KUKA accuracy problem

    Hello, I have a KUKA KR 210 L150-2 2000 (2007 Year), I did mastering with dial and EMT. MADA As much as I could check, MADA is right. Unfortunately If I move A/B/C Axes in WORLD coordinates TCP on flange is moving around +-10mm. Where to look for causes?

    Regards
    Tom

    First: "10mm" -- for how much rotation?

    Second: are you certain you have the correct tool active?

    Third: How does the setting of LOAD_DATA and $LOAD compare to the actual payload?

    Fourth: How did you define the TCP, and what RMS result did you get at the end of it?

    Fifth: If you check each rotation axis individually, is there any pattern to the rotation error? Any axis that is especially bad, or especially good?

    Hello

    How did you define your TCP?
    Tool NULLFRAME now TCP should be on robot flange center

    First: "10mm" -- for how much rotation?
    Aprox 20 degrees

    Third: How does the setting of LOAD_DATA and $LOAD compare to the actual payload?
    Without load (-1)

    Fourth: How did you define the TCP, and what RMS result did you get at the end of it?
    Could You explain "RMS"? Tool NULLFRAME TCP should be on flange center

    Fifth: If you check each rotation axis individually, is there any pattern to the rotation error? Any axis that is especially bad, or especially good?
    A axis almost good (+-1mm)
    B axis bad (+-7mm)
    C axis very bad (+-12mm)

    How to run properly $abs_accur function? I sent an email to KUKA AG regarding calibration files(no answer yet), and I need any manual/instruction how to properly set this function if I get the files.

    Tom

    Default load -1 results in maximal and not zero load. Set your mass to explicitly zero and try again.

    Absolute accuracy can only be used after running a special identification method that has to be carried out for each robot individually. If your robot has not been measured for absolute accuracy in the past by KUKA Kuka can not provide the corresponding accuracy file. You can order a onsite measurement from KUKA but that's probably not cheap. If you are lucky the identification routine has been carried out in the KUKA factory directly after constructing your robot, because the robot was ordered originally with the absolute accuracy package.

    Fubini

    Edited once, last by Fubini (November 1, 2018 at 8:07 PM).

    Fubini:

    I will check tomorrow different mass set. Has anyone managed to get the necessary data from KUKA? Assuming I succeed to get data from KUKA , where can I find instructions on how to use them correctly? I can't find any manual with usual information about.

    What should be the maximum deviations from TCP when rotating around a point(from Your experience), if everything is set appropriately (without options $abs_accuracy)?

    Tom

    Procedure on how to download a absolute accuracy file into the controller depends on your software versions. A information you failed to provide. After downloading the file absolute accuracy package is active and there is nothing else you have to consider apart from setting correct load data, measuring your tools as precisely as possible and so on. But that's pretty much the same stuff you would do to get a non absolute accuracy package robot precise.

    From my experience +-3 mm is not very far from what can be expected without absolute accuracy. With absolute accuracy you will get something in between 0.5 and 1 mm.

    Fubini

    Edited once, last by Fubini (November 1, 2018 at 8:55 PM).

    I will check KSS symbol in the morning(I am not sure at the moment). I would like to use the robot for milling so the absolute accuracy option will be necessary.

    Tom

    EDIT:

    KRC V4.1.7 SP08

    GUI Version
    V3.3.79

    Kernell system version
    KS V 4.97

    Tom

    Edited once, last by Tomek155 (November 2, 2018 at 9:58 AM).

    First: does this robot have an Absolute Accuracy calibration? That has to be purchased as a factory option when the robot is initially ordered, and the calibration is carried out at the factory before shipping.

    If the robot does not have the AA option installed, the only way to "upgrade" it is to have KUKA make an expensive field service call and perform the calibration on-site.

    AA, in my experience with it, is not a great option. It does make the robot slightly more accurate, but it's very fussy, and vulnerable to large tool reorientations. It also has very specific steps you have to go through, even after the calibration is done:
    1. No-load mastering (before anything is mounted to the robot
    2. Tool mounting, with exact payload Mass, CG, and MoI data
    3. Teach Offset Mastering, for the particular tool
    4. Repeat Step 2&3 for any other tools the robot will carry

    AA can also be turned off, even if installed, so you need to check the robot Properties screen -- it will say "Position Accurate Robot" if AA is active.

    Second: how are you measuring the tool motion, if you're using $NULLFRAME? Get a pointer, set it up, and make precise measurements.

    I don't know yet od it has AA option. I was contact with KUKA in this case, The ordered all information about robot with archive file.

    I will prepare a tool with exact dimensions, write the numeric data nad we will see whats happend.

    Ad the moment when I choose NULLFRAME I should have a TCP on The center od flange, lukę in kuka manual description.

    And last: what do You mean "MOL data"?

    Tom

    Hey, today I mounted robot to the floor and tried to master with EMT with load corrections. Unfortunately I have the same problem. I have a Spike screwed into one of six threaded holes on the flange, tool settings x=0, y=80(half of holes circle), z=43(lenhgt of spike), I set current tool and base (tool 2, base 1). I moved robot to another spike which mounted on base and tried to move along A B C axes. I have a huge inaccuracy (20mm on 20deg flange alignment). I have no idea whats is wrong ???

    Archive and information in attachment

    Hi
    I had a look at your pictures. I don't see any extension on the robotarm. The previous owner might have shortened it for some reason.
    in that case the maschinedata has to be changed. Post a better picture of the robotarm.

    Edited once, last by Schilberg (November 6, 2018 at 7:47 AM).

    Panic Mode

    I am not sure 100% but i have white Security paint on each screw of mastering cartridges nad I think it id okay.

    Schilberg

    I will attach pictrues soon.

    EDIT
    Schilberg probably BINGO! :icon_smile:

    In fact, i don't have a 400mm extension (somebodu just unmount it before)
    And now, how to properly transfer and set right machine data from E: drive?

    Tom

    EDIT
    All problems solved, thank You for help

    Tom

    Edited once, last by Tomek155 (November 17, 2018 at 11:57 AM).

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