A Seminar on ULTRASONIC MOTORS Presented by Prashanth kumar Singh USN:4jn09te402 - PowerPoint PPT Presentation

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A Seminar on ULTRASONIC MOTORS Presented by Prashanth kumar Singh USN:4jn09te402

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Unaffected by external electric or magnetic fields. ... Like traditional motors, ... The Piezo LEGS motor, ... – PowerPoint PPT presentation

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Title: A Seminar on ULTRASONIC MOTORS Presented by Prashanth kumar Singh USN:4jn09te402


1
A Seminar onULTRASONIC MOTORSPresented by
Prashanth kumar SinghUSN4jn09te402
2
Outline
  • Introduction
  • History
  • Classifications
  • Basic Principle
  • Linear USM
  • Spherical USM
  • Future Work
  • Works Cited

3
Introduction
  • An ultrasonic motor (USM) converts ultrasonic
    vibrations into linear or rotary motion.
  • USMs plays an important role a few niche markets
    where the size, torque, speed or other
    requirements could not be satisfied by the
    traditional EM motor.
  • The two largest markets for USMs are cameras and
    automotive. but they are also found in medical
    equipment (MRIs) and as robotic servo motors.

4
Some applications where USMs have been used
are
  • Camera lens autofocus.
  • Spacecraft planetary instruments.
  • Medical equipment (MRIs etc).
  • Small robotic joints.

5
The major advantages of USMs are
  • Compact, lightweight, flexible and robust.
  • High positioning accuracy.
  • High low-speed torque and holding torque.
  • Unaffected by external electric or magnetic
    fields.
  • Quiet drive system.
  • Hard brake with no backlash.
  • Variable stroke.
  • Quick response.

6
History
  • 1980. The first USM was developed by Sashida.
  • 1986. Cannon pioneers the ring type USM for use
    in SLR camera lens autofocus.
  • 1990. The first micro USM is developed by Canon
    to for a new camera autofocus.
  • 2003. Cannon released a new micro USM that is ½
    the size of the first with the same output
    torque.
  • 2005. An international conference was held in
    Yokohama Japan to aid development of multiple DOF
    USMs.

7
Classifications
  • USMs can be classified in the following ways
  • Mode of operation
  • Static
  • Resonant
  • Type of motion
  • Rotary
  • Linear
  • Shape of implementation
  • Beam
  • Rod
  • Disk

8
Basic Principle
  • One thing all USMs have in common is their use of
    piezoelectric material to transform electrical
    energy to mechanical energy.
  • USMs typically use ceramics derived from
    lead-zirconate titanate (abbreviated PZT).
  • After the PZT ceramic is shaped and fired, it is
    then electric field polarized. This allows the
    material to deform with a changing electric
    field.

9
Basic Principle
  • Here we will discuss the operation of a ring type
    USM. Like traditional motors, USMs have a stator
    and a rotor
  • Some USMs use a toothed stator to increase the
    holding torque. Other motors simply rely on
    frictional forces.
  • As shown in the illustration on the right, the
    bottom layer of the stator is composed of the PZT
    material mentioned earlier.

10
Basic Principle
  • Two electrical signals with orthogonal modes
    (like sin(wt) and cos(wt)) are introduced in the
    stator material.
  • If a constant phase difference exists between the
    two modes a traveling wave is created in the
    stator. Otherwise the wave is standing.

11
Basic Principle
  • The repeated rolling motion of the stator creates
    microscopic orbit of the stators surface
    particles (much like water drops in a water wave.
    These small movements move the rotor forward.
  • Thus, the traveling wave in the flexural stator
    material moves in the opposite direction of the
    rotor spin.

12
Basic Principle
  • The stator may drive the rotor using tiny teeth
    or simply the force of friction.
  • While the angular velocity of the rotor is
    proportional to the frequency of the traveling
    wave, that does not mean they are equal. The
    traveling wave may pass through the stator
    several times for a single rotation of the rotor.

13
Linear USM
  • Linear USMs, sometimes called tube or rod
    USMs, also use piezoelectric metals or ceramics
    for actuation.
  • Show here is a picture of New Scale Technologies
    tiny Squiggle motor.
  • The Squiggle motor weighs about 30gm and boasts a
    stall force of 10N. Micro deformations also give
    resolutions as high as 1nm, and max speeds of
    15mm/sec

14
Linear USM
  • The Piezo LEGS motor, developed by MicroMo
    Electronics Inc., illustrates one popular
    technique for linear USM actuation.
  • Like other USMs, the LEGS motor generates motion
    in discrete steps.
  • 4 bimetallic metal/ceramic legs are positioned
    around a single nut on a threaded rod.

15
Linear USM
  • Applying voltage to a PZT leg causes it to change
    shape. This strain in the leg causes the nut to
    bend and shift on the threaded rod.
  • By synchronizing the 4 legs an elliptical force
    pattern moves the rod in either the forward or
    reverse direction.
  • Because deformations are small, several thousand
    pulses/sec are needed.

16
Spherical USM
  • Spherical USMs may be employed when more than one
    degree of freedom is needed. Potential
    applications include surgical robots or robotic
    eyes
  • The concept of a spherical USM is simple. Three
    separate ring USMs control actuation in the x, y
    and z directions. Thus, the sphere can be given
    any orientation in 3 space

17
Future Work
  • USMs have lots of potential for use in medical
    applications. One very promising research area
    is in medical diagnostic instruments.
  • The Robotics Institute of Carnegie Mellon
    University and the Division of Cardiac Surgery at
    the University of Pittsburgh are teaming up to
    create a tiny robot called the HeartLander

18
Future Work
  • The Heart Lander is a tiny robot that surgeons
    could insert into a patients chest cavity
    through a minimally invasive incision. This tiny
    robot could then move along the surface of the
    heart and perform interventions.
  • The surgeon would be able to control every
    movement via a controller and monitor external to
    the patients body.

19
Works Cited
  • Canon. (2007). Using Ultrasonic Vibrations to
    Drive Focus and Zoom Lenses. Retrieved March 2,
    2009, from Canon www.canon.com
  • Carnegie Mellon University. (2007). HeartLander.
    Retrieved February 22, 2009, from CMU
  • www.cs.cmu.edu
  • Toyama, D. S. (2008, April). Sherical ultrasonic
    motor, piezoelectric actuator, spherical sensing
    system. Retrieved March www.tuat.ac.jp

20
THANK YOU
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