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Real Time Visualization of Structural Response through Wireless

Communication using MEMS Sensors

Real Time Visualization of Structural Response through Wireless

Communication using MEMS Sensors

Presented by Tomoyuki EnomotoHung-Chi Chung, Tomoyuki Enomoto, Kenneth Loh*,

Supervised by Masanobu ShinozukaCivil and Environmental Engineering

University of California, Irvine CA*REU student (from Johns Hopkins University)

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ContentsContentsBackgroundObjective Proposed MethodologyPreliminary Study

Analog Devices MEMS Acc ADXL202E Silicon Designs MEMS Acc SD2210

Real Time Visualization of Response of Steel BridgeBridge Response under Jumping Load Simulation with SAP 2000SummaryFuture PlanReferences and Acknowledgment

BackgroundObjective Proposed MethodologyPreliminary Study

Analog Devices MEMS Acc ADXL202E Silicon Designs MEMS Acc SD2210

Real Time Visualization of Response of Steel BridgeBridge Response under Jumping Load Simulation with SAP 2000SummaryFuture PlanReferences and Acknowledgment

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Background ~Structural MonitoringBackground ~Structural Monitoring

!Cable-based data acquisition systems　present some difficulties for structural health monitoring

!Cabling and electromagnetic interference

!Early damage detection (even invisible)!Effective, economical and long-term

structural inspection and maintenance

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Background ~Micro-Electro Mechanical SystemsBackground ~Micro-Electro Mechanical Systems

Rapid advances of MEMS technologies such as mechanical elements, sensors, actuators, and electronics on a common silicon substrate through micro fabrication technology

Advantages of MEMS Accelerometer!Small

!Low-cost!Low Power Consumption

Analog Deviceshttp://www.analog.com/

MEMSnethttp://www.memsnet.org/

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ObjectiveObjective

Development of a reliable and robust devices with MEMS accelerometer and wireless transmitter for the structure monitoring in a field environments

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Preliminary StudyPreliminary Study

Experimental Setup

ADXL202E UnitShaker Test

Silicon Designs (SD) 2210-002 Unit

http://www.silicondesigns.com/

SD Unit Technical Flow

Shaker Test

Impact Experiment

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Experimental Set UpExperimental Set Up

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ADXL202EADXL202EMost Popular MEMS AccelerometerLow Cost & Low Power Consumption2 Axis; ±2g

4”

2-1/2”

ADXL202E MEMS Accelerometer

ADXL202E MEMS Accelerometer

44””

22-1/21/2”

RS232 PortRS232 Port

Battery RoomBattery Room

Micro ControllerMicro Controller

Main board of sensor

ADXL202E

Transmitter & Receiver Unit

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Shaker Test of ADXL202E Sensor UnitShaker Test of ADXL202E Sensor Unit

Noise level is too high for bridge health monitoring

RMS = 3.0mg

-15

-10

-5

0

5

10

15

0 0.5 1 1.5 2 2.5 3Time (s)

Acc (

mg)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

10 100 1000

Acceleration (mg)

AD

XL U

nit/ R

efe

rence A

cc

Shaker test at 2Hz 10mg Linearity Curve

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Silicon Designs SD-2210-002Silicon Designs SD-2210-002Low Cost & Low Power Consumption

1Axis; ±2g

Bigger Mass than ADXL 202E

Wide Range of Output Voltage;± 4V against ± 2g http://www.silicondesigns.com/

Accelerometer Packaging Sense Element Chip

http://www.silicondesigns.com/

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Silicon Designs Sensor & Receiver UnitSilicon Designs Sensor & Receiver Unit

Sensor Unit Receiver Unit

Sensor Unit Receiver Unit

2 ½“

4 ½“

Serial PortSerial PortMicro ControllerMicro Controller

9V Battery9V Battery

Micro ControllerFM Receiver9V Serial Port

Micro ControllerFM Transmitter9V SD Acc

Antenna

Antenna

Sensor

Receiver

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Sensor Unit & Receiver Unit Data Flow Sensor Unit & Receiver Unit Data Flow

9V Battery

Regulator5V SD

Sensor

Micro Controller FM

Transmitter

Antenna

9V Battery

Regulator5V

FM Receiver

Antenna

SD 2 Voltage AON,AOP

Calculation the deference between AON and AOP

PWM Output

Decide the Pulse Width

FM Transmitter

FM Receiver

Antenna

Antenna

Micro Controller

Input Capture Interrupt

Count the Pulse Width

Serial Output

9V Battery

TxRx

Sensor Receiver

RS232C

SerialPort

Laptop Computer

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Real-time Data Acquisition System Real-time Data Acquisition System

Real-time Visualization Software

Data Acquisition System

1Axis; ±2gTransmit Range up to 400 ftPowered by 9V Battery Connected by RS232C Cable

HardwareHardware

Real-time Visualization200Hz SamplingData Logger system

Read the Serial Port SoftwareSoftware

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Noise Level of SD Sensor UnitNoise Level of SD Sensor UnitReduce 50% noise comparing with ADXL202E Unit

RMS = 1.5mg

-15

-10

-5

0

5

10

15

0 0.5 1 1.5 2 2.5 3Time (s)

Acc (

mg)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

10 100 1000

Acceleration (mg)

SD

Unit/ R

efe

rence A

cc

Linearity CurveShaker test at 2Hz 10mg

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Steel Truss Bridge at UCISteel Truss Bridge at UCI

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Experimental SetupExperimental Setup

PCB 393C

SD Wireless

ADXL202E

Data Acquisition

10 m

Accelerometers

ADXL202E Sensor Unit and TransmitterPowered by UPS

3 type Accelerometers3 type Accelerometers

Seismic Piezoelectric Accelerometer PCB 393C

Silicon Design Wireless Sensor Unit

Data Acquisition at 10 m Away from Sensors

Impact Test at the Center of Bridge

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Experimental Results Time DomainExperimental Results Time Domain

-80-60-40-20

020406080

0 2 4 6 8Time (s)

Acc

eler

atio

n (m

g)

-80-60-40-20

020406080

0 2 4 6 8Tim e (s)

Acc

eler

atio

n (m

g)

-80-60-40-20

020406080

0 2 4 6 8Tim e (s)

Acc

eler

atio

n (m

g)

Seismic Piezoelectric Accelerometer PCB 393C

Mesurement Range 2.5g pkResolution 0.1mg

Sampling Rate 60Hz

Silicon Design

Mesurement Range +-2gResolution 1.5mg

Sampling Rate 200Hz

ADXL 202E

Mesurement Range +-2gResolution 3mg

Sampling Rate 50Hz

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Experimental Results Frequency DomainExperimental Results Frequency Domain

0200400600800

1000120014001600

0 2 4 6 8 10 12 14 16 18 20

Frequency (Hz)

Pow

er S

pect

ral

0200400600800

1000120014001600

0 2 4 6 8 10 12 14 16 18 20

Frequency (H z)

Pow

er S

pect

ral

0200400600800

1000120014001600

0 2 4 6 8 10 12 14 16 18 20

Frequency (Hz)

Pow

er S

pect

ral

12 3

12

3

12 3

Seismic Piezoelectric Accelerometer PCB 393C

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Frequency (Hz)4.126.00

13.63

Silicon Design

Frequency (Hz)

ADXL 202E

123

4.086.12

13.17

Frequency (Hz)12

4.205.96

13.573

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Bridge Response Under Jumping Load Simulation with SAP 2000Bridge Response Under Jumping Load Simulation with SAP 2000

Construction Design on Paper

SAP 2000 3D Model (to scale of actual bridge)

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Modal AnalysisModal Analysis

Mode 1

Vertical Mode

Mode2

Lateral Mode

Natual FrequencyMode 1 5.04 HzMode 2 6.19 HzMode 3 10.80 HzMode 4 11.01 HzMode 5 13.13 Hz

Mode 5

Torsional Mode

Mode 3

Vertical Mode

Mode 4

Local Mode

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Time History AnalysisTime History Analysis

-80-60-40-20

020406080

0 2 4 6 8

Time (s)

Acc

eler

atio

n (m

g)

"LoadingImpact load simulated by rectangular function

Load

(kg)

120

1.00

0.03 Time (s)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 5 10 15 20

Frequency (Hz)

Pow

er

Spe

ctr

al

Damping Ratio = 0.01

Damping Ratio = 0.02

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SummarySummaryADXL202E is popular, low cost, and low power consumption. It is good for detection of larger acceleration such as severe earthquakes.

Silicon Design SD-2210-002 shows better performance than ADXL202E in noise level. SD-2210 can measure much smaller acceleration. It provides a good sensor option for bridge healthmonitoring.

SD-2210 is integrated with wireless transceiver module in a sensor system. Real-time visualization on laptop computer is demonstrated for the first time in the field test.

In the field test, cable based traditional accelerometer is also used. Comparison show the reliability of wireless device and data acquisition system for bridge health monitoring.

Results of structural analysis by SAP 2000 show the validity of the experimental results.

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Future PlanFuture Plan

Apply developed sensor units to Caltrans’ highway bridges for ambient vibration experiment

Power consumption is a problem to be solved. By using a 9V battery in a sensor unit, the battery power can run out in 5 hours.

Apply Bluetooth module for Multiple wireless communication

Solar Power for the power consumption problem

Long-term Future Plan

Near Future PlanNear Future Plan

Long-term Future Plan

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Caltrans’ freeway bridgesCaltrans’ freeway bridgesWest St. On-RampWest St. On-Ramp

Jamboree Rd. Overcrossing

Jamboree Rd. Overcrossing

West St. On-Ramp

UCI

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ReferencesReferences1. J. Lynch, K. Law, A. Kiremidjian, E. Carryer, T. Kennedy, A.

Partridge, A Sundararajan, (2002), “Validation of a wireless modular monitoring system for structures”, the SPIE 9th Annual International Symposiums on Smart Structures and Materials, San Diego, CA, USA, March 17-21.

2. High Performance Wireless Research and Education Network (HPWREN), http://hpwren.uscd.edu

3. Analog Devices, http://www.analog.com

4. Silicon Designs, http://www.silicondesigns.com

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AcknowledgmentAcknowledgment

This research is supported by the National Science Foundation (NSF) and Federal Highway Administration (FHWA) through the Multidisciplinary Center for Earthquake Engineering Research (MCEER), and also by California State Department of Transportation (CalTrans).