Page 21
22882-D02
Single-Channel Piezo Controller, 75 V to 150 V
2) Notice how the total travel for the associated piezo is displayed in the ‘Travel’
window - see Fig. 4.2.
Fig. 4.2 Piezo Controller Software GUI
The APT User utility will be used throughout the rest of this tutorial to interface with
the piezo controller.
4.3 Setting the Position Sensor Zero
The position sensor is a strain gauge fitted to the piezo actuator. Due to limitations in
manufacture, the strain gauge may give a small signal when the actuator is at zero
position with zero volts applied. This ‘offset’ signal must be removed before the
position attained by a specific applied voltage and the position attained by a
corresponding specified distance can be rationalized.
Each actuator has a unique offset value. Therefore the offset should be adjusted
whenever an actuator is replaced. Temperature and prolonged use can affect the
performance of the strain gauge and therefore the offset value. It is good practice to
adjust the offset value whenever the unit is powered up.
To adjust the offset zero:
1) In the GUI panel, click the ‘Zero’ button. Notice that the led in the button flashes
to indicate that zeroing is in progress and the displayed position counts down
towards zero (but may not reach zero).
2) When the zeroing move has been completed, the ‘Zero’ LED is lit and the
controller switches to closed loop mode.
