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 1
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 2
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 3
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 4
From Wire- -based Sensing to Wireless Sensing based Sensing to Wireless Sensing From Wire 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 � 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. 5
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 6
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 7
Wireless SHM Unit Prototypes from Stanford and UMich UMich Wireless SHM Unit Prototypes from Stanford and Dr. E. G. Straser, Prof. Dr. J. P. Lynch, Prof. K. A. Kiremidjian (1998) H. Law et al . (2002) L. Mastroleon, Prof. A. Kiremidjian et al (2004) Y. Wang, Prof. J. P. Lynch, Prof. K. H. Law (2005) 8
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 9
Picture of the Prototype with Wireless Modem Picture of the Prototype with Wireless Modem 10
Prototype Double- -layer Circuitry Board layer Circuitry Board Prototype Double Address Latch for Atmega128 the External Micro-controller Memory Power Switch Connector to Wireless Modem 128kB External Sensor Memory Connector 4 Channel, 16-bit A2D Converter 11
Wireless Sensing Unit Prototype Package Wireless Sensing Unit Prototype Package Antenna Length: 5.79” (14.7cm) Power supply requirement: 5.2V Container Dimension 4.02” x 2.56” x 1.57” (10.2cm x 6.5cm x 4.0cm) 12
Hardware Performance Summary Hardware Performance Summary � 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 13
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 14
Wireless Sensing Network Wireless Sensing Network Prototype system: simple star topology network Server-side computer software Firmware for wireless sensing units 15
Reliable Beacon Signal Synchronization Protocol Reliable Beacon Signal Synchronization Protocol Central Server Wireless Sensing Unit Restart and Inform WSUs* one acknowledge with by one to restart CS**, wait for Beacon signal * WSU: Wireless Sensing Unit ** CS: Central Server Received beacon signal Broadcast Beacon signal to Begin sensor data all WSUs sampling and storage Wireless communication and its direction Y Verify with each Wait and WSU if it Respond to Receive restart received the Beacon command Beacon signal verification A pproxi m at e begi nni ng synchroni zat i on Wait for data preci si on: 20 m i cro- collection Y A WSU didn't receive S econds. command from CS the Beacon signal Received data collection request and Y data is ready Start data collection from WSUs one by one, and Y round by round Transmit data to Finish one round of CS data transmission 16
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 17
Geumdang Bridge Test, Korea Bridge Test, Korea Geumdang A but m ent P i er P i er P i er 14 13 12 10 9 8 7 6 5 4 3 2 1 11 N O R TH 18.7m 46.0m 18.7m 18
19 Bridge Traffic Excitation Bridge Traffic Excitation
Wire- -based System versus Wireless System based System versus Wireless System Wire PCB Piezoelectric PCB MEMS Capacitive Sensor Property (Cable System) (Wireless System) Maximum Range 1 g 3 g Sensitivity 10 V/g 0.7 V/g Bandwidth 2000 Hz 80 Hz 50 µ g RMS Resolution (Noise Floor) 0.5 mg Sampling Frequency 200Hz 70Hz 20
Time History Comparison Between Two Systems Time History Comparison Between Two Systems KAIST Data Aquisition System 0.04 Sensor Location #8 Wire-based System Acceleration (g) 0.02 0 -0.02 -0.04 155 160 165 170 175 180 185 190 Time (sec) Wireless Data Aquisition System 0.04 Sensor Location #8 Wireless System Acceleration (g) 0.02 0 -0.02 -0.04 155 160 165 170 175 180 185 190 Time (sec) � Difference in sensors and signal conditioning 21
Comparison of FFT Results Comparison of FFT Results FFT - KAIST DAQ 4 Sensor Location #8 Wire-based System 3 Magnitude 2 1 0 0 2 4 6 8 10 12 14 16 Frequency (Hz) FFT - Wireless DAQ 0.8 Sensor Location #8 Wireless System 0.6 Magnitude 0.4 0.2 0 0 2 4 6 8 10 12 14 16 Frequency (Hz) 22
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 � 23
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 24
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 25
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 26
27 The End The End
Recommend
More recommend
