Choosing Sensors for Industrial Apps
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This webinar discusses choosing the right sensors for industrial applications. It begins with introductions and an overview of temperature sensor applications and common temperature sensing technologies. It then covers integrated circuit thermal management solutions, temperature sensing considerations for downhole drilling tools, and analog temperature sensing options. The webinar concludes with a discussion of positioning technologies for applications in manufacturing and logistics.
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Choosing Sensors for Industrial Apps
- 1. Choosing the Right Sensors for Industrial Applications
- 2. Before We Start This webinar will be available afterwards at designworldonline.com & via email Q&A at the end of the presentation Hashtag for this webinar: #DWwebinar
- 3. Presenters Moderator Randy Frank Emmy Denton Tim Shotter Dan Bruski Design World Texas Instruments All Sensors SICK
- 4. in Industrial Environments Emmy Denton Applications Engineer May 29, 2013
- 5. Temperature Sensor Applications Temperature Sensors have 3 key functions in electronic systems • Calibration • Monitoring & Protection • Control Temp sensing is EVERYWHERE! – Industrial: Factory Automation, Medical, Down Hole Drilling, Instrumentation … 6
- 6. Common Temperature Sensing Technologies ATS Thermistor Thermocouple RTD -267 to +2316 -240 to 700 Criteria Temp Range (°C) -55 to +150 -100 to +500 (-55 to +200 digital) (-60 to +200 SMD) Accuracy Good Good Good Best Linearity Best Least Better Better Sensitivity Better Best Least Less Simplest Simpler Complex Complex Lowest Low High High $ $ $$ $$$ Circuit Simplicity Power Consumption Cost 7
- 7. Integrated Circuit Thermal Management Solutions Local Analog Local Digital Remote Digital Voltage output proportional to temperature Reports temperature at location of the sensor Measure any Diode, Transistor, or CPU/GPU/FPGA Smallest Highest Accuracy Lowest Power Highest Temp Most Popular Low Cost Small Low Power Popular Interfaces (I2C, SPI, One-wire …) Highest Temp (200°C) Highest Accuracy (0.5°C) Ind. Standard (LM75) Multiple Channels Int. Power Monitor Beta Correction Contactless IR Switches/Thermostat Fan Control /HW Monitors Measures passive IR to determine object temperature without making contact Simple hardware over temperature protection Complex with Many Functions in addition to temperature sensing Dual Alerts Resistor Prog Pin Programmable Factory Preset Analog Temperature Outputs 2 Wire Interface Fan Control Monitor Monitor & Control (ADC and DAC) Voltage Comparators 8
- 8. Downhole Drilling Tools • • • • Over-Temp Protection of PCB Components Predict life expectancy of tool Customer billing purposes Tool Oil Degradation Accuracy (°C) +130 to +160 Reasons for Temp Sensing Temp Range (°C) ±1.0 +160 to +175 ±2.0 +175 to 200 ±3.0 +120 to +130 ±2.0 -40 to +120 ±3.5 Key Specifications • Up to +200°C temperature range • • • • • Digital Interface – redundant ADC High accuracy and resolution Alarm output and shutdown mode Requires reliability – additional qualification required Packaging must withstand extensive temperature (usually ceramic or die) LM95172 • Located at the tip of the drill in order to protect the other circuitry above 9
- 9. Thermocouple Cold Junction Compensation T_hot T_cold Reasons for Temp Sensing • Up to +70°C - 85°C temperature range • • ADC is usually available in AFE • Thermocouple measures difference temperature of two junctions – Junction at zone being measured – Junction back to copper Required to determine temperature of zone being measured Key specifications • Accuracy added to accuracy of zone being measured • Must be mounted on isothermal block for good temperature conduction 10
- 10. Analog Temperature Sensing Options LMT84 Curve • Most Micros Include Multiple Channel ADCs • Analog Temp Sensor Advantages: Higher accuracy over wider temperature range Linear across temp range Lower Power Dissipation – draw less than 10uA over temp range Simpler design that utilizes less board space – no additional external components Simpler to use 11
- 11. vs. ATS Output Voltage vs. Temperature (°C) THERMISTOR THERMISTOR ATS ATS 12
- 12. Analog Temp Sensor Accuracy • Accuracy is very linear for 96 units plotted • ±0.7°C Max and Min Accuracy over 0 to 150°C • Sensing temps approaching 200°C possible • Some Devices Can Achieve +/0.1°C Spread without Temperature Calibration! 13
- 13. THANK YOU! – Emmy Denton
- 14. All Sensors PRESSURE SENSORS… RESOLUTION AND BANDWIDTH
- 16. All Sensors Familiar Specifications • • • • • • Pressure Range Sensitivity Offset Linearity Temperature Effects Accuracy
- 19. All Sensors What Your Mom Didn’t Tell You…
- 20. All Sensors System Basics Review
- 24. All Sensors Revised BW/Resolution Trade-offs
- 25. What is “positioning?” What are we positioning? • • • To know the location of something To move a target with respect to that known location Everything’s relative o o Objects are positioned with respect to something fixed Key for evaluating specs like accuracy, repeatability, resolution Focus application areas • Positioning in manufacturing Knives, slitters, saws, welding tips, drills, tools • Logistics Cranes, ASRS, shuttles, rail cars
- 26. Positioning Technology Choices High speed High resolution Low cost Slippage and wear errors Mechanical Simple setup Non-contact – long life Many choices of range, precision, outputs Line of sight only Optically challenging environments Rotary and wire draw encoders Linear magnetic encoders Lasers Hybrid High speed High resolution Rugged in challenging environments Difficulty with non-linear paths Strict mounting requirements Cost Navigates non-linear paths Path can be obstructed by other vehicles or objects Need to mount reference tape
- 27. Selection Criteria Range •Sensor must not only be able to measure the absolute distance from the sensor to the target to be positioned, but also have the appropriate span. •How small of a movement is need to be controlled? Resolution Repeatability •Repeatability is KEY. This describes how close to the desired location it will be when the sensor output indicates it has reached its final position Output rate •The output rate of the sensor is how often the sensor updates the measured position and needs to be matched up with the speed of the target. Output type •The output type simply needs to match the input of the control system/PLC/PC.
- 28. Tips and Tricks • A reflective target is preferred over natural targets for positioning o o • Response time vs. output rate o o • Don’t get hung up on an accuracy spec, because you don’t need it for positioning applications until you replace a sensor Excess gain o • Response time refers to lateral movement into the beam – used for detection, not positioning Output rate is what matters after the target is locked-in Accuracy trap o • Strong and consistent signal return “Safe” – if reflector is blocked, an erroneous position is not returned Don’t worry about using a sensor with way more range than needed – this gives you useful excess gain Long range alignment o Utilize vendor-supplied alignment brackets
- 29. 30
- 30. Questions? Design World Randy Frank R.Frank@ieee.org Twitter: @SensorTips All Sensors Tim Shotter TShotter@allsensors.com Phone: 408.225.4314 Twitter: @AllSensors Texas Instruments Emmy Denton emmy.smaragda.denton@ti.com Phone: 408.721.3267 SICK Dan Bruski Dan.Bruski@sick.com Phone: 612.217.1326
- 31. Thank You This webinar will be available at designworldonline.com & email Tweet with hashtag #DWwebinar Connect with Twitter: @DesignWorld Facebook: facebook.com/engineeringexchange LinkedIn: Design World Group YouTube: youtube.com/designworldvideo Discuss this on EngineeringExchange.com