A feasibility study of damage tracking through the diffusive communication of wireless sensors

The objective of this paper is to investigate the feasibility of wireless sensors in the development of an autonomous structural health monitoring system. A collaborative searching algorithm is developed such that massively deployed wireless sensor nodes in a structure conveniently comprise a group and constitute a damage-surveillance perimeter. Wireless sensors in this perimeter spontaneously activate themselves for damage-tracking tasks by networking with neighboring sensors. When the damage-sensitive parameter that is measured by a sensor node exceeds a certain threshold, the process of damage-tracking begins. The proposed damage-tracking algorithm does not require any type of global control. Instead, sensor-networking and a pairwise-comparison algorithm that is implemented at each sensor node allows collaborative decision-making for tracking the changes, such as local strain, in structural properties. The extant autonomous, damage-tracking algorithms have been demonstrated through only numerical simulations for a single-damage case. Here, the study is further expanded to address the problem of simultaneously tracking multiple instances of damage in three-dimensional space by using improved algorithms for sensor networking. An event-based task-executing functionality of individual sensor nodes is successfully implemented and verified using four wireless strain sensors that are mounted on a cantilevered beam structure. Experimental results reveal that the overall capability of wireless sensor nodes is functional enough to enable a wireless-based autonomous structural health monitoring system.