Piezoelectric Actuators Stack Actuators - Translators

1
Piezoelectric ActuatorsStack Actuators -
Translators

• Jeanell Sealy
• ECE 5320 - Mechatronics
• Assignment 1

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Outline

• References
• Further Exploration Sources
• Major Applications
• Basic working Principles
• Typical Sample Configuration in an application
• Major Specifications
• Advantages
• Limitations

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References

• http//www.physikinstrumente.de/products/section1/
  link2.php
• http//www.hyperdictionary.com/dictionary/piezoef
  fect
• http//www.physikinstrumente.com/tutorial/4_9.html
  
• http//www.physikinstrumente.com/tutorial/4_10.htm
  l
• http//www.csaengineering.com/techpapers/technical
  paperpdfs/csa2002-4698-53-lindler-anderson.pdf

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Further Exploration Sources

• www.physikinstrumente.com/tutorial
• www.me.sc.edu/esearch/AARG/development_of_a_closed
  _loop_con.htm
• www.americanpiezo.com/products_services/stack_actu
  ators/stack_background.html
• www.ce.utexas.edu/em2000/papers/GendChen.pdf

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Major Applications

• Life Science, Medicine, Biology
• Scanning microscopy
• Patchclamping
• Gene manipulation
• Micromanipulation
• Cell penetration
• Microdispensing
• Semiconductors, Microelectronics
• Nanometrology
• Wafer and mask positioning/alignment
• Critical dimension measurement
• Microlithography
• Inspection systems
• Vibration cancellation
• Optics, Photonics, Fiber-Optics Metrology and
  Measuring Technology
• Fiber optic alignment switching
• Image stabilization

• Precision Mechanics and Mechanical Engineering
• Fast tool servos
• Out-of-roundness finishes (boring, drilling,
  turning)
• Vibration cancellation
• Smart structures / Structural deformation
• Wear correction
• Needle-valve actuation
• Micro pumps
• Knife edge control in extrusion tools
• Micro-engraving systems
• Data Storage
• MR head testing
• Pole tip recession
• Spin stands
• Disk testing
• Vibration cancellation

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Basic Working Principles

• Piezo effect electricity produced by mechanical
  pressure on certain crystals (notably quartz or
  Rochelle salt) alternatively, electrostatic
  stress produces a change in the linear dimensions
  of the crystal.
• (http//www.hyperdictionary.com/dictionary/piez
  oeffect)

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Basic Working Principles

• The piezo effect is caused by the asymmetry of
  the crystal structures.
• The shape and configuration of the crystals have
  natural spontaneous polarization and deformation
• Polarization and deformation of the crystalline
  material causes energy to be released.
• This behavior can be amplified by applying an
  electric field.

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Basic Working Principles

• Fabrication of PZT (zirconate titanate)
• Mixing Balling of Raw Materials
• Partial Heating to 75 of the sintering
  temperature to accelerate material reaction
• Shaping and Pressing of Ceramic with binding
  material
• Sintering of material (heating above below
  melting point)
• Poling process, the ceramic materials are charged
  with and oil bath with electrical fields up to
  several kV/mm

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Basic Working Principles

• Stack Actuators (Translators)
• Stack of ceramic layers with two electrical leads
  most common structure
• http//www.physikinstrumente.com/tutorial/4_10.htm
  l

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Typical Sample Configuration in an Application

• Piezoelectric Direct Drive Servo-valve
• (Used for Power Translation)
• http//www.csaengineering.com/techpapers/technical
  paperpdfs/csa2002-4698-53-lindler-anderson.pdf
• Used to drive the hydraulic actuator see above

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Typical Sample Configuration in an Application

• http//www.csaengineering.com/techpapers/technical
  paperpdfs/csa2002-4698-53-lindler-anderson.pdf

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Typical Sample Configuration in an Application

• http//www.csaengineering.com/techpapers/technical
  paperpdfs/csa2002-4698-53-lindler-anderson.pdf

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Major Specifications

• P-845 Closed Loop LVPZT Translator
• internal spring preload and integrated
  high-resolution strain gage position sensor
• displacement to 90 microns and stiffness to 400
  N/mm
• loads up to 300 kilograms and withstand pulling
  forces to 700 N

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Advantages

• Repeatable nanometer and sub-nanometer sized
  steps at high frequency can be achieved with PZTs
  because they derive their motion through solid
  state crystal effects. There are no moving parts
  (no "stick-slip" effect).
• PZTs can be designed to move heavy loads (several
  tons) or can be made to move lighter loads at
  frequencies of several 10 kHz.
• PZTs act as capacitive loads and require very
  little power in static operation, simplifying
  power supply needs.
• PZTs require no maintenance because they are
  solid state and their motion is based on
  molecular effects within the ferroelectric
  crystals.
• Resolution is based upon ionic shift and
  orientation of the PZT unit cells, and depends on
  the electrical field applied and is theoretically
  unlimited.
• http//www.physikinstrumente.com/tutorial/4_9.html
  

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Limitations

• Temperature Damage
• If the materials within the actuator are heated
  above threshold, the material will not regain its
  piezoelectric properties
• Hysteresis (Open-Loop PZTs)
• The lag in response is due to crystalline and
  molecular effects of the PZT material.
• Creeping (Drift) (Open-Loop PZTs)
• Caused by remnant applied voltage in the piezo
  ceramics
• Causes position discrepancies
• Aging
• Reduces the gain as a result of the depoling
  process