Siemens SINUMERIK 840D sl Function Manual page 115

The start angle
value of the previous block. The constant coefficient of the polynomial is defined by the
starting angle of the polynomial.
The rotation vector is always perpendicular to the current tool orientation and forms the angle
THETAin conjunction with the basic rotation vector.
Note
During machine configuration, the direction in which the rotation vector points at a specific
angle of rotation can be defined, when the tool is in the basic orientation.
Formula
In general, the angle of rotation is interpolated with a 5th degree polynomial:
θu=θ
For the parameter interval 0 ... 1, this produces the following values for linear coefficients:
d =θ
1
Interpolation of the rotation vector
The programmed rotation vector can be interpolated in the following way, using modal G-
codes:
• ORIROTA (orientation rotation absolute):
The angle of rotation THETA is interpreted with reference to an absolute direction in space.
The basic direction of rotation is defined by machine data.
• ORIROTR (orientation rotation relative):
The angle of rotation THETA is interpreted relative to the plane defined by the start and end
orientation.
• ORIROTT (orientation rotation tangential):
The angle of rotation THETA is interpreted relative to the change in orientation. That
means the rotation vector interpolation is tangential to the change in orientation for
THETA=0.
This is different to ORIROTR, only if the change in orientation does not take place in one
plane. This is the case if at least one polynomial was programmed for the "tilt angle" PSI
for the orientation. An additional angle of rotation THETA can then be used to interpolate
the rotation vector such that it always produces a specific angle referred to the change in
orientation.
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
q
is derived from the start value of the rotation vector, resulting from the end
s
2 3 4
+d u+d u +d u +d u
s 1 2 3 4
− θ − d − d − d − d
e s 2 3 4
5
+d u
5
5
F2: Multi-axis transformations
1.11 Orientation vectors
(14)
(15)
115