Development of a 3-DOF structural displacement sensor based on a two-stage Kalman filter

Abstract

Structural displacement is one of the important indicator for monitoring and assessing the safety of civil infrastructures. GPS-RTK has been one of the widely used sensor for displacement measurement, but the GPS-RTK has low sampling rate and its precision and accuracy are easily affected by stability of satellite and environmental conditions. To overcome the limitations of GPS-RTK, a novel 3-DOF structural displacement sensor is developed in this study. The developed sensor measures 3-DOF displacement, velocity and acceleration of large-scale civil structures based on data fusion of acceleration measured from a force feedback accelerometer, and velocity and displacement obtained from a low cost GPS-RTK using two-stage Kalman filtering. The developed 3-DOF structural displacement sensor offers the following advantages over the existing GPS-RTK sensors: (1) The proposed sensor can measure 3-DOF displacement, velocity and acceleration simultaneously, (2) A better accuracy (around 2 mm) and a better sampling rate (up to 100 Hz) can be achieved, compared to the conventional GPS-RTK sensors, and (3) The performance is less affected by weather conditions and multi path problems, which deteriorate the performance of conventional GPS-RTK sensors. The performance of the proposed sensor was validated through a series of lab scale tests and a field test conducted on Yeongjong Grand Bridge.