Siemens sinumerik 840d Programming Manual page 152

Special Motion Commands
5
5.2 Spline interpolation
840D 840D
NCU 571 NCU 572
NCU 573
Additional notes
A, B and C splines are modally active and belong to
the group of motion commands. The toolradius
offseet may be used. Collision monitoring is carried
out in the projection in the plane.
Axes that are to interpolate in the spline grouping are
selected with command SPLINEPATH (further
details on the following pages).
Sequence
A SPLINE
The A spline (Akima spline) passes exactly through
the intermediate points. While it produces virtually no
undesirable oscillations, it does not create a
continuous curve in the interpolation points.
The akima spline is local, i.e. a change to an
interpolation point affects only up to 6 adjacent
points.
The primary application for this spline type is
therefore the interpolation of digitized points.
Supplementary conditions can be programmed for
akima splines (see below for more information). A
3rd-degree polynomial is used for interpolation.
5-152
FM-NC 810D 840Di
A spline (Akima spline)
P3
P2
P1
P1 to P7: Predefined coordinates
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA) − 04.00 Edition
04.00
5
P6
P7
P4
P5
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