Micro Strain Wireless Sensors Aircraft Structural Health Monitoring 2008

MicroStrain IncMicroStrain, Inc.

Wireless Sensors forWireless Sensors for Structural Health Monitoring

Steve Arms, Presidentsales@microstrain [email protected]

© MicroStrain, Inc. 2008 all rights reserved

MicroStrain’sMicroStrain’s Smart SensorsSmart Sensors

DisplacementDisplacement OrientationOrientation WirelessWireless

DVRTDVRT®® MicroMicro--AHRSAHRSGG--LinkLink®,®, VV--LinkLink® , ® ,

SGSG--LinkLink®, ®, TCTC--LinkLink®®

Automated test Automated test & & semiconsemicon mfgmfg

Unmanned Unmanned systemssystems

Machine Machine monitoringmonitoring&& s os o gg sys ssys s monitoringmonitoring

© microstrain, inc. 2008

Sensing Sensing the Futurethe Futurethe Futurethe Future

Wireless sensors, in the billions, will become Wireless sensors, in the billions, will become deeply embedded within structures &deeply embedded within structures &deeply embedded within structures & deeply embedded within structures & machines. machines.

Sensed information will be automatically Sensed information will be automatically compressed & forwarded for conditioncompressed & forwarded for conditioncompressed & forwarded for condition compressed & forwarded for condition based maintenance.based maintenance.


Market Size?Market Size?Wireless sensor market will reach $4.6 Billion by Wireless sensor market will reach $4.6 Billion by 2011, up from $500 Million in 2007*2011, up from $500 Million in 2007*

MicroStrain’sMicroStrain’s Partners:Partners:

•• Navy: NAVAIR/NAVSEANavy: NAVAIR/NAVSEA•• Bell HelicopterBell Helicopter•• SikorskySikorsky•• CaterpillarCaterpillar


*ON World report, "WSN for Smart Industries”, Nov 2007www.assetmgmtnews.com “Industrial Sector Embraces Wireless Sensors” Jan 2008

The Economist April 28th – May 4th

2007“We’re wearing out…plan to replace us soon”

2007

Problem:Problem:Problem:Problem:

Wh ill l billi fWh ill l billi fWho will replace billions of Who will replace billions of dead batteries?dead batteries?dead batteries?dead batteries?


Solution*:Solution*:Solution :Solution :•• Harvest & store energy from strain vibrationHarvest & store energy from strain vibration•• Harvest & store energy from strain, vibration, Harvest & store energy from strain, vibration,

light, and light, and motionmotion

•• Use power management to balance the energy Use power management to balance the energy ““checkbook”checkbook”

•• Use embedded processors to compress data, Use embedded processors to compress data, compute fatigue lifecompute fatigue lifecompute fatigue lifecompute fatigue life

*D.L. Churchill et al., “Strain Energy Harvesting for Wireless Sensor Networks”, Smart Structures and Materials SPIE vol 5005 pp 319 327 2003


Smart Structures and Materials, SPIE, vol. 5005, pp. 319–327, 2003

M.J. Hamel et al., “Energy Harvesting for Wireless Sensor Operation and Data Transmission”, US Patent #7081693, issued July 25th, 2006

AircraftMonitoringg

The case forThe case forThe case for The case for monitoringmonitoring

•• Boeing F/ABoeing F/A--18 18 designed for 6,000 flight hours designed for 6,000 flight hours

•• Existing hardwired multiExisting hardwired multi--channel monitoring channel monitoring allows F/Aallows F/A--18 to reach 13,000 flight hours18 to reach 13,000 flight hours

•• New aircraft req’d to achieve the additional New aircraft req’d to achieve the additional flightflight--hours would cost ~$11Bhours would cost ~$11B


MicroStrain’sMicroStrain’s NAVY NAVY PhIPhI, II, & III SBIRs: , II, & III SBIRs: H li t St t l H lth M it i S tH li t St t l H lth M it i S tHelicopter Structural Health Monitoring System Helicopter Structural Health Monitoring System (patents issued & (patents issued & pending)pending)

© microstrain, inc. 2008Patents pending

Pitch Link w/ Energy Harvesting, Sensing, Data Pitch Link w/ Energy Harvesting, Sensing, Data Storage, & WirelessStorage, & Wireless Communications*Communications*Storage, & Wireless Storage, & Wireless CommunicationsCommunicationsMicroStrainMicroStrain, Inc. patents pending, Inc. patents pending

RF antenna

Sikorsky H-60 Blackhawk

Circuit board module, microprocessor, and

electrochemical batteryy

Piezoresistive strain gauge

Electrical insulation EMIElectrical insulation, EMI shielding,

& protective covering(shown transparent for

illustration purposes)

Piezoelectric energy harvesting elementsharvesting elements


* S.W. Arms et al., “Energy Harvesting Wireless Sensors for Helicopter Damage Tracking”, AHS Phoenix, AZ, May 2006

MicroStrain’sMicroStrain’s Wireless Wireless Strain & Load Sensing NodesStrain & Load Sensing Nodes

Fractal antennas

Components on both sides

dComponents on 1 side

Patents Pending © microstrain, inc. 2008 all rights reserved

Measuring Strains

Wirelessly

MicroStrain’sMicroStrain’s Wireless Wireless Strain System Strain System di d l i idi d l i ipatents pending data logging transceiverspatents pending data logging transceivers


MicroStrain’sMicroStrain’s embedded embedded firmware: firmware: optimized optimized for strain gaugesfor strain gauges

•• Wireless offset adjust Wireless offset adjust •• Wireless gain adjustWireless gain adjust•• Wireless control of sample ratesWireless control of sample ratese ess co t o o sa p e atese ess co t o o sa p e ates•• Wireless shunt cal Wireless shunt cal –– bits to bits to microstrainmicrostrain•• LowLow tempco’stempco’s::•• Low Low tempco stempco s: :

offset: offset: --.007%/C , span: .007%/C , span: ..015%/015%/C C •• Mux’dMux’d pulsed & regulated bridge excitationpulsed & regulated bridge excitation•• Mux dMux d, pulsed & regulated bridge excitation, pulsed & regulated bridge excitation


How accurate areHow accurate areHow accurate are How accurate are MicroStrain’sMicroStrain’sMicroStrain sMicroStrain s

wireless strainwireless strainwireless strain wireless strain gauges?gauges?gauges?gauges?

Lockheed Martin Aerospace (LMA)Lockheed Martin Aerospace (LMA)F tiF ti T tiT ti E i tE i tFatigue Fatigue Testing Testing EnvironmentEnvironment


Lockheed Martin Aerospace Lockheed Martin Aerospace Accuracy Accuracy dd d ld l **Tests: Tests: Hard Hard Wired vs. Wireless Wired vs. Wireless Strain*Strain*

(Baldwin Precision Calibrator used for strain input)(Baldwin Precision Calibrator used for strain input)

•• HBM HBM MGCplusMGCplus ®®

vs.vs. MicroStrainMicroStrain

Wireless vs. Hard-Wired Correlation y = 1.0002x + 1.1267R2 = 1

7000

8000

vs. vs. MicroStrainMicroStrainVV--Link Link ®®

•• Each system Each system provided bridge provided bridge 4000

5000

6000

7000

nk (m

icro

stra

in)

p gp gexcitation excitation

•• R^2=1R^2=1•• Max wirelessMax wireless

1000

2000

3000

Wire

less

V-L

i

Max wireless Max wireless error: 2.5 error: 2.5 ustrainustrain

00 1000 2000 3000 4000 5000 6000 7000 8000

Hard-wired HBM MGCplus (microstrain)

© MicroStrain, Inc. 2008, all rights reserved

* S.W. Arms et al., “Wireless Strain Measurement Systems for Aircraft Test”, Aerospace Test Expo, Anaheim, CA, Nov 2006

Wired vs. Wireless Gauge Comparison on DSTO F 18 C t B l T t B dDSTO F-18 Center Barrel Test Bed

• Two wireless SG-• Two wireless SG-Links sampled at 10 Hz

• DSTO wired system collected strain datacollected strain data at peaks

• Time synchronized• Time synchronized at beginning & end of testof test


DSTO F-18 Center Barrel Test Bed


DSTO F-18 Center Barrel Test Bed(m

icro

stra

in)

(


(microstrain)

MILMIL--STD 810STD 810MILMIL--STD 810 STD 810 Test ResultsTest ResultsTest ResultsTest Results

MILMIL--STD STD 810F tests 810F tests (three pitch link modules tested)(three pitch link modules tested)

MethodMethod Test ParametersTest Parameters ResultsResults501.4 501.4 -- High TemperatureHigh Temperature 85 degrees C 85 degrees C

2 hour soak2 hour soakPassed*Passed*

501.4 501.4 -- Low TemperatureLow Temperature --55 degrees C55 degrees C2 hour soak2 hour soak

Passed*Passed*

503 4503 4 -- Temperature ShockTemperature Shock 85 degrees C85 degrees C --45 degrees C45 degrees C Passed*Passed*503.4 503.4 Temperature ShockTemperature Shock 85 degrees C 85 degrees C 45 degrees C45 degrees Cwithin 5 minuteswithin 5 minutes

PassedPassed

*TC Offset *TC Offset --0.007% of FS/deg C0.007% of FS/deg CTC Span 0.015% FS/deg CTC Span 0.015% FS/deg C

l il i ff d b d ff fd b d ff f513.5 513.5 –– AccelerationAcceleration Centrifuge testCentrifuge test60 g continuous60 g continuous20 minutes20 minutes

Passed, no observed effect of Passed, no observed effect of acceleration on outputacceleration on output


Communicating gWirelesslyy

2.4 GHz license 2.4 GHz license free bands: free bands:

(802 ) &(802 ) &WiFiWiFi (802.11.x) & (802.11.x) & Zi bZi b (802 15 4)(802 15 4)ZigbeeZigbee (802.15.4)(802.15.4)

i t f lli t f llcoexist peacefullycoexist peacefully

802.15.4 Channels

15, 20, 25, & 26

802.15.4 Channels

15, 20, 25, & 26

are non-overlapping

with 802.11b

are non-overlapping

with 802.11b

802.15.4 Channels

15, 16, 21, & 22

are non-overlapping

802.15.4 Channels

15, 16, 21, & 22

are non overlappingpp g

with 802.11.bare non-overlapping

with 802.11.b

S h i iSynchronizing Wireless &

Wired Networks

MicroStrain’sMicroStrain’s Data AggregatorData Aggregator™™MicroStrain sMicroStrain s Data AggregatorData AggregatorSynchronizes both wireless & wired sensor nets *Synchronizes both wireless & wired sensor nets *

© microstrain, inc. 2008 patents pending

* S.W. Arms et al., “Energy Harvesting, Wireless Structural Health Monitoring System”, 4th ESHM, Cracow, Poland, Jul 2008

MicroStainMicroStain Data AggregatorData Aggregator(TM) (TM) Features:Features:

•• Open Open architecture, UC Linux operating system architecture, UC Linux operating system

•• Synchronizes wired & wireless sensor networksSynchronizes wired & wireless sensor networks

•• Data Data are collected from various sensors, at widely different are collected from various sensors, at widely different sample rates, and aggregated sample rates, and aggregated into into a single, scalable a single, scalable data data basebase

•• Multiple bus interfaces supported:Multiple bus interfaces supported:•• CANCANCANCAN•• IEEE802.15.4IEEE802.15.4•• EthernetEthernet•• RS232/RS422 (HUMSRS232/RS422 (HUMS))


Timing Results Summary*Timing Results Summary

• Synch beacon sent once at start of test only providedSynch beacon sent once - at start of test only - provided ~5 ms timing accuracy over 2 hours, subjected to -40 to +85 C.

• Synch w/ periodic (60 sec) beacon provided +/- 50 us timing accuracy over 13 hours, subjected to -40 to +85 C.g y , j

• Conservative approach: send resynch beacon every 20 minutes to achieve sub millisecond timing accuracy whenminutes to achieve sub-millisecond timing accuracy when temperatures may be extreme.


* S.W. Arms et al., “Energy Harvesting, Wireless Structural Health Monitoring System”, 4th ESHM, Cracow, Poland, Jul 2008

M ki th tMaking the most of the 2.4 GHz

ISM band

MicroStrain’sMicroStrain’s ScaleableScaleable Wireless Wireless NetworksNetworks

TDMA/CSMA:TDMA/CSMA: 600 nodes*3 600 nodes*3 chch= = 1800 1800 strain gauges, all updating @ 5Hzstrain gauges, all updating @ 5Hzadd FDMA:add FDMA: 1800 strain gauges*16 radio1800 strain gauges*16 radio chschs== 28,80028,800 strain gaugesstrain gaugesadd FDMA: add FDMA: 1800 strain gauges 16 radio 1800 strain gauges 16 radio chschs 28,80028,800 strain gaugesstrain gauges

Time Division Multiple Access (TDMA) &

Frequency Division Multiple Access (FDMA)


Carrier Sense Multiple Access (CSMA)

How many nodes will the system support?How many nodes will the system support?Aggregate sample rate: ~10K / total sensor channelsAggregate sample rate: ~10K / total sensor channelsAggregate sample rate: 10K / total sensor channelsAggregate sample rate: 10K / total sensor channels

10000Synchronized TDMA/CSMA Capacity

10001000

500

Update rate (samples/sec)

100

node

s

250

200

100

50

25

10

Max

# o

f n 20

10

5

2

1

0.1

11

0

Active channels per node (1 min, 8 max)


Flight Testsg

Bell M412 Flight Test *Bell M412 Flight Test *•• MicroStrainMicroStrain

piggypiggy--backed backed p ggyp ggyon Bell’s on Bell’s planned flight planned flight teststests

•• Wired (slip Wired (slip rings) datarings) datarings) data rings) data could be could be collected collected simultaneouslysimultaneouslysimultaneously simultaneously w/ wireless w/ wireless datadata

Patents pending © microstrain, inc. 2008

* S.W. Arms et al., “Tracking Pitch Link Dynamic Loads with Energy Harvesting Wireless Sensors”, AHS 63nd Annual Forum, Virginia Beach, VA, May 2007

FlightFlightFlight Flight TestTestResultsResults•• Energy harvesting Energy harvesting wireless wireless component (pitch link) component (pitch link)

installed installed on on Bell M412 Feb 2007 (first time ever flown)Bell M412 Feb 2007 (first time ever flown)

•• Passed Passed –– inin--flightflight EMIEMI evaluationsevaluationsinin flight flight EMI EMI evaluationsevaluations–– rotor rotor track track & balance verification& balance verification–– wireless data wireless data collection during scripted collection during scripted flight with flight with

no indication of data loss.no indication of data loss.© microstrain, inc. 2008

Bell M412 Wired Bell M412 Wired vs. Wireless vs. Wireless Pitch Link Flight Test DataPitch Link Flight Test DataPitch Link Flight Test DataPitch Link Flight Test Data

from 2 separate & distinct strain gaugesfrom 2 separate & distinct strain gaugesWireless PitchLink Loads

VNE dive test Flight Record #3664 Hz wireless sensor sample rate - 500 Hz slip ring sample rate

1.5

0.5

1

ed)

-0.5

00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Out

put (

Nor

mal

ize

-1

0.5

500 Hz Slip Ring

-1.5

Time

64 Hz Wireless


MicroStrainMicroStrain, Inc. High Sample Rate Bench Test:, Inc. High Sample Rate Bench Test:hardhard--wiredwired reference bridge vs. wireless pitch linkreference bridge vs. wireless pitch linkhardhard wired wired reference bridge vs. wireless pitch linkreference bridge vs. wireless pitch link

(two separate & distinct strain gauge bridges bonded to a single steel plate in 4(two separate & distinct strain gauge bridges bonded to a single steel plate in 4--pt bending)pt bending)

ostr

ain)

Stra

in (m

icro


ConclusionsConclusions•• An energy harvesting wireless pitch link load An energy harvesting wireless pitch link load

B ll 412 h b d l d b hB ll 412 h b d l d b h

Conclusions Conclusions

sensor Bell 412 has been developed, bench sensor Bell 412 has been developed, bench tested, & flight testedtested, & flight tested

•• Under extremely low usage levels, the amount Under extremely low usage levels, the amount of energy generated exceeds the amount of of energy generated exceeds the amount of gy ggy genergy consumedenergy consumed

•• This enables an onThis enables an on--board wireless load sensor board wireless load sensor to operate perpetually without battery to operate perpetually without battery maintenancemaintenancemaintenance. maintenance.

Patents pending © MicroStrain, Inc. 2008, all rights reserved

Conclusions (con’t)( )• An accurate time synchronization capability has been

developed for wireless & hard wired sensor networksdeveloped for wireless & hard-wired sensor networks that does not require GPS to maintain synchronization.

• The system supports a wide range of e-harvesting nodes, including strain, pressure, torque, & temperature; as well as wired inertial & GPS sensorsas well as wired inertial & GPS sensors.

• Data Aggregator node is stand-alone includes mobileData Aggregator node is stand alone, includes mobile phone capability & scalable web-enabled database


MicroStrain Competitive AdvantagesMicroStrain Competitive Advantagesp gp g

Features Benefitsembedded intelligenceembedded intelligence sense, record, & report sense, record, & report

damage & fatiguedamage & fatiguepatent pending data loggingpatent pending data loggingtransceiverstransceivers

eliminates costly wiringeliminates costly wiring

patent pending energy patent pending energy harvestersharvesters

eliminates battery eliminates battery maintenancemaintenance

base station GSM/SAT uplinkbase station GSM/SAT uplink no human intervention no human intervention required to get reportsrequired to get reports

l ff l bl ff l bwireless offset, calibrationwireless offset, calibration fast installation & testfast installation & test


Abo t Mic oSt ain IncAbo t Mic oSt ain IncAbout MicroStrain, Inc.About MicroStrain, Inc.

36 l ( l 4 i t )36 l ( l 4 i t )•• 36 employees (plus 4 interns)36 employees (plus 4 interns)•• 80% revenue from product sales80% revenue from product sales•• products developed w/ SBIR fundsproducts developed w/ SBIR funds•• growing at 35%/yeargrowing at 35%/yearg g /yg g /y•• zero debtzero debt•• no outside investment to dateno outside investment to date•• no outside investment to dateno outside investment to date


Want more info?

New products & white papers:

www.microstrain.com/customer-docs.htm

References:References:•• M.J. Hamel et al., M.J. Hamel et al., “Energy “Energy Harvesting for Wireless Sensor Operation and Data Harvesting for Wireless Sensor Operation and Data

Transmission”, Transmission”, US US Patent #7081693, issued July 25Patent #7081693, issued July 25thth 20062006

• D L Churchill et al “Strain Energy Harvesting for Wireless Sensor Networks• D.L. Churchill et al., Strain Energy Harvesting for Wireless Sensor Networks, Smart Structures and Materials”, SPIE, vol. 5005, pp. 319–327, 2003

• S.W. Arms et al., “Wireless Wireless Strain Measurement Systems for Aircraft Strain Measurement Systems for Aircraft Test”Test”, Aerospace Test Expo Anaheim CA Nov 2006Aerospace Test Expo, Anaheim, CA, Nov 2006

• S.W. Arms et al., “Energy Harvesting Wireless Sensors for Helicopter Damage Tracking”, American Helicopter Society (AHS) 62nd Annual Forum, Phoenix, AZ May 2006AZ, May 2006

•• S.W. Arms, C.P. Townsend, D.L. Churchill, M. S.W. Arms, C.P. Townsend, D.L. Churchill, M. AugustinAugustin, , D.YearyD.Yeary, P. Darden, , P. Darden, N. Phan, “N. Phan, “Tracking Pitch Link Dynamic Loads with Energy Harvesting WirelessTracking Pitch Link Dynamic Loads with Energy Harvesting WirelessN. Phan, N. Phan, Tracking Pitch Link Dynamic Loads with Energy Harvesting Wireless Tracking Pitch Link Dynamic Loads with Energy Harvesting Wireless Sensors”, Sensors”, AHS 63nd Annual Forum, Virginia Beach, VA, May 2007AHS 63nd Annual Forum, Virginia Beach, VA, May 2007

• S.W. Arms, J.H. Galbreath, C.P. Townsend, D.L. Churchill, N. Phan, “Energy gyHarvesting, Wireless Structural Health Monitoring System”, 4th European Workshop on Structural Health Monitoring, Cracow, Poland, July 3rd, 2008

Acknowledgements:Acknowledgements:

V t EPSC RVermont EPSCoRNavy/NSF/DHHS SBIR

B ll H li tBell HelicopterCaterpillar

DSTO M lbDSTO MelbourneSikorsky

L kh d M tiLockheed Martin

Thank You!Thank You!© microstrain, inc. 2008

Micro Strain Wireless Sensors Aircraft Structural Health Monitoring 2008

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