Lecture 9: Motors and Actuators
Working At The Boundary Between
EE/CSE/EPE, Mechanical and Materials
Engineering
7/1/2016
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Magnetism
• One of the first
compasses, a fish
shaped iron leaf
was mentioned in
the Wu Ching
Tsung Yao written
in 1040
Trinity College, Dublin
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Animal Magnetism
• A frog suspended in an intense magnetic field
– all of us are paramagnetic
• Much money is wasted on magnetic therapy
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Electromagnetic Revolution

 D  

 B  0

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B
 E  
t

  D
 H  J 
t
• These four equations epitomize the electromagnetic
revolution. Richard Feynman claimed that "ten
thousand years from now, there can be little doubt
that the most significant event of the 19th century will
be judged as Maxwell's discovery of the laws of
electrodynamics"
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Magnetic Attraction
• It is possible to produce motion using
magnetic attraction and/or repulsion
• Either permanent magnets or electromagnets
or both can be used
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Magnetic Attraction and Repulsion
• One of the many facts we all recall from
our earliest science education
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2 Minute Quiz
Name______Sec_____Date______
• True or false, unlike magnetic poles attract
and like magnetic poles repel one another.
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DC Motors
• The stator is the stationary outside part of a motor.
The rotor is the inner part which rotates. In the motor
animations, red represents a magnet or winding with
a north polarization, while green represents a magnet
or winding with a south polarization. Opposite, red
and green, polarities attract.
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DC Motors
• Just as the rotor reaches alignment, the
brushes move across the commutator
contacts and energize the next winding. In
the animation the commutator contacts are
brown and the brushes are dark grey. A
yellow spark shows when the brushes switch
to the next winding.
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DC Motor Applications
• Automobiles
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Windshield Wipers
Door locks
Window lifts
Antenna retractor
Seat adjust
Mirror adjust
Anti-lock Braking
System
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•Cordless hand drill
•Electric lawnmower
•Fans
•Toys
•Electric toothbrush
•Servo Motor
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Beakman’s Motor
• A simple DC motor made with a battery, two
paperclips, a rubber band and about 1 meter
of enameled wire.
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Brushless DC Motors
• A brushless dc motor has a rotor with
permanent magnets and a stator with
windings. It is essentially a dc motor turned
inside out. The control electronics replace the
function of the commutator and energize the
proper winding.
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Brushless DC Motor Applications
• Medical: centrifuges, orthoscopic
surgical tools, respirators, dental
surgical tools, and organ transport
pump systems
• Model airplanes, cars, boats,
helicopters
• Microscopes
• Tape drives and winders
• Artificial heart
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Full Stepper Motor
•
This animation demonstrates the principle for a stepper motor using full step
commutation. The rotor of a permanent magnet stepper motor consists of
permanent magnets and the stator has two pairs of windings. Just as the rotor
aligns with one of the stator poles, the second phase is energized. The two
phases alternate on and off and also reverse polarity. There are four steps. One
phase lags the other phase by one step. This is equivalent to one forth of an
electrical cycle or 90°.
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Half Stepper Motor
•
This animation shows the stepping pattern for a half-step stepper motor. The
commutation sequence for a half-step stepper motor has eight steps instead of
four. The main difference is that the second phase is turned on before the first
phase is turned off. Thus, sometimes both phases are energized at the same
time. During the half-steps the rotor is held in between the two full-step positions.
A half-step motor has twice the resolution of a full step motor. It is very popular
for this reason.
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Stepper Motors
•
This stepper motor is very simplified. The rotor of a real stepper motor usually
has many poles. The animation has only ten poles, however a real stepper motor
might have a hundred. These are formed using a single magnet mounted inline
with the rotor axis and two pole pieces with many teeth. The teeth are staggered
to produce many poles. The stator poles of a real stepper motor also has many
teeth. The teeth are arranged so that the two phases are still 90° out of phase.
This stepper motor uses permanent magnets. Some stepper motors do not have
magnets and instead use the basic principles of a switched reluctance motor.
The stator is similar but the rotor is composed of a iron laminates.
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More on Stepper Motors
• Note how the phases are driven so that
the rotor takes half steps
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More on Stepper Motors
• Animation shows how coils are
energized for full steps
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More on Stepper Motors
• Full step sequence
showing how binary
numbers can control
the motor
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• Half step
sequence of
binary control
numbers
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Stepper Motor Applications
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Film Drive
Optical Scanner
Printers
ATM Machines
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I. V. Pump
Blood Analyzer
FAX Machines
Thermostats
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2 Minute Quiz
Name______Sec_____Date______
• Name one mechatronic device that you own
or use on a regular basis
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Switched Reluctance Motor
•
A switched reluctance or variable reluctance motor does not contain any
permanent magnets. The stator is similar to a brushless dc motor. However, the
rotor consists only of iron laminates. The iron rotor is attracted to the energized
stator pole. The polarity of the stator pole does not matter. Torque is produced as
a result of the attraction between the electromagnet and the iron rotor in the
same way a magnet is attracted to a refrigerator door. An electrically quiet motor
since it has no brushes.
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Switched Reluctance Motor Applications
• Motor scooters and other electric and hybrid
vehicles
• Industrial fans, blowers, pumps, mixers,
centrifuges, machine tools
• Domestic appliances
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Brushless AC Motor
• A brushless ac motor is driven with ac sine wave voltages.
The permanent magnet rotor rotates synchronous to the
rotating magnetic field. The rotating magnetic field is
illustrated using a red and green gradient. An actual
simulation of the magnetic field would show a far more
complex magnetic field.
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AC Induction Motor
•
The stator windings of an ac induction motor are distributed around the stator
to produce a roughly sinusoidal distribution. When three phase ac voltages are
applied to the stator windings, a rotating magnetic field is produced. The rotor
of an induction motor also consists of windings or more often a copper squirrel
cage imbedded within iron laminates. Only the iron laminates are shown. An
electric current is induced in the rotor bars which also produce a magnetic field.
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AC Induction Motor
•
The rotating magnetic field of the stator drags the rotor around. The rotor does not
quite keep up with the the rotating magnetic field of the stator. It falls behind or slips
as the field rotates. In this animation, for every time the magnetic field rotates, the
rotor only makes three fourths of a turn. If you follow one of the bright green or red
rotor teeth with the mouse, you will notice it change color as it falls behind the
rotating field. The slip has been greatly exaggerated to enable visualization of this
concept. A real induction motor only slips a few percent.
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Huge List of Applications from Hurst
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Aircraft Window Polarizing Drives
Antenna Positioning and Tuning Devices
Audio/Video Recording Instruments
Automated Inspection Equipment
Automated Photo Developing Equipment
Automated Photo Slide Trimming &
Mounting Equipment
Automatic Carton Marking & Dating
Machines
Automatic Dying and Textile Coloring
Equipment
Automatic Food Processing Equipment
Automatic I.V. Dispensing Equipment
Automatic Radio Station Identification
Equipment
Automotive
Automotive Engine Pollution Analyzers
Baseball Pitching Machine
Blood Agitators
Blood Cell Analyzer
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Warning Light Flashers
Railroad Signal Equipment
Remote Focusing Microscopes
Resonator Drives for Vibraphones
……..
Silicone Wafer Production Equipment
Solar Collector Devices
Sonar Range Recorders and Simulators
Steel Mill Process Scanners
Tape Cleaning Equipment
Tape Input for Automatic Typewriters
Telescope Drives
Ultrasonic Commercial Fish Detectors
Ultrasonic Medical Diagnostic Equipment
Voltage Regulators
Water and Sewage Treatment Controls
Weather Data Collection Machines
Welding Machines
X-Ray Equipment
XY Plotters
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Stepper Motor from Mechatronics
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Mechatronics Stepper Motor Continued
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Mechatronics
• Mechatronics is at the intersection between
several disciplinary areas, as represented by
these Venn diagrams
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What Is Mechatronics?
• Mechatronics is the synergistic integration of
mechanical engineering, electronics, controls,
and computers; all integrated through the
design process.
• EXAMPLES:
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robots
anti-lock brakes
photocopiers
consumer products (e.g., clothes dryers)
disk drives
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MEMS
• Micro-Electro-Mechanical Systems (MEMS) is the
integration of mechanical elements, sensors,
actuators, and electronics on a common silicon
substrate through the utilization of microfabrication
technology. While the electronics are fabricated using
integrated circuit (IC) process sequences (e.g.,
CMOS, Bipolar, or BICMOS processes), the
micromechanical components are fabricated using
compatible "micromachining" processes that
selectively etch away parts of the silicon wafer or add
new structural layers to form the mechanical and
electromechanical devices.
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MEMS Stepper Motor
• This motor is very much like the other
stepper motors mentioned above,
except that it is 2D and very small
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MEMS
• The potential complexity of the MEMS device
increases exponentially with the number of
unique process features and individual
structural layers.
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MEMS: Steam Engine
• Water inside of three compression cylinders is heated by electric
current and vaporizes, pushing the piston out. Capillary forces
then retract the piston once current is removed.
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MEMS
• Rotary motor
• Steam Engine (single piston)
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MEMS Gear Trains
• Six gear planar train at various speeds
• Close up of six gear train
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Power MEMS
• 80 Watt gas microturbine designed and
built at MIT for MEMS power
applications
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Integrated MEMS
• This six-degrees-offreedom micro-inertial
measurement system
combines
microelectronic
circuitry [top right] with
a couple of
• micromechanical
elements: an
accelerometer [center
right] and gyroscope
[bottom right].
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Integrated MEMS
•
Types of micromechanical
devices that might be used in
integrated microsystems of
the future [shown clockwise
from right] include this gear,
pop-up mirror, mirror
assembly, and hinge. The
gear is part of an assembly
that has demonstrated torque
ratios of up to 3 million to 1.
The silicon mirror is fabricated
flat on the silicon wafer, then
"popped up" to its raised
position using the gear
assembly.
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Integrated MEMS
•
Sample collection regions for
concentration, microseparation
channels, sensor arrays for
detection, and an exit region are
illustrated in schematic of the
chemical analysis section of a
micro-chemlab. Chemicals are
detected measuring the
response of surface acousticwave devices to a chemical's
presence. The photograph is of
an array of micromachined 3-µm
silicon posts in a microchannel
being studied as a tool for
enhancing electrokinetically
driven liquid separations.
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MEMS Displays
• Iridigm Display -- The iMoD element uses interference to
create color in the same way that structural color works in
nature. Microscopic structures on butterfly wings and
peacock feathers cause light to interfere with itself, creating
the shimmering iridescent colors that we see in these
creatures. (Used in PDAs)
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MEMS Displays
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The iMoD element is a simple MEMS device that is composed of two
conductive plates. One is a thin film stack on a glass substrate, the
other is a metallic membrane suspended over it. There is a gap
between the two that is filled with air. The iMoD element has two stable
states. When no voltage is applied, the plates are separated, and light
hitting the substrate is reflected as shown above. When a small voltage
is applied, the plates are pulled together by electrostatic attraction and
the light is absorbed, turning the element black.
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MEMS Displays
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iMoD elements are minuscule, typically 25-60 microns on a side (4001,000 dots per inch). Therefore, many iMoD elements are ganged and
driven together as a pixel, or sub-pixel in a color display. The color of
the iMoD element is determined by the size of the gap between the
plates. As shown, the blue iMoD has the smallest gap and the red has
the largest. To create a flat panel display, a large array of iMoD
elements are fabricated in the desired format (i.e. 5" full color VGA) and
packaged. Finally, driver chips are attached at the edge to complete the
display.
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References
• Motor Operation Principles from
Motorola
• Basic Stepper Motor Concepts
• MEMS Clearinghouse
• Mechatronics at Rensselaer
• Mechatronics.org
• Beakman’s Motor: Electronic
Instrumentation and Fields and Waves I
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2 Minute Quiz
Name______Sec_____Date______
• Which engineering majors are some
interest to you? Electrical, Computer &
Systems, Electric Power, Nuclear,
Mechanical, Aeronautical, Biomedical, Civil,
Industrial & Management, Materials,
Chemical, Environmental, Engineering
Physics
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Primary Course Goal for IEE
•
Assure that each EE and CSE student has a
minimum of 20 hours of practical electronics and
instrumentation experience before they begin
taking disciplinary courses.
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For students with no experience – 20 hours
successfully completing labs
For students with some experience – 20 hours
completing labs, expanding their knowledge base
and helping those with less experience
For students outside of EE and CSE – provide a
working knowledge of electronics
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2 Minute Quiz
ANSWERS
• True or false, unlike magnetic poles attract and like
magnetic poles repel one another.
TRUE
• Name one mechatronic device that you own or use on a
regular basisCD PLAYER, DISHWASHER
• Which engineering majors are some interest to you?
Electrical, Computer & Systems, Electric Power, Nuclear,
Mechanical, Aeronautical, Biomedical, Civil, Industrial &
Management, Materials, Chemical, Environmental,
Engineering Physics
• ELECTRICAL-THE ONLY ONE
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Where Will You See This Material Again?
• Mechatronics: MANE-4490 Mechatronics,
MANE-4250 Mechatronic Systems Design,
MANE 6960 Sensors & Actuators in
Mechatronics
• Motor Drives: ECSE/EPOW-4080
Semiconductor Power Electronics and
EPOW-4090 Power Electronics Lab
• Motor Control: ENGR-2350 Introduction to
Embedded Control
• Concentration in Power Electronics: EPOW4080 and MANE-4490
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