Omron NJ501-1400 User Manual page 403

Problem
Operation cannot be
started, positioning is not
completed, or positioning
takes too much time to
complete.
Abnormal noise
Motor shaft shakes.
NJ-series CPU Unit Motion Control User's Manual (W507)
Cause
The in-position range of
the Servo Drive is too nar-
row, and thus the current
position does not enter the
in-position range. (The
current operation does not
complete until the current
position enters the in-posi-
tion range, so you cannot
start the next motion.)
Servo Drive gain is low.
The axis does not remain
in the in-position range
due to an external force.
Mechanical vibration
Insufficient adjustment of
the Servo Drive gain (high
gain)
Incorrect Servomotor
selection (adjustment not
possible).
Misalignment of the cou-
pling that connects the
motor shaft and machine
Insufficient adjustment of
the gain (low gain)
Gain cannot be adjusted
due to low machine rigid-
ity.
Mechanical configuration
prone to stick slip (highly
sticky static friction)
Incorrect Servomotor
selection (adjustment not
possible)
Failure
11 Troubleshooting
Item to check
---
---
Check the axis input infor-
mation for the Axis Vari-
ables to see if the
difference between the
command current position
and the actual current
position is within the in-
position range.
Check the moving parts of
the machine for intrusion
of foreign matter, dam-
age, deformation, and
loosening.
---
Select another motor
(check the torque and
inertia ratio).
---
---
In particular, this condi-
tion occurs on vertical
axes, SCARA robots, pal-
letizers, and other sys-
tems whose axes are
subject to bending or ten-
sional loads.
---
Select an appropriate
motor (check the torque
and inertia ratio).
---
Countermeasure
Increase the in-position
range.
Adjust the Servo Drive
gain.
If you stop the axis so that
a position inside the in-
position range is not
achieved, such as holding
control, you can use the
following error reset output
to forcibly achieve the in-
position range.
Correct the problem.
Perform auto-tuning. Man-
ually lower the gain.
Change to an optimal
motor.
Adjust the motor and
machine installation.
Perform auto-tuning. Man-
ually increase the gain.
Increase the machine
rigidity. Readjust the gain.
Perform auto-tuning. Man-
ually adjust the gain.
Change to an optimal
motor.
Replace the Servo Drive.
Replace the Servomotor.
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