This document discusses ultrasonic motors (USMs). USMs use a piezoelectric material as an actuator to generate high-frequency mechanical vibrations in a stator. When a rotor is placed in frictional contact with the stator, it is driven by these vibrations without requiring electrical contacts. USMs offer advantages like high torque, efficiency, power-to-weight ratio, and ability to work in extreme environments. However, they require high-frequency power supplies and the piezoelectric materials used are expensive. Potential applications of USMs include cameras, watches, automotive components, robotics, aerospace and medical devices.

2. DEVICE THAT CONVERTS ELECTRICAL
ENERGY TO MECHANICAL ENERGY.
ELECTOMAGNETIC MOTORS
CURRENT CARRYING CONDUCTOR KEPT IN A
MAGNETIC FIELD EXPERIENCES A FORCE OR
TORQUE ( FARADAY’S LAW OF EMI).
ELECTRICAL ENERGY MAGNETIC ENERGY
MECHANICAL ENERGY.

3. Noisy operation.
Surge currents and spikes.
Electromagnetic interference.
Magnetic losses (Eddy currents &
Hysteresis).
High power consumption & high
temperature.
Low power factor.
Comparatively lesser efficiency.

4. A pressure applied across a pair of opposite
faces of a crystal, results in a PD developed
across the other pair
Mechanical
Pressure
Mechanical
Pressure
Potential
Difference

5. When an AC is applied across a pair of
opposite faces, alternating compressions
and elongations (mechanical vibrations)
are obtained across the other pair of
opposite faces.
As a result, a surface wave is formed over
the crystal driving force
of the USM

7. A piezoelectric material (Quartz, Barium Titanate,
Tourmaline, Rochelle Salt) is used as actuator.
Actuator is fixed on the stator using thin metal sheets
and bearings.
Actuator is directly connected to the supply mains.
Stator is made of any malleable material Steel.
Ring, Cylindrical or Rod shaped.

8. Same material as that of the stator.
Same shape as that of the stator(Ring, Cylindrical or
Rod).
Frictional coupling.
Cylindrical, Disc or Box shaped.
Non- corrosive alloys or Fiber.
To provide protection against abrasion & external
interferences .

11. Surface of contact b/w rotor & stator is made
uneven, so that they never slip off frictional
coupling.
During motion, rotor is levitated from the stator
in the perpendicular direction less wear &
tear.
Care is to be taken that friction doesn't cause
the interlocking of rotor & stator.

12. If the wave produced in the stator causes the particles to
experience both horizontal and vertical movement.
Produced by double actuators.
If the wave produced in the stator causes the particles
to experience only vertical movement.
Single actuator is required.

13. High o/p torque & efficiency.
High power to weight ratio.
Good positioning accuracy.
Capable of working in extreme
environmental conditions.
No magnetic interference.
Simple construction.
Small size, light weight, less
noise.
Requires high frequency power
supply(kHz range).
Piezoelectric material is
expensive.
Ultrasonic noise occurs.
Drooping torque-speed
characteristics

14. Auto focusing & optical zooming in digital
cameras & surveillance cameras.
Wrist watches & Clocks.
Power steering, Power windows, Tilt steering,
ORVM, Car seat adjustment etc.
Robotics.
Aerospace.
Medicine
Hardware positioning (Hard disks, Floppy &
CD Drives) etc.

15. The above mentioned advantages and
applications, concludes the scope of
USMs in the day-to-day life.
However the disadvantages brings up the
need for further researches in the field.

16. .
Piezoelectric effect was discovered by
Jacques Curie & Pierre Curie
[France-1880].
1st Ultrasonic Motor was developed by
V V Lavrinenko [Russia-1965].