5
04.00 Special Motion Commands
5.4 Pol
nomial inter
olation
POLY
5
840D
NCU 571
840D
NCU 572
NCU 573
810D
840Di
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Siemens AG 2000. All rights reserved
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA)
−
04.00 Edition
5-163
5.4 Polynomial interpolation, POLY
The control system is capable of traversing curves
(paths) in which every selected path axis is operating
according to a function (max. 3rd degree
polynomial).
The equation used to express the polynomial
function is generally as follows:
f(p)= a
0
+ a
1
p + a
2
p
2
+ a
3
p
3
The letters have the following meaning:
a
n
: Constant coefficients
p: Parameters
By assigning concrete values to these coefficients, it
is possible to generate a wide variety of curve
shapes such as line, parabola and power functions.
By setting the coefficients as a
2
= a
3
= 0,
it is possible to create, e.g. a straight line with
f(p) = a
0
+ a
1
p
Meanings:
a
0
= Axis position at end of preceding
block
a
1
= Axis position at end of definition
area (PL)
Definition
Polynomial interpolation (POLY) is not one of the
real types of spline interpolation. Its main purpose is
to act as an interface for programming externally
generated spline curves where the spline sections
can be programmed directly.
This mode of interpolation relieves the NC of the
task of calculating polynomial coefficients. It can be
applied optimally in cases where the coefficients are
supplied directly by a CAD system or postprocessor.
X
Y
0
1
1
2
2
3
3
4
(PL)
1
2
3
4
4
Result in XY plane
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