9 Adjustments
9.4.8 Speed Feedback Compensation
9-20
• Adjustment Procedure
The following procedure explains how to adjust when the speed loop gain cannot be increased due to vibra-
tions in the mechanical system. When adding a speed feedback compensation, observe the position error and
torque reference with the analog monitor while adjusting the servo gain. Refer to
9.5 Analog Monitor
on
monitoring the position error and torque reference.
1. Set parameter Pn110 to “0002” so that the following conditions are satisfied.
• To use the speed feedback compensation
• Not to use the online autotuning function
2. With PI control, gradually increase the Speed Loop Gain in Pn100 and reduce the Speed Loop Integral
Time Constant Pn101, so that the setting the Position Loop Gain in Pn102 to the same value as that of the
Speed Loop Gain in Pn100.
Use the result from the following equation as an initial estimate when setting the Speed Loop Integral
Time Constant in Pn101.
Speed loop gain units: Hz
Check the units when setting the Speed Loop Integral Time Constant in Pn101. The value in Pn101 is set
in units of 0.01 ms.
Set the same value for the speed loop gain and position loop gain even though the speed loop gain units
(Hz) are different form the position loop gain units (1/s).
3. Repeat step 2 to increase the speed loop gain while monitoring the settling time with the analog monitor’s
position error and checking whether vibration occurs in the torque reference. If there is any vibrating
noise or noticeable vibration, gradually increase the Torque Reference Filter Time Constant in Pn401.
4. Gradually increase only the position loop gain. When it has been increased about as far as possible, then
decrease the Speed Feedback Compensation in Pn111 from 100% to 90%. Then repeat steps 2 and 3.
5. Decrease the speed feedback compensation to a value lower than 90%. Then repeat steps 2 through 4 to
shorten the settling time. If the speed feedback compensation is too low, however, the response waveform
will oscillate.
6. Find the parameter settings that yield the shortest settling time without causing vibration or instability in
the position error or torque reference waveform being observed with the analog monitor.
7. The servo gain adjustment procedure is complete when the positioning time cannot be reduced any more.
The speed feedback compensation usually makes it possible to increase the speed loop gain and position loop
gain. Once the speed loop gain and position loop gain have been increased, the machine may vibrate signifi-
cantly and may even be damaged if the compensation value is changed significantly or Pn110.1 is set to “1”
(i.e., speed feedback compensation disabled).
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Speed loop integral time constant (Pn101)
4000
2
Pn100
IMPORTANT
Summary of Contents for Sigma-II Series
Page 384: ...8 3 8 Operation...
