institute for complex engineered systems embedded and reliable information systems laboratory...
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Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Sensors and Sensor Networks
Mike Bigrigg
March 16/18, 2004
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Sensors/S’nets IntroCannot just measure anythingAnalog is dirty;
Digital is clean and prettySecondary data is important in order to
answer the “why” questionsSensor network management systems
have costs too! Sometimes lots!
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Motion Detectors
Motion detectors do not detect motion
Motion detectors do not detect motion
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Sensor ComponentsDetector
Has a material change based on physical phenomena
Analog-to-Digital Conversion Electronics can measure resistance and
frequencyProcessing
Analog isn’t pretty
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Simple Temperature Sensor
20KΏ
Resistance of the material
changes based on
temperature
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Simple Temperature Sensor
30KΏ
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Simple Temperature Sensor
10KΏ
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Thermostat (Mechanical Sensor)Bimetal plate in a spiral. Grows as the
temperature expands one side faster than the other side.
on off
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Computer Data Acquisition Sensor DevicesAnalog
Microphone Gameport
Digital Serial/USB Parallel
Other Special PCI card
Otherwise most sensors tied directly to actuator (e.g. home thermostat)
Otherwise most sensors tied directly to actuator (e.g. home thermostat)
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Commercial Sensors$150-$15000 Logger
Interfaceto Computer
Wireless MOTES
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
CMU Critter Sensor
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Analog DataData not very smoothCommercial sensors not like this
Data not very smoothCommercial sensors not like this
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Degree Changes Between Readings9 Degrees
24 Degrees
2623 Degrees
622
Good? Bad?Good? Bad?
Data Set A10x / minute1 week; June 2003
Data Set A10x / minute1 week; June 2003
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Why not more identical?Why such a big range?
Why not more identical?Why such a big range?
Two Sensors; Same Room
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Pattern?
10x / minute ; 1 week10x / minute ; 1 week
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Correlated Pattern?Why?Why?
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Support AdministrationECE Facilities Group
Supports 2,000 machines Staff of 10 full time sysadmins (Plus CMU Network support)
Sensor InstallationSensor Maintenance/Replacement
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Storage Costs10 x / minute (10 bytes per reading)500MB a year2,000 sensors = 1TB a year (1,000GB) (Times number of sensor types) (Times lifetime – historical trends) (Times backup! Offsite storage?)Plus server plus network plus …
~$1/GB~$1/GB
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
CMU Critter Sensor
Everyone else paying for the support PRICESLESS!PRICESLESS!
Everyone else paying for the support PRICESLESS!PRICESLESS!
Thermistor $0.70Wire $0.02Connector $0.30
Thermistor $0.70Wire $0.02Connector $0.30
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Lifetime Costs Hoover Dam
What sensors? Costs? Lifetime?
Institute for Complex Engineered SystemsEmbedded and Reliable Information Systems Laboratory
Lifetime Costs II Highway system
What sensors? What costs?
Inertia of system Upgrades Replacement Degradation