IAI America PCON-CA - Manual (Page 203)

Chapter 7 I/O Parameter
POWER CON
PCON-CA/CFA
195
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.
Ɣ 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 (Note 1) “Velocity loop proportional gain””, or
“parameter No.32 (Note 1) “Velocity 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.
Ɣ Make the condition optimized with Parameter No.7 “Servo gain
number” and Parameter No.31 (Note 1) “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.
For high trace precision, equi-speed performance, and response
of the actuator in such a use as application, it is better to use ball
screws with small leads in the actuator as much as possible and
an actuator of motor capacity higher by at least one level.
The best method is to calculate the load inertia to select the
proper actuator.
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.
Ɣ 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 (Note 1) “Velocity loop proportional
gain”.
Note 1 For the actuators (RCP4) available for high output, set four sets of Velocity Loop
Proportional Gain and select a parameter to use. [Refer to Item [88] in 7.2 Detail
Explanation of Parameters for the details.]