KUKA status bit flip/no-flip, J5 sign is irrelevant?

  • Our kuka code is generated by our own motion planner, and therefore we need to add all Status and Turn bits to the move commands.

    Now I'm very confused with getting the 2nd status bit, that describes if the wrist is pointing up or down. This is what the documentation says;


    It clearly says that the sign of joint 5 is irrelevant, but from my testing this seems to be not true.

    Also reading further it says that pointing up is relative to zero position of j4, but what exactly does that mean?

    If I have all the joint angles, how would I calculate this status bit?

  • HawkME

    Approved the thread.
  • If A4 is at 0, then A5>0 will point down, and A5<0 will point up. If A4 is 180deg, then the opposite will be true.

    That said, there seems to be some documentary ambiguity here. I have a KSS 5 and KSS 8 manual that both show the following:

    And a chart a couple pages later:

  • yes there are mistakes in some of the documents.

    status bit does matter and as SkyeFire mentioned, wording is sometimes ambiguous.

    did not really look at this but maybe the status bit and A5 angle sign do not always match up.

    probably the thing to keep in mind is that there are different arm geometries. on some robots A2 and A3 joints are offset so that centerlines do not necessarily cross at joint but a little bit away. I'm thinking of console robots (suffix -KS), KR30, some of the newer robots like KR8, hollow wrists etc.

    so the safest option is to test on a real robot - move the axis and see how the value changes for that model.

    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

  • Thanks for comments, I did test it on our robot (KR 60-3, so with an offset between j3 and j4) and it does seem like this this status bit is exactly the the same as the sign of j5.

    I'm very confused because of the documentation, but also because this information is already in turn bits.

    So for future reference; the status bit is 1 if j5 < 0

    Since we only have one KUKA at our facility it would be absolutely amazing if someone could confirm this on their KUKA

  • Did a quick&dirty test with my OfficePC (which is set up as a KR2210), and got the following data. It'll probably format better copy&pasted into a spreadsheet as CSV data.


















  • Thanks a lot for getting some more data!

    It does confirm what I found above, I guess this one is answered then!

  • kwint

    I know this is a bit confusing - but it also depends on the type of the robot.

    If axis 5 may only turn around less then 180° then your conclusion is absolutely correct

    (just check SW Limits of Axis 5)

    Or check the first picture from SkyFire at post #3 or just check post #2

  • Sorry for the delay

    If you find a line in the $machine.dat

    and then check

    $SOFTP_EN[5] or $SOFTN_EN[5]

    you will see that the values are about +/-120°

    Having more than 180° would mean you are using a different wrist (like WSH or others)

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