Aerotech UNIDEX 600 Series, Руководство пользователя

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AerTune U600 User’s Guide
5-8
Aerotech, Inc.
Version 1.4
5.3.4. Identifying an Instability within the Servo Loop
Using the AerTune utility:
1. Activate the “Cursor” toolbar from the “Tools” menu.
2. Select “100 points” from the “Display” menu.
3. Exercise (move) the axis in question.
You may now utilize the FFT Analysis (Section 5.3.2.) selection on the Tools menu of
AerTune, or follow steps 4 and 5.
4. If a repeating sinusoidal waveform is now visible on the torque or velocity plots,
click (left mouse button) on the peaks of two sequential sinusoids.
5. The frequency of the disturbance will be displayed within the “F” frequency box
on the cursor toolbar.
Using the Aerotech Filter utility (Section 11.1):
6. Select the “Low Pass” radio button and enter a “Stop Freq” approximately 20 Hz
below the frequency determined from step 5. For example, if step 5 identified a
disturbance frequency of 170 Hz for the “Stop Freq”.
7. Click the “Calculate Coeff.” Button
8. The required values of the A1, A2, B0, B1, and B2 axis parameters will be
displayed. Enter these values into the axis parameters for the axis in question.
You should now be able to successfully Auto Tune the axis.
5.3.5. Minimizing Position Error due to Torque Ripple or Amplifier
Offsets
If the position error is a cyclic sinusoid repeating every electrical cycle of the motor, it is
most likely due to offsets in the amplifier current loop, or possibly poor Hall effect
alignment. One electrical cycle of the motor can be determined from Aerotech’s motor
specifications. Assuming that you do not have an inductive current probe, follow this
procedure:
Cycle the axis through multiple electrical cycles while monitoring the position error, in
AerTune:
1. Adjust the PHASEAOFFSET axis parameter for the axis +/- in increments of 50
till you minimize the position error as best you can.
2. Now do the same for the PHASEBOFFSET axis parameter for the same axis.
3. Repeat steps 1 and 2 with a +/- 25 increment of the parameters.
4. Repeat steps 1 and 2 with a +/- 10 increment of the parameters.
5. Repeat steps 1 and 2 with a +/- 5 increment of the parameters.