performance and applications of l1b2 ultrasonic motors presentation final.pdf · compact ultrasonic...
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Page 1 Confidential
Performance and Applications of L1B2
Ultrasonic Motors
Alan Feinstein, Nanomotion Ltd.
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Introduction
Compact ultrasonic motors
– Principle of operation: transferring electrical energy into mechanical
momentum by frictionally coupling a vibrating elastic stator to a moving stage
Technology Advantages
– High power density
– Unlimited travel
– Direct drive
– Compact dimensions
– High resolution
– High dynamic range
– Fast response time
– Superior ―move and settle‖ performance
– Built in brake
– Built in ―clutch‖
– No intrinsic magnetic field / No EMI
– UHV Compatible
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The Piezoelectric Effect
Direct Effect: – Converts mechanical strain into
electric charge
– This effect is used in
microphones, accelerometers,
gas lighters etc.
Reverse Effect: – Converts electrical fields into
crystal deformation
– An effect used for generating
vibrations and motion in
actuators, transducers etc.
F
F
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Quadratic electrode design
producing L1&B2 vibration
modes by diagonal excitation
L1B2 Ultrasonic Motor – Basic Principles
Stiff bearing for backing the ceramic
strip
Side spring
with side
bearing
mechanism
for
backlash
free motion
Hard
ceramic tip
and strip
enable
friction
force
transfer
Back spring
maintain constant tip
contact force
Bending Mode Longitudinal Mode
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Architecture of a Precision Motion Solution
Closed loop motion control
– Ultrasonic motor coupled to a motion axis
– Motor driver
– Motion controller
– Position feedback (position encoder)
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Basic Driver Design
Translates controller command to motor voltage
Motor Velocity to Controller Command relationships:
– With dead zone
– Without dead zone
– Actuator mode, for increased accuracy near the target area
Nanomotion AB1A driver*, HR type motor Nanomotion AB5 driver*, HR type motor
* Nanomotion Ltd. User Manual HR Motors. Available online: http://www.nanomotion.com/wp-content/
uploads/2015/09/HR00458000-00-HR-Motor-User-Manual.pdf.
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Basic Driver Design
Coupling between the mechanical resonance of a vibrating piezo-
ceramic and the electrical resonance of an AC driving circuit
– Relatively high vibration amplitude
– Low DC supply voltages
– High efficiency in (low) DC to (high) AC voltage conversion • Small driver can power a large number of motors in parallel
Nanomotion AB1A driver* architecture
*AB1A Driver . Available online: http://www.nanomotion.com/wp-content/uploads/2015/01/AB1A458000-00-User-Manual-AB1A1.pdf .
Diagram of the output stage with an internal LC card (single
channel with a direction switch)
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Open Loop Motion Generation
Force-Velocity Performance determined by:
– Amplitude and Frequency of tip motion • Element Geometry
• d31 piezoelectric coefficient
• Amplitude of the applied electric field
• Quality of the mechanical and electrical resonances
– Friction Forces: element Preload force and Friction Coefficient • Correct choice of the friction couple materials
Velocity Profile
– 𝑉 𝑡 = 𝑉𝑚𝑎𝑥𝐶 ∙ 1 − 𝑒−
𝑡
𝜏 , 𝜏 =𝑚𝑉𝑚𝑎𝑥
𝐹𝑚𝑎𝑥
– 𝐹𝑚𝑎𝑥 = Maximal Force
– 𝑉𝑚𝑎𝑥 = Maximal Velocity
– 𝑚 = moving mass
– 𝑉𝑚𝑎𝑥𝐶 = Max. Vel. at a given command level
Nanomotion HR2 motor
Nanomotion AB1A driver
Linear motion axis (mass 235 gram)
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Closed Loop Control Scheme
Closed Loop Control
– High bandwidth PIV controller with a non-linear mechanism
– Servo loop special position control elements • Offset mechanism—provides an initial command starting value to overcome the inherent dead
zone
• Zero Feed Forward mechanism—improves the stage settling time
• Dead Zone mechanism—takes advantage of the motor intrinsic friction to prevent jitter and
improve settling time
* Nanomotion Ltd. XCD Software Version 1.4.0.7. Available online: http://www.nanomotion.com/wp-
content/uploads/2014/05/XCD-software-version-1-4-0-7.pdf.
Motion controller servo loop block
diagram Nanomotion XCD
controller*
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Operational Conditions
Proper choice of materials allows smooth motor
operation
– In a high vacuum (e.g. Nanomotion high vacuum motors)
– In a clean room (e.g. Nanomotion motors for semiconductor
metrology)
– Wide Temperature range
• NM standard HR motors: from 0° to +50°C
• NM Edge motors: from -55° to +80°C
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Example: Positioning Accuracy
NM HR8-V motor, linear stage with a 0.5 kg
mass (FB75-100-HR8 stage) – 10 mm movements back and forth
– Settling time < 100 ms
– Settling window <50 nm
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Example: Positioning Accuracy w/DC mode
NM HR8-V motor, linear stage with a 0.5 kg mass
4 nm step
Peled, G.; Yasinov, R.; Karasikov, N. Performance and Applications of L1B2 Ultrasonic Motors. Actuators 2016, 5, 15.
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Example: High Accuracy Metrology Stage
28 kg inspection stage, NM HR motors, DC mode active
– 1 mm steps, at 3 mm/s, 100 mm/s^2
– Convergence target radius: 10 nm
– Position error after each step < 2 nm
– Drift Specification: less than 2 nm in 2.5 hours
Position Drift 3 hours after the end of motion Position Error after each 1mm step
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Example: High Accuracy Metrology Stage
28 kg inspection stage, NM HR motors, DC mode active 1 mm steps, at 3 mm/s, 100 mm/s^2
Position error after each step < 2 nm
Example Convergence to
less than 30 nm in 100 ms,
to less than 2 nm in 200 ms
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Example: Positioning Accuracy – Rotary stage
Nanomotion FBR60, powered by two NM HR2 vacuum motors
Consecutive 90° moves
Position error is measured 10 seconds after the end of motion
Peled, G.; Yasinov, R.; Karasikov, N. Performance and Applications of L1B2 Ultrasonic Motors. Actuators 2016, 5, 15.
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Example Applications – Vacuum/Space
NM HR2 vacuum motor
230 gram linear vacuum stage
Operating in high vacuum (1E-6 Torr)
– Back and forth 1.8 mm steps
– 90 million cycles
– 40 mm/s velocity
– Average rms position error below 3 um
Motion Profile
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Example Applications – Semiconductor Metrology
Example
Semiconductor
and Metrology
stages
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Example Applications – Optics/Optronics
NM Edge type motor
– Max. vel. > 200 mm/s, a
– Max. (stall) force > 0.35 N
– Motor Stiffness > 0.06 N/µm
Example NUC shutter stage
– 15 grams
– Aperture area: 14.7 × 17.0 mm
– Open/Close time: 150 ms
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Markets Served
Semiconductors Medical Defense
Custom solutions
Building blocks
components
Markets
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Standard components
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Building Blocks –Subsystems- Solutions