TCP Z value changes when Jogging robot in X or Y axis in Cartesian mode

    Hi there,
    I'm facing this issue. Why if I jog the robot in cartesian mode with the KCP keys in X or Y direction also Z value change?
    Any idea?
    Best,
    Marco

    Kuka KR150-2 KRC2 ed05 V5.6.11<br />VFD TDE Macno<br />Spindle HSD ES915 with Automatic tool changer<br />Sprutcam 11

    Edited once, last by Marco (March 10, 2016 at 6:29 PM).

    Well I suppose it is calibrated as it comes from KUKA and it is a Position Accurate robot and the PID ic correctly loaded. What do you mean by correct MADA? All files in there are the ones from the factory.

    Kuka KR150-2 KRC2 ed05 V5.6.11<br />VFD TDE Macno<br />Spindle HSD ES915 with Automatic tool changer<br />Sprutcam 11

    what is the history of this robot? you just received it straight from Kuka? what is the KSS version? what is shown on pendant as robot model? does it match what is on the sticker/plate on the robot arm?

    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

    Yes, I defined the reference tool (with calibrated TCP and orientation) that I use for calibration with $NULLFRAME to get the worldcoordinates. So checking the $AXIS_ACT in the monitor I see that if I rotate only AXIS1 all other values stay the same, so if the robot was installed completely in plane and the end effector would in a perfectly aligned position, while rotating Axis 1 the tip of the tool should move on a plane. But if I read TCP Coordinates they actually change, which means that the robot and end effector in general are not completely straight so I have a certain rotation in space. My table for milling is 3 meters long so little differences matter! ......I do not get it...

    How can I check if I have the right Mada?

    Kuka KR150-2 KRC2 ed05 V5.6.11<br />VFD TDE Macno<br />Spindle HSD ES915 with Automatic tool changer<br />Sprutcam 11

    Yes I did 4 points. The error is that If I move TCP through Cartesian Jogging on X or Y also Z changes, while Z should stay the same. I check the coordinates on the monitor, which I understood it approximates values, so maybe there is a manner to show precise Cartesian coordinates (with same precision of the $Axis_Act monitor) to double check if Z is actually changing or it is only a monitor approximation issue?
    Best,
    Marco

    Kuka KR150-2 KRC2 ed05 V5.6.11<br />VFD TDE Macno<br />Spindle HSD ES915 with Automatic tool changer<br />Sprutcam 11

    Edited once, last by Marco (March 10, 2016 at 6:34 PM).

    It seems as though you are trying to jog your newly calibrated TCP in the $NULLFRAME in the X (or Y) direction and you are observing from the "Display" position screen that your are also moving in the Z direction.

    Several things to check.
    1) make sure you have the correct TCP selected
    2) make sure you have the correct base selected (in your case, I believe, base 0)
    3) make sure you are jogging with respect to the correct base (again, in your case the world). for example, make sure you are not jogging with respect to the TCP (or axis specific, or base).

    If you are observing positions of your TCP in the world but are jogging with respect to TCP (for example) then it would make sense that you see motion in other axes

    Have a look at Fubini's answer:

    Quote from Fubini


    Hi,
    driving in T1 absolute accuracy is deactivated, but the value reading $pos_act still has absolute accuracy included.
    Fubini

    Or look at my old post:

    Quote from Puck

    Yes, if you jog an absolute robot with the teach pendant, e.g. a rotation round z, the other components (x, y, z, b ,c) may/will change too. If you run a programme, e.g. a rotation round z, the other components (x, y, z, b ,c) will (hopefully) not change.

    The difference between jogging the robot and running a program:


      • Running a program: The motion planning is done a with the absolute accurate robot planning algorithm (abs. acc. forward kinematics and inverse kinematics) and the display shows the result of absolute accurate robot planning algorithm (abs. acc. forward kinematics).

      • Jogging: The motion planning is done without the absolute accurate robot planning algorithm, but the display shows the result of absolute accurate robot planning algorithm (abs. acc. forward kinematics).

    An absolute accurate robot allways knows and shows the correct position and orientation of the TCP (within the tolerances of the absolute accurate robot model), which is calculated by absolute accurate forward transformation.

    Bye Puck

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