How to calculate the coordinate with Fanuc R-J3iB

  • I work with a Robot Fanuc 100iD with a R--J3iB CONTROLLER.

    This a Welding Robot. The robot use a rotating table MotoFil mount

    on the X axe. So, when the table moves, the Y and Z change.


    I welded a part when the table was at 45 degrees.

    I wrote the coordinates of joints J4, J5 and J6.

    The coordinates of this piece was:

    GP1:

    UF : 5, UT : 1, CONFIG : 'N U T, 0, 0, 0',

    X = 297.592 mm, Y = 255.413 mm, Z = -211.301 mm,

    W = -31.373 deg, P = 54.176 deg, R = 154.253 deg,

    E1= 148.760 mm

    GP2:

    UF : 5, UT : 1,

    J1= 225.001 deg

    };


    I tried to weld a piece located in the opposite direction.

    I looked at the new coordinate and it was:

    GP1:

    UF : 5, UT : 1, CONFIG : 'N U T, 0, 0, 0',

    X = 384.336 mm, Y = 255.413 mm, Z = -211.301 mm,

    W = -31.373 deg, P = 54.176 deg, R = 36.000 deg,

    E1= 235.504 mm

    GP2:

    UF : 5, UT : 1,

    J1= 225.000 deg

    };


    I thought I saw as coordinated:

    W = -31.373 deg, P = 54.176 deg, R = 25.474 deg


    Why there is a difference on R (J6) and if I try R=24.474, the robot points to different place ?


    Thanks for your help

  • AD
  • You have a misunderstanding of how the Cartesian representation in Fanucs works. WPR does not represent the the last 3 joints of the the robot. They represent the rotations of the point, relative to the frame the point is taught in.

    Check out the Fanuc position converter I wrote here!

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