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4. Servo Adjustment
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(2) Adjusting for feed forward control
When using feed forward control (high-speed high-accuracy control), the feed forward control must
be stopped (fwd_g =0) before adjusting the overshooting compensation. After adjusting the
overshooting compensation with normal control, set the overshooting compensation non-sensitive
zone (SV034 (SSF3)/bitC to F (ovsn) to 1 (2µm) and start up feed forward control.
If overshooting compensation is used during feed forward control, the overshooting will increase,
or protrusions could appear during arc cutting. This is because, when the NC is carrying out feed
forward (fwd) control, overshooting equivalent to the operation fraction unit occurs in the position
command, and the OVS compensation is recognized as a change in the command direction,
resulting in compensation in the reverse direction. This can be improved by setting the
overshooting compensation non-sensitive zone width.
If overshooting does not occur during normal control, and occurs only during feed forward control,
adjust the feed forward gain (fwd_g).
No. Abbrev. Parameter name Explanation Setting range
SV031 OVS1 Overshooting
compensation 1
Increase in increments of 1%, and find the value where overshooting does
not occur. The value is set in both the ± directions when OVS2 is set to 0.
-1 to 100
(Stall [rated]
current %)
SV042 OVS2 Overshooting
compensation 2
Set to "0" as a standard.
Set this to change the compensation amount according to the direction.
-1 to 100
(Stall [rated]
current %)
SV027 SSF1 Servo function
selection 1 F E D C B A 9 8 7 6 5 4 3 2 1 0
aflt zrn2 afse ovs lmc omr zrn3 vfct upc vcnt
bit Meaning when "0" is set Meaning when "1" is set
A Set the compensation amount with SV031 (OVS1) and SV042 (OVS2).
B
ovs
00: Overshooting compensation stop 10: Overshooting compensation type 2
01: Overshooting compensation type1 11: Overshooting compensation type 3
SV034 SSF3 Servo function
selection 3 F E D C B A 9 8 7 6 5 4 3 2 1 0
ovsn has2 has1
bit Explanation
C
D
E
ovsn
F
Set the non-sensitive band of the overshooting compensation type 3 in
increments of 2µm at a time.
In the feed forward control, the non-sensitive band of the model position
droop is set, and overshooting of the model is ignored. Set to the
standard 2µm (0001).
POINT
When using feed forward control (high-speed high-accuracy control), stop the
feed forward control (fwd_g=0) before adjusting the overshooting
compensation. If overshooting occurs during subsequent feed forward control,
adjust the feed forward gain (fwd_g).