THORLABS TPZ001, User Manual

Page: 36 / 60

36 HA0143T Rev 12K Sept 2015
Chapter 5
5.6.4 Entering the piezo percentage position
1) Click the Set Arrow to display the Target window..
Fig. 5.14 Target Position Popup Window
2) Enter a position as a percentage of total piezo travel. This can be entered directly
into the field, or by clicking on the up/down arrows.
5.6.5 Setting the Position Sensor Zero
On actuators with position feedback, the position sensor is a strain gauge fitted to the
piezo actuator. The strain gauge may give a small signal when the actuator is at zero
position with zero volts applied (due to limitations in manufacture, or temperature
fluctuations). 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.
Each time the Strain Gauge T-Cube is powered up, the display will flash a default
reading until the position sensor is zeroed.
To zero the position sensor:
1) Ensure that the Piezo Driver T-Cube output is zero. Turn the OUTPUT control to
minimum and remove any input on the rear panel EXT IN connector.
2) Either press and hold the button on the Strain Gauge T-Cube, click the 'Zero'
button in the Strain Gauge T-Cube GUI panel, or call the 'SG_ZeroPosition'
method in the application software.
3) The display on the Strain Gauge T-Cube shows ‘
nULL
’ and counts down to zero.