Research and design of bridge distributed monitoring system based on LoRa technology

Bridges are a kind of infrastructure constructed to save urban space, to relieve traffic congestion, and to show urban modernisation. Therefore, bridge safety has become the focus of social attention. To know the structural condition of the bridge in real-time, it is necessary to develop an intelligent and efficient bridge health monitoring system. However, the traditional bridge health monitoring system has poor real-time performance, low efficiency, and a low degree of automation. The development of LoRa technology is expected to improve this situation. In this study, we designed a bridge-distributed monitoring system based on LoRa technology, which has end nodes, relay nodes, a collect node, and a monitoring centre. In detail, the STM32H743XI processor is combined with the radio frequency SX1268 chip to form the above nodes. Furthermore, the end node contains the pulse vibration excitation circuit, and pick-up signal conditioning circuit of the vibrating string crack metre, and the signal conditioning circuit of the temperature sensor AD590 and the humidity sensor HM1500LF. Finally, the data preprocessing of sensors and the communication performance of the two-stage relay network of the LoRa module, which represent the key technologies to effectively and efficiently meet the real-time monitoring of bridge conditions, are tested and discussed. This distributed monitoring system for the bridge can provide feasible solutions for the application field of bridge monitoring, which is helpful for the daily maintenance management and risk warning decision-making of bridges.