The common deterioration of civil infrastructure systems and the threat of extreme loadings require facility managers to improve their knowledge regarding the health of the structures that they manage. A dense array of wireless sensors installed in a structure could provide ample amounts of empirical data for monitoring structural health. In addition to being a low cost alternative to traditional cable-based monitoring systems, wireless sensor networks offer a distributed computing paradigm that allows sensors to self interrogate structural response data.
Researchers at the University of Michigan have implemented IEEE 802.15.4 Protocol Stack, including the physical (PHY) and media access control (MAC) layers for wireless sensors for structural health monitoring. In such wireless sensing units, direct implementation of IEEE 802.15.4 standard for wireless communication facilitates peer-to-peer computing. In particular, MAC layer may control beacon management, channel access, guaranteed time slot management, frame validation, and acknowledged frame delivery. The MAC layer in turn accesses the PHY, which controls activation and deactivation of the radio transceiver, energy detection, link quality indication, channel selection, and the act of physically transmitting and receiving packets. The wireless sensor is programmed in such a manner that the user needs only to give commands in the application layer; the MAC and PHY layers will automatically carry out the required functions without additional user commands.
Applications and Advantages
- Wireless sensors for structural health monitoring
- Scalable, peer-to-peer communication that is adaptable to network changes without reprogramming