Siemens SINUMERIK 840DE sl Function Manual page 190

F2: Multi-axis transformations
3.8 Restrictions for kinematics and interpolation
Figure 3-22
End point within the circle
If the end point is within the circle, the first axis comes to a standstill and the second axis moves
until the difference between target and actual orientation is minimal. However, since the first
rotary axis does not move, the orientation will generally deviate from the programmed value
(see previous figure). However, the programmed orientation can at least be reached exactly if
the first rotary axis happens to be positioned correctly.
Note
In the previous Figure the resulting path is a straight line because the position of the first rotary
axis is constant on that path. This representation is always correct, irrespective of the angle
between the two rotary axes. The orientation vector only moves in a plane, however, if the two
rotary axes and the basic orientation are all mutually perpendicular. In all other cases, the
orientation vector describes the outside of a cone.
End point outside the circle
If the orientation interpolation describes a path through the circle, while the end point is outside
the circle, the end point is approached with axis interpolation. This applies in particular if the
interpolation starting point is located inside the circle. Path deviations from the programmed
setpoint orientation are thus unavoidable.
190
Generic 5-axis transformation; end point of orientation inside tolerance circle.
Function Manual, 06/2019, A5E47435470B AA
Transformations