Mitsubishi Electric MELDAS MDS-B-SVJ2 Series Specifications And Instruction Manual page 130

(2) Adjusting for feed forward control
Use OVS compensation type 2 if overshooting is a problem in contour cutting during feed forward
control.
If OVS compensation type 2 is used to attempt to compensate overshooting, the overshooting
may conversely become larger, or projections may appear during arc cutting. This is because
overshooting equivalent to the operation fraction unit occurs in the position commands when the
CNC is carrying out feed forward control. Because of this, the OVS compensation recognizes a
change in the command direction, and executes the compensation in the opposite direction.
If the compensation is in the opposite direction when carrying out feed forward control, adjust with
the non-sensitive band (SV040: LMCT) during feed forward control in the same way as during
LMC compensation. By ignoring overshooting of a set width in the LMCT or less, the command
direction change point is correctly recognized, and the OVS compensation is correctly executed.
Because this phenomenon is due to the same causes as the phenomenon during LMC
compensation, it is adjusted with the same parameters. The adjustment is completed if the correct
setting is possible during whichever compensation.
This parameter is insignificant when feed forward control is not used.
<Adjustment method>
If the OVS compensation is carried out in reverse during feed forward control, increase the LMCT
setting by 1μm at a time.
Note that 2μm are set even when the LMCT is set to 0.
POINT
No. Abbrev. Parameter name
SV027 SSF1 Servo function selection 1
Parameter
No. Abbrev.
name
SV031 OVS1 Overshooting
compensation 1
SV042 OVS2 Overshooting
compensation 2
SV040 LMCT Non-sensitive
band during feed
forward control
POINT
Chapter 5 Adjustment
OVS compensation type 2 is used if overshooting is a problem during feed
forward control.
The overshooting compensation starts with the following parameter.
F E
aft zrn2
bit
A
ovs
B
Unit
Stall % (rated Increase the value by 1% at a time, and find the value where
current %) overshooting does not occur. When OVS2 is set to 0, the
setting value will be applied in both the ± directions.
Set 0 as a standard.
Stall % (rated
Set this when the compensation amount is to be changed
current %)
according to the direction.
μm This setting is valid only during feed forward control.
2μm are set when the LMCT is set to 0. Adjust by raising
1μm at a time.
1. When either parameter SV031: OVS1 or SV042: OVS2 is set to 0, the same
amount of compensation is carried out in both the positive and negative
direction, using the setting value of the other parameter (the parameter not
set to 0).
2. To compensate in only one direction, set -1 in the parameter (OVS1 or
OVS2) for the direction in which compensation is prohibited.
3. For contour cutting, the projection at the arc end point is compensated with
OVS compensation. LMC compensation is carried out at the arc starting
point.
Explanation
D C B A 9 8
ovs lmc
Explanation
01: Overshooting comp. stop
11: Overshooting comp. type 1
Explanation
OVS compensation LMC compensation
Cutting direction
5-22
7 6 5 4 3 2 1
vfct
10: Overshooting comp. type2
11: Setting prohibited
Setting range
–1 ~ 100
–1 ~ 100
0 ~ 100
0