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Encoders and Sensors

Encoders and Sensors. By: Chris Christensen Mike Mantyla. October 8 th , 2007. Table of Contents. What is a Sensor…………………………...............3 Sensor Requirements………………………………4 How are Sensors Categorized…………...............5-7 How are Sensor Mathematically Represented…….8

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Encoders and Sensors

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  1. Encoders and Sensors By: Chris Christensen Mike Mantyla October 8th, 2007

  2. Table of Contents What is a Sensor…………………………...............3 Sensor Requirements………………………………4 How are Sensors Categorized…………...............5-7 How are Sensor Mathematically Represented…….8 Who Uses Sensors, and What do They Cost..….....9 MEMS – The Newest, Greatest………………10-12 What is an Encoder…………………………..…..13 How Does an Encoder Work…………………14-16 Different Types of Encoders……………………..17 Encoder Details……………..………………...18-19 Important Vendors and Encoder Specs…….…….20 Important Limitations and Standards……….……21 Summary…………………….………………..22-23 Class Exercise…………….………………...……24 Solution……………………….………………….25 References………………………………………..26

  3. Fingerprinting mouse i.e. Basic Thermometer What is a Sensor? ○A hardware device which responds to some physical stimulus by outputting a readable signal ○A form of transducer (changes energy from one form to another) ○ Sensors are a fundamental component for automation in manufacturing, without which the process could not take place

  4. Sensor Requirements ○Needs to be sensitive to the measured variable ○Needs to avoiding changing or influencing the measured variable ○Needs to avoid influence from all other variables (noise)

  5. I. Measurement Type ○ Analog Ex. Magnetic compass, Strain Gauges, Barometers Require an analog-to-digital converter ○ Discrete - Binary 0 1 0 0 1 1 Ex. Proximity Switch, Limit Switch - Digital Ex. Optical Encoder, Photoelectric Sensor Array How are Sensors Categorized?

  6. How are sensors categorized…Continued? II.Measurement Variable ○ Thermal - thermometers, thermocouples, thermistors, bolometer, calorimeter ○ Mechanical -altimeter, barometer, anemometer, flow meter, strain gauge ○ Electrical -voltmeter, galvanometer, ammeter, ohmmeter, multimeter ○ Chemical -oxygen sensors, ion-selective electrodes, pH glass electrodes ○ Magnetic - magnetic compass, magnetometer, Hall effect device ○ Radiation -proximity sensor, photo-electric tubes, photocells, phototransistors ○ Biological – can sense: light, motion, temperature, magnetic fields, gravity, humidity, pressure, electrical fields, sounds, toxins, nutrients, hormones, oxygen levels

  7. How are sensors categorized…Continued? III. Input Power Requirement ○ Active – No power needed to respond to stimulus ○ Passive – External power supply needed to work

  8. How are sensors represented mathematically? Transfer Function: S = f (s) Where s =stimulus input and S is output (i.e. voltage) Binary Sensors: S = 1 if s >0 and S = 0 if s<0 Ideal Analog Sensors: S = C + ms Where C =stimulus value at zero and m = sensitivity

  9. ○ Cost range: $0.20 - $3500.00 Who uses Sensors, and What do They Cost? ○ Everyone Uses Sensors!!! ○ The questions for a consumer to ask in determining what type of sensor is needed are: What is the target variable to be measured? How do I want the output measurement displayed? How small of a resolution do I need? Are there restricting power requirements?

  10. MEMS The Newest, Greatest ○ Microelectromechanical systems are the current focus of developers and researchers ○ MEMS are found in cameras, watches, game consoles, cell phones, etc. ○ Allow for lighter, faster, and more resolute and precise robots

  11. Simple MEMS sensors can be 1μm in lengthand complex ones can be as small as shown! Coriolis flowmeter

  12. ○ In conjunction with microchip technology, the advancement of these better and smaller sensors drives the capabilities and standards of the manufacturing industry

  13. What is an Encoder? An encoder is a sensing device which takes motion from a physical component and converts it into a digital pulse, which is then sent to a controller and manipulated for a desired purpose.

  14. The signal goes to the controller To perform a desired function The disk moves by some type of automatic rotation The filter transforms the sinusoidal wave into a square wave The photo sensor responds to the oscillating light by outputting a sine wave The LED points orthogonally at the disk How Does an Encoder Work? There are many differences in the various types of encoders, but the two main ones are: rotary and linear encoders (both examples are optical) Rotary Encoder

  15. How Does an Encoder Work…Continued? • Two Types of Optical Encoders: • Incremental • Absolute • Incremental (Single or Quadrature) • - Reads high and low signals • Indicates movement from one • position to another • - Single does not indicate direction • Absolute • Generates unique word pattern • Each word signifies an angular position • Indicates movement from base frame

  16. How Does an Encoder Work…Continued? This type of sensor detects the distance between lines or bearings along a linear path and takes that data to output a digital signal. The encoder resolution is dependent upon the spacing of the lines. It can be as small as 2 µm – 1 nm, reading paths that have more than 1300 lines/inch and moving at speeds as fast as 30 feet/second. Linear Encoder

  17. Hollow Shaft Magnetic Brake Different Types of Encoders The most current type of encoders: Rotary Linear

  18. Mice and Trackballs Cutting Machines Rotating Radar Platform Photographic Lenses Micrometers ENCODER DETAILS Encoder Costs Different Encoder Applications Cheap – $15 - $30 Light – $30 - $100 Medium – $100 - 400 Heavy Duty – $400 + There are also many places where you can get customized encoders, these are usually expensive, but not as expensive as the high-end heavy duty encoders

  19. Supporting Technology Controllers LCDs Software Power Input to the Rotary and Sensors ENCODER DETAILS…CONTINUED WHO USES ENCODERS? Research and Development – encoders assist in data collection Robotics Companies – position sensors, accelerometers, etc. Manufacturing – CNC machines, automation tools Universities – experiments, research, etc. People – creating things for personal use

  20. www.quantumdev.com/products/optical_encoders/hr12.html www.quantumdev.com/products/optical_encoders/jr12.html www.quantumdev.com/products/optical_encoders/qd200.html www.quantumdev.com/products/optical_encoders/qd787_hollow.html www.quantumdev.com/products/optical_encoders/qr12.html Important Vendors and Encoder Specs TURCK www.turck-usa.com/Products/Encoders/ US DIGITAL www.usdigital.com EPC www.encoder.com/quickreference.html BAUMER ELECTRIC www.baumerelectric.com/usa/ BEI ENCODERS www.bei-encoder.com/ (They seem to be #1, or at least on the net) GPI ENCODERS www.gpi-encoders.com/ ELCIS www.elcis.com/ENGLISH/index.html LENORD AND BAUER www.lenord.de/en/ QUANEM DEVICES INC. www.quantumdev.com/products/optical_encoders/index.html OMRON www.omron247.com/Industrial-Automation/Store/

  21. Important LIMITATIONS AND STANDARDS PPR = Pulses Per Revolution, or inches for linear encoders, can be up to 150,000 Voltage input is usually ±5 volts, but can be up to25 volts Frequency Response should be around 500kHz Type of Format = Incremental Single or Quadrature, or Absolute Accuracy is around ±1° mechanical Temperature is very important, should have an average operating temp. of -20 to 115° C Maximum Shaft Speed = around 8000 RPM Also look at vibration, how it can be mounted, moment of inertia, storage temperature, etc. How Encoders Can be Integrated? Encoders are part of sensor and actuator systems, in which during automated processes feedback is given to ensure precise location of the TCF and other joints.

  22. SUMMARY SENSORS A sensor is a device that responds to a physical stimulus by outputting a readable signal. The two measuring types are: analog and discrete (digital) The measurement variables are: thermal, mechanical, electrical, chemical, magnetic, radiation, biological The power inputs: active (no power required), passive (external power source required) When purchasing a sensor you should know: What is being measured? How do I want the measurement displayed? How small do I need the resolution? How much power is necessary to run the sensor How much am I willing to spend? MEMS (Microelectromechanical systems) are the top-of-the-line sensors used in industry They can be found in all most any technology: cameras, watches, cell phones etc. They are lighter, faster, smaller (can be as small as 1 μm)

  23. SUMMARY ENCODERS Encoders are very close to sensors, they receive physical feedback and convert it into a digital signal which is then read by a controller for a desired purpose. Two main different types of encoders: Rotary – Absolute, Incremental (Single and Quadrature) – Digital output from slit along disk Linear – Digital signal from lines along a linear path of the LED sensor Encoder Beneficiaries: Universities, Robotics Companies, Manufacturers, R & D, Individuals Supporting Technology – Controllers, Digital Readouts, Software, Power to the Rotary When buying an encoder always check: Voltage (±5 volts - 25volts), Frequency Response (500 kHz), Type of Format (Incremental: Single or Quadrature; or Absolute), Accuracy (±1° mechanical), Temperature (operating temp. -20 to 115° C or better), Max. Shaft Speed (8000 RPM), Also: vibration, how it can be mounted, moment of inertia, storage temperature

  24. Class Exercise During calibration, an Iron/Constantan thermocouple is zeroed (set to emit a zero voltage) at 0˚C. At 750˚ C, it emits a voltage of 38.8 mV. A linear output/input relationship exists between 0˚C and 750˚C. Determine: a. The transfer function of the thermocouple b. The temperature corresponding to a voltage output of 29.6 mV

  25. Solution: Input Variable (s): Temperature Output Variable (S): Voltage a. 0.0388 V = q (750°C) =>S = 0.00005173 (q) b. 0.0296 V = 0.00005173(T°C) =>T = 572.2°C

  26. References Pictures http://www.physikinstrumente.com/en/primages/pi_m122_2dd_i4c_o.jpg http://www.digiball.com/images/linear%20encoder.jpg http://www.anilam.com/Uploads/Image/2006%20Images%20New/alttech.jpg http://www.newall.com/images/led_cutaway_dro.jpg http://www.infotechfrance.com/london/upload/photo_11280.jpg http://www.sscnet.ucla.edu/geog/gessler/topics/encoder-rot-large.jpg http://mechatronics.mech.northwestern.edu/design_ref/sensors/gray.jpg http://www.turck-usa.com/assets/index_Encoders.jpg http://www.neg.co.jp/cgp/neoceram/image/leps04.jpg http://store01.prostores.com/allianceparts/catalog/1027776.jpg http://www.avtron.com/images/jpgs/m460.jpg http://www.phytron-elektronik.de/antrieb/images/produkte/SM_zsh_133.jpg http://home.planet.nl/~nwkaan/images/rotaries/fds_picture.jpg http://www.lions-wing.net/lessons/hardware/Trackball2.jpg http://content.answers.com/main/content/wp/en-commons/thumb/5/5d/250px-Lens_Nikkor_18-70mm.jpg http://www.lsainc.com/technologies/waabs/Image15-342x618.jpg www.dkimages.com www.tchinese.tyloon.com www.tiresias.org www.spie.org www.panasonic-electric-works.com www.flowcontrolnetwork.com www.kebaili.com www.answers.com www.gyre.org www.subwaysurfer.com Explanation of Sensors www.sensedu.com/ en.wikipedia.org/wiki/Sensor www.sensorsmag.com/sensors/article/articleDetail.jsp?id=399828 www.omron247.com/Industrial-Automation/Store/ www.mdpi.org/sensors/ Explanation of Encoders http://clrwtr.com/Accu-Coder-Encoders-How-To.html http://zone.ni.com/devzone/cda/tut/p/id/3321 http://wikipedia.org/wiki/Rotary_encoder http://wikipedia.org/wiki/Linear_encoder Videos http://www.youtube.com/watch?v=zTEgC5hSEm0&mode= related&search=Joral%20rotary%20encoder%20non-contac t%20misalignment

  27. Questions and Answers

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