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4 Servo Adjustment
MITSUBISHI CNC
(3) Adjusting the in-position width
Because there is a response delay in the servomotor drive due to position loop control, a "settling time"
is also required for the motor to actually stop after the command speed from the CNC reaches 0.
The movement command in the next block is generally started after it is confirmed that the machine has
entered the "in-position width" range set for the machine.
Set the precision required for the machine as the in-position width. If a high precision is set needlessly,
the cycle time will increase due to a delay in the settling time.
The in-position width is validated with the servo parameter settings, but there may be cases when it is
validated with the NC parameters. Refer to each NC Instruction Manual.
【#2224】 SV024 INP In-position detection width
Set the in-position detection width.
Set the positioning accuracy required for the machine.
The lower the setting is, the higher the positioning accuracy will be. However the cycle time (settling
time) becomes longer.
The standard setting value is "50".
---Setting range---
0 to 32767 (μm)
(4) Adjusting the settling time
The in-position width setting and confirmation availability depend on the CNC parameters.
The settling time is the time required for the position droop to enter
the in-position width after the feed command (FΔT) from the CNC
reaches 0.
The settling time can be shortened by raising the position loop gain
or using SHG control. However, a sufficient response (sufficiently
large VGN1 setting) for the speed loop is required to carry out sta-
ble control.
The settling time during normal control when the CNC is set to lin-
ear acceleration/ deceleration can be calculated using the follow-
ing equation. During SHG control, estimate the settling time by
multiplying PGN1 by .
POINT
0
0
F
ԥ
T
Position
droop
F
Time
Setting time
In-position
In-position width
G0tL
ln
㧙
Settling time (ms) =
PGN1 : Position loop gain1 (SV003) (rad/s)
F : Rapid traverse rate (mm/min)
G0tL : Rapid traverse linear acceleration/
deceleration time constant (ms)
INP : In-position width (SV024) (Ǵm)