Prepared by: Berk Demirgok
Dept. of Electrical and Computer Engineering
Utah State University
3/15/2012
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Overview of position sensors
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Applications of position sensors
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Types of position sensors
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Applications
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Study Rotary Encoders in position sensors
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Specifications
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Purchasing
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References
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“Mechatronics – An Integrated Approach” by
Clarence W. de Silva
Wikipedia
Mechanical measurements by Thomas G.
Beckwith, Roy D. Marangoni, John H. Lienhard
http://www.automationdirect.com/adc/Over
view/Catalog/Sensors_-z_Encoders/Encoders?source=google&keyword
=rotary%20encoders%20incremental&type=sea
rch&gclid=CMOT44X19q4CFQUZQgodyHEJz
A
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http://www.electronicstutorials.ws/diode/diode_8.html
http://www.electronicstutorials.ws/io/io_2.html
http://www.eowave.com/products.php?prod
=21
http://www.autonics.com/products/products
_2.php?big=01&mid=01/06
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http://www.sensorstransducers.machinedesign.com/guiEdits/Con
tent/bdeee4/bdeee4_3.aspx
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A position sensor is a device allowing position
measurements.
The sensor can either be to some fixed point or
position or from some fixed point or position.
A position sensor can measure any positions,
such as linear positions, angular positions and
rotary positions.
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Linear Positions
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Angular Positions
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Rotary Positions
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Servomotors
Amusement equipment
Music live control
Computer game joysticks
Steering wheels
Robot applications
Industrial applications
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Rotary encoders are also called shaft encoders.
Rotary encoder converts angular position of
mechanical movement of a shaft or axle to an
analog or digital signal.
Generally, digital signal is preferred.
• http://www.google.com/imgres?q=rotary+encoders&hl=en&sa=X&rlz=1C1CHFX_
enUS474US474&biw=1024&bih=624&tbm=isch&prmd=imvns&tbnid=2Rz18G1gJ9Bn
XM:&imgrefurl=http://www.karacnc.com/products.html&docid=bc9LaH0jfjAktM
&imgurl=http://www.karacnc.com/images/rotaryencoder.jpg&w=277&h=277&ei=
FT9pT431IqeYiQKW4dDbBg&zoom=1&iact=hc&vpx=270&vpy=292&dur=807&hovh
=221&hovw=221&tx=102&ty=133&sig=103248373012637440328&page=5&tbnh=133&
tbnw=136&start=72&ndsp=20&ved=1t:429,r:6,s:72
• http://todbot.com/blog/wp-content/uploads/2008/06/rotary-encoder-closeup300x221.jpg
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Rotary encoder works just like an optical
encoder.
Lights from LED or infra-red light visible
semiconductor diodes goes through a rotating
encoded disk which contains the required code
designs in binary grey code. Then, photo
sensors examine the disk while it is rotating.
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While the disk rotates, an electronic circuit
procedures the information from rotating disk
into a digital information in binary code.
Converted digital output is in binary code form
because, binary code helps controllers to
determine the actual angular position of the
shaft or axle.
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After the output converted into digital signal, a
rotary encoder can helps us to know position
or distance. Moreover, rotary encoders also can
provide information about speed, revolution.
• http://en.wikipedia.org/wiki/Rotary_
encoder#Incremental_rotary_encoder
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Incremental rotary encoders
Delivers only cyclical outputs when the encoder is
rotating.
 Incremental rotary encoders can get one of three
following signal categories:

 Quadrature
 Single channel
 Pulse
 Direction
Incremental rotary encoder looks like this
http://img.deusm.com/designnews/289/
289447-Incremental_Optical_Encoder.jpg
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Standard rotary encoders
http://www.industrystock.com/pressene
wsimages/orig/cde86e815031c45457c1ba2
73b8c88d0.jpg
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Modular rotary encoders

Modular rotary encoders are the most sensitive to
motor shaft run-out and axial movement. They are
commonly used in servomotors.
http://img.directindustry.com/images_di
/photo-m2/miniature-optical-incrementalrotary-encoder-734405.jpg
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Kit rotary encoders
http://images.tradekool.com/199762700/
Encoder-Module-Kit-Encoder-OpticalEncoder-Rotary-Encoder.jpg
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Single channel rotary encoders
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Rotary encoders have very wide-range
application areas and some of them are
mentioned as:
Industrial Controls
 Robotics
 Photographic Lenses
 Cellphones
 Computers
 Automotive
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Rotary Position sensor can be easily purchased
from many online stores
Here is some good web-sites to look if you
want to buy rotary position sensor.
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www.digikey.com
www.mouser.com
http://honeywell.com
www.eowave.com
http://www.marshbellofram.com/servote
k/Rotary%20Encoders.JPG
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Light Duty use rotary encoders
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Medium Duty use rotary encoders
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$25-$125
$75-$200
Heavy Duty use rotary encoders
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$150-$300