Theory and Applications of Piezo Actuators and PZT NanoPositioning Systems
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In 30 years of designing nanometer level motion control solutions, PI has developed advanced techniques that allow to achieve highest precision, as fast as possible. Examples are Parallel-Kinematics flexure designs, Preshaping, Adaptive Following Error Correction, Active Trajectory Control and the unique Mach Throughput Processor(TM) that eliminates resonant ringing, and allows rapid motion without settling. Today, PI offers the largest selection of research and industrial-reliability Piezo Actuators , PiezoNanoPositioning Systems , Steering Mirrors and Control Electronics worldwide.
In addition to the hundreds of models presented in this catalog, we manufacture custom designs tailored to the customer's requirements. In PI is highly vertically integrated, controlling each manufacturing step from PZT raw materials to finished systems thus ensuring the best quality .
Ultra-low-inertia solid state PZT nanopositioning stages can repeatedly move bidirectional nanometer level steps, up to hundreds of Hz if required. Capacitive position feedback ensures highest linearity and longterm stability. Minimized recoil forces are a by-product of the ultra-low inertia approach. Design of Simple Flexure Lever Amplifier Data showing Impact of Active Trajectory Control on Guiding Precision: Sub-Nanometer Runout Design of PZT Stack Actuator
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- Introduction p. 4-1
Advantages of Piezoelectric Positioning Systems p. 4-3
Applications for Piezo Actuators p. 4-4- Tutorial Contents p. 4-5
Glossary p. 4-7
Symbols and Units p. 4-8- Basic Introduction to NanoPositioning with Piezoelectric Technology p. 4-9
Low-Voltage and High-Voltage PZTs Resolution p. 4-10
Open and Closed-Loop Operation p. 4-11
Dynamic Behavior p. 4-11
Mechanical Considerations p. 4-12
Power Requirements p. 4-12
Different Piezo Actuator Designs to Suit Various Applications p. 4-13
Design Points to Remember p. 4-14- Fundamentals of Piezoelectricity and Piezo Actuators p. 4-15
Material Properties p. 4-15
PZT Ceramics Manufacturing Process p. 4-16
Definition of Piezoelectric Coefficients and Directions p. 4-17- Resolution p. 4-18
Amplifier Noise p. 4-18
Displacement of Piezo Actuators (Stack &Contraction Type) p. 4-19
Hysteresis (open-loop PZTs) p. 4-20
Creep (Drift)(open-loop PZTs) p. 4-20
Aging p. 4-20- High-Resolution Sensors p. 4-21
Strain Gauge Sensors p. 4-21
Linear Variable Dif erential Transformers (LVDT 's) p. 4-21
Capacitive Position Sensors p. 4-22- Mechanical Considerations p. 4-23
Maximum Applicable Forces (Compressive Load Limit,Tensile Load Limit) p. 4-23
Stiffness p. 4-23
Static Large-Signal Stiffness p. 4-24
Dynamic Small-Signal Stiffness p. 4-24
Force Generation p. 4-25
Displacement with External Forces p. 4-26
Mechanical Considerations for Dynamic Operation of PZTs p. 4-27
Dynamic Forces p. 4-27
Resonant Frequency p. 4-28
How Fast Can a Piezo Actuator Expand? p. 4-29- Electrical Requirements for Piezo Operation 4-30
General p. 4-30
Static Operation 4-30
Dynamic Operation (Analog) p. 4-31
Dynamic Operating Current Coefficient (DOCC)4-32
Dynamic Operation (Switched) p. 4-32
Heat Generation in a PZT in Dynamic Operation p. 4-33
Position Servo-Control (Closed-Loop Operation) p. 4-34- Methods to Improve Piezo Dynamics p. 4-36
Input Shaping ™ Stops Structural Ringing Caused by High--Throughput Motions p. 4-36
SignalPreshaping4-37- Temperature Effects 4-38
Linear Thermal Expansion p. 4-38
Temperature Dependency of the Piezo Effect p. 4-38
Environmental Considerations p. 4-39
PZT Operation in Normal Atmosphere p. 4-39
PZT Operation in Inert Gas Atmosphere 4-39
Vacuum Operation of PZTs p. 4-39
Lifetime of PZTs p. 4-40- Basic Designs of Piezoelectric Positioning Elements p. 4-41
Stack Design p. 4-41
Laminar Design (Contraction-Type Actuator) p. 4-41
Tube Design p. 4-42
Bender Type Actuators (Bimorph and Multimorph Design) p. 4-43
Piezo Actuators with Integrated Lever Motion Amplifier p. 4-44
PZT Flexure NanoPositioners p. 4-45
Electrostrictive Actuators p. 4-46- Mounting Guidlines p. 4-47
Summary p. 4-47- Units of Measure and Conversion Tables p. 4-48
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