Mitsubishi Electronics MR-J2S- A For position control, Suppression of machine resonance

7. GENERAL GAIN ADJUSTMENT

(c)Adjustment description

1) Speed control gain 2 (VG2: parameter No. 37)

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 response frequency(Hz)	VG2 setting
	(1 ratio of load inertia moment to motor inertia moment) 2

2) Speed integral compensation (VIC: parameter No. 38)

To eliminate stationary deviation against a command, the speed control loop is under proportional integral control. For the speed integral compensation (VIC), 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:

VIC setting(ms)	2000 to 3000
	VG2 setting/ (1 GD2 setting 0.1)

(2) For position control

(a) Parameters

The following parameters are used for gain adjustment:

Parameter No.	Abbreviation	Name
6	PG1	Position control gain 1
34	GD2	Ratio of load inertia moment to servo motor inertia moment
37	VG2	Speed control gain 2
38	VIC	Speed integral compensation

(b) Adjustment procedure

Step	Operation	Description
1	Set an estimated value to the ratio of load inertia moment to servo
	motor inertia moment (parameter No. 34).
2	Set a slightly smaller value to the position control gain 1 (parameter
	No. 6).
	Increase the speed control gain 2 (parameter No. 37) within the	Increase the speed control gain.
3	vibration- and unusual noise-free range, and return slightly if vibration
	takes place.
4	Decrease the speed integral compensation (parameter No. 38) within	Decrease the time constant of the speed
	the vibration-free range, and return slightly if vibration takes place.	integral compensation.
5	Increase the position control gain 1 (parameter No. 6).	Increase the position control gain.
	If the gains cannot be increased due to mechanical system resonance or	Suppression of machine resonance
	the like and the desired response cannot be achieved, response may be	Refer to Section 8.1.

6increased by suppressing resonance with adaptive vibration suppression control or machine resonance suppression filter and then executing steps 3 to 5.

7	While checking the settling characteristic and rotational status, fine-	Fine adjustment
	adjust each gain.

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