Robot Orientation

    I am trying to gain a better understanding of the orientation parameters. Rotation about x (Rx), Rotation about y (Ry), and Rotation about z (Rz). Are these rotation angles measured with respect to the current tool frame? Or are they measured with respect to the world/user frame? Thanks

    They're measured relative to a frame of reference. What that frame of reference is, depends.


    When creating a UFrame, UFrames are always referenced to World, which on Fanucs is located (IIRC) at the intersection of J1 and J2, with Z+ pointing straight up, and X+ pointing straight "ahead" -- the direction the robot points when J1 is at 0deg.


    A point, OTOH, is always programmed referenced to a UFrame. A UFrame could be identical to World, or very different.


    On Fanucs, the Euler sequence is X-Y'-Z". So the values recorded in the W,P,R elements of a point define the orientation of that point, relative to the UFrame, as follows:

    1. Start at the orientation of the UFrame
    2. Rotate around X by W deg
    3. Now, rotate around the new Y axis (Y') by P deg
    4. Now, rotate around the new Z axis (Z") by R deg

    Right-hand rule applies.

    So (firatgzl) are you saying they are always measured with respect to the world frame regardless of the specific user frame the point was taught in? Just trying to reconcile your response with (SkyeFire). Thanks

    Looks like there are several different responses to this question. This is why I asked the question in the first place. When I get back to my shop I am going to try and confirm the answer by trial and error. I feel like the rotations should be about the reference tool frame. This would allow the TCP to rotate about the TCP without changing the X,Y,Z coordinates. An interesting and basic question for sure.

    Every six coordinates describe the position of the actual tool (utool, tcp) in relation to the actual user frame (uframe). Nothing else makes sense.

    This is common sense and essential for all industrial robots I know.

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