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Chapter 10 Adjustment
10–5
10-2-3 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. 47 (SHG control) is set as a standard. Set the same position loop gain value
between interpolation axes.
When PGN1 is raised, the position tracking will improve, 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 that
occurs in the position loop is generally 10Hz or less. (The VIA vibration that occurs is 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 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 47 as a standard. If PGN1 is increased, the settling time will be
shortened, but a sufficient speed loop response will be required.
1 to 200
(rad/s)
SV004 PGN2 Position loop gain 2 Set 125 as a standard. (For SHG control) 0 to 999
SV057 SHGC SHG control gain Set 281 as a standard. (For SHG control) 0 to 1200
CAUTION
Always set the same value for position loop gain between 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
during spindle
synchronization
Set 15 as a standard. 1 to 200
(rad/s)
SV050 PGN2sp Position loop gain 2
during spindle
synchronization
Set 0 as a standard.
(For SHG control)
0 to 999
SV058 SHGCsp SHG control gain
during spindle
synchronization
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.