A Novel Smart Sensor Node with Embedded Signal Processing Functionalities Addressing Vibration–Based Monitoring

Extreme–edge computing is becoming increasingly appealing for Structural Health Monitoring applications because it allows the optimal management of the available processing resources. This fosters the possibility to enhance the responsiveness and power management of the inspection system. To this end, particular attention should be warranted to the extreme–edge implementation of system identification (SysId) algorithms, which represent one of the most powerful means for dynamics analysis and, consequently, for vibration–based structural assessment. However, to implement this near–sensor processing, the design of an optimized hardware is fundamental. In this work, we fulfil this goal by proposing a novel smart accelerometer node, which is built on the combination of a wireless communication module, a high–performance microcontroller unit (MCU) and two tri-axial MEMS accelerometers, necessary to efficiently trigger the acquisition on energy thresholds while maximizing the energy saving. In normal operating mode, the MCU benefits from a clock frequency up to 80 MHz, Digital Signal Processing functionalities and a Floating Point Unit which make feasible the computation of SysId techniques at the extreme edge. Tested on a laboratory steel beam under varying damage levels, the developed system showed promising accuracy in tracking the variations of the vibration response of the structure.