Mitsubishi Electric MELSERVO-J4 series, Instruction Manual

Page: 245 / 646

6 NORMAL GAIN ADJUSTMENT
6.4 Manual mode
243
6
■
Parameter adjustment
• [Pr. PB09 Speed loop gain]
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.
• [Pr. PB10 Speed integral compensation]
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 to motor inertia 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.
• [Pr. PB07 Model loop gain]
This parameter determines the response level to a speed command. Increasing the value improves trackability to a speed
command, but a too high value will make overshoot liable to occur at settling.
For position control
■
Parameter
The following parameters are used for gain adjustment.
■
Adjustment procedure
Parameter Symbol Name
PB06 GD2 Load to motor inertia ratio/load to motor mass ratio
PB07 PG1 Model loop gain
PB08 PG2 Position loop gain
PB09 VG2 Speed loop gain
PB10 VIC Speed integral compensation
Step Operation Description
1 Brief-adjust with auto tuning. Refer to the following.
 Page 239 Adjustment procedure by auto tuning

2 Change the setting of auto tuning to the manual mode ([Pr. PA08]: _ _ _ 3).

3 Set the estimated value to the load to motor inertia ratio/load to motor mass ratio. (If the estimate
value with auto tuning is correct, setting change is not required.)

4 Set a small value to the model loop gain and the position loop gain. Set a large value to the speed
integral compensation. 
5 Increase the speed loop gain within the vibration- and unusual noise-free range, and return slightly if
vibration takes place. Increase the speed loop gain.
6 Decrease the speed integral compensation within the vibration-free range, and return slightly if
vibration takes place. Decrease the time constant of the speed
integral compensation.
7 Increase the position loop gain, and return slightly if vibration takes place. Increase the position loop gain.
8 Increase the model loop gain, and return slightly if overshoot takes place. Increase the model loop gain.
9 If the gains cannot be increased due to mechanical system resonance or the like and the desired
response cannot be achieved, response may be increased by suppressing resonance with the
adaptive tuning mode or machine resonance suppression filter and then executing steps 3 to 8. Suppression of machine resonance
 Page 247 Machine resonance
suppression filter
 Page 250 Adaptive filter II
10 While checking the settling characteristic and motor status, fine-adjust each gain. Fine adjustment
(1 + Load to motor inertia ratio) × 2
π
Speed loop gain
Speed loop response frequency [Hz] =
2000 to 3000
Speed loop gain/(1 + Load to motor inertia ratio)
Speed integral compensation setting [ms]
≥
(1 + Load to motor inertia ratio)
Speed loop gain
8
1
4
1
to × Model loop gain guideline
≤