User manual of EL8-EC***F AC Servo
81
Pr1.09
Label
2
nd
Torque Filter Time
Constant
Mode
F
Range
0~2500 Unit
0.01ms Default
126
Index
2109h
Activation
Immediate
Position loop, velocity loop, velocity detection filter, torque command filter eachhave 2 pairs of
gain or time constant (1st
and 2nd).
Pr1.10
Label
Velocity feed forward
gain
Mode
PP
HM
CS
P
Range
0~1000
Unit
0.10% Default
300
Index
2110h
Activation
Immediate
Used for decreasing following error caused by low responsiveness of velocity loop. Might cause
overshoot or increase in noise if set value is too high.
Pr1.11
Label
Velocity feed forward
filter time constant
Mode
PP
HM
CS
P
Range
0~6400
Unit 0.01ms Default
50
Index
2111h
Activation
Immediate
Set velocity feed forward low pass filter to eliminate high or abnormal frequencies in velocity feed
forward command. Often used when position command with low resolution or high electronic gear
ration to smoothen velocity feed forward.
Position deviation under constant velocity can be lowered with higher velocity feed forward gain.
Please to refer to the equation below.
Position deviation[Uint]=
Pr1.12
Label
Torque feed forward
gain
Mode
PP PV HM
CS
P
CS
V
Range
0~100
0
Unit
0.1%
Default
0
Index
2112h
Activation
Immediate
Before using torque feed forward, please set correct inertia ratio. By increasing torque feed
forward gain, position deviation on constant acceleration/deceleration can be reduced to close to
0. Under ideal condition and trapezoidal speed profile, position deviation of the whole motion can
be reduced to close to 0. In reality, perturbation torque will always exist, hence position deviation
can never be 0.
