UC San Diego

Wireless Sensor Networks (WSN) for Structural Health Monitoring (SHM) applications can provide the data collection necessary for rapid structural assessment after an event such as a natural disaster puts the reliability of civil infrastructure in question. Unfortunately, there are many technical challenges associated with employing such a WSN in civil infrastructure for operation over multiple decades with maintenance costs low enough to justify the integration of such a WSN into a given structure. The technical challenges include ensuring power is maintained at the sensor nodes, reducing installation and maintenance costs, and automating the collection and analysis of data provided by a wireless sensor network. In this work a new WSN paradigm to address these challenges is presented. The new WSN paradigm is called the "mobile host" WSN. In a mobile host WSN, the sensor nodes are placed on the structure with no internal electrical power source. Instead the node is equipped with hardware to collect energy delivered to it wirelessly by a mobile host on an as-needed basis in order to perform its intended data acquisition and interrogation functions. When an event of interest occurs which might compromise the integrity of the structure, the sensor nodes capture relevant data from the event. In order to collect the data captured by the sensor network, a "mobile host" is sent to each sensor node and wirelessly charges it up. Once the sensor node is fully charged, it turns on and transmits its data wirelessly to the mobile host. The mobile host receives and stores the data and then implements appropriate structural health monitoring (SHM) data interrogation algorithms. If deemed necessary the mobile host then proceeds to interrogate other sensor nodes of interest on the structure. In this way a remote system is presented that can then be used to make a health assessment of the structure. This dissertation addresses the research challenges encountered when implementing a mobile host Won. A sensor node (THINNER) capable of collecting data tirelessly in the absence of electrical power was developed. A peak displacement and bolted joint p reload sensor capable of interfacing with the THINNER sensor node were designed and implemented. A wireless energy delivery package capable of being carried by an airborne mobile host was developed. Lastly, the system engineering required to implement the overall sensor network was carried out. The culmination of this work resulted in the first field demonstration of a mobile host wireless sensor network. The field demonstration took place on an out-of-service, full-scale bridge near Truth- or-Consequences, New Mexico