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ENCODERS

ENCODERS. Presented by Jianguo (Max) Wang October 4, 2004. Concepts related to encoders. What is a sensor? A sensor is a device that detects the state of the environment such as energy, heat, light, magnet, supersonic, etc. and convert them to electric signals.

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ENCODERS

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  1. ENCODERS Presented by Jianguo (Max) Wang October 4, 2004

  2. Concepts related to encoders • What is a sensor? A sensor is a device that detects the state of the environment such as energy, heat, light, magnet, supersonic, etc. and convert them to electric signals.

  3. Concepts related to encoders • What is an encoder? An encoder is a sensor for converting rotary motion or position to a series of electronic pulses

  4. Basic architectures of encoders • Linear architecture Linear encoders, which consist of a long linear read track (analogous to the code disk of a rotary encoder), together with a compact read head, address these concerns. We offer three grades of linear encoders, to suit a variety of application requirements.

  5. Basic architectures of encoders • Rotary architecture Rotary encoders serve as measuring sensors for rotary motion and for linear motion when used in conjunction with mechanical measuring standards such as leadscrews, and convert rotary motion(incremental or absolute) into electrical signals. They are both effective and low cost feedback devices. In high-accuracy applications, a number of error sources (leadscrew cumulative and periodic error, thermal expansion, and nut backlash, for example) render rotary feedback inadequate.

  6. The types of encoders • Absolute encoders • Absolute encoders have a unique code that can be detected for each angular position • Absolute encoders are much more complex and expensive than incremental encoders

  7. The types of encoders • Incremental encoders • Pulses from LEDS are counted to provide rotary position • Two detectors are used to determine direction (quadrature) • Index pulse used to denote start point • Otherwise pulses are not unique

  8. The applications • Positioning While a lead screw or rack-and-pinion converts rotary motion to linear motion, an encoder converts the same motion into electronic pulses. The pulses typically are used as input signals for counters, PLCs, or numerical-control equipment

  9. The applications • Length measurement Roll or sheet materials need to be measured during transport through converting or cut-to-length machinery. An encoder, when combined with a measuring wheel or coupled to a roller, will produce electronic pulses equal to units of length. Since fractional units may be measured, very precise operation is possible

  10. Current state Encoders are wildly used in industry • machine tools • textile machinery • printing presses • wood working machines • handling technology • conveying and storage technology • robotics

  11. Costs of encoders From less than 100$ to more than 10,000 $. It depends on your requirement.

  12. Rules and limitations of encoders • Linear & rotary Linear encoders are more accurate. • Absolute & incremental Absolute encoders are more expensive. Incremental encoders spend more time for startup

  13. Rules and limitations of encoders • Magnetic & Optical

  14. Vendors • Heidenhain • Renco • Renishaw • autonics • Stegmann • Pepperl+Fuchs

  15. How to Choose an encoder • What the encoder is used for? • Cost • Working environment • Resolution • Requirement for the output standard of the encoder • Dimensions • Limits such as warm-up or startup time, maximum operating speed, bear life and so forth • Choose an appropriate model and type of encoder

  16. An example for choosing an encoder

  17. Specification examples • Linear encoders

  18. Specification examples • Rotary encoders

  19. How to integrate

  20. Application examples Model 716 (Cube Encoder) made by ECP were equipped on the lumber devices to produce up to 15% more lumber from each log

  21. Application examples The Company of Ground Force mounts EPC encoder on the trucks used at mining operationsto measure the rotation of pump shafts and of augers. The pumps deliver wet ingredients, while the augers deliver the dry ingredients.

  22. Application video

  23. Class Application • Robots uses rotary encoders wildly

  24. References • H.R. Everett,“Sensor for Mobile Robots”, page41-45. • http://machinery.articleinsider.com • http://www.sick.de • http://web6.automationdirect.com • http://www.euchner-usa.com • http://news.managingautomation.com • http://www.renco.com • http://www.ssirobotics.com • http://www.senix.com • http://www.heidenhain.com • http://www.ab.com • http://www. encoderdevices.com

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