A Small, Light and Low-Power Passive Node Sensor for SHM of Composite Panels

The aim of this work is to develop a miniaturized, self-contained and ultra-low power SHM system for impact detection and localization in composite panels. The system is based on a sparse array of piezoelectric (PZT) transducers along with the dedicated sensor node. Methodologically, when the stress guided waves generated by an impact cross a certain mV threshold at one PZT, signals are acquired by all sensors. Next, a dedicated signal processing that combines filtering and dispersion compensation algorithms estimates the wave time difference of arrival among the different sensors. The processing framework, embedded within the sensor node, is optimized for speed and power consumption. Finally, data are wirelessly transferred to a remote station, for further structural monitoring actions. The wireless communication technology allows long distance data transmission without wiring, simplifying the deployment of large multi-device SHM monitoring systems such as those based on mesh-type or star-type networks, whereas each node in the network is able to communicate with the central gateway. The system performances in terms impact localization accuracy and power consumption are tested on a composite Zstiffened panel of 1000x1000x3 mm.