Development of Atmel SAM-Based Wireless Sensor Node for Bridge Structural Health Monitoring (SHM)

Monitoring the structural health of civil structures is an important research area for continuously monitoring the condition of structures and predicting possible damage. One example is bridge monitoring. To estimate the damage to the bridge structure, it is necessary to continuously monitor the modal parameters, namely the natural frequency of the structure. This is generally measured using the accelerometer sensor. The accuracy of the monitoring system depends not only on accurate sensors, but also on the wireless sensor network used to collect data and transmit it from the sensor nodes to the processing center. In calibrating the accelerometer sensor, we use the VCD21D vibration calibrator tool to test and calibrate the accuracy of the sensor. The experiment was carried out by comparing the accelerometer measurement results with the reference value from the vibration calibrator. The experimental results show that the accelerometer calibration works well, resulting in a maximum measurement error of about 0.3 %. In addition, we also tested WSNs (Wireless Sensor Networks) synchronization using the RBS (Reference Broadcast Synchronization) method with a synchronization error of
$\boldsymbol{2049.5}\ \boldsymbol{\mu}\mathbf{s}$
. The experimental results show that the RBS method successfully synchronizes the sensor nodes in the WSNs accurately and efficiently. The time difference between neighboring nodes is measured in very small timescales (microseconds).