Improvement and Application of Sensor Device Capable of Autonomously Keeping Accurate Time Information for Buildings and Civil Infrastructures

摘要

In this research, sensor devices were developed for application to seismic observation to understand damage conditions after earthquakes and to structural health monitoring for the maintenance of buildings and civil infrastructures. To apply the sensor devices, they must be densely installed in a broad area and measurement data with synchronized time must be obtained. It is desirable that the sensor devices themselves keep accurate time information even in environments with no available network or Global Positioning System (GPS) signals. Therefore, a sensor device was developed that keeps accurate time information autonomously using a Chip Scale Atomic Clock (CSAC), which consumes ultra-low power, can be mounted on a small board, and is an ultra-high precision clock. This paper explains the CSAC and a mechanism to add highly accurate time information to the measured data using the CSAC. Next, the paper discusses the process of development from prototype to practical device as well as improvement results to solve challenges Identified in the actual use at a bridge. Finally, the paper demonstrates the usability of the developed sensor device using a case study where seismic observation was implemented by installing the improved devices in an actual building.