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9. Adjustment
9 - 7
9-2-3 Position loop gain
(1) Setting the position loop gain
The position loop gain (SV003 (PGN1)) is a parameter that determines the trackability to the
command position. 33 is set as a standard. Set the same position loop gain value between
interpolation axes.
When PGN1 is raised, the trackability will be raised and the settling time will be shortened, but a speed
loop that has a responsiveness that can track the position loop gain with increased response will be
required. If the speed loop responsiveness is insufficient, several Hz of vibration or overshooting will
occur during acceleration/deceleration. Vibration or overshooting will also occur when VGN1 is
smaller than the standard value during VIA adjustment, but the vibration in the position loop occurs
generally 10Hz or less. (The VIA vibration occurs from 10 to 20Hz.) When the position control includes
machine resonance points (Position control machine resonance points occur at the machine end
parts, etc.) because of insufficient machine rigidity, the machine will vibrate during positioning, etc. In
either case, lower PGN1 and adjust so that vibration does not occur.
If the machine also vibrates due to machine backlash when the motor stops, the vibration can be
suppressed by lowering the PGN1 and smoothly stopping.
If SHG control is used, an equivalently high position loop gain can be maintained while suppressing
these vibrations. To adjust the SHG control, gradually raise the gain from a setting where 1/2 of a
normal control PGN1 where vibration did not occur was set in PGN1. If the PGN1 setting value is
more than 1/2 of the normal control PGN1 when SHG control is used, there is an improvement
effect in position control. (Note that for the settling time the improvement effect is at 1/
2
or more.)
No. Abbrev. Parameter name Explanation Setting range
SV003 PGN1 Position loop gain 1
Set the position loop gain. The standard setting is "33".
The higher the setting value is, the more precisely the command can be
followed and the shorter the positioning time gets, however, note that a
bigger shock is applied to the machine during acceleration/deceleration.
When using the SHG control, also set SV004 (PGN2) and SV057
(SHGC).
1 to 200
(rad/s)
SV004 PGN2 Position loop gain 2 Set 0. (For SHG control) 0 to 999
SV057 SHGC SHG control gain Set 0. (For SHG control) 0 to 1200
CAUTION
Always set the same value for the position loop gain between the interpolation
axes.
(2) Setting the position loop gain for spindle synchronous control
During spindle synchronous control (synchronous tapping control, etc.), there are three sets of
position loop gain parameters besides the normal control.
No. Abbrev. Parameter name Explanation Setting range
SV049 PGN1sp Position loop gain 1
in spindle
synchronous control
Set 15 as a standard. 1 to 200
(rad/s)
SV050 PGN2sp Position loop gain 2
in spindle
synchronous control
Set 0 as a standard.
(For SHG control)
0 to 999
SV058 SHGCsp SHG control gain in
spindle synchronous
control
Set 0 as a standard.
(For SHG control)
Set the same parameter as the
position loop gain for the spindle
synchronous control.
0 to 1200
CAUTION
Always set the same value for the position loop gain between the spindle and
servo synchronous axes.