Wireless and Low-Power System for Synchronous and Real-Time Structural-Damage Assessment

The rise of Internet of Things (IoT) systems and the evolution of Low-Power Wide-Area Networks have directly contributed to the emergence of a new generation of Structural Health Monitoring (SHM) systems based on the Non-Destructive Test approach. Consequently, this article presents the design and development of a synchronous, low-cost, real-time, wireless, and low-power consumption SHM system for pre-existing buildings and infrastructures, which has been validated on a structure built in the High Middle Ages forming part of the historical heritage of the city of Seville (Spain). The system proposes a modular and scalable design with the capacity for synchronous monitoring of the accelerations of a structure thanks to the deployment of several reduced-size nodes that acquire and transmit the accelerations of the structures through a Secure Sockets Layer (SSL) NB-IoT connection. This aspect and Firmware Over The Air (FOTA) capability enables the permanent deployment of sensor nodes, thereby not only obviating the use of costly traditional devices but also granting access to the structures to be monitored for each test and maintenance task and hence supporting the tasks related to the preventive conservation of heritage. The experimental tests carried out demonstrate the low impact of GPS time synchronization and FOTA on the autonomy of the system. The precision of the system is also validated by comparing the results with a precision system in a real field test. Furthermore, continuous monitoring is guaranteed through the graphical interface developed as a composition of microservices, which enables management of the deployed networks.