sh030051g.pdf - 第156页
6 - 11 6. GENERAL GAIN ADJUSTMEN T 6.4 Interpolation mode The interpolation mode is used to match the position lo op gains of the axes when performing the interpolation operation of servo motors o f two or more axes for …
6 - 10
6. GENERAL GAIN ADJUSTMENT
(c) Adjustment description
1) Speed loop gain (VG2: parameter No.PB09)
This parameter determines the response level of the speed control loop. Increasing this value
enhances response but a too high value will make the mechanical system liable to vibrate. The actual
response frequency of the speed loop is as indicated in the following expression.
Speed loop gain 2 setting
Speed loop response
frequency(Hz)
(1 ratio of load inertia moment to servo motor inertia moment) 2
2) Speed integral compensation (VIC: parameter No.PB10)
To eliminate stationary deviation against a command, the speed control loop is under proportional
integral control. For the speed integral compensation, set the time constant of this integral control.
Increasing the setting lowers the response level. However, if the load inertia moment ratio is large or
the mechanical system has any vibratory element, the mechanical system is liable to vibrate unless
the setting is increased to some degree. The guideline is as indicated in the following expression.
2000 to 3000
Speed loop gain 2 setting/
Speed integral compensation
setting(ms)
(1 ratio of load inertia moment to
servo motor inertia moment 2 setting)
3) Model loop gain (PG1: Parameter No.PB07)
This parameter determines the response level to a position command. Increasing the model loop gain
improves track ability to a position command, but a too high value will make overshooting liable to
occur at the time of setting.
Model loop gain
guideline
Speed loop gain setting
(1 ratio of load inertia moment to servo motor inertia moment)
to
1
4
1
8
4) Model loop gain (PG1: parameter No.PB07)
This parameter determines the response level to a position command. Increasing position loop gain 1
improves track ability to a position command but a too high value will make overshooting liable to
occur at the time of settling.
Model loop gain
guideline
to
Speed loop gain 2 setting
1
4
1
8
(1 ratio of load inertia moment to servo motor inertia moment)
6 - 11
6. GENERAL GAIN ADJUSTMENT
6.4 Interpolation mode
The interpolation mode is used to match the position loop gains of the axes when performing the interpolation
operation of servo motors of two or more axes for an X-Y table or the like. In this mode, manually set the model
loop gain that determines command track ability. Other parameters for gain adjustment are set automatically.
(1) Parameter
(a) Automatically adjusted parameters
The following parameters are automatically adjusted by auto tuning.
Parameter No. Abbreviation Name
PB06 GD2 Ratio of load inertia moment to servo motor inertia moment
PB08 PG2 Position loop gain
PB09 VG2 Speed loop gain
PB10 VIC Speed integral compensation
(b) Manually adjusted parameters
The following parameters are adjustable manually.
Parameter No. Abbreviation Name
PB07 PG1 Model loop gain
(2) Adjustment procedure
Step Operation Description
1 Set to the auto tuning mode. Select the auto tuning mode 1.
2
During operation, increase the response level setting (parameter
No.PA09), and return the setting if vibration occurs.
Adjustment in auto tuning mode 1.
3 Check the values of model loop gain. Check the upper setting limits.
4 Set the interpolation mode (parameter No.PA08: 0000). Select the interpolation mode.
5
Set the model loop gain of all the axes to be interpolated to the same
value. At that time, adjust to the setting value of the axis, which has the
smallest model loop gain.
Set position loop gain.
6
Looking at the interpolation characteristic and rotation status, fine-adjust
the gains and response level setting.
Fine adjustment.
(3) Adjustment description
(a) Model loop gain (parameter No.PB07)
This parameter determines the response level of the position control loop. Increasing model loop gain
improves track ability to a position command but a too high value will make overshooting liable to occur
at the time of settling. The droop pulse value is determined by the following expression.
60
Rotation speed (r/min)
Model loop gain setting
Droop pulse value (pulse)
262144(pulse)
6 - 12
6. GENERAL GAIN ADJUSTMENT
6.5 Differences between MELSERVO-J2-Super and MELSERVO-J3 in auto tuning
To meet higher response demands, the MELSERVO-J3 series has been changed in response level setting
range from the MELSERVO-J2S-Super series. The following table lists comparison of the response level
setting.
MELSERVO-J2-Super MELSERVO-J3
Parameter No.9 setting
Guideline for machine resonance
frequency [Hz]
Parameter No.PA09 setting
Guideline for machine resonance
frequency [Hz]
1 10.0
2 11.3
3 12.7
1 15 4 14.3
5 16.1
6 18.1
2 20 7 20.4
8 23.0
3 25 9 25.9
4 30 10 29.2
11 32.9
5 35 12 37.0
13 41.7
6 45 14 47.0
7 55 15 52.9
16 59.6
8 70 17 67.1
18 75.6
9 85 19 85.2
20 95.9
A 105 21 108.0
22 121.7
B 130 23 137.1
C 160 24 154.4
25 173.9
D 200 26 195.9
27 220.6
E 240 28 248.5
29 279.9
F 300 30 315.3
31 355.1
32 400.0
Note that because of a slight difference in gain adjustment pattern, response may not be the same if the
resonance frequency is set to the same value.