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LPS710E Long Travel Piezo Stage and Controller
The following section describes details a typical tuning procedure
1) Mount the stage to the worksurface.
2) Weigh and note the load, then attach the load to the stage.
3) Connect the stage to the controller.
4) Switch on the controller and leave to warm up in open loop mode (default) for at
least 30 minutes.
5) Run the APT software.
6) In the Settings panel, ensure that the Notch Filter 1 and Notch Filter 2 are ticked
as "Enabled" - see Section 5.2.2.
7) Set the notch filter central frequency as explained in Section 5.2.2.
8) Set the PID parameters as explained in Section 5.2.2.
9) Switch to closed loop mode.
10)The stability of position display should be better than ± 0.02 µm with a stable
worksurface. While monitoring the position display on the APT GUI, reduce P and
I parameters one at a time, by 10% steps to optimise display jittering.
11)To ensure the settling time is optimised, increase P, I and D with 10% increments
until position display indicates a large ringing effect, in the range of microns.
Consider this point as threshold for stability.
12)Reduce the threshold values by 10% to 20%, to ensure a safe margin and a fast
response is guaranteed.
13)In case of a high level ringing, e.g. amplitude in order of 10s of microns (especially
if it is audible), switch to Open Loop mode, set parameters as explained above,
then switch back to Closed Loop. In such situations, it is advisable to have starting
P, I and D parameter values well below the last set of values that caused ringing.
4.5 Limitations on the Displayed Position Values
The controller can report small negative position values and APT can display these;
however negative position values below approximately 4% of the full travel range (i.e.
more negative than -32 um for a 800 um stage) might be clipped and therefore
incorrect. Position values above the maximum travel range are clipped to the
maximum travel. In other words, the position display is clipped to -4% to +100% of the
maximum closed loop travel range.
Warning
Prolonged high amplitude vibration (audible ringing) could damage the piezo.
