Solving Common Sensor Application Problems
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This document provides an overview of common sensor application issues and solutions presented in a webinar. The webinar agenda covers temperature effects on humidity, solder sensitivity, dust and liquid protection, dealing with multiple devices on an I2C bus, and development tools. Common sensor applications include remote monitoring, home automation, automotive, industrial equipment, and healthcare. Silicon Labs' Si7013/20/21 sensors address issues with legacy humidity sensor solutions by being low-cost, small, reliable, and easy to use.
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External Use | 23
Pd
B
d
Pd = pitch diameter
Bd = ball diameter
Nb = number of balls
S = speed (revolutions/sec
= contact angle
BSF = Ball Spin Frequency
BPFO= Ball Pass Frequency of Outer Trace
BPFI = Ball Pass Frequency of Inner Trace
Bearing faults have specific
frequency signatures
Defect signals may be swamped by
other noise in the system, in which case
enveloping or wavelet techniques may
be used to extract the signature.
For ball defects:
BSF = ½ (Pd/Bd) x S x [1 – (Bd/Pd x cos)2]
For outer trace defects:
BPFO = ½ Nb x S x [1 – (Bd/Pd x cos)]
For inner trace defects:
BPFI = ½ Nb x S x [1 + (Bd/Pd x cos)]](https://image.slidesharecdn.com/2014-05-29-dw-sensor-application-problems-140530080614-phpapp01/85/Solving-Common-Sensor-Application-Problems-23-320.jpg)
Solving Common Sensor Application Problems
- 1. Solving Common Sensor Application Problems
- 2. Thank You To Our Sponsor
- 3. This webinar will be available afterwards at www.designworldonline.com & email Q&A at the end of the presentation Hashtag for this webinar: #DWwebinar Before We Start
- 4. Moderator Presenters Randy Frank Design World Dr. Rolf Weber IR Products, OSRAM Opto Semiconductors Mike Stanley Freescale Semiconductor John Gammel Sensor products, Silicon Labs
- 5. www.silabs.com Temperature and Humidity Sensing Application Issues and Solutions Dr. John C. Gammel May 29, 2014
- 6. 6 Common applications for relative humidity (RH) and temperature sensors Overview of Silicon Labs’ RH and temperature sensors Temperature effect on humidity Solder sensitivity Dust and liquid protection Dealing with multiple devices on the I2C bus Development tools Agenda
- 7. 7 Humidity Sensor Applications Remote Monitoring • Windshield Defogging • Automobile Climate Control • Manufacturing Environmental Monitoring • Compressed Air Systems • Asset Tracking • Food and Pharmaceutical Storage • Telecom Cabinets and Datacenters • Cellular Base Stations • HVAC/R Thermostats and Smoke Alarms • Consumer Weather Stations • Wireless Sensor Nodes • Cellular Phone and Accessories • Respiratory Therapy • CPAP Machines • Ventilators Remote Monitoring Home Automation and Consumer Devices Automotive and Industrial Equipment Healthcare
- 8. 8 • Negligible BOM cost • Small 3x3 mm size • SMT compatible • Highest reliability • Filter cover protects against contamination • High cost • Large size • Not SMT-compatible • Low reliability • Risk of contamination • Large BOM • User calibration • Not SMT-compatible • Low reliability • Risk of contamination Si70xx vs. Legacy RH & Temperature Sensor Solutions Manufacturing Cost and Complexity Discretes (R/C) MCMs and Hybrid Modules Si701x/2x Monolithic ICs Si701x/2x RH & temperature sensors reduce cost and complexity, and improve ease of use vs. legacy solutions Time
- 9. 9 Introducing Si701x/2x Relative Humidity Sensors High-precision relative humidity & temperature sensors offer unmatched ease of use Accurate sensing Full factory calibration and internal compensation +/-3% RH / ±0.4°C max accuracy Industry’s lowest power consumption 2.2 µW @ 3.3 V, 8-bit, 1 sample/second Si701x/2x feature set provides unmatched ease of use Unique, optional low-profile protective cover Industry-standard PCB footprint and software interface Support for 2-zone temperature sensor (Si7013) Standard CMOS fab process ensures high-volume production capacity and high reliability
- 10. 10 Si701x/2x RH Sensor Family Overview Higher accuracy and lower power than Silicon Labs’ first-generation Si7005 sensor Extended -40 to +125 °C temperature range AEC-Q100 automotive qualified Optional cover/filter available for all devices Shown with optional Cover/Filter Part No.(s) Package Typical Accuracy Max Accuracy Features Si7013 3 x 3 mm DFN-10 ±2% RH ±0.3°C ±3% RH ±0.4°C High precision RH and 2-zone temperature sensor with I2C interface Si7021 3 x 3 mm DFN-6 ±2% RH ±0.3°C ±3% RH ±0.4°C High precision RH/T sensor with I2C interface. Industry-standard PCB footprint and software interface Si7020 3 x 3 mm DFN-6 ±3% RH ±0.3°C ±4% RH ±0.4°C Compact RH/T sensor with I2C interface. Industry-standard PCB footprint and software interface
- 11. 11 The “rule of thumb” for how temperature affects humidity is at 100% humidity 1°C of heating will reduce humidity by 5% This decreases linearly to zero as RH reduces For accurate reading of humidity level the sensor must be placed well away from any heat sources If the amount of heating is known, it is possible to compensate A thermistor near the heat source can be used to determine the amount of heating and aid in the compensation The Si7013 two-zone temperature sensor can be used to digitize and linearize the thermistor voltage In some applications, such as window fog sensing dew point is of more interest than relative humidity Dew point is the temperature at which condensation occurs for a given air temperature and relative humidity Dew point is not affected by heating Temperature Effect on Relative Humidity 1 °C 5%RH
- 12. 12 Many IC type sensors are susceptible to shift in readings in soldering This is particularly true for all humidity sensors (not just Silicon Labs) Solder flux can contaminate the sensor Excessive heat will cause shifts in readings The optional protective cover for Si7013/20/21 sensors is solder compatible and provides protection against contaminates during soldering as well as after soldering Use industry standard solder reflow profile 260 °C maximum Do not use solder flux and use “no clean solder” Cleaning in an ultrasonic alcohol bath will contaminate the sensor Do no use hot air rework tools directed at the sensor Limit solder touch up or hand soldering to 5 seconds per lead Rework with new parts Solder Sensitivity
- 13. 13 All humidity sensors are sensitive to dust and liquids and must be protected A membrane that will allow water vapor to pass but will block liquids and dust is recommended Generally, these type of membranes are made of expanded Polytetrafluoroethylene (ePTFE) and are available from several manufacturers Polytetrafluoroethylene is known by the brand name Teflon The best know type of ePTFE is Gore-Tex The ePTFE cover available for Si7013/20/21 sensors is solder compatible and factory applied IP67 for dust and moisture resistance Blocks liquid water to 2.7bar (39 PSI) Oleophobicity (oil resistance) rating of 7 ePTFE barriers do not protect against chemical vapors Use low volatile organic compounds (VOC) for other materials used in PCB assembly such as under fill and conformal coating Avoid cleaning agents such as alcohol or ammonia Dust and Liquid Protection Optional Cover/Filter
- 14. 14 The Si7013/20/21 family and many other standard sensors have the option of “no hold” or “hold” mode commands Hold mode commands are more convenient because the device will hold the I2C bus (clock held low) until the conversion is complete This avoids having to set a timer or poll for conversion complete, but it does hold the bus for the conversion time (typically 10 msec) If the no-hold command is used, then the bus is not held and the device will not ACK until data is ready Most sensors have a fixed I2C address so you cannot put more than one device of the same type on the bus Some RH sensors such as the Si7013 have a pin-programmed address For larger numbers of devices of the same type, switch the I2C bus The I2C bus is bidirectional on both SDA and SCL so a digital gate generally will not work; in this case use an analog switch If no hold mode commands are used and care is taken not to use a high-bus speed, clock stretching is avoided and SCL can be digitally switched In either case, be careful to leave SCL high when the device is not addressed Multiple Devices on the I2C bus
- 15. 15 Si701x/2x EVBs and Development Kits Si7013USB-DONGLE • USB Dongle with Si7013 • “Postage stamp” boards for Si7013, Si7020, Si7021 Si7013EVB-UDP Si7013EVB-UDP-F960 (8-bit) Si7013EVB-UDP-M3L1 (32-bit) • UDP port header card • 8-bit MCU development kit • 32-bit MCU development kit P/N Description Si7013USB-DONGLE General-purpose evaluation platform for “plug and measure” evaluation of Si7013, Si7020 and Si7021 SENSOR-EXP-EVB Sensor expansion card for EFM32 Zero Gecko MCU Starter Kit Si7013EVB-UDP UDP port header card for Silicon Labs MCU development boards Si7013EVB-UDP-F960 (8-bit) Si7013EVB-UDP-M3L1 (32- bit) Si7013 UDP port header card + MCU development kit Si701x/2x General-Purpose EVB SENSOR-EXP-EVB • Sensor expansion card for Zero Gecko MCU Starter Kit
- 16. 16 Si701x/2x Collateral and Software Collateral Si7013, Si7020 and Si7021 data sheets AN607: Si70xx Humidity Sensor Designer’s Guide Software For Si7013USB-DONGLE: • Evaluation software GUI • USB drivers and source code For Si7013EVB-UDP and MCU development kits: • Demonstration software and source code • Data logger application, GUI and source code Android driver and demonstration app Linux driver (Lm-sensors framework) All Si701x/2x collateral and software is available at http://www.silabs.com/products/sensors/humidity- sensors/
- 18. External Use TM Layered Intelligence and the Internet of Things Design World Web Event M a y 2 0 1 4 Michael Stanley Manager, Algorithm Development Freescale Sensor Solutions Division
- 19. TM External Use | 19 Freescale Semiconductor Sensors Solutions Division - Market Focus Safe & Efficient Automobiles Safe driving, front/side impact Tire information system Active driver assistance Passenger occupancy detection Industrial Sensor Networks Connected intelligence Fault monitoring/prognostication High precision modules Extreme Portable Electronics Low profile packages Low power consumption Submersible sensors Automotive Consumer • Standalone sensing systems • Ruggedized packages • Wide sensing ranges • Accelerometer • Gyroscope • Pressure • Magnetometer • MCU integrated sensors
- 20. TM External Use | 20 Topics • Condition-Based Maintenance (CBM) • Condition-Based Monitoring • Prognostics and Health Management (PHM) systems • Machine Monitoring • Predictive Maintenance All mean essentially the same thing, which forms the basis for a • mature industry, that was • doing IoT before there was an IoT Lowered costs in sensors and communications imply that CBM techniques may be poised to extend into new areas – IF we can simplify the software side of things.
- 21. TM External Use | 21 figure source; http://en.wikipedia.org/wiki/File:Centrifugal_Pump-mod.jpg This machine includes: • rotating motor • centrifugal pump • linkage between the two Each is subject to its own array of problems. These might include: • Bearing failures • load imbalance • shaft misalignment • looseness • gearbox faults • drive belts • resonance
- 22. TM External Use | 22 TangentialAxial Radial Aligned Angular misalignment causes axial vibration at 1X running frequency Parallel misalignment causes radial vibration at 2X running frequency Shaft Misalignment
- 23. TM External Use | 23 Pd B d Pd = pitch diameter Bd = ball diameter Nb = number of balls S = speed (revolutions/sec = contact angle BSF = Ball Spin Frequency BPFO= Ball Pass Frequency of Outer Trace BPFI = Ball Pass Frequency of Inner Trace Bearing faults have specific frequency signatures Defect signals may be swamped by other noise in the system, in which case enveloping or wavelet techniques may be used to extract the signature. For ball defects: BSF = ½ (Pd/Bd) x S x [1 – (Bd/Pd x cos)2] For outer trace defects: BPFO = ½ Nb x S x [1 – (Bd/Pd x cos)] For inner trace defects: BPFI = ½ Nb x S x [1 + (Bd/Pd x cos)]
- 24. TM External Use | 24 24 http://commons.wikimedia.org/wiki/File:NonSynchronousGearBoxSF.jpg gear mesh speed = shaft speed X # of teeth So = Si X Ti/To where: Ti = number of input teeth To = number of output teeth Si = input speed So = output speed Gears also have specific frequency signatures
- 25. TM External Use | 25 Courtesy of Volvo Construction Equipment (mages.volvoce.com) Credit: IBM Research (http://www- 03.ibm.com/press/uk/en/photo/43250.wss) Predictive maintenance is a must when you cannot afford downtime.
- 26. TM External Use | 26 CBM Breakdown Condition based maintenance diagnostics prognosticswhat went wrong? includes estimation for remaining useful life data driven physics-based require sufficient samples that were run to failure must understand the physics of expected failure progression and how to get parameters required for the model more mature than prognostics statistical machine learning
- 27. TM External Use | 27 Maintenance Scenarios maintenance preparation actual maintenance scheduled maintenance maintenance preparation continuous RUL estimation Fault Detection Down Time Down Time Unscheduled Maintenance Managed Maintenance From “Major Challenges in Prognostics: Study on Benchmarking Prognostics Datasets” by Eker, Camci and Jennions Notice that in the 2nd scenario, we can minimize inventory and do prep work while still “line-up”
- 28. TM External Use | 28 • General Electric • Techenomics International • Vibrotech reliability services • Condition Monitoring Services Inc. • Vikon • STI Vibration Monitoring • ALS Limited • Fluke • GeoSonics / Vibra-Tech • Timken • Vipac Engineers and Scientists Ltd. • Wagner Equipment Co. • KIM Gruppen • Allied Reliability Group • Tezzco Inc. • Sterling SIHI BmbH • Bentley Nevada Services • Monition Limited • ROZH • GasTOPS Ltd. • Critical Software • Azima DLI • Balmac Inc. • Diagnostic Solutions • Siemens • Prosig • Condition Analyzing Corporation • Metso Corporation • Dresser-Rand • dB Prűftechnik • KCF technologies • Schenck USA • Machine Monitoring Systems There are lots of players in this field. Many are service companies.
- 29. TM External Use | 29 ISO 13374 Provides a Standard Architecture for Condition Monitoring & Diagnostics Sensor / Transducer / Manual Entry Data Acquisition (DA) Data Manipulation (DM) State Detection (SD) Health Assessment (HA) Prognostic Assessment (PA) Advisory Generation (AG) External systems, data archiving and block configurati on Technica l displays and informati on presenta tion DA Basically a “server of calibrated digitized sensor data records”. Outputs include digitized data, timestamps, data quality indicators DM Extracts features from digitized sensor data. Examples: FFT, wavelet, virtual sensor, filtered data, normalized data, etc. SD Compares DA & DM outputs against expected baselines / operational limits to determine health indicators. Outputs might include enumerated state values, threshold alerts, rate of change alerts, deviation severities, etc. HA Determine the current health of the system and diagnose fault conditions PA Estimate remaining useful life Predict faults / failures Generate recommendations AG Integrate outputs from all other blocks and provide optimized recommendations, courses of action, advisories, prioritized operational & maintenance actions, etc.
- 30. TM External Use | 30 Freescale is developing collateral designed to simplify implementation of condition monitoring systems. Data Acquisition (DA) Data Manipulation (DM) State Detection (SD) Health Assessment (HA) Prognostic Assessment (PA) Advisory Generation (AG) Sensor / Transducer / Manual Entry Development Board Matlab Choices include: • Sensor Type • Axis (X, Y, Z, temp, etc) • Sample Rate Feature Extraction choices include: • FFT • Wavelets • Entropy • RMS noise • peak value • etc. Use Freescale supplied GUIs and embedded apps to experiment with data capture and feature selection, then utilize Matlab machine learning algorithms to develop higher level ISO 13374 functions.
- 31. TM External Use | 31 In real time, the user can change: • Sensor • Axis • Window • Filter All FFT computations are done on the sensor board. Data can be logged, replayed, and transferred to Matlab. A similar tool for Wavelet analysis is in development. Freescale Xtrinsic Vibration Monitoring
- 32. TM External Use | 32 To Learn More Organizations: • Open Operations & Maintenance Initiative (http://www.openoandm.org) • Machinery Information Management Open System Alliance (http://www.mimosa.org) • International Organization for Standardization (http://www.iso.org) • Center for Intelligent Maintenance Systems (http://www.imscenter.net) References: 1. “Commercialization of Prognostics Systems Leveraging Commercial Off-The Shelf Instrumentation, Analysis and Data Base Technologies”, Preston Johnson 2. “Vibration Diagnostic Guide”, SKF Reliability Systems 3. “Harris Shock and Vibration Handbook”, 6th edition, Allan G. Piersol & Thomas L. Paez, McGraw Hill 4. “A Review of PHM System’s Architectural Frameworks”, Surya Kunch, Chaochao Chen & Michael Pecht. 5. “Review of Vibration Analysis Methods for Gearbox Diagnostics and Prognostics”, Mitchell Lebold, et. al.
- 33. TM © 2014 Freescale Semiconductor, Inc. | External Use www.Freescale.com
- 34. Matchbox Demo: Intelligent Proximity Sensing
- 35. Why a packaged demo? Challenges for proximity sensing: Cross talk due to reflection from a cover glass => Demo with cover glass and light barrier is more realistic Cross talk
- 36. PCB top view SFH 7770 E6: 3 prox. channels and ALS SFH 4059 LEDs Externally switched SFH 4059S LED for long range SFH 7743 for application selection
- 37. IR LEDs Proximity sensing for consumer devices: Small LEDs are essential SFH 4640 / 4641 / 4441 SFH 4645 / 4646 / 4140 SFH 4046 SFH 4045N
- 38. Application Modes Proximity sensing (1”, 4” & 6”) Place / remove hand
- 39. Application Modes Slide Slide left / right for LED on. Slide right / left for LED off.
- 40. Application Modes Rotary Rotate finger clockwise to increase brightness. Counter-clockwise will reduce brightness
- 41. Application Modes Touch Tap for LED on / off. Hold finger to increase / reduce brightness
- 42. Application Modes Wave Wave left / right for LED on. Wave a second time for LED off.
- 43. Application Modes 0.00 20.00 40.00 60.00 80.00 100.00 120.00 0 50 100 150 Relativesignalstrength Time in ms Proximity signals 2 ms apart Prox 1 Prox 2 • Two pulses 2 ms apart: • One measurement every 10 ms • Centroid time = Σ time * signal / Σ signal • Prox 1: 61.16 ms • Prox 2: 59.64 ms => Prox 2 before Prox 1
- 44. Application Modes Ambient Light Sensor Ambient light will increase brightness
- 46. Demo Kit Content Sensor demo with Micro USB jack 3 x AAA batteries Battery pack with Micro USB connector USB cable
- 47. Getting Started • Use the battery pack or USB cable to power the demo. 1a. Battery Pack • Insert AAA batteries in the battery pack • Connect the battery pack to the demo • Switch on battery pack 2. Operating the demo 1b. USB Cable • Connect the USB cable to demo and a computer • See: Software Installation and Graphical User Interface Indicator LED layouts and respective hand motions
- 48. Software Download and installation of the GUI and USB driver: • http://ledlight.osram-os.com/matchboxdemo Source code: • LabVIEW VI available on request • Demo board C Code available on request • Contact: rolf.weber@osram-os.com
- 49. Questions? Randy Frank Design World r.frank@ieee.org Dr. Rolf Weber IR Products, OSRAM Opto Semiconductors Rolf.Weber@osram-os.com Mike Stanley Freescale Semiconductor Mike.Stanley@freescale.com John Gammel Sensor products, Silicon Labs john.gammel@silabs.com
- 50. Thank You This webinar will be available at designworldonline.com & email Tweet with hashtag #DWwebinar Connect with Design World Discuss this on EngineeringExchange.com