Wireless Sensor Networks for Structural Health Monitoring

1
Wireless Sensor Networks for Structural Health
Monitoring
Sukun Kim, Shamim Pakzad, David Culler, James
Demmel, Gregory Fenves, Steve Glaser, Martin
Turon
EECS, UC Berkeley CEE, UC Berkeley
Crossbow
Overview
Vibration Data from the Footbridge

• Ambient vibrations of the structure are
  monitored and used to determine the health status
  of the structure.
• With a Wireless Sensor Network, low cost
  monitoring is possible without interfering with
  the operation of the structure.

First Vertical Mode of Vibration
Challenges

• High Fidelity Data
• High Frequency Sampling with Low Jitter
• Time Synchronized Sampling FTSP
• Large-scale Multi-hop Network Mint
• Reliable Command Dissemination Broadcast
• Reliable Data Collection Straw

Accelerometer Board
Estimated results match with a FE model of the
bridge (SAP)
Deployment at the Golden Gate Bridge

• Two measurement axis each with two
  accelerometers
• Thermometer, 16bit ADC, Low-pass filter
• On-board Digital Signal processing
• Calibration for manufacturing variation and
  temperature

• Nodes on the main span and the south tower
• Distance between nodes on the west span is
  either 100ft or 50ft
• Exposed to strong and salty wind and fog

Software Architecture

• When sampling, only necessary components are
  turned on to reduce jitter
• Straw provides reliable data collection
• Selective-NACK is used complexity is drawn
  from the sender (mote) to the receiver (PC)
• Rate-based control
• Pipelining increases channel utilization

Node, Battery, Antenna
Rusting of C-clamp
Base station in Tower
Deployment at the Footbridge

• Vertical, Quarter span
• North of the South Tower

(b) Vertical, Quarter span South of the North
Tower