The document outlines the design of a wireless sensor network to monitor the health and performance of bridges. It discusses using sensors such as strain gauges and piezoresistors to detect pressure and structural deformation. The network would include sensor nodes, transmitters to send data to a central command station, and a receiver. The design process includes planning, literature reviews on sensor components, conceptual designs, calculations, and analysis to select an economic design that meets requirements for real-time monitoring, alerts, and diagnostics reporting.

1. Wireless Sensor Networks
Carl Freeman (Chairman)
Jarred Hayes
Kanaan Kanaan
Mohamed Nabolsi
Dr. Warsame Ali Dr. Penrose Cofie

2. Table of Contents
• Problem Formulation
 Problem Statement
 Objectives
 Limitations & Constraints
• Project Planning
 Work Breakdown Structure
 Gantt Chart
• Literature Review
 Updated Literature Review
• Calculations
• Conceptual Designs
 Preliminary Design
 Final Design
 Final Functional Design
• Design Analysis
• Hardware/System Software
• System Implementation
• References

3. Problem Formulation
Need
The collapse of the I-35W Highway Bridge has brought attention to the
lack of data consumption about the status and health of infrastructures
around the globe.
Objective
The objective of the project is to design an electronic device
that will monitor the health and performance of the bridge
and periodically send a diagnostics report to the command
and control station.

4. Limitations & Constraints
• Inexpensive
• Durable & Easy System Maintenance
• High-speed data transmission
• Excess weight and pressure detection
• Real-time alerts

5. Objective Table

6. Gantt Chart

8. Literature Review
Piezoresistors (Pressure sensor)
• Resistors whose resistivity changes with applied strain.
By applying pressure you get a voltage that will relate to the amount of
pressure that has been applied which in turn can determine how much
deformation has occurred to a bridge.
Bao, Minhang. "Piezoresistive Sensors." Piezoresistive Sensors. Lausanne:
Elsevier-Sequoia, 1991. 207-44. Http://www.mech.northwestern.edu. Web.

9. Transmitter
• It can easily fit into a breadboard and work well with microcontrollers to
create a very simple wireless data link.
• Since these are only transmitters, they will only work communicating data
one-way. you would need two pairs (of different frequencies) to act as a
transmitter/receiver pair.
• Transmitter generates a radio frequency.
• The purpose of transmitters is to send information over a distance.
Transmission Systems for Communications, 3rd ed., Western Electric Co.,
Winston-Salem, NC, 1985, pp. 44–60.

10. Receiver
• Device that receives radio waves and converts the information.
• Extracts the desired information, as need ( Audio , images, digital)
B. Chappel, et. al. “Fast CMOS ECL Receivers With 100 mV Sensitivity”, IEEE
Journal of Solid State Circuits, vol. 23, no. 1,
Feb. 1988.

11. Updated Literature Review
• Feltrin, G., J. Meyer, R. Bischoff, and M. Motavalli. Proc. of 4th
International Conference on Structural Health Monitoring of
Intelligent Infrastructure, Zurich, Switzerland. N.p., July 2009. Web
 System Design: Wireless Sensor Network components
1. Sensing interface
2. Computational core
3. Wireless transceiver
4. Actuation interface
5. Application Software
 Testing & Node Placement
Multiple nodes will be placed at different locations. Commination
between the nodes and sink node will send the raw data of the natural
frequencies and can be cleaned by a filter for better readings

12. • Network architecture: this network is divided into groups sensors units. Each group has a
Local Site Master, this network work as:
1. Lower Tier: groups of sensor units communicating with their corresponding LSM
2. Upper Tier: LSM communicating with each other and the controller.
TWO-TIER WIRELESS SENSOR NETWORK
Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan, “Energy-
efficient communication protocols for wireless microsensor networks,” Proceedings of
the Hawaii International Conference on Systems Sciences, Jan. 2000.

13. Wireless Sensor Networks
•The WSN is built of "nodes” each node is connected to one sensors. Each
such sensor network node has typically several parts: a radio transceiver with
an internal antenna or connection to an external antenna, a microcontroller,
an electronic circuit for interfacing with the sensors and an energy source.
•A wireless sensor network (wsn) consist of spatially distributed
autonomous sensors to monitor physical or environmental conditions
such as temperature, sound, pressure, strain, ect.
 Kayiram Kavitha, 2012 Workload-Aware Tree Construction Algorithm for
Wireless Sensor Networks, International Journal on Applications of
Graph Theory In wireless Ad Hoc Networks And sensor Networks

14. Wireless Modular Monitoring System For
Structures
 Lynch, J. P. 2002 Decentralization of wireless monitoring and control technologies for smart civil
structures.Technical Report No. 140, John A. Blume Earthquake Engineering Center. Stanford, CA: Stanford
University.
•Computational core
The computational core is primarily responsible for the
operation of the wireless sensing unit, including collection of data from
the sensor interface, execution of embedded computing procedures and
managing the flow of data through the wireless communication channel.
The flexibility of the wireless communication network of system sensors
allows for system modularity as well as reduced dependence upon a
centralized data acquisition unit to coordinate the activities of the system.

15. Circuit Diagram
Half Bridge Type II
• Sensitive to bending Strain
• Rejects Axial strain
• Sensitivity ~ 1.0
per , for GF = 2.0
R1 and R2 – Half-Bridge completion
resistors
R3 – measuring compression from
Poisson effect
R4 – measuring tensile strain
GF – Gage Factor
v – Poisson’s ratio
Vch – Measured voltage of the bridge
VEX – Excitation Voltage
Vr - Offset compensated ratiometric
bridge output

16. Calculations
V =Vs(
R1
R1+ R4
)-Vs(
R2
R2+ R3
)
• Communication Standard IEEE 802.15.4
• Pressure Senor
Wheatstone Bridge
•
•

17. Preliminary Design
Tilt Sensor
Weather
Transmitter
Microcontroller
Strain Gauge
Data Logger
Pressure/Temp
Logger
Microprocessor
Data Station
Strain Gauge

18. Data storage
center
Add time
stamp
DataAcquisitionSystem
Senspot 1
(Humidity)
Senspot 2
(Tilt)
Senspot 4
(Tilt/Pressure)
Senspot 3
(Crack)
via active RF
Communication
Computer Analysis with
SenScope software
Warning
Alert
Prime
Lithion
Battery
Yes NoParameter
Breach?

19. TracSen
Corrosion Sensor
Crack Sensor
Strain Gauge
Tilt Sensor
Temperature Transmitter
Alert
Is the
operating
temperature
between -10
to 70°C (14 to
158°F)
Yes
User
Constant data
transfer through
RF
Clear Alert
Request Data
Storage
Data Logger
Receive Data
Daily data readings
transferred through RF
Does pressure
exceed limit?
Detected more
than 0.1 degrees
inclination?
Yes
System clear
No
Design Concept 2
NoYes No
Communication
Standard IEEE
802.15.4

20. Economical Analysis
Design Comparison
VS.
1. Strain Resolution: 1m Strain
2. Acceleration & Vibration: resolution: 1mg, range adjustable
to ±2g, ±4g, ±8g, (g = acceleration due to gravity)
3. Tilt & Inclination resolution: 12.9 arc second (0.003 degrees)
4. Crack Width Accuracy 0.1mm
5. Humidity & Moisture resolution: 1% RH
6. Temperature resolution: 1°F
$150 - $200 per device
Easy-to-use software
Lithion Battery lifespan 30 years
Active RF Technology
$120 per device
Editable Software Package
Programmable Serial Ports
Programmable LEDs
Senspot XBOW Sensor Board

21. National
Instruments
NI WSN-3214
Programmable
4 Ch, Quarter-
/Half-/Full-
Bridge and Strain
Gage Node
Qty: 1 $792.23
SGT-1LH/350-
TY41
Half Bridge
Uniaxial Strain
Gage
Qty: 2
Pack of 5
$42.80(2)
=$85.60
TX4-100 Sensor and
Transducer Wire
and Multi-
Conductor Cable
Qty: 1 $35.00
Equipment & Cost
Total: 912.83

22. Final Functional Design:
Wireless Sensor Network Strain Gage/Bridge Completion Node
• support for hardware-timed
waveform acquisition to the
NI wireless sensor network
(WSN) platform
• flexible analog front end,
you can define sample rate,
waveform size, and
waveform interval
• high-speed and high-
resolution analog input
modes
• LabVIEW WSN Module, you
can use graphical
programming to customize
the node’s behavior and add
intelligence to perform local
control, analysis, and data
reduction
• support for logging,
alarming, and web-based
data visualization

23. National Instruments
NI WSN-3214 Programmable
4 Ch, Quarter-/Half-/Full-Bridge and Strain
Gage Node
• four 1.5 V, AA alkaline or lithium battery
cells
• 2.4 GHz, IEEE 802.15.4 radio that
provides up to 300 m outdoor range
• -40 to 70 °C operating temperature and
50 g shock, 5 g vibration
• Low-power operation with up to 3-year
battery life
Advances: Single WSN Gateway Connection
 Star Topology – ability to connect 8 end
nodes
 Mesh Topology – connect up to 36
measurement nodes
4 Ch. Programmable Strain Gage

24. If Strain
Approaching
Max Strain
And Strain > Max
Threshold
Trigger
Alarm
Log Strain
Readings in
Excel
Threshold Set Point
Trigger
Warning
Flow Chart Based on LabView Code

25. Software: NI Labview Block Diagram

26. LabView Node Specifications Window

27. Software: Sensing Interface Front Panel
Data Frequency Captured with weight added

28. System Implementation
Aluminum Block
Strain Gauge
NI-3214
Strain Node
Electronic Warning System
Red Bulb: Max Strain
Green Bulb: Operational
Yellow Bulb: Approaching Max
Strain Gauge
Transducer Wire NI-9791
Ethernet Gateway

29. References
1. Lynch, J. P. 2002 Decentralization of wireless monitoring and control technologies for smart
civil structures.Technical Report No. 140, John A. Blume Earthquake Engineering Center.
Stanford, CA: Stanford University.
2. Lynch J.P2005 Design of a wireless active sensing unit for localized structural health
monitoring. J. Struct. Control Health Monit. 12, 405–423. doi:10.1002/stc.77.
3. Lynch, J. P., Law, K. H., Kiremidjian, A. S. & Carryer, E. 2002. Validation of a wireless modular
monitoring system for structures. In Proc. of the 9th Annual Int. Symp. on Smart Structures
and Materials, vol. 4696, pp. 124–135. San Diego, CA: SPIE—International Society for Optical
Engi
4. Bao, Minhang. "Piezoresistive Sensors." Piezoresistive Sensors. Lausanne: Elsevier-Sequoia,
1991. 207-44. Http://www.mech.northwestern.edu. Web.
5. Held G. (2001). Data over wireless networks: Bluetooth, WAP, & wireless LANs. New York,
New York :McGraw-Hill
6. Madisetti V.K., & willimas D.B. (Eds.). (1998). The digital signal processing handbook, Boca
Raton,Florida: CRC Press.
7. Receiver. (n.d.). Retrieved from http://www.citrix.com/go/receiver.html
8. Automation, Canberra, Australia. B. Elsener, H. Böhni, Potential Mapping and Corrosion of
Steel in Concrete, Corrosion Rates of Steel in Concrete, ASTM STP 1065 (1990) 143 – 156.
9. Lynch, Jerome P., and Kenneth J. Loh. A Summary Review of Wireless Sensors and Sensor
Networks for Structural Health Monitoring. Rep. University of Michigan, Mar. 2006

30. References
12. Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishnan, “Energy-efficient
communication protocols for wireless microsensor networks,” Proceedings of the Hawaii
International Conference on Systems Sciences, Jan. 2000.
13. Feltrin, G., J. Meyer, R. Bischoff, and M. Motavalli. Proc. of 4th International Conference on
Structural Health Monitoring of Intelligent Infrastructure, Zurich, Switzerland. N.p., July
2009. Web