PI PiezoWalk E-712 - Relax State and Relax Procedure; Simple Relax Procedure; Iterative Relax Procedure

User Manual
E712T0010, valid for E-712.N1, E-712.1AM, E-712.1AN, .2AN, .3AN
CMo, BRo, 10/31/2024
Physik Instrumente (PI) SE & Co. KG, Auf der Römerstraße 1, 76228 Karlsruhe, Germany page 12 / 40
Phone +49 721 4846-0, fax +49 721 4846-1019, e-mail info@pi.ws, www.pi.ws
INFORMATION
If the PiezoWalk Driving Mode parameter is set to nanostepping mode (1), after stepping motion in open-
loop operation a simple relax procedure (RNP command) is required before analog mode motion is possible.
Irrespective of the PiezoWalk Driving Mode selection, analog mode is applied by the iterative relax
procedure. This iterative relax procedure is started automatically when switching to open-loop operation
(set servo off with SVO) with axes driven by one PiezoWalk® drive and measured by one sensor.
4 Relax State and Relax Procedure
In the relaxed state, all piezo actuators of the piezo drive modules are in contact with the runner. The piezo
voltages for the clamping and shearing components are 0 V. The position is held stable without any supply
current, with maximum holding force. The relaxed state serves the following purposes:
 Provides defined transitions between the individual driving and servo modes
 Increases lifetime of the PiezoWalk® drives, minimizes heat generation, minimizes supply current
The relaxed state is achieved by a relax procedure which can be as follows:
4.1 Simple Relax Procedure
All piezo voltages are set to 0 V, with minimum motion of the runner. The position deviation can be up to 1 µm
after this procedure. The simple relax procedure is started as follows:
 In open-loop operation using the RNP command
 By switching to open-loop operation with
SVO <AxisID> 0
if the axis is driven by more than one PiezoWalk® drive and/or measured by more than one sensor
 In full-step mode performed automatically after the last step, irrespective of the current servo mode
selection. In closed-loop operation, afterwards the driving mode is switched to analog mode to reach the
target position.
4.2 Iterative Relax Procedure
This iterative procedure also sets all piezo voltages to 0 V, but tries to further minimize the position deviation
down to values in the range of 100 to 200 nm. For that purpose, it starts with the simple relax procedure, then
switches to closed-loop operation (analog driving mode by default) and afterwards repeats the simple relax
procedure (in open-loop operation). When the iterations are finished, the driving mode is switched back to the
mode which was active at the start of the procedure. For further details see below.
The iterative relax procedure is started by switching to open-loop operation with
SVO <AxisID> 0
if the axis is driven by one PiezoWalk® drive and measured by one sensor only.
During the iterative relax procedure, the servo mode is switched between closed-loop and open-loop operation.
The procedure ends in open-loop operation.