Sensors you should know about

1
Sensors you should know about

• Thomas Edwards
• http//www.t11s.com

2
Passive Infrared (PIR) Sensor

• Detects motion of warm moving objects
• If nothing is moving, there is no detection
• Commonly used in security systems
• Very Long range (50 feet)
• Binary or relay opening output
• 10
• http//www.mpja.com/directview.asp?product15840S
  C
• http//www.parallax.com/detail.asp?product_id555-
  28027

3
Microwave Motion Detector

• Uses microwave doppler shift to detect motion
• Range 10 feet
• May have fewer false positives than PIR
  detectors
• 35 kit
• http//www.ramseyelectronics.com/cgi-bin/commerce
  .exe?preaddactionkeyMD3C

4
Active IR Sensors

• Bounces invisible IR beam off of target
• Uses triangulation to determine distance
• Range up to 5 feet
• Analog distance output or binary fixed range
  detection output
• 10-20
• http//www.acroname.com/robotics/parts/c_Sensors.
  html

5
Ultrasonic Sensors

• Uses travel time of sound echos to detect
  distance
• Range up to 15 feet
• Outputs can be analog, serial, or PWM
• Old, expensive Polaroid sensor
• New, cheaper ones today 25
• http//www.maxbotix.com/

6
Accelerometers

• New ones based on Micro-Electro-Mechanical
  Systems (MEMS) devices very small
• Can measure acceleration in up to three axes
• Even can sense gravitational pull of earth
• 25 and up
• http//www.sparkfun.com/commerce/product_info.php
  ?products_id692

7
Magnetic Reed Switches

• Magnet in one part causes reed switch to
  open/close on second part
• Commonly used in security systems
• Range very short (1 inch)
• Good for limit switch
• 5 or under

8
Force Sensing Resistors

• Pressure reduces resistance
• Analog voltage measured across resistor divider
  circuit
• Can measure a few ounces to 100 lbs depending on
  model
• 10-25
• http//www.parallax.com/detail.asp?product_id300
  56
• http//www.phidgetsusa.com/cat/viewsubcategory.as
  p?category5000subcategory5210

9
Touch Sensors

• Measure changes in capacitance
• Can sense touch through 4 inches of dielectric
  objects (glass, plastic)
• 10-20
• http//www.phidgetsusa.com/cat/viewproduct.asp?ca
  tegory5000subcategory5100SKU1110

10
CMU Cam

• Microcontroller and camera combo
• Track user defined color blobs
• Track motion using frame differencing
• Controls up to 5 servos
• Other video processing capabilities
• Serial I/O
• 169
• http//www.cs.cmu.edu/cmucam2/

11
Laser Range Finder

• Very accurate distance measurement
• Time-of-flight determines distance
• Range 4m
• 270 degrees of measurement
• 0.36 degrees angular resolution
• RS-232/USB output
• 2695
• http//www.acroname.com/robotics/parts/R283-HOKUY
  O-LASER1.html

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Sensors you should know about

• Thomas Edwards
• http//www.t11s.com