6.1 Parameter
B6-29
ME0384-4A
[Positional Feedforward Gain (Parameter No. 71)]
No. Name Unit
Input range
Default initial value setting
Specifications
71
Positional feed
forward gain
－ 0 to 100
0
AC servo motor specification
Stepper motor specification
50
DC brush-less motor specification
Sets the feed forward gain amount of the position control system.
Performing this setting increases the servo gain and improves responsiveness of the position
control loop. Properly adjust Parameter No. 7 "Servo Gain Number" and Parameter No. 31
"Velocity Loop Proportional Gain", etc., to further improve the tact time and following
performance. As a result, positioning time can be shortened.
Gain adjustment of position, speed, and current loop in the feedback control directly changes
the response of the servo control system, so affecting the stability of the control system due to
inappropriate setting may cause vibration and abnormal noise. However, this parameter only
changes the speed command value, so it is irrelevant to the servo loop, and it does not make
the control system unstable or generate persistent vibration and noise. However, if the setting is
excessive, every time it operates, vibration and noise may be generated until the machine
follows the command value.
For the trapezoidal operation pattern, the value obtained by multiplying speed command by
"feed forward gain" is added to the speed command so as to reduce the following delay of the
speed and the position deviation.
Control delay occurs in feedback control that performs control according to the results. In
contrast, compensation control independent of control delay is performed.
Caution
● Vibration damping control function cannot be used when using feed forward gain
(setting other than 0).
Speed
Speed command value (trapezoid pattern)
Actual speed
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