IAI America MSCON - Manual (Page 289)

Chapter 7 Parameter
281
No. Situation that requires
adjustment
How to Adjust
4 Abnormal noise is
generated.
Especially, when
stopped state and
operation in low speed
(less than 50mm/sec),
comparatively high
noise is generated.
x Input the “Torque Filter Time Constant”. Try to increase by 50 as
a reference for the setting. If the setting is too large, it may cause
a loss of control system stability and lead the generation of
vibration.
[Important] Prior to Adjustment:
This phenomenon is likely to occur when the stiffness of the
mechanical components is not sufficient. The actuator itself may
also resonate if its stroke is over 600mm or it is belt-driven type.
Before having an adjustment, check if:
1) The value for Parameter No.7 “Servo gain number”, Parameter
No.31 “Speed loop proportional gain”, or Parameter No.32
“Speed loop integral gain” are excessive.
2) The stiffness of the load is sufficient as much as possible, or the
attachments are not loosened.
3) The actuator unit is mounted securely with a proper torque.
4) There is no waviness on the actuator mounting surface.
Trace precision is
desired to be improved.
Equi-speed performance
is desired to be
improved.
5
Response is desired to
be improved.
x Make the condition optimized with Parameter No.7 “Servo gain
number” and Parameter No.31 “Velocity loop proportional gain”
adjusted by referring to the way to adjust stated in No.1 to 3 in
the previous page.
[Reference]
The most important factor is to select the actuator (motor).
The servo is extremely sensitive to the inertia of the load. If the
inertia moment of the load is too large in comparison with the
inertia moment of the servo motor itself, the motor is highly
affected by the load. This may cause the actuator to be
controlled unstably.
Therefore, to improve the precisions of the trace, position, speed
and response of the actuator, the load inertia ratio must be made
small.
Large static friction of
load makes actuator
start slowly.
Large load inertia makes
response of actuator low
at start and stop.
6
Takt time is desired to
be shortened.
x Set parameter No.71 “Feed forward gain”.
Select a value in the range from 10 to 50 roughly. The larger the
setting value is, the smaller the deviation is. Then the response
is improved.
Setting a large value may cause vibrations and/or noises to
occur.
Set the feed forward gain in order to improve the response of the
actuator further after adjusting Parameter No.7 “Servo gain
number” and Parameter No.31 “Speed loop proportional gain”. 
7 There is an impact at the
start or stop.
x Change the setting in Parameter No.55 “Position command
primary filter time constant” to approximately 50ms.
If there is no improvement in situation, try to increase the setting
gradually. If there is an improvement, try to decrease the setting
gradually to the boundary. Making a change to this setting will
make the settling time longer thus the takt time also becomes
longer. The accuracy for the positioning also becomes worse. It
is recommended, to solve the problem from the root cause, to
replace the host positioning unit with one that is equipped with
acceleration/deceleration function.