Design of a low-power structural monitoring system to locate impacts based on dispersion compensation

One of the major concerns in structural health monitoring (SHM) for aerospace systems is the impact localization in plate-like structures. The aim of this paper is to develop a miniaturized, self-contained and ultra-low power device for automated impact detection that can be used in a distributed scheme to control the structural integrity of large isotropic plates, such as those that can be found on an aircraft, without central coordination. The proposed system is based on a geometric composition of 4 different conventional piezoelectric transducers connected to a STM32F4 board equipped with an ARM Cortex-M4 microcontroller and a IEEE802.15.4 wireless transceiver. The processing framework and the algorithm are implemented on-board and optimized for speed and power consumption. The difference in travelled distances (DDOA) and the localization of the impact point are obtained by cross-correlating the signals related to the same event acquired by the different sensors in the warped frequency domain. The performance of the proposed SHM system is analysed in terms of DDOA accuracy and power consumption, showing the effectiveness of the proposed implementation.