Electronics for piezoaction
Power supplies
Strain gage position detection
Closed loop positioning

Content

1.1 Analogue amplifiers SVR150/x
low power for ultra precision positioning
wide voltage range : -30 V / +150 Vvery low noise3

1.2 Analogue amplifier LE150/100
high power for enhanced dynamics
Unipolar output: 0V / +150 V
Low noise4

2. Strain gage amplifier DMS.x
for operating precision strain gages e.g. for piezo based
precision positioning tasks

5

3. Feedback controllers PosiCon 150/x

8for closed loop precision positioning, based on PIEZOMECHANIK strain gages
includes strain gage amplifier
feedback electronics
output -30V/+150 for max. stroke

On request
Electronics for -50V/+180V operating voltages up to +180V
SVR180/x -50V/+180V max. current 50 mA
LE180/080
0V/+180V max. current 800 mA

Electronics for even more power / higher current outputs
for highly dynamic piezo-excitation

2 electronics for piezoactionwww.piezomechanik.com

1.1 Analogue amplifiers SVR150/X

Max. semi-bipolar range-30V/+150V
for maximum stroke/force generation
Very low noise
Manual setting of DC-offset
Variable attenuation for input signal matching
SVR150/1
single channel
SVR150/3
three independent channels

Input:
Signal:Impedance:
Connector:+/–5 V (+/–10 V with attenuation)
5 kOhms
BNC

Output:Connector:
BNC
Voltage total:–30 V thru +150 V
DC-Offset range: –30 V thru +150 V
Gain:
30 (without attenuation)
Max. current:
60 mA
Noise:
0.3 mVpp (for 4.7 µFarad load)
Display:
LCD
Dimensions W x D x H (mm):single channel:
165 x 200 x 65
3-channels:
260 x 320 x 155
Weight:single channel:
1.75 kg
3-channels:
4.7 kgOn request
SVR180/x

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output -50V/+180V
max. current 50 mA

electronics for piezoaction: amplifier3

1.2 Analogue High Power Amplifier LE150/1

Voltage range
0V/+150V
Wide bandwidth up to 70 kHz(depends on capacitive load)
Low noise
Manual setting of DC-offset
Variable attenuation for input signal matching
Single channel device

Input:
Signal:Impedance:
Connector:+/–5 V (+/–10 V with attenuation)
5 kOhms
BNC

Output:Connector:
BNCVoltage total:
0 V thru +150 V
DC-Offset range: 0 V thru +150 V
Gain:
30 (without attenuation)
Peak current:
1200 mA
Average current: 350 mA
Noise:
20 mVpp (for 4.7 µFarad load)
Display:
LCD
Dimensions W x D x H (mm):260 x 320 x 165
Weight:6.8 kgOn request
LE180/080

4 electronics for piezoaction: amplifier

output0V/+180V
max. current 800 mA

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2. Strain gage amplifier DMS

DMS01
Single channel amplifier
W x D x H (mm) 120 x 120 x 60
weight 350 g(power supply included)
DMS03
Triple channel amplifier
W x D x H (mm) 240 x 120 x 60
weight 550 g(power supply included)

Strain gage amplifi ers DMS01 and DMS 03

Accessories● LEMO connectors 0S304 fitting to DMS signal

input sockets● 4-wire extension cables, shieldedwith LEMO 0S304 connector/coupler
length 2 m, 3 m, 4 m● 4-wire cables, shieldedwith one side LEMO 0S304 connector,1 side blunt
length 1.5 m (other lengths on request)

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electronics for piezoaction: DMS5

Strain and Position Detection● Analog Signal Output:● Variable gain

0V/+5V equivalent piezo actuator’s max. strain
Impedance: 1 kOhms
Connector BNC

The original signal height of a strain gage arrangement depends mainly on the strain gage
characteristics (k-factor) and the number of active
bridge elements (full bridge, half bridge, 2-quarterbridge etc).
The DMS-amplifiers shows a variable gain adjust foradapting the DMS output exactly to 0V / +5V range
for a defi ned piezo stroke/strain.

● Readout

3 1/2 digit LC-display
Amplifier adjusts via mini-potentiometers● Zero setting● Calibration of display for position readout

The absolute length of a piezo stack varies with thepreload conditions during mounting, thermal statusetc.
Therefore a zero point setting procedure can be
carried out for piezo actuator’s operation tocompensates for all mechanical offsettings during
the installation of the actuator.

● in µm

A steady or slow varying position with submicrometer resolution is shown in terms of fractionsof µm on a large LC-display.
A simple calibration procedure allows the user toadapt the readout to a distinct piezo actuator /sensor confi guration.
Power supply:
12V

Schematic arrangement of a 4 active elements
Wheatstone bridge

SGSGContacts:
Connector LEMO 0S 304 pin-numbers or
stranded wires/insulation color (for blunt ends)
Supply voltage inSignal out

SG

3 Lemo1 Lemo6 electronics for piezoaction: DMS

bridge diagonal 1-2 / red-black
bridge diagonal 3-4 / white-green

SG

4 Lemo2 Lemowww.piezomechanik.com

Position Sensing by strain gages

Strain gage circuits produce very small signals in
the mV and µV-range. A high quality amplifier likethe DMS device is needed to convert this original
signal into a reasonable standard analog output
voltage level (e.g. 5 V) or other kind of usable
information.
● All kinds of strain gages with a resistance of350 Ohms up to 5 kOhms can be operated by theDMS amplifiers.

● The DMS 01 and 03 amplifiers show high resolu-tion capability down to a strain variation < 10-6.
● High dynamics with a 30 kHz bandwidth.
● The DMS amplifiers are stand-alone devices.

This allows to locate the amplifiers rather near tothe strain gage arrangement independently ofother piezo-electronics. Hereby, any electricalnoise pick up due to long distances from gage toamplifier is strongly reduced.

● The DMS amplifi ers are a complete detection

units comprising the strain gage electrical supply
and the signal detection unit. No other attributes
are necessary to run a strain gage measurement.

4 active-elements strain gage-bridge configuration on apiezo stack Typical gage resistance: 1.2 kiloOhms.

www.piezomechanik.com►Therefore, the strain gage amplifiers DMS areexcellently suitable to be combined with piezo
actuator borne strain gages for high resolution,high dynamic position monitoring.

Basic position control equipment. Piezo-actuator withstrain gage position sensor. Position read out by DMS 01
unit. Piezo-actuator supply electronics SVR 150 (left).

electronics for piezoaction: DMS

7

3. Feedback controllers PosiCon 150/X

The “PosiCon” piezo positioning system is acomplete system comprising all necessary
electronic subsystems for closed loop piezo
actuator control:• position sensor signal amplifier stage• feedback control logic• piezo voltage amplifier• piezo voltage rage: -30V/+150V
For feedback/closed loop operation, the piezo
actuator must accept the voltage range of thePosiCon device and show option “positionsensor” (see actuator’s data sheet).
A wide range of positioning applications are covered with respect to precision and response time.
The amplifier stages provide semi-bipolar operation
for largest stroke and feature lowest noise for highly
stable positions together with a smooth reaction
characteristic of the positioning system.
Dual use:
The PosiCon devices can be operated in “closedloop” or “open loop” mode.
The mode selection is done simply by a switch on
the front panel.

3-channel PosiCon 150/3
The PosiCon-controllers are avaible assingle channel PosiCon 150/1
three channel PosiCon 150/3

For multichannel devices, each channel can be set
individually. In the “open loop” mode the PosiConacts as simple piezo amplifier.
Position information is provided even in the “openloop” mode (see “Display” and “Monitor”).

What are the advantages of the feedback controlled PosiCon systemPiezoactuators stroke is measured by a position
sensor (strain gage) applied directly onto thepiezostack inside the casing:
Hereby the sensor detects all internal andexternal effects influencing the strain status of
the stack:The result is a
● highly linear and reproducible motion of theactuator according the input reference signal(elimination of piezomaterials creep,hysteresis, nonlinearity).
● automatic selfcompensation for varying load

forces, potentially changing the strain of apiezo stack: the PosiCon system shows
virtually infinite stiffness (no change of strain
under varying forces).
8 electronics for piezoaction: PosiCon

Variety of piezoactuating components with surface
mounted strain gauges.

● Special thermally compensated strain gages

are used which compensate even for apotential thermal expansion of the actuator.
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Functional elements, operation“Open/closed loop” selector switch “Feedback”
Each channel of the PosiCon can be selected by aswitch for “open loop” or “closed loop” operation.
In the “open loop” mode, the PosiCon behaves likea normal piezo amplifier.
Position detection remains active, so position
information is provided via “LC-Display” and“Monitor”.
“Offset”
Closed loop operation:
A manual setting of the position can be done.
The position varies linearely with “Offset”, nohysteresis and creep.
Variations in position by varying load forces arecompensated for automatically.
The “offset” setting is superimposed to externalsignals.
Open loop operation:
A manual setting of the output piezo voltage can bedone.
The position of the actuator varies with “Offset”
resulting in the normal open loop behaviour withhysteresis and creep.
The “offset” setting is superimposed to externalsignals.
LC-displays
for individual “µm” and “Volt” reading per channel
Zero-setting:
The starting point of piezo actuator’s action candepend on various side conditions like mounting
forces, preloading etc.
To get a reasonable position read-out, each channel
for the PosiCon can be set to “zero” individually bya potentiometer in the front panel.
Gain factor:
The amplifier gain factor of each channel of thePosiCon can be set individually by a switch toaccept alternatively 5V or 10 V input signal for fullstroke action.
“Monitor”
Via BNC connectors on front and rear panel, analog
signals are provided as real time information for
position and piezovoltage for each channel
individually.
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Piezovoltage is reduced by a factor 1:1000.
Position is represented as a 5 V swing equivalent
full stroke.
Sensor input:
The PosiCon unit requires a signal from a 4 activeelement Wheatstone bridge for input.
This sensing element is usually applied to the piezo
actuator (Option: position detection).
But the sensor can be attached to an externalmechanism too.
Electrical connector, 4-pole LEMO 0S.304.
Piezovoltage output:
BNC.
Optionally, other connecting systems like
LEMO 00 250 are available.
Output voltage:
PosiCon 150: –30V thru +150V/
max. current: 60 mA
Calibration:
Calibration is only necessary to set the position
read outs of the PosiCon (“µm”-LCD and “Monitor”)
to the actuator performance.
Calibration is done at PIEZOMECHANIK factory andis valid for the distinct actuator-PosiCon
combination.
Uncalibrated systems work in “closed loop”
feedback mode too (compensation for hysteresis,creep etc.), only the position read outs are not valid.
Repeatability, Sensitivity
Precision means the tolerance range for hitting awanted position upon application of the equivalent
input signal.
A, for random access addressing of a position, thePosiCon system can show a repetition toleranceof about +/– 0.1%.
A 50 mm actuator can be operated within a+/– 50 nanometer tolerance field (residualhysteresis)
B, the repeatability is still better for cyclic motion
profilesC, the minimum resolvable relative shift in position
is about 5 nm in the closed loop mode.
electronics for piezoaction: PosiCon

9Precision positioning by piezoactuators

One essential feature of a piezoceramic actuatoris its ability to make infinitely small movements,
when a correspondingly small voltage signal isapplied.This feature enables piezoactuators forultraprecise positioning tasks (unlimited relativepositioning sensitivity).
On the other hand, when a large change in thevoltage signal is applied to a piezoactuator, theactual position stepwidth can be influenced by a lotof internal and external parameters acting onto theactuator, so that in the first instant, the relationshipbetween voltage and the induced motion can only
roughly be predicted. This can be easily
demonstrated by applying a series of random
voltage steps to a piezoactuator or by running acycle over a distinct voltage range producing thewellknown hysteresis loop.

Open loop correlation of piezo actuator’s position anddriving voltage for a sequence of random voltage steps.
The randomly generated sequence of points is filling up
the area envelopped by the hysteresis cycle.
Additionally the usual hysteresis cycle for a continuous fullscale voltage variation is shown.

To get this information about the actual position, theactuator is combined with a suitable kind of position
sensitive effect or sensor. “Suitable” means:sufficiently high in accuracy, repeatability, linearity.

signal. When there is a difference between wanted(reference) and real position, the feedback control
cancels it immediately out (closed actuator-sensor
loop operation) and the systems settles at theperfect position.

By a feedback control logic, the real position of theactuator is permanently compared with the wantedposition, defined by the magnitude of the input

Relation stroke – reference input voltage to a piezomechanical system in
A open loop operation (by standard amplifier or PosiCon
A in “feedback off” mode).
A Result: typical piezoactuator nonlinear hysteresis
A characteristic. Hysteresis about 15 %B closed loop operation of a PosiCon system together
B with an actuator with position sensor.
B Result: linear characteristic with a residual hysteresis:
B order of magnitude 0.1 % of actuators maximum stroke.

10 electronics for piezoaction: PosiCon

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Piezo actuators
Piezo data sheet● Ranging from bare elements for space-saving designs● up to contained versions● Wide spectrum of size
● Suitable for exotic driving conditions.

Summary
Use of cofired monolithic
piezo-ceramic stacks and chips

A few basics about cofired monolithic piezo-ceramic
actuators and chips regarding handling, properties,modifications, technology.

Overview

ExtendedPiezoaction in practiceThermograph of a dynamically operated piezo stack

More details on PZT- actuating structures, operating
parameters, design aspects, “must not”s and theinteraction between PZT-actuators and attachedmechanics as well as the importance of a well-adapted
electronics to get the optimum performance out of yoursystem.

PIEZOMECHANIK is a globally recognized supplier of first-class piezo systems.
Our actuator specialists are excellent connoisseurs of the current actuator scene.
This allows you to point out certain intricacies of the topic, which you will not find in the usual company scripts.
PIEZOMECHANIK successfully provides advice and development contributions even for unorthodox
piezoaktorian applications, some of which go far beyond the classical approaches.

Piezomechanik · Dr. Lutz Pickelmann GmbH
Berg-am-Laim-Str. 64 · D-81673 Munich · Phone ++ 49 /89 /4 3155 83 · Fax ++ 49 /89 /4 316412
e-mail: info@piezomechanik.com · http://www.piezomechanik.com

Stand: März 2021

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