Integration of GPS, Accelerometer and Optical Fiber Sensors for Structural Deformation Monitoring (original) (raw)
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The Complementary Characteristics of GPS and Accelerometer in Monitoring Structural Deformation
2000
Traditionally structural response due to severe conditions has been measured using accelerometers. However it is a relative acceleration measurement. The displacement from acceleration measurement cannot be obtained directly by simply applying the laws of motion through double integration. GPS-RTK offers direct displacement measurements for dynamic monitoring, but it has its own limitations. The measurement accuracy can be affected by multipath and depends strongly on the satellite geometry.
The latest displacement and velocity sensors such as LDV and LiDAR have limited application in large-scale civil structures, because it is difficult to find an appropriate sensor installation position on which the sensors can aim at the measurement point. Instead, GPS-RTK is widely applied to large civil engineering structures, but GPS-RTK has low sampling rate, accuracy and precision, and is frequently affected by environmental conditions such as bad weather and surrounded obstacles. In the study, a new structural response measurement system has been developed for the online measurement of displacement, velocity and acceleration of large-scale civil structures. The proposed system estimates the structural responses with high sampling rate, accuracy and precision by fusing measurements obtained from GPS-RTK and accelerometer based on two-stage Kalman filter. The proposed system has the following advantages over GPS-RTK sensors: (1) 6 DOF displacement, velocity and acceleration can be measured simultaneously with a single sensor system, (2) The accuracy (around 2 mm) and sampling rate (up to 100 Hz) of the proposed system are better than those of GPS-RTK, and (3) The performance of the system is less affected by environmental conditions. To verify the performance of the proposed system, a field experiments at Yeongjong grand bridge was performed.
Optimal GPS/accelerometer integration algorithm for monitoring the vertical structural dynamics
Journal of Applied Geodesy, 2014
The vertical structural dynamics is a crucial factor for structural health monitoring (SHM) of civil structures such as high-rise buildings, suspension bridges and towers. This paper presents an optimal GPS/accelerometer integration algorithm for an automated multi-sensor monitoring system. The closed loop feedback algorithm for integrating the vertical GPS and accelerometer measurements is proposed based on a 5 state extended KALMAN filter (EKF) and then the narrow moving window Fast Fourier Transform (FFT) analysis is applied to extract structural dynamics. A civil structural vibration is simulated and the analysed result shows the proposed algorithm can effectively integrate the online vertical measurements produced by GPS and accelerometer. Furthermore, the accelerometer bias and scale factor can also be estimated which is impossible with traditional integration algorithms. Further analysis shows the vibration frequencies detected in GPS or accelerometer are all included in the ...
Engineering Structures, 2006
During the last few years the kinematic versions (real time kinematic (RTK) and post-processing kinematic (PPK) modes) of the satellite Global Positioning System (GPS) have been used to monitor quasi-static and dynamic deformations of large slender engineering structures. However, the accuracy of the method, the outlier level (including missed and false alarms) and its limitations have not been statistically determined. For this reason we made a large number of experiments, in which harmonic movements were simulated by a rotating GPS receiver antenna, and the recorded coordinates were compared with the real ones. The outcome of this study is that in mid-latitude regions (ϕ < 50 • ) a simple monitoring system consisting of two GPS receivers and a commercial data processing software permits a standard accuracy of up to 15 mm and 35 mm in horizontal and vertical coordinates, respectively, at 1.5% outlier level. Harmonic frequencies in the range 0.1 Hz < f < 0.5 Hz to approximately 2 Hz can also be determined.
Seismic Response of a Tower as Measured by an Integrated RTK-GPS System
2004
SUMMARY Monitoring structural response induced by seismic waves is an efficient way to mitigate the damage of earthquakes. For example, the measured signal can be used to activate an alarm system in order to evacuate people from an endangered building, or to drive a control system to suppress earthquake-excited vibrations so as to protect the integrity of the structure, or
GPS in Pioneering Dynamic Monitoring of Long-Period Structures
Earthquake Spectra, 2002
Global Positioning System (GPS) technology with 10–20-Hz sampling rates allows scientifically justified dynamic measurements of relative displacements of long-period structures. The displacement response of a simulated tall building in real time and permanent deployment of GPS units at the roof of a building are described. To the authors’ best knowledge, this is the first permanent deployment of GPS units (in the world) for continuous dynamic monitoring of a tall building. Data recorded from the building during a windy day is analyzed to determine the structural characteristics. When recorded during extreme motions caused by earthquakes and strong winds, such measurements can be used to compute average drift ratios and changes in dynamic characteristics, and therefore can be used by engineers and building owners or managers to assess the structural integrity and performance by establishing pre-established thresholds. Such information can be used to secure public safety and/or take s...
A dynamic GPS system for on-line structural monitoring
2001
A structural monitoring project in Singapore is described, in which an RTK-GPS system comprising a pair of Leica GPS receivers installed on the Republic Plaza building (at 280m, the maximum height of any Singaporean building) will be used to generate time series of antenna positions. This system will contribute to a project of monitoring that commenced in 1995 with the installation of two pairs of accelerometers and two UVW anemometers. The GPS results will complement and corroborate the acceleration and wind velocity data to provide the complete picture of building displacement across the full spectrum of loading frequencies, allowing for direct estimation of lateral loads. The aim of the project is to characterise the building loading and dynamic response during strong winds and remote earthquakes, in order to aid local design code development. The GPS system design and installation is described, as well as the technique for online data analysis that is under development.
2001
The aim of this paper is twofold. First, it describes a pilot project in Singapore, in which an RTK-GPS system has been installed for the purpose of monitoring the behaviour of a high rise building. This system will contribute to a project of monitoring that commenced in 1995 with the installation of two pairs of accelerometers and two UVW anemometers. The aim of this project is to capture the building loading and dynamic response during strong winds and remote earthquakes to aid local design code development. The GPS monitoring system installed on the Republic Plaza building (at 280m, the maximum height of any Singaporean building) generates on-line antenna coordinate measurements. These will complement and corroborate the acceleration data to provide the complete picture of the building displacement across the full spectrum of loading frequencies, allowing for direct estimation of lateral loads. The system design and installation is described. The second objective of this paper is to describe a wavelet analysis procedure that has been proposed for the extraction of both the high and low frequencies of the structural dynamics from the 'raw' RTK-GPS results. The results of tests of this time series analysis procedure will be presented.
Monitoring oscillations of slender structures with GPS and accelerometers
Slender structures (such as the chimney of thermo-electrical power plants) oscillate due to dynamic loading by wind, temperature differentials and earthquakes. The Italian Centre for Experimental Electric Science (CESI) started a project, in cooperation with the Polytechnic of Milan, to monitor the structural integrity of an industrial chimney and to identify at any time signs of stiffness changes, perhaps due to breaches, enervations or material fatigue. To this aim, an integrated system combining GPS and accelerometers measurements, from very low frequencies up to 100 Hz, is being set up. The goals are first to identify the principal modes of oscillation to characterize the response of the chimney and later to monitor structure behaviour to detect critical situations in nearly real time. The prediction capability of the system will stand principally on tracking the evolution of the eigenfrequencies and of the maximum amplitude of oscillation of the chimney connected to the intensity of the loads.