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Design of a Low-Power Wireless Structural Monitoring System for - - PowerPoint PPT Presentation

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Design of a Low-Power Wireless Structural Monitoring System for Collaborative Computational Algorithms Yang Wang, Prof. Kincho H. Law Department of Civil and Environmental Engineering, Stanford University Prof. Jerome P. Lynch Department of

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Design of a Low-Power Wireless Structural Monitoring System for Collaborative Computational Algorithms

Yang Wang, Prof. Kincho H. Law Department of Civil and Environmental Engineering, Stanford University

  • Prof. Jerome P. Lynch

Department of Civil and Environmental Engineering, University of Michigan SPIE, San Diego, CA, March 6, 2005

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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Large-scale field validation tests Future direction

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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Large-scale field validation tests Future direction

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Structural Health Monitoring (SHM) Structural Health Monitoring (SHM)

  • S. Chase (2001), NBIP Report: Nearly 60,000 bridges in U.S.

evaluated as structurally deficient.

Over 580,000 highway bridges in U.S. mandated for biannual

evaluations. Advanced Sensing Technology for Autonomous SHM: Rapid, accurate, low-cost

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From Wire From Wire-

  • based Sensing to Wireless Sensing

based Sensing to Wireless Sensing

  • E. G. Straser, and A. S. Kiremidjian (1998): Installation of wired

system can take about 75% of testing time

  • M. Celebi (2002): Each sensor channel and data recording system: $2,000;

Installation (cabling, labor, etc.) per wired channel: $2,000. Traditional DAQ System: wire-based Future Wireless DAQ System

Wireless SHM prototype system Jointly developed by researchers in Stanford University and the University of Michigan

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Challenges in Wireless Structural Sensing (1) Challenges in Wireless Structural Sensing (1)

Requirements for long-distance high-speed wireless data

acquisition, and extensive local data processing HIGHER PERFORMANCE LOWER POWER

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Challenges in Wireless Structural Sensing (2) Challenges in Wireless Structural Sensing (2)

Hardware Restricted communication range Limited bandwidth Unreliable wireless transmission Software Difficulty for data synchronization Difficulty for robust communication design

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  • Dr. E. G. Straser, Prof.
  • A. Kiremidjian (1998)
  • Dr. J. P. Lynch, Prof. K.
  • H. Law et al. (2002)
  • Y. Wang, Prof. J. P. Lynch,
  • Prof. K. H. Law (2005)

Wireless SHM Unit Prototypes from Stanford and Wireless SHM Unit Prototypes from Stanford and UMich UMich

  • L. Mastroleon, Prof. A.

Kiremidjian et al (2004)

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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Large-scale field validation tests Future direction

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Picture of the Prototype with Wireless Modem Picture of the Prototype with Wireless Modem

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Atmega128 Micro-controller Sensor Connector 4 Channel, 16-bit A2D Converter Address Latch for the External Memory 128kB External Memory Power Switch Connector to Wireless Modem

Prototype Double Prototype Double-

  • layer Circuitry Board

layer Circuitry Board

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Container Dimension 4.02” x 2.56” x 1.57” (10.2cm x 6.5cm x 4.0cm) Antenna Length: 5.79” (14.7cm)

Wireless Sensing Unit Prototype Package Wireless Sensing Unit Prototype Package

Power supply requirement: 5.2V

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Power consumption: 75 – 80mA when active; 0.1mA standby Communication range: 90m indoor, 300m outdoor 16bit Analog-To-Digital conversion, 4 A2D channels Local data processing Point-to-multipoint, and peer-to-peer communication Low hardware cost

Hardware Performance Summary Hardware Performance Summary

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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Large-scale field validation tests Future direction

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Wireless Sensing Network Wireless Sensing Network

Prototype system: simple star topology network Firmware for wireless sensing units Server-side computer software

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Reliable Beacon Signal Synchronization Protocol Reliable Beacon Signal Synchronization Protocol

Broadcast Beacon signal to all WSUs Begin sensor data sampling and storage Verify with each WSU if it received the Beacon signal A WSU didn't receive the Beacon signal Inform WSUs* one by one to restart * WSU: Wireless Sensing Unit ** CS: Central Server

Y Received beacon signal

Wait and Respond to Beacon verification Restart and acknowledge with CS**, wait for Beacon signal Wait for data collection command from CS Receive restart command

Y

Start data collection from WSUs one by one, and round by round Transmit data to CS Received data collection request and data is ready

Central Server Wireless Sensing Unit

Finish one round of data transmission Wireless communication and its direction

Y Y

A pproxi m at e begi nni ng synchroni zat i on preci si on: 20 m i cro- S econds.

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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Large-scale field validation tests Future direction

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Geumdang Geumdang Bridge Test, Korea Bridge Test, Korea

1 2 14 12 11 10 9 8 7 6 5 4 3 13 N O R TH P i er P i er P i er A but m ent 46.0m 18.7m 18.7m

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Bridge Traffic Excitation Bridge Traffic Excitation

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0.5 mg 50 µg RMS Resolution (Noise Floor) 80 Hz 2000 Hz Bandwidth 0.7 V/g 10 V/g Sensitivity 3 g 1 g Maximum Range PCB MEMS Capacitive (Wireless System) PCB Piezoelectric (Cable System) Sensor Property

Wire Wire-

  • based System versus Wireless System

based System versus Wireless System

Sampling Frequency 200Hz 70Hz

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155 160 165 170 175 180 185 190

  • 0.04
  • 0.02

0.02 0.04 KAIST Data Aquisition System Time (sec) Acceleration (g) Sensor Location #8 155 160 165 170 175 180 185 190

  • 0.04
  • 0.02

0.02 0.04 Wireless Data Aquisition System Time (sec) Acceleration (g) Sensor Location #8

Time History Comparison Between Two Systems Time History Comparison Between Two Systems

Wireless System Wire-based System

Difference in sensors and signal conditioning

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2 4 6 8 10 12 14 16 1 2 3 4 FFT - KAIST DAQ Frequency (Hz) Magnitude Sensor Location #8 2 4 6 8 10 12 14 16 0.2 0.4 0.6 0.8 FFT - Wireless DAQ Frequency (Hz) Magnitude Sensor Location #8

Comparison of FFT Results Comparison of FFT Results

Wireless System Wire-based System

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Validation Results Summary Validation Results Summary

  • Rapid installation, and low cost
  • Communication range: 50 – 60m in box girder
  • Networked real-time and non-stopping data collection: up to 24 wireless

sensors at 50Hz sampling frequency

  • Data is near-synchronized: modal analysis
  • Local data processing capability: 4096-pt FFT by wireless sensing unit
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Agenda Agenda

Research background Hardware design of the latest wireless

sensing unit prototype

Software design of the latest wireless SHM

system

Lab validation tests Large-scale field validation tests Future direction

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Future Direction Future Direction

To be improved for current prototype system:

Sensor signal conditioning Greater wireless communication range, higher data rate Large-scale data collection from densely allocated sensors Local data analysis and damage identification algorithm

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Acknowledgement Acknowledgement

National Science Foundation CMS-9988909 and CMS-0421180 The Office of Technology Licensing Stanford Graduate Fellowship The University of Michigan Rackham Grant and Fellowship Program

  • Prof. Chung Bang Yun, Prof. Jin Hak Yi, and Mr. Chang Geun Lee, at the

Korea Advanced Institute of Science and Technology (KAIST)

  • Prof. Law, Prof. Kiremidjian and Prof. Miranda
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The End The End