© Copyright 2011 MicroStrain Inc. Energy Harvesting Sensor Networks for Maintenance-Free Health Monitoring of Structures and Condition Monitoring of Machinery

© Copyright 2011 MicroStrain Inc.

Energy Harvesting Sensor Networks Energy Harvesting Sensor Networks for Maintenance-Free Health for Maintenance-Free Health Monitoring of Structures and Monitoring of Structures and

Condition Monitoring of MachineryCondition Monitoring of MachineryMicroStrain IncMicroStrain IncMike RobinsonMike Robinson

www.microstrain.com; ; [email protected]


Energy CheckbookEnergy Checkbook

Just like a bank account – what comes out must be less than what goes in and need to maintain a minimum balance

•Power consumption of the sensor•Available ambient energy•Storage mechanism

2


Elements of Energy HarvestingElements of Energy Harvesting

Power Consumption•Sensor Type•Sample Rate•Duty cycle•Protocol (e.g. bufffered)

Ambient Energy•Vibration•Strain•Solar•Thermal

Energy Storage•Super capacitor•Thin film battery


MicroStrain Extended Range, Synchronized MicroStrain Extended Range, Synchronized Wireless Sensing System Overview (mXRS)Wireless Sensing System Overview (mXRS)

System Components:

• Extended Range Synchronized Sensor Nodes

• V-LINK-mXRS™• SG-Link-mXRS™• DVRT-Link-mXRS™• G-LINK-mXRS™•TC-LINK-mXRS-1CH™•TC-LINK-mXRS-6CH™• SG-Link-OEM-mS (Sync Only)

•WSDA-Base •Node Commander Software


What is a Wireless Sensor NodeWhat is a Wireless Sensor Node

8 bitlow power,

microcontroller

Radio Frequency(RF) transceiver

Flash EEPROM for sensor logging

12, 16 or 24 bit A/D converter

Lithium thionyl chloride battery

Sensor Inputs

Sensor signalconditioning

multiplexer, PGinstrumentation

amplifier


MicroStrainMicroStrain’’s Wireless Sensor Nodes Wireless Sensor Node(Datalogging Transceivers)(Datalogging Transceivers)

• IEEE 802.15.4 compliant IEEE 802.15.4 compliant • 2 MB flash memory stores up to 2 MB flash memory stores up to

1,000,000 data points1,000,000 data points• 16 bit node ID16 bit node ID• Datalogging up to 2 kHzDatalogging up to 2 kHz• Real-time streaming up to 512 HzReal-time streaming up to 512 Hz• Quasi real-time streaming of bursts up Quasi real-time streaming of bursts up

to 2 kHz to 2 kHz • Programmable range – 70 m to 2kmProgrammable range – 70 m to 2km• 16 operating frequencies within the 16 operating frequencies within the

2.4 GHz band2.4 GHz band• Rechargeable or primary batteries or Rechargeable or primary batteries or

an energy harvesteran energy harvester


Features & Benefits of mXRS™ Features & Benefits of mXRS™ Wireless SystemWireless System

• Nano power ultra-stable real-time clock on nodes provides timing reference of ± 3 ppm

• Extended Range Wireless Communication programmable:

0dBm (1 mW) – 70 m 16 dBm (40 mW) – 2 km 10 dBm (10 mW) – 1 km

• Node-to-node synchronization of ±32 μseconds• Multiple nodes on single RF channel• Scalable – up to 16 channels• Nodes operating continuously and in burst mode on

same RF channel


Harvesting Harvesting Ambient Ambient EnergyEnergy


Energy SourcesEnergy Sources• RF FieldsRF Fields• StrainStrain• VibrationVibration• PhotovoltaicPhotovoltaic• ThermalThermal• KineticKinetic


Power from Power from electromagnetic electromagnetic

fieldsfields


Smart Medical DevicesSmart Medical Devices

• Embedded coil and microelectronics module are hermetically sealed within a titanium package.

• Implant monitors static & dynamic forces and moments across knee in vivo.

US patents 6529127, 7256695


Radiographs courtesy Scripps Clinic, La Jolla, CAD ’Lima et al, J. Biomechanics


Practical application:

• Torque and temperature on rotating components

• production line monitoring


Power from strainPower from strain


Pitch Link w/ Energy Harvesting, Sensing, Data Pitch Link w/ Energy Harvesting, Sensing, Data Storage, & Wireless Communications Storage, & Wireless Communications

RF antenna

Circuit board module, microprocessor, and

electrochemical battery

Piezoresistive strain gauge

Electrical insulation, EMI shielding,

& protective covering(shown transparent for illustration purposes)

Piezoelectric energy harvesting elements

Sikorsky H-60 Blackhawk

(patents issued)


MicroStrainMicroStrain’’s Wireless Pitch-Link for s Wireless Pitch-Link for Bell M412 Bell M412 (patent pending)(patent pending)

Electronics Module: 8.2 gr

PZT total weight: 4.3 gr/patch x 12 patches = 52 gr

Cold shrink weight: 7 gr/inch x 8 inches = 56 gr(Bell chose clamps w/ counter-balance)


How much How much energy can energy can

be harvested be harvested from strain?from strain?


It depends on the strain amplitude, It depends on the strain amplitude, frequency, and the PZT area frequency, and the PZT area

for Strain Powered Bell ‘407 Mast Node [7] :

• Macro fiber composite PZT patches (qty 8, 2x5 cm) bonded to mast . During straight level flight on Bell 407 mast (+/- 500 µЄ, 5 Hz) generated ~2.5 mW

• Power/Area/Strain = 62.5 nW/cm^2/µЄ @ 5Hz


M412 Pitch Link, 5 Hz sine input M412 Pitch Link, 5 Hz sine input PZT power output vs. load PZT power output vs. load

(measured at output storage cap)(measured at output storage cap)


Harvesting Strain EnergyHarvesting Strain Energy

• Macro Fiber Composite, P2 type (Smart Material Corp., Sarasota, FL)

• Ongoing PZT fatigue testing: OK after 10 billion cycles (>9 years at 30 Hz)

• 4 point bending fixture delivers uniform strain field to PZT

• PZT patch area: 3” x 1”


Power from Power from vibrationvibration


ApplicationAccel (Gs)

Freq (Hz)

Displacement (uin)

Gearbox 1 800-2K ~30 at 1KHz

Rotating Structure(s) 0.2 4-20 ~6000 at 20Hz

Helicopter Vibrations


Tuned Vibration HarvesterTuned Vibration Harvester


Tunable, Resonant Piezoelectric Tunable, Resonant Piezoelectric Vibration Energy HarvesterVibration Energy Harvester

Power Output Profiles 52 Hz, 50-200 mG,

P2 MFC (Smart Materials, Inc.)

MicroStrain’s Resonant Harvesterfactory tunable from 20 Hz to 200 Hz

field tunable w/ external screw +/-8Hz

MicroStrain, Inc. patents pending


FEA model predicts resonant frequency &strain levels

ActualActual FEAFEA

Resonant Resonant Frequency (Hz)Frequency (Hz)

8181 80.880.8

Strain on PZT Strain on PZT elements (elements (μεμε))

220220 250250


Vibration Energy Harvesters:Vibration Energy Harvesters:Gearbox ApplicationsGearbox Applications

• Prime BPrime B gearbox datagearbox data• 16g mass for ~1000 Hz 16g mass for ~1000 Hz

resonanceresonance• 5.0 mW output5.0 mW output• 1.6 cc volume1.6 cc volume• ~0.3 mW/gram~0.3 mW/gram• ~3.2 mW/cc~3.2 mW/cc

• Prime A Prime A gearbox gearbox datadata

• 25g mass for ~100 25g mass for ~100 Hz resonanceHz resonance

• 2.9 mW output2.9 mW output• 3.6 cc volume3.6 cc volume• ~0.1 mW/gram~0.1 mW/gram• ~0.8 mW/cc~0.8 mW/cc

Patents pending


Static FEA (ANSYS) Static FEA (ANSYS) • Ensure that endurance limit in amplifier not exceeded.• Estimate mean strain in Piezo Stack

Mechanical Amplifier Piezo Stack


Latest Vibrational Energy Harvester being Latest Vibrational Energy Harvester being Developed under NAVAIR Phase II SBIR ContractDeveloped under NAVAIR Phase II SBIR Contract


Inductive HarvesterInductive Harvester

Patents Pending MicroStrain proprietary information


Pitch-LINK Inductive Energy Harvesters:Pitch-LINK Inductive Energy Harvesters:

Patents pending

Pitch Link Inductive Energy Harvester Output: 3.4 mWVolume: 155 cc , Weight: 70 gramsEnclosure weight: 130 grams

MicroStrain proprietary information


Power from lightPower from light


Solar Powered WirelessSolar Powered WirelessStrain GaugeStrain Gauge

• Two Panasonic BP-243318 Solar Modules (40 x 30 x 0.5 mm^3)

• Indoor lighting produced a wide range of output power (~100 to 6500 microwatts)

• Results depended heavily on the type of lighting used and the distance from the light source


Solar Cell Output vs. ConditionsSolar Cell Output vs. ConditionsLight Source Output Power

34W Fluorescent, 200 cm 76 uW34W Fluorescent, 10 cm 1368 uW60W Incandescent, 100 cm 942 uW60W Incandescent, 10 cm 4728 uWWindow sill, cloudy day 1564 uWWindow sill, sunny day 19554 uWOutdoors, sunny day 20612 uWIndoors, 1500W Halogen, 1 m

6512 uW

Indoors, 1500W Halogen, 3 m

1258 uW


Power From HeatPower From Heat


Micropelt’s Integrated Micropelt’s Integrated Thermoharvester w/ heat sinkThermoharvester w/ heat sink

http://www.micropelt.com/applications/te_power_probe.php


Storing Storing EnergyEnergy


• Trickle charged from microwatt source• Low leakage• High number of charge/discharge

cycles• Support peak energy pulse required for

brief radio transmission

Critical Storage Critical Storage Requirements:Requirements:


Thin Film Lithium Batteries Thin Film Lithium Batteries

• 10 uA/Hr battery cell Cymbet, Inc. (Minneapolis, MN)

• 1 mA/Hr Infinite Power Solutions (Golden, CO)

Copyright ©2009 MicroStrain Inc


Saving Energy Saving Energy During Wireless During Wireless CommunicationsCommunications


Strategies that save powerStrategies that save power

• Sleep processor between samples• Open up filters on analog chain• Optimize signal cond. turn-on sequence• Use high impedance sensors (or no power

sensors)• Transmit buffered super-packet• Collect data in bursts• Use data compression


Node type and sample rate RF comm. Distance (70 m)

RF comm. Distance (1 Km)

SG-Link-mXRS 8 Hz(w/ 1000 Ohm strain gauge)

0.68 mA 0.85 mA

SG-Link-mXRS 128 Hz(w/ 1000 Ohm strain gauge)

4.00 mA 5.85 mA

G-Link-mXRS 8 Hz 0.37 mA 0.45 mA

G-Link-mXRS 128 Hz 2.10 mA 2.89 mA


Power Consumption w/ Standard Power Consumption w/ Standard MicroStrain Wireless SensorsMicroStrain Wireless Sensors

• Temperature 1 Hz 1 ma• Strain 512 Hz 9.4 ma• Accelerometers 512 Hz 9.4 ma• General Sensors 25 Hz 2

ma


Battery Life w/ 2 Tadiran AA Battery Life w/ 2 Tadiran AA (4.8 Amp-Hr capacity)(4.8 Amp-Hr capacity)

• Temperature 1 Hz 1 ma 200 days• Strain 512 Hz 9.4 ma 21 days• Accel. 512 Hz 9.4 ma 21 days• Gen. Sensors 25 Hz 2 ma 100 days


Battery Life w/ Tadiran D-Cell Battery Life w/ Tadiran D-Cell (19 Amp-Hr capacity)(19 Amp-Hr capacity)

• Temperature 1 Hz 1 ma 2.1 years• Strain 512 Hz 9.4 ma 84 days• Accel. 512 Hz 9.4 ma 84 days• General Sensors 25 Hz 2 ma 1.1 year


Consuming EnergyConsuming Energy::

work to balance the work to balance the ““energy checkbookenergy checkbook””


Critical Design Features:Critical Design Features:

• Powering down between samples greatly reduces power consumption

• Embedded routines allow microelectronics to adapt to the amount of available energy


EH-Link™ Harvests Power from EH-Link™ Harvests Power from Multiple SourcesMultiple Sources

Converts AC and DC voltages from vibration, thermal, solar, and strain energy harvesters into DC power for immediate use and/or energy storage.

Includes embedded triaxial accelerometers, temperature, and relative humidity sensors

Supports external bridge sensors

Supports external energy storage

(patents issued and pending)


Army AATD H-60A Army AATD H-60A Wireless Sensor Wireless Sensor

InstallationInstallation


NAVAIR MH-60S

ARMY UH-60A

NASA UH-60 RASCAL

Pitch-Link

SG-Link Mil

G-Link Mil

HS-Link

WSDA-Mil

RFID

MicroStrain Flight TestNode Locations


Full System Overview

Patents pending


HS-Link 100KHzHS-Link 100KHz Energy Harvesting, High Speed Accelerometer Energy Harvesting, High Speed Accelerometer

• High-speed, 16 bit, burst data-logging rates up to 100 KHz

• On-board buffer stores up to 125,000 measurements per sampling burst, 1,000,000 points can be stored in the nodes non-volatile flash memory

• Harvester produces 100 mW on simulated H-60 main gearbox vibration profile. 1 mAhr onboard thin film energy storage

Patents pending


G-Link-MILG-Link-MIL Wireless Triaxial AccelerometerWireless Triaxial Accelerometer

• Rugged, sealed wireless tri-axial MEMS accelerometer

• 2G or 10G accelerometer range, onboard temperature sensor

• Quick install with single ¼ -28 bolt through design

Patents pending


SG-Link-MILSG-Link-MIL Wireless Strain SensorWireless Strain Sensor

• Rugged, sealed wireless strain acquisition unit

• 3 bridge channels, capable of interfacing with a single gauge or rosette

• Designed for quick installation with either traditional bonded foil or CRL type strain gauges

• Can be installed on top of strain gauge(s), or nearby via shielded cable

Patents pending


ID-LINK™ Active RFID Tags

• Powered by an internal battery• Capable of both read and write• Structural tags can include critical data: time and date of specific

flights on specific aircraft, number of flight hours, lifespan expended.

• Autonomous, periodic transmit-on-demand (ToD) protocol• Data packet is 96 bit DoD RFID w/ framing & checksum bytes.

The DoD 96 bit code includes a serial number and enables unique IDs for up to 2^96 = 7.9 x 10^28 tagged items.


3DM-GX3-25 3DM-GX3-25 Inertial & Magnetic SensorsInertial & Magnetic Sensors

• Smallest commercially available attitude, heading, reference sensor (AHRS)

• Pitch, roll, and yaw computed with embedded software

• Simultaneously samples inertial & magnetic sensors at 30KHz, outputs at 1KHz

• Digital outputs : USB, RS-232/422/485• Time syncs w/ data aggregator


WSDA-MIL WSDA-MIL Sensor Sensor Data AggregatorData Aggregator

• Ruggedized, sealed, fanless single board computer with 600 MHz Intel XScale processor, 2GB Compact Flash, Linux 2.6

• Integrated 3DM-GX3-25 Intertial Sensor• Ethernet, USB, and serial interfaces• Synchronizes to GPS time• 3 ppm backup timing reference

Patents pending


Army AATD H-60A Army AATD H-60A Wireless Sensor InstallationWireless Sensor Installation

CRL Strain Gauge SG-Link-MIL



WSDA-MIL, G-Link-MIL, ID-Link ID-Link



Energy Harvesting HS-Link-MIL Pitch-Link


NAVAIR H-60S UGR NAVAIR H-60S UGR Flight Test SystemFlight Test System


NAVAIR UGR MH-60S Wireless Sensor Installation

Pitch-Link SG-Link-MIL


NAVAIR UGR MH-60S NAVAIR UGR MH-60S Wireless Sensor InstallationWireless Sensor Installation

SG-Link-MIL G-Link-MIL


Preliminary NAVAIR UGR Flight Test

Results


Tailcone Strain Rosette Node 9002, Takeoff & LandingNAVAIR Safe Separation Flight Test 1

Wheels up

Wheels down


Level Turn Right: Vehicle angular (pitch) rate data vs. time in the upper graph, with simultaneous energy harvesting wireless pitch link loads data in the lower graph.


Acknowledgements:Acknowledgements:

Navy/NAVAIR SBIR PH II Navy/NAVAIR SBIR PH II Navy BAA Navy BAA Army AATDArmy AATD

Bell HelicopterBell HelicopterSikorsky HelicopterSikorsky Helicopter

Thank You!Thank You!

Documents

© Copyright 2011 MicroStrain Inc. Energy Harvesting Sensor Networks for Maintenance-Free Health Monitoring of Structures and Condition Monitoring of Machinery