Universal Robots CB3 Manual
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Universal Robots CB3 Manual

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Kinematic Calibration Manual for CB3
Copyright 2009 – 2014
Version 0.9.3

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Summary of Contents for Universal Robots CB3

  • Page 1 Kinematic Calibration Manual for CB3 Copyright 2009 – 2014 Version 0.9.3...

  • Page 2: Table Of Contents

    Contents 1 Plate Calibration 1.1 Required Equipment ............1.2 Accessing the Functionality .

  • Page 3: Plate Calibration

    1. Plate Calibration 1 Plate Calibration This user manual goes through the calibration method for the kinematics, implemented on the Universal Robots controller from software version 1.4. The manual is organised as a step by step tutorial. Figure 1.1: Robot mounted on a plate with holes to align the robot tool flange.

  • Page 4: Accessing The Functionality

    1. Plate Calibration 1.2 Accessing the Functionality The starting point for the steps of the tutorial is a screen that looks like Figure 1.2. The steps are as follows: (1) The functionality can be found in the Expert Mode on the controller screen by pressing the "Kinematics Calibration"...

  • Page 5: Measuring Positions

    1. Plate Calibration 1.3 Measuring Positions Multiple metal plates with a number of holes can be used. Add a plate to start adding positions. (3) Add the first plate for the positions. (4) Add the first position to the selected plate by pressing "Add new position". Figure 1.4: Add a plate for the hole positions.
  • Page 6 1. Plate Calibration Figure 1.8: Configuration need to be used.

  • Page 7: Calibration

    1. Plate Calibration 1.4 Calibration Now all the needed positions for the calibration are added to the tree. In this example 26 Positions on one plate are used. (11) Select the top of the tree item "Positions" on the left to be able to select the level of calibration, see Figure 1.9.

  • Page 8: Evaluation

    1. Plate Calibration 1.5 Evaluation (14) After the calibration has been performed the results needs to be evaluated to ensure that the calibration is successfully. The results from the calibration are the parameters displayed in the "Parameter overview" tab and the calculated statistics of the archived precision for the given positions.

  • Page 9: Calibration Statistics

    1. Plate Calibration 1.5.1 Calibration Statistics An example of the printed statistics: ############## 0.000292995 Measurement data[20] error: Mean: ] ( 0.000175164, 0.000134324, 0.00027655 ) rot[rad] ( 0.00348157 ) StdDev: ] ( 0.000218127, 0.000201774, 0.000344546 ) rot[rad] ( 0.00428109 ) Max: ] ( 0.000518104, 0.000596791, 0.000853992 ) rot[rad] ( 0.00936474 ) Q range: [ 10.3565, 2.10395, 4.97534, 4.41847, 6.28554, 0.478753 ] Evaluation data[6] error:...

  • Page 10: Reset Calibration

    1. Plate Calibration 1.6 Reset Calibration The kinematic calibration can be removed by deleting the root .urcontrol calibration.conf file, placed together with the other configurations. It can also be removed by manually replace all the decimal and hex numbers, in the configuration files, to zeros like in Listing 1.2.

  • Page 11: Dual Robot Calibration

    The method requires a pair of UR5 or UR10 robots with control box CB3. The bases are connected with the Calibration Horse and the 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 12: Required Equipment

    2.1 Required Equipment The method requires one pair of UR5 or UR10 robots with control box CB3. The bases are connected with a device (Figure 2.2) and the tools are connected by a device (Figure 2.3). This creates a closed chain where the distance between the bases and the tools are fixed to known distances.

  • Page 13: Mounting The Robots To The Base Calibration Tool

    2. Dual Robot Calibration 2.2 Mounting the Robots to the Base Calibration Tool (1) Mount the Calibration Horse to a robot stand of a height of at least 0.5 m and mount the robots to the base tool, as in Figure 2.5. (2) Mount two robots of same type and version on the Calibration Horse, see Figure 2.5.

  • Page 14: Accessing The Functionality

    2. Dual Robot Calibration 2.3 Accessing the Functionality The starting point for the method to select Kinematics Calibration in Expert Mode, see Figure 2.8. Secondly select Dual Robot Calibration, see Figure 2.9. Figure 2.8: Select Kinematics Calibration in Expert Figure 2.9: Select Dual Robot Calibration to select the Mode.

  • Page 15: Master Slave Connection

    2. Dual Robot Calibration 2.4.1 Master Slave Connection A Master Slave connection works by connecting two robots via a network cable or over a network switch. One robot have to be selected as master and the other as slave. Selecting one of these cases sets up the IP address automatically.

  • Page 16: Before Starting

    2. Dual Robot Calibration 2.5 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 2.15. Figure 2.15: 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 17: Mounting The Ur Dual Robot Calibration Connector

    2. Dual Robot Calibration 2.6 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 2.16. (10) Ensure that the robots are in the Home position. (11) Continue the procedure by pressing Connect Robots, see 2.17.
  • Page 18 2. Dual Robot Calibration (12) Attach the tool connector to the master robot (Robot 1) as in Figure 2.20. (13) When the tool is mounted on the master robot (Robot 1), Press Proceed in the pop-up Figure 2.21. (14) The slave robot (Robot 2) now enters free drive mode. Move the slave towards the connector and attach the screws with washers.

  • Page 19: Measuring Positions And Calibration Statistics

    2. Dual Robot Calibration 2.7 Measuring Positions and Calibration Statistics After step no.: 15, 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 2.24 and 2.25.

  • Page 20: Applying The Calibration

    2. Dual Robot Calibration Expected results The calibration is passed successfully if: Mean deviation will be less than 1 mm and 2 mrad Standard deviation is less than 0.5 mm and 1 mrad The different between the Calibration and Control results is not more than 50% different 2.8 Applying the Calibration After step no: 15 the calibration is applied to the controller and saved to be used in the future.

  • Page 21: Validation

    2. Dual Robot Calibration 2.8.1 Validation Next a validation procedure follows. Here both robot tool flanges need to complete free from e.g. screws, pins. (17) Remove the calibration tool and alignment pins etc. and Proceed with the validation, see Figure 2.30. The robots TCP will now approach one another.

  • Page 22: Reset Calibration

    2. Dual Robot Calibration Secondly the robots will move to their new calibrated home position. Here it is important that the robots are fully stretch out and that the tools are pointing in the right direction, like in Figure 2.33. After completion of step no.

  • Page 23: Appendices

    A. Calibration Plate A Calibration Plate 785mm 775mm Plate dimension: 800x800x12[mm] (630,630) (630,504) (630,378) (630,252) (630,126) (630,0) Drawing 63mm 31.002.05 Ø63 [H7] (567,567) (567,441) (567,315) (567,189) (567,63) 63mm (504,630) (504,504) (504,378) (504,252) (504,126) (504,0) 640mm Ø8 [H7] 63mm (441,567) (441,441) (441,315) (441,189) (441,63)

  • Page 24: B Dual Robot Tools

    B. Dual Robot Tools B Dual Robot Tools Cable Figure B.1: A sketch of the UR dual robot calibration horse, item no. 82353 Figure B.2: A sketch of the UR dual robot calibration tool connector, item no. 82352...

  • Page 25: C Robot Parameter

    C. Robot Parameter C Robot Parameter C.1 UR5 The robots kinematic transformations for each link are given by Denavite-Hartenberg parameters. The parame- ters for UR5 is displayed in tabel C.1 to C.3. r a d r a d Joint 1: 0.08920 Joint 2: 0.42500...

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