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Prepared by: Jonathan Tran Dept. of Electrical and Computer Engineering Utah State University

ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Passive Infrared Sensor. Prepared by: Jonathan Tran Dept. of Electrical and Computer Engineering Utah State University E: jon.tran@aggiemail.usu.edu F: (435)797-3054 (ECE Dept.). 3/11/2010. Outline.

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Prepared by: Jonathan Tran Dept. of Electrical and Computer Engineering Utah State University

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  1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Passive Infrared Sensor Prepared by: Jonathan Tran Dept. of Electrical and Computer Engineering Utah State University E: jon.tran@aggiemail.usu.edu F: (435)797-3054 (ECE Dept.) 3/11/2010

  2. Outline • Reference List • To Probe Further • What is a Passive Infrared Sensor? • Major Applications • Practical Applications • How It Works • Physical Appearance • Major Specifications • Limitations • Cost ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  3. Reference List • http://www.ladyada.net/learn/sensors/pir.html • http://www.glolab.com/pirparts/infrared.html • http://itp.nyu.edu/physcomp/sensors/Reports/PassiveInfraRedSensor • http://www.reuk.co.uk/PIR-Sensors.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  4. To Explore Further (survival pointers of web references etc) • http://en.wikipedia.org/wiki/Passive_infrared_sensor • http://www.ladyada.net/learn/sensors/pir.html • http://www.gadgetshack.com/motionsensor.html • http://en.wikipedia.org/wiki/Fresnel_lens ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  5. What is a Passive Infrared (PIR) Sensor? • Used to detect motion • Basically made up of pyroelectric sensors • Detect levels of infrared radiation • Does not emit any radiation, only detects, hence passive ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  6. Major applications • Motion Detection • Lighting Systems • Security Systems • Automation (doors, air conditioning, etc.) • Measuring Temperature Differentials • Measure temperatures of remote objects ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  7. Practical Applications • Automatic doors • Interactive Rooms • Activate when person enters room • Remote triggered cameras • Take photos/start recording when person enters room ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  8. How It Works – Theory • Infrared radiation exists in the EM spectrum • Can’t be seen, but can be detected • Objects that generate heat also generate IR radiation • PIR sensor consists of two sensing elements • One gives a frame of reference and the other detects the change • Can only detect the difference in temperatures between the two sensors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  9. How It Works – Theory (cont.) • For example: A PIR sensor is pointed into a room. An animal, with a temperature greater than the wall, walks into the room. As the animal crosses the first sensor, a positive pulse is produced. When the animal is in front of both sensors, there is no sensed change. As it crosses the second sensor, a negative pulse is emitted. These pulses are what is detected. • An illustration of this example is shown on the next slide ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  10. How It Works – Theory (cont.) http://www.glolab.com/pirparts/infrared.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  11. How It Works – Fresnel Lens • Captures more IR radiation • Focuses the radiation into a smaller point • Condenses the light and provides a larger range of IR to the sensor http://www.ladyada.net/learn/sensors/pir.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  12. How It Works – Fresnel Lens (cont.) • Focal point moves across the sensor as the IR source moves, exposing one element at a time • Grooved side usually face the PIR sensor http://www.ladyada.net/learn/sensors/pir.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  13. How It Works – Fresnel Lens (cont.) • A Plano Convex lens that has been collapsed on itself to form a flat lens • Much smaller in thickness, so less absorption loss http://www.glolab.com/pirparts/infrared.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  14. How It Works – Fresnel Lens (cont.) • Usually thin and flexible • About 0.015 inches thick • Made of material opaque to visible light • Materials that pass visible light will not pass infrared radiation (e.g. glass, plastic, etc.) http://www.ladyada.net/learn/sensors/pir.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  15. How It Works – Summary • Fresnel lens directs IR radiation at two pyroelectric sensors • Impulse gives the difference in temperature between two sensors • Motion is detected when a body with different temperature than the surroundings enters the frame of the sensor ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  16. Physical Appearance – Housing • Housed in a sealed metal can to improve noise/temp/humidity immunity • Three pin output – Drain, gate, & source http://www.ladyada.net/learn/sensors/pir.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  17. Physical Appearance – Sensor Window • Sensing elements can be seen through the IR window http://itp.nyu.edu/physcomp/sensors/Reports/PassiveInfraRedSensor ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  18. Major Specifications • Power requirements • Communication (Output) • Single bit high/low output • Dimensions • Operating Temperature • Range • Detection Angle ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  19. Limitations • Sensing can be confused • Motion too close to sensor • Motion is not passed through sensor one at a time • Cannot detect slow moving or stationary objects • Sensor is approached straight on • Limited range in most sensors • Temperature sensitive ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

  20. Typical Cost/Where to Buy • Typical cost is about $10.00 for complete module • Discounts are given if ordering in large quantities • http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/CategoryID/36/List/0/Level/a/ProductID/83/Default.aspx?SortField=ProductName%2cProductName • http://www.hvwtech.com/products_view.asp?ProductID=270 • http://www.futurlec.com/PIR_Sensors.shtml ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

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