Validation of an Integrated Network Validation of an Integrated Network System for Real- -time Wireless time Wireless System for Real Monitoring of Civil Structures Monitoring of Civil Structures 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 IWSHM, Stanford, CA, September 14, 2005 1
Outline Outline � Research background � Hardware and software design of the latest wireless SHM system � Real-size laboratory structure tests at NCREE, Taiwan � Large-scale field validation tests at Geumdang Bridge, Korea � Future research 2
From Wire- -based Sensing to Wireless Sensing based Sensing to Wireless Sensing From Wire WHY THE CHANGE? � E. G. Straser, and A. S. Kiremidjian (1998): Installation of wired system can take about 75% of testing time for large structures � M. Celebi (2002): Each sensor channel and data recording system: $2,000; Installation (cabling, labor, etc.) per wired channel: $2,000 INDUCED CHALLENGES � Limited power consumption � Restricted communication range, bandwidth, and reliability � Difficulty for data synchronization 3
Wireless SHM Unit Prototypes Wireless SHM Unit Prototypes Dr. E. G. Straser, Prof. Dr. J. P. Lynch, Prof. K. A. Kiremidjian (1996) H. Law et al . (2001) L. Mastroleon, Prof. A. Kiremidjian et al (2003) Y. Wang, Prof. J. P. Lynch, Prof. K. H. Law (2004) 4
Double- -layer Circuitry Prototype Board layer Circuitry Prototype Board 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 5
Final Package of the Latest Prototype Unit Final Package of the Latest Prototype Unit Antenna Length: 5.79” (14.7cm) Container Dimension 4.02” x 2.56” x 1.57” (10.2cm x 6.5cm x 4.0cm) � Total power consumption at 5V power supply � 75 – 80mA when active; 0.1mA standby � Wireless communication with MaxStream 9XCite modem � Communication range: 90m indoor, 300m outdoor � Wireless data rate: 40kbps � Total unit cost using off-the-shelf components � $130 for small quantity assembly 6
Latest Wireless SHM Prototype System Latest Wireless SHM Prototype System Structural Structural ...... Sensors Sensors Signal Signal ...... Conditioning Conditioning Wireless Wireless ...... Sensing Unit Sensing Unit Wireless Sensor Network Server Internet Online Online Graphical Graphical ...... Access to Access to Sensor Data Sensor Data 7
Wireless Sensing Network Wireless Sensing Network Server-side computer software Firmware for wireless sensing units Simple star topology network � Near-synchronized and reliable data collection from all wireless � sensing units 8
Laboratory 3- -Story Structure on a 6 Story Structure on a 6- -DOF Shaking Table DOF Shaking Table Laboratory 3 A2 A1 Collaboration with Prof. C. H. Loh , National Taiwan University & A3 National Center for Research on Earthquake Engineering WSU6 A8 A4 A5 WSU5 A12 A7 A6 WSU4 S43 S44 WSU2 A9 A10 A11 S42 S41 WSU1 WSU3 9
Wireless Sensor Installation Details Wireless Sensor Installation Details 120 Ohm Wireless Strain Gage Sensing Unit (S42) WSU2 & WSU3 Crossbow Wireless Accelerometer Sensing Unit A5 WSU5 10 10
Structural Response Data Structural Response Data 11 11
On- -board FFT Analysis board FFT Analysis On 4096-point complex valued FFT computation � Results for interested frequency spectrum wirelessly transmitted � 12 12
Geumdang Bridge Test, Korea Bridge Test, Korea Geumdang Collaboration with Prof. Chung Bang Yun, Prof. Jin Hak Yi, and Mr. Chang Geun Lee, Korea Advanced Institute of Science and Technology (KAIST) Accelerometer Location Pier 4 Pier 5 Pier 6 1 2 3 4 5 6 7 8 9 10 11 12 13 Abutment 14 17 19 26 25 24 15 23 22 21 20 18 16 36m 46m 36m N Sensor Allocation for Tests at Geumdang Bridge, Dec 2004 13 13
Wire- -based System vs. Wireless System based System vs. Wireless System Wire PCB Piezoelectric PCB MEMS Capacitive Sensor Property (Wire-based 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 500 µ g RMS Resolution (Noise Floor) Sampling Frequency 200Hz 70Hz 14 14
Comparison Between Two Systems Comparison Between Two Systems Accelerometer Location Pier 4 Pier 5 Pier 6 12 13 1 2 3 4 5 6 7 8 9 10 11 Abutment 14 17 19 26 25 24 15 23 22 21 20 18 16 36m 46m 36m N Wire-based DAQ, Sensor #13 FFT - Wire-based DAQ, Sensor #13 0.04 Acceleration (g) 0.02 Magnitude 2 0 1 -0.02 Frequency (Hz) Time(s) -0.04 0 155 160 165 170 175 180 185 190 0 5 10 15 FFT - Wireless DAQ, Sensor #13 Wireless DAQ, Sensor #13 0.04 Acceleration (g) 0.8 Magnitude 0.02 0.6 0 0.4 Frequency (Hz) -0.02 0.2 Time(s) -0.04 0 155 160 165 170 175 180 185 190 0 5 10 15 15 15
Latest Bridge Tests with Sensor Signal Conditioning Latest Bridge Tests with Sensor Signal Conditioning � Mean shifting : any analog signal to 2.5V mean � Amplification : 5, 10 or 20 � Anti-alias filtering : band pass 0.02Hz – 25Hz Accelerometer Location Pier 4 Pier 5 Pier 6 1 2 3 4 5 6 7 8 9 10 11 Abutment 12 13 14 15 16 17 18 19 20 21 22 36m 46m 36m N Sensor Allocation for Tests at Geumdang Bridge, Jul 2005 16 16
Comparison for Wireless DAQ with Signal Conditioning Comparison for Wireless DAQ with Signal Conditioning Wire-based DAQ FFT - Wire-based DAQ 0.02 Acceleration (g) 4 Magnitude 0 2 -0.02 Time (s) Frequency (Hz) -0.04 0 15 20 25 30 35 0 5 10 15 Wireless DAQ FFT - Wireless DAQ 0.02 Acceleration (g) 4 Magnitude 0 2 -0.02 Frequency (Hz) Time (s) 0 15 20 25 30 35 0 5 10 15 Comparison between FFT to the Acceleration Data Comaprison between Wire-based and Wireless DAQ 5 0.02 Wire-based Wire-based Wireless Wireless 4 0.01 Acceleration (g) Magnitude 3 0 2 -0.01 1 -0.02 Time (s) Frequency (Hz) 0 -0.03 2.5 3 3.5 4 4.5 5 28 29 30 31 32 33 17 17
Future Research (1) Future Research (1) Collaboration with Prof. C. H. Loh , National Taiwan University & National Center for Research on Earthquake Engineering Gi-Lu Cable-Stayed Bridge, Chi-chi, Taiwan Span: 120m (L) + 120m (R) 18 18
Future Research (2) Future Research (2) Collaboration with Prof. C. H. Loh , National Taiwan University & National Center for Research on Earthquake Engineering Magneto-Rheological (MR) Damper � Stroke : 300mm or +/- 150 mm � Capacity : 20 kN 19 19
Invitation to a Live Lab Demo Invitation to a Live Lab Demo MEMS Accelerometer Actuation Server Sensing Server Sensing Unit Table Monitoring unit LVDT Actuation Unit Presented by : Yang Wang, Prof. Kincho H. Law, Stanford University Prof. Jerome P. Lynch, University of Michigan Time: Rm 106, Bldg. 540, John A. Blume 4:30pm, Wednesday, Sep 14 th Earthquake Engineering Center 20 20
Acknowledgement Acknowledgement � Prof. Chin-Hsiung Loh , National Taiwan University (NTU) and National Center for Research on Earthquake Engineering (NCREE) � Prof. Chung Bang Yun, Prof. Jin Hak Yi, and Mr. Chang Geun Lee , Korea Advanced Institute of Science and Technology (KAIST) � Prof. Anne Kiremidjian from Civil Engineering, and Prof. Ed Carryer from Mechanical Engineering at Stanford University � National Science Foundation CMS-9988909 and CMS-0421180 � The Office of Technology Licensing Stanford Graduate Fellowship 21 21
22 22 The End The End
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