Mitsubishi Electric MELSERVO MRJ2S-B, Instruction Manual

Page: 118 / 200

Operation Gain
4 - 32
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Position control
The following table gives an overview of the parameters used for position control for the manual
setting of the gain factor.
For the setting please follow the instructions which are given below:
Set an estimated value to the ratio of inertia (parameter No. 12).
Set a slightly smaller value to the position control gain 1 (parameter No. 13).
Set pr. 16 to a low value in the vibration- and noise-free range. Increase the value gradually
and reduce it again as soon as vibrations set in. The optimum value is reached shortly before
vibrations set in.
Set pr. 17 to a value in the vibration- and noise-free range. Decrease the value gradually
and increase it again as soon as vibrations set in. The optimum value is reached shortly
before vibrations set in.
Increase the position control gain 1 (parameter No. 13)
If the gain cannot be increased due to mechanical system resonance and the desired
response cannot be achieved used the low-pass filter (parameter No. 25) or the machine
resonance suppression filter (parameter No. 18) for executing steps
to .
While checking the settling characteristic and rotational status, fine-adjust each gain.
The response level of the position control loop is specified via the gain factor PG1 (pr. 6).
Increasing position control gain 1 improves trackability to a position command but a too high
value will make overshooting liable to occur at the time of settling. The position control gain PG1
is as indicated in the following expression:
The response level of the revolution speed control loop is specified via the gain factor VG2
(pr. 16). Increasing this value enhances response but a too high value will make the mechanical
system liable to vibrate. The response frequency of the speed loop is as indicated in the
following expression:
The setting of the I-portion of the speed control loop VIC occurs via pr. 17 and can be calculated
as follows:
Parameter Symbol Name
12 GD2 Ratio of load inertia moment to servo motor inertia moment
13 PG1 Position control gain 1
16 VG2 Speed control gain 2
17 VIC Speed intergral compensation
Tab. 4-20: Parameter adjusted for position control
PG1
VG2
1 ratio of inertia +
( )
--------------------------------------------------
1
3
---
to
1
5
---
⎝ ⎠
⎛ ⎞
× ≤
speed loop response frequency [Hz]
VG2
1 ratio of inertia +
( )
2
π ×
---------------------------------------------------------------- =
VIC [ms]
2000 to 3000
VG2 1 GD2 +
( ) ⁄
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