Siemens SINUMERIK 840D sl Programming Manual page 286

Special motion commands
4.5 Polynomial interpolation (POLY, POLYPATH, PO, PL)
It is possible to program polynomials without the POLY G code being active. In this case,
however, the programmed polynomials are not interpolated; instead the respective
programmed end point of each axis is approached linearly (G1). The polynomial interpolation
is then activated by programming POLY.
Also, if G code POLYis active, with the predefined subprogram POLYPATH(...), you can
select which axes are to be interpolated with polynomial.
Special features of the denominator polynomial
Command PO[]=(...) can be used to program a common denominator polynomial for the
geometry axes (without specifying an axis name), i.e., the motion of the geometry axes is
then interpolated as the quotient of two polynomials.
With this programming option, it is possible to represent forms such as conics (circle, ellipse,
parabola, hyperbola) exactly.
Example
Program code
POLY G90 X10 Y0 F100
PO[X]=(0,–) PO[Y]=(10) PO[]=(2,1)
The constant coefficient (a
specified end point is not dependent on G90 / G91.
The result obtained from the above example is as follows:
X(p) = 10(1) / (1+p
Y(p) = 20p / (1+p
with 0 ≤ p ≤ 1
As a result of the programmed start points, end points, coefficient a
intermediate values are as follows:
Numerator (X) =
Numerator (Y) =
Denominator =
286
) of the denominator polynomial is always assumed to be 1, the
0
) and
2
)
2
10+0*p-p
2
0+20*p+0*p
2
1+2*p+1*p
2
Comments
; Geometry axes traverse linearly to
position X10 Y0.
; Geometry axes traverse along the
quadrant to X0 Y10.
and PL=1, the
2
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
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