# Fanuc Series 15i/150i-MA (Programming) Operators Manual

B-63324EN/03 PROGRAMMING 4.INTERPOLATION FUNCTIONS
- 101 -
Fig.4.14 (a) Spline interpolation
- Three-dimensional offset
Spline interpolation can be executed in the three-dimensional tool
compensation mode. The spline interpolation function automatically
produces vectors for three-dimensional tool compensation in the spline
interpolation mode. In the three-dimensional tool compensation mode,
a spline curve connects the specified points which are offset by the
vectors for three-dimensional tool compensation.
The spline interpolation function determines the vectors for three-
dimensional tool compensation as shown below:
1) Three-dimensional tool compensation vector at the start point
The three-dimensional tool compensation vector specified in the
block of three-dimensional tool compensation command is used.
Three-dimensional tool compensation vector K specified by G41 Ii
Jj Kk Dd; has components Kx, Ky, and Kz, each of which is
calculated as follows:
priKx ÷×= )(
prjKy ÷×= )(
prkKz ÷×= )(
where
r is the offset corresponding to the specified offset number d.
222
++=
2) Three-dimensional tool compensation vector at the second or
subsequent point
Position :The vector is on the plane containing the point,
previous point, and next point. It is perpendicular to
the straight line connecting the previous and next
points.
Direction :The direction of the vector is close to that of the
three-dimensional tool compensation vector at the
previous point. (When the direction of three-
dimensional tool compensation vector V at the point
is close to that of three-dimensional tool
compensation vector V0 at the previous point, the
angle ˘ between V0 and V satisfies the following
condition : |θ| < 90° )
Magnitude :The magnitude of the vector is the offset
corresponding to the offset number specified by G41.
P
1
P
2
P
3
P
4
P
5
P
n
P
n+1