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9. Adjustment 
 
 
 
 
 
9 - 27
 
(2)  Acceleration feed forward 
 
Vibration may occur at 10 to 20 Hz during acceleration/deceleration when a short time constant of 
30 ms or less is applied, and a position loop gain (PGN1) higher than the general standard value or 
SHG control is used. This is because the torque is insufficient when starting or when starting 
deceleration, and can be resolved by setting the acceleration feed forward gain (SV015 (FFC)). 
This is also effective in reducing the peak current (torque). 
 
While measuring the current command waveform, increase FFC by 50 to 100 at a time and set the 
value where vibration does not occur. 
 
100
80
60 
40 
20
0
Time (ms) 
200 
100 
100
80
60
40 
20 
0
 
 
200
Current 
command 
(%) 
 
100
 
0
 
 
 
Time (ms) 
 
 
 
 
    No FFC setting  
 
 
With FFC setting 
 
 
Acceleration feed forward gain means that the speed loop gain during acceleration/deceleration is 
raised equivalently. Thus, the torque (current command) required during acceleration/deceleration 
starts sooner. The synchronization precision will improve if the FFC of the delayed side axis is 
raised between axes for which high-precision synchronous control (such as synchronous tapping 
control and superimposition control). 
 
No. 
Abbrev. 
Parameter name 
Explanation 
Setting range
SV015 FFC Acceleration 
rate 
feed forward gain 
When a relative error in the synchronous control is large, apply this 
parameter to the axis that is delaying. The standard setting value is “0”.  
For the SHG control, set to "100". 
To adjust a relative error in acceleration/deceleration, increase the value 
by 50 to 100 at a time. 
0 to 999 
(%) 
 
 
 
POINT
 
Overshooting occurs easily when a value above the standard value is set during 
SHG control.