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

B-63324EN/03 PROGRAMMING 4.INTERPOLATION FUNCTIONS
- 109 -
Explanation
- Function of spiral interpolation
Spiral interpolation in the XY plane is defined as follows:
(X-X
0
)
2
+(Y-Y
0
)
2
=(R+Q’)
2
X
0
: X coordinate of the center
Y
0
: Y coordinate of the center
R : Radius at the beginning of spiral interpolation
When the programmed command is assigned to this function, the
following expression is obtained:
(X-X
S
-I)
2
+(Y-Y
S
-J)
2
= (( R + (L’+
360
θ
)Q)
2
where
X
S
: X coordinate of the start point
Y
S
: Y coordinate of the start point
I : X coordinate of the vector from the start point to the center
J : Y coordinate of the vector from the start point to the center
R : Radius at the beginning of spiral interpolation
Q : Radius increment or decrement per spiral revolution
L' : (Current number of revolutions)-1
θ : Angle between the start point and the current
position(degrees)
- Controlled axes
For conical interpolation, two axes of a plane and two additional axes,
that is, four axes in total, can be specified. A rotation axis can be