Page 24 3. Program Correction by Key-waypoints...

  • Page 25: Appendices

    A. Dual Robot Tools A Dual Robot Tools Cable Figure A.1: A sketch of the Dual Robot Calibration Horse Figure A.2: A sketch of the Dual Robot Calibration Tool Connector Figure A.3: Go tool used in the validating procedure (1.5 mm thickness) Figure A.4: No Go tool used in the validating procedure (3.5 mm thickness)

  • Page 26: B Robot Dh Parameter

    B. Robot DH Parameter B Robot DH Parameter The robots kinematic transformations for each link are given by Denavite-Hartenberg(DH) parameters. B.1 UR3 r a d r a d Joint 1: 0.118 Joint 2: 0.2437 Joint 3: 0.2133 Joint 4: 0.1124 Joint 5: 0.0854 Joint 6:...

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