
B-65270EN/05 4.SERVO FUNCTION DETAILS
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(3) Setting parameters
<1> Enable PI control and the feed-forward function.
#7 #6 #5 #4 #3 #2 #1 #0
1808 (FS15i)
PIEN
2003 (FS30i, 16i)
PIEN (#3) 1: To enable PI control
#7 #6 #5 #4 #3 #2 #1 #0
1883 (FS15i)
FEED
2005 (FS30i, 16i)
FEED (#1) 1: To enable the feed-forward function
<2> Specify the feed-forward coefficient.
1961 (FS15i)
Feed-forward coefficient (FALPH)
2068 (FS30i, 16i)
FALPH = α × 100 or α × 10000
When FALPH is smaller than or equal to 100: In units of 1%
When FALPH is greater than 100: In units of 0.01%
[Typical setting] 70 or 7000
<3> Specify the velocity feed-forward coefficient.
1962 (FS15i)
Velocity feed-forward coefficient (VFFLT)
2069 (FS30i, 16i)
VFFLT = 50 (50 to 200)
<4> Switch the NC off, attach the servo check board, then switch the
NC on again. ⇒ See Sec. 4.19.
Run a program to move the axis for cutting feed at maximum
feedrate. Under this condition, check whether the VCMD
waveform observed on the servo check board overshoots and
what the shock caused during acceleration /deceleration is like.
⇒ If an overshoot occurs, or the shock is big, increase the
acc./dec. time constant, or reduce α.
⇒ If an overshoot does not occur, and the shock is small, reduce
the acc./dec. time constant, or increase α.
Linear acc./dec. is more effective than exponential acc./dec.
Using acc./dec. before interpolation can further reduce the figure
error.