Zigbee-enabled structural health monitoring using the SmartBrick system

This thesis describes the design, testing, and proposed extended field test of a wireless sensor network based on the SmartBrick, a structural health monitoring (SHM) device developed at Missouri S&T. The SmartBrick serves as the base station for the network, which utilizes additional sensor nodes to monitor the structure. Each node measures a range of environmental and structural phenomena, including vibration, tilt, humidity, and strain. The nodes use Zigbee short-range communication to transmit their data to the base station, which in turn uses the GSM cellular network to provide long-range communication capability and support for remote control. Unlike many SHM systems, this network has been designed from the outset to minimize power consumption. This minimization includes careful selection of hardware, as well as software control of peripheral power and dynamic clock switching. The network as a whole is projected to operate autonomously for up to four years without requiring on-site maintenance, due largely to the minimal power consumption and rugged design. The low power consumption makes the system especially suited to more permanent monitoring applications. This thesis discusses the most recent stage in the evolution of the SmartBrick, primarily the addition of short-range wireless communication using Zigbee. This short-range communication allows several devices to be used to measure larger structures, such as multi-span bridges. Additionally, this thesis describes laboratory testing and results, as well a proposed second field test in which several units collaborate to monitor a larger structure. For this field test, the wireless sensor network will be installed on a three-span bridge to be constructed in Washington County, Missouri in Summer 2009. Results of laboratory testing are included and discussed in detail, demonstrating the unique capabilities of the proposed SHM system --Abstract, page iii