Wireless Sensor Networks for Crack Displacement MeasurementPublic Deposited
Miniaturized, wireless instrumentation is now a reality and this thesis describes development of such a system to monitor crack response. Comparison of environmental (long-term) and blast-induced (dynamic) crack width changes in residential structures has lead to a new approach to monitoring and controlling construction vibrations. In wireless systems transducer power requirements and continuous surveillance challenge available battery power, which declines with decreasing size of the system. Combining low power consumption potentiometer displacement transducers with a short communication duty cycle allow the system described herein to operate for many months with changing its AA size batteries. The system described won third place honors in the 2005 Crossbow Smart Dust Challenge, which represented the best executable ideas for wireless sensor networks that demonstrate how it is used, programmed and deployed to positively impact society. Wireless communication basics are introduced along with operational principles and necessary components. Two different configurations were investigated and produced based on the communication between the remote nodes; single-hop and multi-hop customizations. Battery lifetime, and wireless communication were enhanced by adoption v of the multi-hop protocol. Both of the systems were field tested to evaluate the long-term performance of the software and the hardware components. This thesis also describes the qualification process of the potentiometer through several tests. Potentiometers were chosen for use with the wireless sensor network because of their extremely low power consumption (0.5 mA), which is crucial for the long-term, uninterrupted operation of wireless system relying on only 2 AA batteries. Three different test mechanisms were established to quantify the consistency of the potentiometer response against the hysteresis, drift, noise and transient displacements.
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