Mastering kuka robot in a position very different from the indicated by kuka (KR 8 R2100-2 arc HW)

  • Good morning everybody,

    I am currently working with a KR 8 R2100-2 arc HW kuka robot. Its mastering was carried out by the robot integrator in the creation of the MIG-MAG welding cell. The robot is mounted on a rail (Axis E1) upside down.
    The integrator mastered the robot with axes 2 and 3 in very different positions than indicated by the comparator's attachment points on the robot's axes.

    My questions are:
    1-Can this be done in kuka robot without compromising the good performance of the robot?

    -Mastering posicion indicated by KUKA:

    (all axes aligned with the comparator connection mark)

    -Current mastering done by the integrator:

    (A1=0º, A2=-90º, A3=+110º, A4=0º, A5=0º, A6=0º) (angle with respect to the measurement locations indicated on the robot arm for the comparator)

    2-Can a mastering with deviations of more than 90º in relation to the positions marked by the kuka on the axes compromise the robot's ability to generate circles using instruction "CIRC ..."?



    Edited once, last by ruicfc ().

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  • looks like you have a major problem there. if someone screwed up mastering (which is a basic of any commissioning) who knows what else is there, it is quite possible that soft limits are not adapted. wrong mastering will not only change what robot knows about its position but it also poses a huge risk of reaching hard-stops at significant velocity. this could result in a serious physical damage to the robot. even at low speed those things are not nice.

    yes, mastering errors can have huge effect on linearity of output,

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

  • What "marks" are you referring to? Because the white marks on the axes are usually the starting position for the Mastering, not the actual zero position.

    The most important question: Did the integrator Master the robot using a KUKA EMT? Or did they just "eyeball" it? Or just use the paint marks?

    Do you have an EMT? KUKAs use the EMT to eliminate any "eyeball error" when carrying out Mastering. Barring physical damage to the mastering gauge on each axis, it's nearly impossible to Master the robot incorrectly using an EMT.

    Your photo shows what I would typically expect of a KUKAbot posed with all 6 axes at 0deg. Actual Mastering position should have A2 at -90, A3 at +90 (although certain models may have some differences), and the robot arm making an "L" shape. That photo looks very wrong.

  • Example: Unlike most of the competition, on KUKAs, the white paint marks are the starting point for the Mastering motion. When the paint marks are aligned, the axis will actually be slightly positive of the actual Mastering position.

    The KUKA Mastering process uses the EMT to measure the engagement of the gauge pin with the reference notch while in motion. The pin is basically dragged across the notch, and the EMT detects the moment the pin finds the bottom of the notch.

    If you don't have an EMT, you can use Dial Mastering, as described in the manual, to "cheat". But doing that correctly requires either having the dial gauge adapter from KUKA, or carefully "feeling" the engagement of the mastering gauge pin.

    As everything depends on the robot's Mastering, take the time to make sure it's done right, before starting anything else.

  • Good to everyone again,

    Thanks for your help with your answers.


    In fact, the integrator who built the cell did the mastering as you can see in the 1nd image.

    The answer to what appeared to be a wrong mastering, is that in the case of the KUKA robot after mastering, the robot will interpret axes 2 and 3 with the following degrees:

    A2 = -90º (Quantec Model A2 = -90º)

    A3 = +90º (Quantec Model A3 = +110º)


    Edited once, last by ruicfc ().

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