
6.NTERPOLATION FUNCTION B-63323EN-1/03
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6.18.1 NURBS Interpolation Additional Functions
The following functions are added to the NURBS interpolation for the
FANUC Series 15i.
- Parametric velocity control
The maximum speed of each segment is determined by the specified
speed and acceleration. For consecutive segments, the segment start
speed and end speed are determined as stated below to allow the speed
to change continuously during movement from the start point to the end
point. This function is valid only for NURBS interpolation when
parameter FDI (bit 5 of parameter No. 8412) is 1.
- High-precision knot command
When parameter HIK (bit 1 of parameter No. 8412) = 1, it is possible to
use the knot command in a range between 12 digits to the left of the
decimal point and 12 decimal places. This function is valid only for a
floating-point knot command (address K) during NURBS
interpolation.
- Simplified start command
When parameter EST (bit 0 of parameter No. 8412) is 1, it is possible to
omit a control point command for the first control point. Because the
first and second blocks have the same knot value, a knot command for
the first block can also be omitted.
- Supporting maximum cutting feedrate for individual axes
With the conventional specification, the speed F specified during
NURBS interpolation is clamped at the minimum of the maximum
cutting feedrates (parameter No. 1422) of each axis, using the
following expression:
))(),(),(),(),(Min(
maxmaxmaxmaxmax
BFAFZFYFXFF ≤
If the maximum cutting feedrate F
max
for a rotation axis is low, the
speed F specified during NURBS interpolation is clamped at F
max
,
resulting in an increased machining time.
This function uses a different method of clamping the specified speed F,
as described below.
The specified speed F is clamped in such a way that the each axis
component of the F will not exceed the maximum cutting feedrate
(parameter No. 1422) for the target axis. (Fig. 6.18.1(a))