Справочник Пользователя для Mitsubishi Electronics IB-1500193(ENG)-D

4 - 42

If the motor and machine coupling or machine system's rigidity is low (ex. large machine, etc.) when using a 

closed loop system, the response during acceleration/deceleration will vibrate and cause overshooting. This 

can cause the position loop gain from increasing. The dual feedback function is effective in this case.

To validate the dual feedback function, use position feedback with a motor side detector in ranges with high 

acceleration to enable stable control. In ranges with low acceleration, use position feedback with the 

machine side detector (scale). This will make it possible to increase the position loop gain.

The state will approach the semi-closed loop system as the primary delay filter's time constant increases, so 

the position loop gain limit will increase. Note that the limit of the position loop gain increased with the dual 

feedback function is the same as the position loop gain limit for a semi-closed system that does not use a 

machine side detector (scale, etc.). In addition, the positioning time will increase as the primary delay filter 

time constant increases.

1. Dual feedback control is a function that compensates symptoms resulting from insufficient machine 

rigidity. If there are items that can be improved on the machine (improvement of scale installation 

position, etc.) improve those first.

2. The position loop gain limit will not increase compared to the semi-closed loop system even when 

using dual feedback control.

ENC  

SV051 

+

+

+

-

-

-

Position control  

Primary 
delay filter  

High frequency 
FB element  

Position 

command 

Position droop  

Servo  

motor  

Linear scale  

Table  

Speed 
command 

Position FB

Position FB

Low
frequency FB
element