Dynamic Monitoring of Deforming Structures: GPS versus Robotic Tacheometry Systems

Abstract

The Global Positioning System has been the leading technology for monitoring the movements of points at high data rates (i.e. 1 Hz). Areas of application include the monitoring of operating cranes, bridge and building vibration studies, and the dynamic alignment of structures during construction. In recent years, robotic tacheometry (“total station”) systems have been developed that can track moving points and make observations of angles and distances at rates up to 1 Hz. This paper compares the accuracy and utility of robotic tacheometry systems to that of GPS. Several issues are uncovered that currently limit the practical use of robotic tacheometry systems in kinematic positioning. The two main problems are a) low EDMI accuracy, which is directly correlated to station velocity along the line-of-sight, b) uneven sampling over time and the lack of observation time-tagging. However, it is also noted that robotic tacheometry systems have the advantage in stop-and-go applications, where they are capable of millimetre level accuracy, compared to centimetre level results when using GPS. 1.