A high quality event capture scheme for WSN-based structural health monitoring

In recent years, there has been an increasing interest in the adoption of wireless sensor networks (WSNs) for structural health monitoring (SHM). However, considering the large amount of sampled data, limited power supply and wireless bandwidth of WSNs, it is generally not possible for sensor nodes to monitor structural condition continuously especially for long-term SHM. From SHM perspective, it is highly desirable to collect data during the occurrence of some certain kinds of events such as earthquakes, large wind, etc, since data collected during these periods are more informative for damage detection purpose. However, these events in SHM occur infrequently and if happen, only last for a very short period of time. To effectively capture these short events using energy-limited wireless sensor nodes is a challenging task that has not been addressed in literature. In this paper, we propose a fast and reliable scheme to capture these short-term events. In terms of hardware, the radio-triggered unit and the vibration-triggered unit are designed in our motes. From software perspective, we develop the event capture scheme to realize fast, reliable and energy-efficient event detection under noisy environment. We mainly study the very first problem of the scheme: sentry selection. The optimization problem is formulated and we show that the problem is a general case of the classical k-center problem. Then we propose a greedy algorithm to solve this problem, and conduct simulation to test the effectiveness of the proposed algorithm.