fernandez jaime actuator

7/29/2019 Fernandez Jaime Actuator

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Piezomotors Ultrasonic Motors

Prepared by: Jaime Fernandez

Department of Electrical and Computer Engineering

Utah State University

ECE 5320 MECHATRONICSActuator Tutorial


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Outline

Reference List

Piezoelectric Notions

Piezoelectric Motor Notions

Major Applications Basics Principles

Major Applications

Major specifications


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Reference List

Wikipedia, http://en.wikipedia.org/wiki/Piezoelectricity

Alexander D. Khazan, Transducers and Their Elements, Prentice Hall

PTR

Robert H. Bishop, Mechatronics Handbook, section 19.2 Manfred Weber, http://www.mmf.de/

Shyh-Shiuh Lih, Yoseph Bar-Cohen, Rotary Ultrasonic Motors Actuated

By Traveling Flexural Waves, http://ndeaa.jpl.nasa.gov/nasa-

nde/lommas/spie-usm97.htm


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Piezoelectric Notions

Piezoelectricity is the ability of certain crystals to generate a voltage in response to

applied mechanical stress. The word is derived from the Greek piezein, which

means to squeeze or press. The piezoelectric effect is reversible in that piezoelectric

crystals, when subjected to an externally applied voltage, can change shape by a

small amount. The deformation, about 0.1% of the original dimension in PZT, is of

the order of nanometers, but nevertheless finds useful applications such as the

production and detection of sound, generation of high voltages, electronic

frequency generation, and ultra fine focusing of optical assemblies.

In a piezoelectric transducer, the acceleration acts on the seismic mass that

develops a force on piezoelectric quartz, or ceramic crystal, or on several crystals.The force causes charges on the crystals proportional to the acceleration.

Wikipedia, http://en.wikipedia.org/wiki/Piezoelectricity

Alexander D. Khazan, Transducers and Their Elements, Prentice Hall PTR

Robert H. Bishop, Mechatronics Handbook, section 19.2


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Piezoelectric Motor Notions

A piezoelectric motor or piezo motor is a type of electric

motor based upon the change in shape of a piezoelectric

material when an electric field is applied.

The ultrasonic motor ( USM ) is a new type of solid state

motor, which is driven by the ultrasonic vibration of a

piezoelectric transducer. The ultrasonic vibration is

transformed into output torque (in rotary USM) or thrust (inlinear USM) by the friction between the stator and the rotor (in

rotary USM) or the moving part (in linear USM).

Manfred Weber, http://www.mmf.de/


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This new breed of motors has many excellent

performances and features such as high torque, lowspeed, simple and compact structure with greatvariability in design, not interfering or being affected

by magnetic field when in operation, power off self-

brake, etc.

The chief drawback of USM lies in the fatiguewearing of the stator due to the frictional driving

mechanism.

Manfred Weber, http://www.mmf.de/


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Major Applications

Camera auto focus lenses,

Watch motors and compact paper handling.

Medical application within micro-surgery and sensor

scanning

Driving fluids

Optoelectronics area

Motion control


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Piezo motors consists mainly of an electro-mechanical resonator and a rotor. The resonatortransfer electric energy into small ellipticalmechanical vibrations that forces the rotor to rotatedue to friction between resonator tip and rotor.Piezoelectric motors have some very nice

characteristics compared to traditional inductionmotors and in general they are characterized by a hightorque at low angular velocity, silent operation, high

positioning precision, simple mechanical construction

and it induces no magnetic fields.Modeling and Control of a Standing Wave PiezoElectric Motor, Brian Andersen.


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Basics Principles

The general principle of the

operation of ultrasonic motors is

to generate gross mechanical

motion through the amplification

and repetition of micro-

deformations of active material.

The active material induces an

orbital motion of the stator at the

rotor contact points and frictional

interface between the rotor and

stator rectifies the micro-motionto produce macro-motion of the

stator.

Development of an Ultrasonic Motor as aFine-Orienting Stage Eko Purwanto, Member, IEEE, and Shigeki Toyama


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The active material, which is apiezoelectric material excites atraveling flexural wave within thestator that leads to ellipticalmotion of the surface particles.Teeth are used to enhance thespeed that is associated with the

propelling effect of theseparticles. The rectification of the

micro-motion an interface isprovided by pressing the rotor ontop of the stator and the frictionalforce between the two causes therotor to spin. This motion transferoperates as a gear leads to a muchlower rotation speed than thewave frequency.

Rotary Ultrasonic Motors Actuated By Traveling Flexural Waves, Shyh-Shiuh Lih, Yoseph Bar-Cohen, http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/spie-usm97.htm


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A stator substrate is assumed to have a thickness, tS, with a set

of piezoelectric crystals that are bonded to the back surface ofthe stator in a given pattern of poling sequence and location.The thickness of the piezoelectric crystals is tp. The totalheight, h, is the sum of the thickness of the crystals and thestators (bonding layer is neglected). The overall height of thestator is also allowed to vary with radial position. The outer

radius of the disk is b and the inner hole radius is a. Togenerate traveling wave, the piezoelectric crystals polingdirection is structured such that quarter wavelength out-of-

phase is formed. This poling pattern is also intended toeliminate extension in the stator and maximize bending. The

teeth on the stator are arranged in a ring at the radial position.



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To generate a traveling wave within the stator two orthogonal modes areactivated simultaneously. These modes are induced by constructing thedrive piezoelectric actuators in a pattern of two poling sections that are

bonded to the stator. Geometrical examination of this pattern shows that

driving the two sections using cos(w t) and sin(w t) signals, respectively,will produce a traveling wave with a frequency of w /2p . Also, bychanging the sign on one of the drive signals, the traveling wave wouldreveres its direction.

The equation of motion of the ultrasonic motor can be derived from

Hamiltons principle. The analytical model has been derived by manyauthors (e.g. Hagood and A. McFarland [5], Kagawa et al [6]). Thegeneralized equation of motion of the stator can be summarized as



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http://www.me.ust.hk/~rickylee/motor-spec.PDF


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USM Prototypes

DOF planar pin-type actuator

The objective of this project is to design and develop a piezoelectric actuator basedon the fundamental operating mechanism of ultrasonic motors. Two pin-typeprototypes with piezoelectric bimorph plate and a contact pin for generating drivingforce in the X-Y direction were designed and fabricated. A test rig was also

constructed for the evaluation of the two prototypes and basic characteristics of theactuators were investigated. The working principle of the actuator was verified andproven during the experiment. Basically, the optimal driving speed of an actuator isdependent on the driving frequency, the input voltage, the contact surface and thefriction coefficient between the stator and motor. An analytical study of theprototypes has been carried out by means of finite element analysis utilizingANSYS5.4. With comparison to the experimental results, it was proven that theoptimal driving condition occurred at the specific resonant mode depending on thepin vibration. Maximum unloaded driving speed was obtained to be approximately0.68 cm/s at a frequency of 14.8 kHz and the optimum input voltage was found tobe approximately 70 Vp-p.

Copyright 2002 Modular robotic & Robot locomotion Group, School of MPE, NTU, http://155.69.254.10/users/risc/www/usm-intro.html


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Bi-directional linear standing wave USM

A standing wave bi-directional linear ultrasonic motor hasbeen fabricated. This linear USM has very simple structureand can be easily mounted onto any commercially availablelinear guide. A high precision positioning x-y table was built

by mounting these individual movable linear guides together.

The basic parameters of our linear USM are: moving range220mm(variable depending on the linear guide), no-load speed80mms/s, ratings 23mm/s at 300gf, stall force 700gf, startingthrust 500gf, resolution


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Rotary Ultrasonic Motor

The characteristics of the rotary disc type motor will be

investigated and theoretical model will be formed to relate the

important components on the power of the motor. The scope

includes designing different motor with various dimensions,

form calculation of the analytical model, experimental testing

and ultimately, setting a standard for practical application of

this particular type of USM. This project will lay the

foundation of the characteristics and performance of the rotary

disc type USMs for future application.



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Spherical ultrasonic motor

Presently a new type of spherical USM is under investigation.

This particular USM consists of a thin square plate, 30x30mm

in area. It can rotate in more than 4 individual directions. Now

we are trying to compile rotation in any direction by using a

computer to control the 4 individual directions properly.



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Suppliers Information

http://alphapiezo.com/

http://www.americanpiezo.com/

http://www.cedrat.com/

http://www.ceramicacelec.com.ar/ http://www.ferroperm-piezo.com/

http://www.matsysinc.com/

http://www.piezosolutions.net/

http://www.physikinstrumente.de/products/section1/index.htm/

http://www.sensortech.ca/
http://eis.jpl.nasa.gov/ndeaa/nasa-nde/nde-aa-l/www.ferroperm-piezo.comhttp://eis.jpl.nasa.gov/ndeaa/nasa-nde/nde-aa-l/www.ferroperm-piezo.comhttp://eis.jpl.nasa.gov/ndeaa/nasa-nde/nde-aa-l/www.ferroperm-piezo.comhttp://eis.jpl.nasa.gov/ndeaa/nasa-nde/nde-aa-l/www.ferroperm-piezo.com

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