A reliable structural health monitoring protocol using wireless sensor networks

In this paper, we present a distributed reliable structural health monitoring (SHM) protocol using hierarchical wireless sensor networks. We assume that the sensor network consists of (i) sensors capable of sensing the structural health conditions (e.g., strain, vibration, pressure, temperature, etc.), (ii) cluster-head nodes that collect and process the sensory measurements from the sensors and prepares a local report and (iii) a sink that collects the local reports. Sensors are organized into single hop clusters, each managed by a cluster-head node. A cluster head should take the sensor-faults into account when preparing the local report based on the measurements of its subordinate sensors. In majority decision-rule for combining measurements, the judgement about health status will follow the majority where a correct majority decision requires that a majority of observing nodes provide accurate measurements. Using Baysian approach to form a judgment is problamatic without additional information or assumptions (for example, the difficulty of knowing conditional probabilities). Dempster-Shafer theory of evidence based approach overcomes these limitations. Unlike the simple binary decision, it produces a judgment value between 0 and 1 that reflects the degree of belief in that judgment. It discounts the unreliable observer's measurements. Our results through extensive simulations show the efficacy of the proposed scheme. We believe that our design might lead to the development of commercial, cost-effective, yet efficient and reliable distributed SHM systems to effectively monitor and intelligently detect structural health under various loads.