Aerotech UNIDEX 600 Series, User Manual

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U600 User’s Guide AerTune
Version 1.4
Aerotech, Inc.
5-35
The initial setting of the Current Limit potentiometer is based upon the peak current
rating of the motor. If the user has a motor with a 10A peak current rating and a
DS16020, which has a maximum current output of 20A, set the Current Limit
potentiometer to midway for a representation of 10A. Then back it off 1/8 turn in the
CW direction. Full CW sets the minimum current and full CCW the maximum.
c. Adjust the Servo Gain (AC gain) potentiometer on the amplifier by first
enabling the axis and then turning the potentiometer CCW until the motor
oscillates (i.e., the axis vibrates). The motor will produce a screeching sound
when it oscillates. Back the gain off by turning it CW until the oscillation
stops. Make another 1/8 turn CW from that position so it’s not on the
borderline of having the motor oscillate.
5. Prepare the AerTune utility for tuning by performing the following steps.
a. Press the maximize button on the AerTune Window so that its window fills
the entire screen.
b. Use the Select pull-down menu to select the axis to be tuned.
c. Use the Show pull-down menu, to select Velocity Command and Position
Error.
d. Set the Distance and Speed entry fields for a typical move profile. Define
the desired AccelMode and DecelModes and enter the appropriate
Accel/Decel Rate/Times into the dialog boxes.
When the user selects the “Step+” or “Step-“ button, the axis moves the specified distance
and direction determined by the Step buttons (positive [+] or negative [-]).
6. Adjust the PGain servo loop parameter such that the position error is at zero at
or near the same time the Velocity Command is at zero. The adjustment to PGain
is made by entering a value in the PGain box. If PGain is set too high, the
position error will oscillate and the motor will vibrate. The user is not striving to
reduce the position error, although that will happen. However, the axis needs to
be rough tuned because the following step will be to fine-tune the potentiometers
on the amplifier.
Since all Servo Gains are set to zero, the user must set the PGain to an initial value,
otherwise the axis won’t move. A typical initial starting value is 5.
Once the axis begins moving, Pgain should be increased until the acual velocity
tracks the commanded velocity, with minimal position overshoot.
If the motor doesn’t move, then PGain is too low. Increase the value of PGain and try
again by pressing the “Step+” or “Step-“ button.
The axis may tend to drift away on its own when it is enabled. Adjusting the
DACOffset axis parameter will null the offset causing the drift.