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ECE 5320 – Mechatronics Literature Survey on Sensors and Actuators 12 March 2010 Ice Sensor

ECE 5320 – Mechatronics Literature Survey on Sensors and Actuators 12 March 2010 Ice Sensor. Marcus A. Cockerham Department of Electrical and Computer Engineering Utah State University m.a.cockerham@usu.edu Ph: ( 435) 363-4500 Fx: (435) 797-3054. Outline. Introduction and Motivation

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ECE 5320 – Mechatronics Literature Survey on Sensors and Actuators 12 March 2010 Ice Sensor

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  1. ECE 5320 – MechatronicsLiterature Survey on Sensors and Actuators 12 March 2010Ice Sensor Marcus A. Cockerham Department of Electrical and Computer Engineering Utah State University m.a.cockerham@usu.edu Ph: (435) 363-4500 Fx: (435) 797-3054

  2. Outline • Introduction and Motivation • Major Applications • Types of Ice Sensors • Operating Principles • Typical Configuration • Key Specifications • Limitations and Caveats • Suppliers • Further Information • References 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -2-

  3. Introduction and Motivation • Ice buildup is a common problem in cold environments. It severely affects transportation and communication, as well as structural and thermal systems. Its impact ranges from the mundane—slippery sidewalks, snow accumulation on a satellite dish, and roof leakage—to the more dramatic—radar obstruction, aircraft failure, and structural collapse. Image: http://www.gdargaud.net/Antarctica/DC2005/20050818_019_Mast.jpg Image: http://www.thecfireport.com/resources/_wsb_508x282_wing$2520ice$2520alb.jpg Image: http://www.warmquest.com/images/radiant-heat/roof_with_ice_dam.jpg 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -3-

  4. Introduction and Motivation (2) • Prevention and correction of these conditions has traditionally been a time-consuming and labor-intensive process. Alternately, attempts at automation proved prohibitively expensive and inefficient, as systems generally took the form of continuous heating of sensitive surfaces. Image: http://www.groundsupportworldwide.com/images/article/1227034085746_f3_01.jpg Image: http://milespowerwashing.com/images/gutter2.gif Image: http://www.unitedhomeexperts.com/Portals/61368/images//deicing%20cables.jpg 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -4-

  5. Introduction and Motivation (3) • In order to take advantage of recent advances in automation and controls systems, it was necessary to develop methods to detect ice formation. These sensors allowed for more efficient application of remedies only when and where they were needed. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -5-

  6. Major Applications • Aerospace: • wing and rotor deicing • instrument deicing • landing pad and runway deicing • Communications: • antenna/dish deicing • tower deicing • Thermal: • defrosting evaporator coils in HVAC/R systems 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey

  7. Major Applications (2) Energy: maintaining PV panels and wind turbines clear and operational Transportation: maintaining clear roads, walkways and bridges Facilities: deicing roofs, towers and other structures 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -7-

  8. Types of Ice Sensors Ice on a structure or device can be detected in a variety of ways. Depending on context, the optimal method could include a combination of detecting: Damping of ultrasonic vibrations Inductance change Resistance change Capacitance change Reflectivity change (at a particular wavelength) Transmissivity change (at a particular wavelength) Optical imaging Moisture + Temperature 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -8-

  9. Operating Principles Due to the wide variety of methods available for detecting ice accumulation, only a small selection will be presented here for closer examination. The interested reader is advised to see the references for more information. Most sensors are similar in that they supply a binary “ice/no ice” signal to whatever system they serve. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -9-

  10. Operating Principle: Ultrasonic Ultrasonic ice sensors typically make use of a vibrating wire or other structure in an area prone to ice accumulation. The increase in mass caused by the ice buildup causes a decrease in the resonant frequency of the structure. This change in frequency is detected and used to indicate the presence of ice. The sensitivity/threshold of frequency change can be modified to change the sensitivity to ice buildup. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -10-

  11. Operating Principle: Capacitive A flexible membrane is deflected periodically. Ice accumulation increases the stiffness of the membrane, limiting the amount of deflection. The amount of deflection is monitored by a change in capacitance between two fixed electrodes, and a decrease from normal rates is interpreted as an indication of ice. The sensitivity of the deflection monitor may be adjusted to change the sensitivity to ice buildup. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -11-

  12. Operating Principle: Transmissive A beam of light of known composition is passed between an emitter and detector. As ice accumulates in the gap, the received spectrum and total flux is modified. The sensitivity can be adjusted to trigger at different levels from a film of liquid water, through varying thickness/kinds of ice. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -12-

  13. Operating Principle:Moisture + Temperature Temperature is monitored by some suitable means. When temperature drops below some threshold, a moisture sensor is monitored (and heated, if necessary). When the combination of low temperature and high moisture is detected, ice is presumed. Temperature and moisture thresholds are both adjustable. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -13-

  14. Typical Configuration The ice sensor typically plays a role in a deicing/ice prevention system. Its output (ice / no ice) is fed to an appropriate controller which activates a deicing system. This output may be logged for system improvement and other interests. The details of the deicing system are beyond the scope of this presentation. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -14-

  15. Key Specifications Continuous vs. intermittent Does the sensor monitor continuously or at intervals? Are those intervals adjustable? Higher frequency measurements consume more energy, causing a decrease in battery life for embedded/remote systems, and a loss in efficiency for on-grid systems. Sensitivity range Does the sensor need to detect any precipitation? Only ice greater than a certain thickness? Certain applications can allow a small accumulation of ice before performance or safety are compromised. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -15-

  16. Key Specifications (2) Coverage How large an area is being monitored for ice formation? An antenna? A wing? A highway bridge? A runway? Some sensors only monitor a relatively small region. Output format Does the sensor present its state with a simple “ice/no ice” indication? Is more information (errors, ice thickness, etc.) needed? Some sensors have a digital serial output, allowing much more detailed information to be received. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -16-

  17. Key Specifications (3) Robustness How sensitive is the device to contamination? Will contamination cause permanent damage, or can it be restored to operation by cleaning? Will it still read if there is dirt/debris on the sensor? How sensitive is the device to mechanical shock or vibration? Some models require “near laboratory” conditions. Operating temperature All ice sensors must work near the freezing point, but some are more sensitive to others at extreme high and low temperatures. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -17-

  18. Key Specifications (4) Size What are the sensor dimensions? What is its mass? Depending on the application, any of these could be a critical or disqualifying factor. Power consumption What are the power needs of the device? Can it be placed in a “sleep” mode? In an embedded, continuous-monitoring situation, power could become a chief concern. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -18-

  19. Limitations and Caveats Performance cost All of these sensors can potentially interfere with proper operation of the overall system. For example, detecting wing icing on an aircraft requires placing a sensor in the skin of the wing, possibly disrupting lift and handling characteristics. As another example, detecting icing of a rain gutter involves placing a sensor in the flow of water. This can become clogged with debris, and restrict the flow to a worse degree than the ice would have. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -19-

  20. Limitations and Caveats (2) Small detection area Each of these sensors can only monitor a specific, limited area. The conditions within this area must be extrapolated to the entire system; possibly leading to false-negatives. Avoiding this situation requires thoughtful placement and redundancy of sensors. 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -20-

  21. Suppliers Ultrasonic: http://www.goodrich.com/portal/goodrich/images/Goodrich%20Content/Business%20Content/Sensors%20and%20Integrated%20Systems/Products/Literature%20Listing/4095%20Ice%20Detector%200871LH1.pdf Temperature + Moisture: Embedded in pavement: http://www.tekmarcontrols.com/prod/090.shtml In roof gutter: http://www.networketi.com/19037.htm 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -21-

  22. Suppliers (2) Reflective (for roadways): http://www.sensice.com/ Transmissive (for avionics and general industry): http://www.newavionics.com/ 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -22-

  23. Further Information • Most readily available information regarding ice sensors appears to be related to commercially available deicing systems. For generalized information, it appears to be necessary to cull from these sources. The following searches proved useful: • http://www.google.com/search?q=ice+detector • http://www.google.com/search?q=ice+sensor • http://www.google.com/search?q=ice+detector+runway • http://www.google.com/search?q=ice+detector+aircraft 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -23-

  24. Further Information (2) For more information regarding the phenomenon of ice accumulation: Roof ice dams: http://www.extension.umn.edu/distribution/housingandclothing/DK1068.html Aircraft wing icing: http://en.wikipedia.org/wiki/Icing_conditions Freezing precipitation: http://en.wikipedia.org/wiki/Soft_rime http://en.wikipedia.org/wiki/Hard_rime http://en.wikipedia.org/wiki/Freezing_rain 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -24-

  25. References • Types of ice sensor:(Science Direct – requires on-campus access): • http://dx.doi.org/10.1016/j.coldregions.2006.06.005 • Ultrasonic: • http://www.freepatentsonline.com/4461178.html • http://www.goodrich.com/portal/goodrich/images/Goodrich%20Content/Business%20Content/Sensors%20and%20Integrated%20Systems/Products/Literature%20Listing/4095%20Ice%20Detector%200871LH1.pdf 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -25-

  26. References (2) Capacitive: http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?all/TM-107432.html Transmissive: http://www.newavionics.com/9734_ind.html Moisture + Temperature: http://www.tekmarcontrols.com/prod/090.shtml http://www.networketi.com/19037.htm 12 Mar 2010 ECE 5320 – Marcus A. Cockerham – Ice Sensor survey -26-

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