Piezo Amplifiers and ControllersSTANDARD AND OEM SOLUTIONS

FAST

PREC ISE

IND IV IDUAL

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PI: Piezo Technology and Precision Positioning

Precision Motion Control for Science and Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Standardized Measurement Logs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Service: Custom-Engineered Products, Certification, Updates, Support . . . . . . . . . . . . . . . . 4

Stability and Precision

Piezo Amplifiers and Controllers for Nanopositioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Product Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Piezo Actuators Out of the Ordinary? Amplifiers and Controllers for ...

Patch Transducers, Bender Actuators, Shear Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

High-Voltage, High-Load Actuators, Bipolar Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Benders, Evaluation of Piezoresistive Sensors, Shaker and Pump Applications . . . . . . 10

Dynamics and Precision for Switching Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Powerful Duo for Continuous Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Solutions for High-Dynamics 24/7 Operation

Switched Amplifiers with Energy Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Product Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Linearized Amplifiers for Piezo Displacement Without Hysteresis

Digital Controllers – Precision, Dynamics and Ease of Operation

Digital Data Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Product Overview and Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

“High-End” or “Low-Cost”? Controller Performance Made to Measure . . . . . . . . . . . . 17

Digital Out of the Ordinary: Controllers for Piezo Stepping and Ultrasonic Drives . . . . 18

Selection Criteria for Piezo Amplifiers and Controllers from PI . . . . . . . . . . . . . . . . . . . . . . 19

Contents

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Piezo, Nano, Positioning

PI offers the world’s largest selectionof positioning and drive systems for pre-cision positioning in the accuracy rangefrom a micrometer down to below a nano-meter.

Piezo actuators are used in a wide range ofintegration levels, be it as direct drive or withlever amplification for greater travel, insingle-axis and multi-axis positioners, withand without position measurement. Piezostepping and ultrasonic drives as well asconventional motors, and their combina-tions, enable PI to provide custom-engineeredpositioning systems. The requirements ofbiotechnology, semiconductor industry,optical metrology or astronomy have onething in common here: The high degreeof precision required and PI as the supplierof the solution.

Just as Flexible as the Drive: The Control

Fast settling or slow speed with high con-stancy, high positional stability, high resolu-tion and high dynamics – the requirementsplaced on piezo systems vary greatly andneed a control with a high degree of flexibi-lity.

PI therefore offers a broad spectrum of piezoelectronics from very versatile controllers tohighly specialized ones: As an OEM boardfor integration, a plug & play bench-top de-vice or in modular form to control almostany number of axes of motion.

Safety, Quality and Responsibility

As far as PI is concerned, the certification ofa quality management system is a commit-ment to continuously improve products andprocesses. Suppliers are integrated into thedevelopment process in order to transfer PI’shigh standards to them. PI’s absolute com-mitment to quality leads it to train its ownstaff in Development and Production, pro-vide laboratories for EMC – instrumentsafety tests and environmental tests, andalso use the latest CAD and simulation tools.A commitment which is crucial for thoseworking in the field of nanotechnology.

Piezo Technology andPrecision Positioning

PREC IS ION MOT ION CONTROL FOR SC IENCE AND INDUSTRY

Modular, digital multi-axis controls with integrated coordinate transformation simplify theoperation of complex parallel-kinematics systems, such as this Hexapod with NEXLINE®piezo stepping drives.

High dynamics PIFOC® objectivescanner and OEM controller.The power supply of the control-ler is usually integrated directlyon the circuit board, the sameapplies to open OEM versions.The operation of the piezo systemthen only requires a stabilizedvoltage of 12 or 24 V.

All PI products are sub-ject to a unrelenting up-dating and developmentprocess which serves tocontinuously improvethese products. Stream-lined manufacturing pro-cesses together with theIntegrated ManagementSystem (certificationaccording to ISO 9001,ISO 14001 and OHSAS18001) ensure high deli-very reliability and qua-lity “made in Germany”.

Nanopositioning systems are an essentialbut costly component in applications. PItherefore individually tests and optimizes thestatic and dynamic parameters of every sys-tem. The measurement log is delivered withthe system. The customer can thereforeretrace the performance of the system atdelivery and which system components be-long together at any time.

PI continually invests in improving the tes-ting methods and testing equipment in orderto be able to supply systems of even higherquality.

Closed-loop nanopositioning systems aretested exclusively with high-quality cali-brated interferometers. The test laboratoriesare insulated against seismic, electromag-netic and thermal effects, temperature stabi-lity is better than 0.25°C in 24 hours.

PI thus sets the standard in the testing andspecification of nanopositioning products.

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PI Nanopositioning systemsare tested before shipping,the relevant log is included inthe delivery.

The scope of supply of a PI system consistingof controller and stage includes everythingrequired to operate it.

� External power supplies

� All power, communication and systemcables

� The comprehensive operating manual inprinted form

� Software CD with set-up function

When developing the instruments, top pri-ority is given to the use of state of the artcomponents. This ensures the systems havea long availability and replaceability evenbeyond the product lifecycle. All positioningsystems from PI’s standard range fulfill theCE and RoHS provisions.

Customized product developments andadaptations are an important part of ourtechnical progress.

We therefore offer

� The complete range of our productspectrum from electronic componentsand complete devices as OEM circuitboard through to the modular encasedsystem.

� Production of small batchesand large series

� Product development according to specialproduct standards (national or market-specific standards such as the MedicalDevice Act, for example) and the corres-ponding certification

� Adaptation of the systems to specialenvironmental conditions (vacuum, space,clean room)

� Copy-exactly agreements

The latest firmware, software and operatingmanual versions are available free of chargevia the Internet. Firmware updates can easilybe carried out via the standard interfaces ofthe controller.

PI offers comprehensive software support. PIsoftware is included in the scope of supplyfor digital equipment and is used to start upthe system and also to analyze and optimizethe system’s behavior. DLLs, LabVIEWdrivers or the support of MATLAB make iteasier to program the system.

PI software is, of course, compatible with thelatest Microsoft operating systems and canalso be operated under LINUX.

Contact

If you have any furtherquestions, please con-tact us at info@pi.ws orinfo@piceramic.de. Ourtechnically experiencedsales staff possesses awide range of applica-tion knowledge and willprovide you with expertadvice.

Standardized Measurement LogsThe Good Feeling when Your Expectations Are Met

Service

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The characteristic properties of piezo actua-tors include the generation of large forcesand fast response. In electrical terms a piezoelement corresponds to a capacitance.A rapid change to the operating voltagebrings about a rapid displacement of theactuator and thus a change in position.When the control voltage suddenly increa-ses, the piezo actuator can achieve its nomi-nal displacement in only a fewmicroseconds.Requirement prerequisite for this is that thepower supply provides sufficient current tocharge the capacitance. In static operation,i.e. when a certain position is maintained,the stability of the power supply is also de-cisive. Noise or drifting must be avoided asfar as possible.

Amplifier Electronics Determine PositionalAccuracy and Dynamics

The control electronics are thus crucial forthe performance of piezo actuators and na-nopositioning systems or tip/tilt-mirrorswhich are based on them. High-stability am-plifiers are required because piezoelectricactuators react to even the smallest changein voltage with a movement. The characte-ristics of the amplifier electronics used thusessentially determine the positional accu-racy and dynamics which a piezo-driven na-nopositioning system can achieve.

Precision in the Positioning or SwitchingFunction: With or Without Servo Loop

At the same time, when selecting suitableamplifier electronics it is necessary to bearin mind that piezo actuators do not exhibit alinear relation between voltage increase andchange in position. This is irrelevant e. g. forswitching applications, like in injectionvalves, that manage quite well withoutclosed-loop operation. The situation isdifferent for accurate positioning tasks,where non-linear characteristics such as hys-teresis, load variations and drift effects mustbe controlled by comparing the specifiedposition (target value) with the positionmeasured by the sensor (actual value). PI’sclosed-loop piezo positioning systems allowrepeatabilities down to the sub-nanometerrange, a non-linearity to below 0.01 % andbandwidths up to 10 kHz.

Up to three E-500 piezo amplifier modulescan be installed in one E-500 chassis. A servo-control submodule for the closed-loop opera-tion or a display and interface submodule canalso be easily installed if required.

Modular Design for Flexibility

The powerful E-505 piezo amplifier modulecan output and sink peak currents of 2 A in avoltage range between -30 and 130 V.

PI provides piezo amplifiers in a wide range of versions:Boards, OEM and bench-top equipment, as well as special adaptations for the customer.

Stability and PrecisionP IEZO AMPL IF IERS AND CONTROLLERS FOR NANOPOS IT ION ING

Piezo amplifiers andcontrollers provide:

� High linearity

� Positioning with sub-nanometer accuracy

� High long-term stability

� Noise approx. 1 mV(RMS value)

� Low power consumption

� Notch filter for higherbandwidth

� Analog interfaces forfast direct commandingin real time

� Short-circuit proof

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Each application has different requirementsin relation to precision, peak current andvoltage, dynamics and linearity, and so thereis no universal control electronics which isequally well suited to all fields of application.PI therefore provides a large selection ofdigital and analog piezo linear amplifiersand piezo controllers.

High-Resolution Signal Processingin Real Time

The high-dynamic operation of piezo actua-tors demands that the charge of their capa-citances can be quickly changed, whichin turn requires very high peak currents.

Analog piezo amplifiers and controllers fromthe PI range are the best option for a widevariety of applications, ranging from high-dynamics switching operation to closed-looppositioning. They do not require analog-to-digital conversion and therefore providehigh-resolution signal processing in realtime. Different designs, output voltages from130 V to 1100 V, different bandwidths and in-terfaces ensure that a custom-made solutionwhich is matched to the piezo actuator tech-nology used can be found for every applica-tion. At the heart of these systems arevery low-noise and high-linearity amplifierelectronics.

Single-Channel Servo Controller E-610The E-610 piezo amplifiers and servo con-trollers integrate a low-noise piezo amplifierwhich outputs and sinks peak currents of140 mA in the low-voltage range.

Piezo Controller E-625 Provides Analogand Digital InterfacesThe single-channel E-625 piezo controller isequipped with a RS-232 and USB interfaceand precision 24-bit A/D converters for ex-ceptional positional stability and resolution.It has an integrated low-noise piezo ampli-fier which can output and sink peak currentsof 120 mA. Servo-controller versions for po-sition sensing with capacitive or SGS sen-sors are available.

� Cost-effective single-channelOEM solution

� Open-loop versions or closed-loopversions for SGS & capacitive sensors

� Notch filter for higher bandwidth

� 18 W peak power

� Integrated 24 bit USB interface

� Network capability with up to12 channels

� 12 W peak power

� Position control for strain gauges &capacitive sensors

� Notch filter for higher bandwidth

� Internal table stores user-defined curves

� Additional broadband analog interface

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Product Examples for Analog Electronics

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Servo-Controller OEM Custom Modelwith Position ControlSpecifically matched to the application:Small package and interfaces to customerspecifications. The functionality is derivedfrom the E-610 standard model.

Powerful Computer Interface,NetworkableThe E-621 is equipped with an RS-232 inter-face and precision 24 bit D/A and A/D con-verters for exceptional positional stabilityand resolution. It has an integrated low-noise piezo amplifier which can output andsink peak currents of 120 mA. Servo-control-ler versions for position sensing with capa-citive or SGS sensors are available.

� Analog electronics with digital interfaces

� One interface to host several channels

E-831 Miniature Module� Open-loop control

� Separate power supply for up to threeelectronics with up to -30 / +130V outputvoltage

� Bandwidth up to several kHz

� For capacitances of up to 20 µF

� Cost-effective 1-channel OEM solution

� Fixed notch filters for higher bandwidth

� Position servo-control for strain gaugesensors

� 8 W peak output power

� Power supply integrated on the circuitboard

� Power can be uprated

� Modular design

� Integrated 24 bit USB interface

� Up to 12 channels in one rack,networkable

� Up to 12 W peak output power

� Position control for strain gauges &capacitive sensors

� Notch filter for higher bandwidth

� Additional broadband analog interface

� Table for user-defined curves

E-660 OEM Module for Quasi-StaticControl� +5 to +110 V

� Plug-in contacts for installation oncircuit board

� Power supply included;battery operation possible

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Piezo Actuators Out of the Ordinary?AMPL IF IERS AND CONTROLLERS FOR PATCH TRANSDUCERS, BENDER ACTUATORS,

SHEAR ACTUATORS

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Bipolar Operation for PiezoelectricDuraAct Patch TransducersDuraAct elements can be used as actuators,sensors or energy harvesters.

E-413 Piezo Amplifier for DuraActand PICA ShearShear actuators offer high linearity, highdynamics and stiffness.

E-650 Piezo Amplifier for MultilayerBender ActuatorsBender actuators with multilayer con-struction provide large travel ranges withmedium forces, e.g. for dynamic switchingapplications.

� OEM module E-835

� Peak output power up to 30 W

� Output voltage range -100 to +250 V

� Compact: 87 x 50 x 21 mm

� High bandwidth of up to 4 kHz and more

� Output voltage range -100 to +400 V or± 250 V

� Peak output power up to 50 W

� OEM module / bench-top for PICA shearactuators

� OEM module for piezoelectric DuraActpatch transducers

� Specifically designed to drive multilayerbimorph actuators without position sen-sor

� Output voltage range 0 to 60 V

� Dual-channel bench-top version or OEMversion for soldering onto circuit board

� Up to 18 W peak output power

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Piezo Actuators Out of the Ordinary?AMPLIF IERS AND CONTROLLERS FOR HIGH-VOLTAGE, HIGH-LOAD ACTUATORS, BIPOLAR CONTROL

E-421, E-471 Modular High-Power PiezoAmplifier / ControllerHigh-load piezo actuators are designed fordynamic operation. They achieve forcegeneration of up to 30,000 N.

E-536 PicoCube® Piezo Controller:High Dynamics and Resolution in up toThree AxesPicoCube® scanner and positioning systemsprovide sub-nanometer accuracy in up tothree axes, e.g. for scanning force micros-copy.

E-616 Multi-Channel Amplifier forPiezo Tilt MirrorFast tilting about two axes and linear posi-tioning for laser beam control.

� Peak output power 550 W

� Output voltage 3 to 1,100 V & bipolar

� Optional: Position control,digital interfaces, display

� Output voltage -250 / +250 V,for PicoCube® P-363 systems

� Versions:

- Peak output power up to 3 x 100 Wfor high-dynamics operation

- Minimal noise below 3 mVpp forhigh-resolution positioning

� OEM electronics with coordinate transfor-mation

� Three integrated amplifiers provide up to10 W peak output power

� Closed-loop and open-loop versions

� Closed-loop control for parallel-kinematics designs (three and four struts)

� Compact and cost-effective design forOEMs or bench-top

� Integrated power supply

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AMPL IF IERS AND CONTROLLERS FOR BENDERS, EVALUAT ION OF P IEZORES IST IVE SENSORS,

SHAKER AND PUMPING APPL ICAT IONS

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E-545 PInano® Piezo ControllerPInano® positioning systems for high-reso-lution microscopy provide coarse as well asfine positioning.

OEM Shaker Electronics for UltrasonicTransducersThe voltage range can be matched to thedisplacement required.

Driving MicropumpsPiezo elements are ideal drives for miniatu-rized pumping and dosing systems.

� 3 channels with 14 W peak power, USBinterface

� TCP/IP, USB and RS-232 interfaces

� Low-noise 24-bit D/A converter

� 25 kHz sample rate

� Notch filter for higher bandwidths

� Wave generator with programmabletrigger I/O

� Integrated linearization for piezoresistivesensors

� Compact dimensions: 35 x 65 x 50 mm

� Bandwidth up to 20 kHz

� Power up to 5 W

� 24/7 operation

� Compact OEM electronics

� Suitable for circuit board mounting(lab-on-a-chip)

� Frequency and amplitude control

� Also available with display

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Piezo Actuators Out of the Ordinary?

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Fast switching cycles require very dynamiccharging and discharging of the piezocapacitance at a rate of some tens of kilo-hertz. The dynamics are limited solely bythe charging or discharging time whichthe electronics can master. Correspon-dingly high currents provide fast riseand decay times of around a few tens ofmicroseconds. Various power classesare available to suit the repetition rates re-quired.

The piezo actuator heats up if it is subjectedto permanently large currents in dynamicoperation. PI recommends a temperaturesensor be used on the actuator for such ap-plications. If a certain temperature limit is ex-ceeded, the power supply is automaticallyinterrupted.

The powerful E-505.10 piezo amplifier moduleis available for the modular E-500 piezocontroller system,which has been optimizedespecially for high-dynamics switching appli-cations. It integrates a low-noise piezo ampli-fier which can output and sink peak currentsof 10 mA for low-voltage piezoelectric actua-tors (-30 to 130 V).

Technical data:

� 1000 W peak power with 10 A peak current

� Bandwidth, small signal > 15 kHz

� Noise 1.0 mV rms

� Closed-loop operation (optional)

� Fast interface module for digitalcommunication (optional)

Dynamics and Precision for Switching ApplicationsHIGH CURRENTS MEAN FAST R ISE T IMES

Powerful E-505.10 piezoamplifier module

Continuous applications such as those intesting units for injection valves place partic-ularly high demands on the dynamics. Themodular E-618 system provides a range ofoptions for the optimum setting up of suchapplications. A bandwidth of 15 kHz is pos-sible with a peak power of 3,200 W and peakcurrents up to 20 A. A further addition is theevaluation for a temperature sensor at theactuator. The amplifier can be upgraded toa piezo controller by means of plug-inmodules with position control. Digital inter-faces are available as optional extras.

Actuators for High-Dynamics Applications

The motion or displacement of the piezoactuator is based on pure solid state effects.The dynamics that can be achieved aretherefore usually limited by the electronics,and not by the mechanical design. Con-tinuous operation with high power and highdynamics nevertheless requires the corres-ponding cables and contacts. PICMA®

actuators with patented, meander-shapedexternal electrodes supply the electric cur-rent evenly to the internal electrodes. The

contact itself remains electrically stable andmechanically flexible even at high currentsof up to 20 A, thus supporting a particularlydynamic control.

PICMA® actuatorswith patented,meander-shapedexternal elec-trodes for up to 20 Acharging current

E-618 high-power piezoamplifier

Piezo actuatorwith integratedpreload for up to300 N tensile load,connection for protective airand temperature sensor. 10 µmtravel at up to 7 kHz

Application examples

� Material testing andprecision engineering

� Shock tests

� Machine testing

� Switches

� Acceleration tests

� Structure analysis

� Active vibrationdamping

� Injection valve control

Powerful Duo for Continuous Applications

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Piezo actuators are often used for the par-ticularly precise machining of materials, e.g.in mechanical engineering for fine position-ing in milling machines and lathes. Theseapplications require large forces and highdynamics. The piezo actuators are dimen-sioned to provide these large forces, i.e.piezo actuators with high capacitance areused. Particularly high currents are used tocharge or discharge the actuators with thedynamics needed. Similar characteristics arenecessary to control valves.

Energy Recovery Minimizes EnergyConsumption in Continuous Operation

Since these applications often operatearound the clock, seven days a week, theenergy consumption of the amplifier is im-portant. PI’s answer is a switched amplifierelectronics, where the pulse width of theinput signal is modulated and thus the piezovoltage ist controlled (PWM). This results ina particularly high efficiency. A patented cir-cuit for energy recovery is also integrated: Itstores a portion of the energy which flowsback as the piezo discharges in a capacitivestore, and makes it available again for thenext charging process. This makes it possi-ble to achieve energy savings of up to 80% .

Moreover, the amplifier does not heat up asmuch and thus does not impact as much onthe actual application.

In contrast to conventional Class D –switched amplifiers, PI‘s switched amplifiersfor piezo elements are current and voltagecontrolled. This patented systemmeans theyare also suitable for applications in the fieldof active vibration control, where it is impor-tant that they be adapted to the dynamicrange required at the time.

Temperature Monitoring Protects thePiezo Actuator

The energy loss in the piezo itself is low –very little waste heat is generated. This can-not be neglected in continuous operation,however. The appropriate electronics cantherefore evaluate the signals of a tempera-ture sensor on the piezo. The ceramic is thusprotected from overheating and prematureaging. Possible fissures, which could causeflashovers, can be prevented.

Applicable Patents

German Patent No. 19825210C2International Patent No. 1080502B1US Patent No. 6617754B1

Solutions for High-Dynamics24/7 Operation

SWITCHED AMPL IF IERS WITH ENERGY RECOVERY

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Linear amplifierSwitching amplifier

Power consumption of a piezo amplifier with linear and switchedpower stage at the piezo output, capacitive load 1 µF. The measuredvalues show clearly that the pulse-width modulated amplifier allowssignificantly higher dynamics than the amplifier operating in conven-tional linear mode. The linear amplifier reaches the upper limit of itspower consumption at frequencies of up to around 700 Hz whereas theswitched amplifier only reaches this limit far above 2 kHz.

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For the same output power PI amplifiers with patented energyrecovery consume only around 20 % of the power consumed bya corresponding linear amplifier.

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Three models of switched amplifier with in-tegrated energy recovery are available. TheE-617.001 (left in picture) is designed for in-stallation on a top-hat rail and is thereforeideally suited for use in automation and in-dustry. The E-617.00F (center) is a compactOEM module designed for installation in achassis. The E-504 power amplifier module(right) supplements the modular E-500 piezocontroller series. A position control and di-gital interfaces or a display can be integra-ted as optional extras.

Technical data:

� Peak output power 280 W

� High average output power 100 W

� Peak current of up to 2 A

� Output voltage range -30 to 130 V

� Bandwidth up to 3.5 kHz

These piezo amplifiers thus make it possibleto have dynamic operation of low-voltage

piezo actuators with high capacitance at abandwidth up into the kilohertz range. Atthe same time, the power requirement of thedevices is extremely low with a maximumof 30 W.

Application examples

� Valve control (e.g.pneumatics)

� Injection valves

� High-dynamicscanning

� Milling machines

� Laser beam control

� Active vibrationdamping

The principle of energy recovery is also avai-lable for high-voltage actuators with a vol-tage swing of up to 1,100 V in unipolar orbipolar control. The modular high-powerE-481 piezo amplifier / controller providesa peak power of 2,000 W and peak currentsof up to 2 A.

E-481 high-power piezo amplifierDigital linearization algorithms can also be implemented to improve the open-loop positioning accuracy inthis high-power version with 2 kW and 2 A. Linearity values of around 99% are then achieved.

An evaluation of a temperature sensor isintegrated to protect the piezo actuatorfrom thermal overload. Piezo current andvoltage can be tapped via monitor connecti-ons. The E-481 is available with the optionof position control, digital interfaces, or dis-play.

Product Examples: Particularly Powerful,Dynamic and Economical

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Dynamic scanning is a typical field of appli-cation for piezo actuators or nanopositioningsystems. Two different methods can bedistinguished here: Step and settle mode,where a position can repeatedly be ap-proached with precision, and rampingmode,where the piezo displacement has a particu-larly linear characteristic. The first case re-quires a closed servo-loop to ensure that thepositions are repeatedly approached with re-liability, and the step size is kept constant.

Ramping mode, with its linear piezo dis-placement, can also be realized via positionfeedback and servo loop, of course. Theservo loop then determines the dynamics ofthe overall system. However, in some casesthis significantly reduces the number ofcycles per unit of time. This can be avoidedwith an alternative amplifier principle; theso-called charge control.

Charge and Displacement

Charge control utilizes the fact that, forpiezos, the relation between electrical chargeand displacement is considerably morelinear than the relation between voltageapplied and displacement. The deviation inthe first case amounts to only around 2 %,while it is about 10 to 15 % for voltage con-trol (see diagrams below). With charge con-trol it is therefore often possible to achievethe necessary precision without servo loop.This improves the dynamics and costs less.It is not only high-dynamic applicationswhich benefit from charge control, thebenefit is also felt at very low operatingfrequencies. However, it is unsuitable fortasks where positions have to be held overlonger periods, because the positional driftof the piezo actuator is not compensated.

Linearized Amplifiers forPiezo Displacement Without Hysteresis

CHARGE CONTROL

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Typical displacement characteristic of piezo actuators as a function of the voltage applied (left) andcharge (right). The hysteresis is significantly reduced by controlling the charge applied.

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For dynamicapplications:

� Active vibrationdamping

� Adaptronics

� Fast mechanicalswitches

� Valve control(e.g. pneumatics)

� Dosing

The E-506.10 piezo amplifier module is designed to work in the E-500 controller system. It features a low-noisehigh-power amplifier for low-voltage piezo actuators and positioners that can output and sink a peak current ofup to 2A in the -30 to +130V voltage range.

� Highly linear amplifier module with charge control

� 280 W peak output power

� Piezo overtemperature protection

� Optional extras: Position control, digital interfaces, display

The electric circuit requires the piezo systems to have a ground-free construction and corresponding connections.

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Digital controllers have advantages overanalog amplifier electronics which are parti-cularly relevant to high-precision positioningtasks: All motion parameters can be specifi-cally influenced by calculation algorithms.This increases the precision and the dynamiccharacteristics.

Software for Easy Operation

The digitalization of all process steps meansthe process parameters can be easily ac-cessed using software. As soon as the loadchanges, for example, the software allowsdigital controllers to change servo parame-ters immediately.

In addition, PI software offers diagnostictools and assistance with the adjustment ofsettings, such as the graphic display of stepresponses for the optimization of parametersettings.

Digital Data Processing

Digital processing improves the system per-formance:

Linearization of the Electronics

All digital PI controllers for nanopositioningoperate in the same way. It is thus possibleto operate any piezo mechanical system thathas been fine-tuned to a digital control withother controllers without loss of perfor-mance. The adjustment data required isstored on the stage’s ID chip and processedby the controller when the system is firststarted up.

Servo Control Loop and ControlCharacteristics

The controller compensates the deviationbetween the actual position and the targetposition. PID controllers are typically usedfor this. Depending on the application,however, different controlling methods incombination with linearization algorithmscan achieve better results. Digital filtersprevent undesired excitations, suppressnoise and thus increase the resolution of thesystems.

Linearization of the Mechanical System

The linearity of the entire system is onecriterion for its positioning accuracy.Piezo actuators have a non-linearity of 10to 15% of the travel range, which has tobe compensated for by the target valuessupplied and the closed-loop control sothat the system reaches the position withmaximum accuracy. Digital controllersreduce the non-linearity of the motion toa value below 0.001% by using polynomialsof higher order in the calculation – in atravel range of 100 µm this value corres-ponds to an accuracy of below one nano-meter.

Dynamic·Linearization

The Dynamic Digital Linearization (DDL) re-duces the deviation of periodic trajectorieseven while the motion is being carried out.This is important for scanning applicationsthat have to identify a particular position andhave to accurately reach this position again,or for applications where there must be nodeviation from the trajectory for specific pro-cessing steps.

Software from PI for ease ofoperation and performanceoptimization of piezo systems:The adjustment tool for parame-ters shows the frequencyresponse of a nanopositioningstage in the Bode plot

Rapid access to the full functionality

Digital ControllersPREC IS ION, DYNAMICS AND EASE OF OPERAT ION

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P I E Z O N A N O P O S I T I O N I N G

Product Overview and Systems

The standard interfacesfor digital nanopositio-ning controllers areRS-232, USB and TCP/IP.On top of this, PI pro-vides additional digitalI/O lines as well asoptions for analoginterfaces or a PIO forreal-time commanding.

Additional Functions of Digital Controllers*

Computing power and memory, which go handin hand with digital controllers, allow usefuladditional functions to be implemented

� Software access to all motion parametersand the graphic display of the effects

� Coordinate transformation for parallel kine-matics for simple commanding in Cartesiancoordinates

� Macro memory to store and retrieve motionswhich can be externally triggered

� Function generator and waveform memoryfor the retrieval of predefined trajectoriesand the generation of customized waveforms

� Data recorders record sensor and controldata for subsequent processing.

� The ID Chip allows the flexible exchange ofcontrollers and nanopositioners without ha-ving to adjust the operational parametersagain

*Not all controllers have all the functions. Theindividual ranges of functions are listed in therespective datasheets.

PICOCUBE® E-712high-speed scanner

Drives Controller platform

Nanopositioning E-753systems with 1 axis

Nanopositioning E-761systems with up to3 axes, low-powerrequirement

Nanopositioning E-725systems with up to3 axes

Nanopositioning E-712systems with up to6 axes

NEXLINE® heavy-duty E-755nanopositioning drive E-712

NEXLINE® parallel- E-712kinematic with up to3 axes

Positioning systems with E-861NEXACT® nanopositioningdrive (with encoderanalysis)

Positioning systems with C-863DC-servo motors and C-867encoder analysis / C-663PILine® ultrasonic piezodrives with encoderanalysis / stepper motors

Hexapods/ Digitalparallel kinematics Hexapodwith any drives controller

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Ideal for all Power Classes

The most important requirement is that ana-log input signals are converted quickly andwith high resolution for the subsequent pro-cessing. Information which is lost duringconversion is lost forever. The same appliesto the generation of the output signal: Thebest algorithms are useless if the output sig-nal cannot be genera ted with high resolu-tion.

PI therefore uses A/D and D/A converterswith at least 20 bit resolution in the mostpowerful controllers for multi-axis high-res-olution positioning systems. This means thatanalog signals are resolved into more thanone million data points.

At the same time, the incoming volumes ofdata must be processed rapidly to achieveresults similar to those of conventional ana-log controllers in terms of real time. This re-quires fast processors: Modern DSPs orpowerful PC solutions, depending on thetask the controller has to fulfill.

A cycle is thus completed in 0.02 millise-conds, for example; this corresponds to aservo rate of 50 kHz. Updated sensor dataand control signals are then provided accor-dingly.

Low-Cost Digital Technology –This is no Contradiction!

PI provides a number of low-cost digitalcontrollers and thus achieves accuraciesranging from one to ten nanometers.The single-channel E-709 supports bothstrain gauge sensors (metal foils and pie-zoresistive) and capacitive sensors.The D/A conversion is 16 bit, the 32 bitprocessor with 150 MHz clock-pulserate allows a servo rate of 10 kHz – i.e.position recalculations are carried out10,000 times per second. The amplifierprovides 5 W continuous power forthe dynamic operation of conventionalnanopositioning systems such as theP-721 PIFOC® objective scanner, for exam-ple.

The digital linearization algorithmsnoticeably improve the performance ofpiezo positioning systems equipped withstrain gauge sensors (SGS).

� Maximum precision for up to 6 axes,and Hexapod control

� 600 MHz processor; servo update rateup to 50 kHz; high-stability 20-bit D/Aconverter

� Real-time operating system foroptimum tracking accuracy

� ID-Chip support for automatic calibra-tion of the controller to the piezomechanical system

Digital E-712 Piezo Controller System for Nanopositioning

Modular System for Maximum Precision for up to Six Axes

� Ethernet, USB, RS-232, optional high-bandwidth analog inputs and outputs

� Comprehensive software package

� Modular design for maximum flexibilityin meeting customer requirements

“High-End” or “Low-Cost”? Controller Performance Made to Measure

The same technology is containedin the E-609 piezo controller and inthe E-709 digital servo controller. Inthe E-609, PI uses a digital controllerin a device with pure analog controlinput. The E-709 additionally provi-des the commanding via SPI, USBand RS-232 interfaces.

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E-861 Controller/Driver for PiezoWalk®NEXACT® Linear Drives and PositionersPiezo stepping drives combine large force,dynamics and unlimited travel.

C-867 Controller for PILine® Piezo LinearDrivesPILine® piezo ultrasonic motors are particu-larly compact and fast.

� Networkable for multi-axis operation

� Complete system with controller, inte-grated power amplifiers and software;parameters changeable on-the-fly

� High performance at low cost

� I/O for automation, joystick for manualoperation, stand-alone functionality

� OEM version for open-loop operation

� Amplifier modules for different driveconcepts: Piezo actuators, NEXLINE® andNEXACT® piezo stepping drives.

� Maximum precision for Hexapod controlas well

� Up to 13 channels in 19‘‘ chassis

� Evaluation of capacitive and incrementalposition sensors

� Real-time data transfer via fast parallelinterfaces

� Real-time operating system for synchro-nization with system components

� Broadband encoder inputs for highspeed and high resolution

� PID servo-control with dynamic parame-ter switching

� Integrated power driver piezo motorwith frequency control

� USB, RS-232 and analog interfaces(e.g. for a joystick)

� 4 + 4 programmable TTL I/Os for flexibleautomation

� Data recorder

� Extensive software support, LabVIEW,DLL, macro programming, etc.

P I E Z O N A N O P O S I T I O N I N G

Digital Out of the Ordinary:Controllers for Piezo Stepping and Ultrasonic Drives

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E-712 Digital Piezo Controller SystemModular design for several axes.

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Choosing the right piezo controller dependson the actual application situation. A widevariety of criteria such as limitations to theinstallation space available, single-axis ormulti-axis solutions, or the necessity of

having PC control determine which amplifieror controller is the right one.

A number of analog and digital controllersare available for nanopositioning tasks:

Selection Criteria for Piezo Amplifiersand Controllers from PI

For more information

A complete descriptionof the products presen-ted in this overviewcan be found on ourwebsite at www.pi.wsand in the PI Main Ca-talog, which we will bepleased to send to youon request.

Detailed informationon digital piezo con-trollers is available inour current brochure„Digital Control – BestPerformance for Posi-tioning Systems“.

Well-presented basicknowledge on the sub-ject of Piezoactuatorsin Nanopositioningcan also be found atwww.pi.ws and on thewebsite of our subsi-diary PI Ceramic(www.piceramic.de).

Your application requires ... Which Piezo servo controller is suitable?

Frequent load changes or changes Set parameters easily with software:to the mode of operation All digital ones from PI, including the E-609 series

Reasonably priced Digital: E-709 or E-609; Analog: E-610, E-625, E-621)

3 to 6 channels Digital: E-725, E-710, E-712; Analog: E-500, E-612

More than 6 channels Networkable controllers such as E-621, E-625, E-665;modular controller such as E-712, E-500

Resolution Digital high-end solutions from PI such as E-753, E-712, E-725;Every analog one

Optimum dynamic linearity Digital high-end solutions from PI with DDL option

Long-term stability (thermal) All piezo controllers and amplifiers from PI

Linearity / accuracy All digital ones from PI, including the E-709 series:Digitalization polynomials up to 5th order; additional DDL option

Position control by means of analog All analog ones;input signal Digital ones E-709, E-609, E-753 or E-712 with analog IN option

Real-time commanding Digital ones with PIO-option; SPI-interface (standard for E-709!),TCP/IP for transmission rates up to 1 kHz;all controllers with analog I/O

Control in real-time or with high All analog ones;servo rates E-712, E-753, E-725

Fast, non-periodic motion E-712in several axes, tracking

Virtual axes and Digital multi-axis controllers such as E-712, E-725multi-axis synchronization

Digital communication interfaces; All digital ones; E-625, E-621, E-665;user-defined periodic motion profiles; Modular controller with E-517 digitaldata recorder operation module

Stand-alone functionality with macros Modular controller with E-517 digital operating unit

Trigger I/Os All digital ones; E-625, E-621, E-665;Modular controllers with E-517 digital operating unit

Your application is highly dynamic ... Which high-power piezo amplifier is suitable?

Positioning with sub-nanometer E-505 amplifier module in the E-505 controller system;accuracy and outstanding stability For long-term stability position control with

capacitive or strain gauge sensors as an optional extra

Dynamic scanning E-506 linearized amplifier with charge controlwith high linearity for maximum dynamics;

E-505 power amplifier with position control

Dynamic scanning in E-617, E-504 switched amplifier with energy recoverycontinuous operation for minimum energy consumption

Dynamic scanning in continuous E-618 with particularly large charging currentoperation, high capacitive loads up to 20 A for very steep rising edges

E-505.10 amplifier with large charging current up to 10 A

Fast switching, low number of cycles E-505.10 amplifier with large charging current up to 10 AE-617, E-504 switched amplifier with energy recovery

P I E Z O N A N O P O S I T I O N I N G

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CHINA

Physik Instrumente(PI Shanghai) Co., Ltd.Building No. 7-106Longdong Avenue 3000201203 ShanghaiTel: +86 (21) 518 792 98Fax: +86 (21) 687 900 98Email: info@pi-china.cnwww.pi-china.cn

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Controller11/03/31.0,5;Subjecttochangewithoutnotice©PhysikInstrumente(PI)GmbH&Co.KG2011

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PI General Catalog

Request it now!The 530 page hardbound catalogue fromPI is the most comprehensive referencebook on the fundamentals of nano-positioning, piezo systems and micro-positioning technology yet. The catalogcontains 200 product families, with morethan 1000 drawings, graphs, images andtechnical diagrams.

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