A New Position Measurement System Using a Motion-Capture Camera for Wind Tunnel Tests

Hyo Park,Ji Kim,Yousok Kim,Se Choi,Jin Kim

doi:10.3390/s130912329

Hyo Park, Ji Kim + Show 3 more

Open Access

https://doi.org/10.3390/s130912329

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Journal: Sensors	Publication Date: Sep 13, 2013
Citations: 62	License type: CC BY 4.0

Affiliation: Daewoo Electronics (South Korea), Yonsei University

Abstract

Considering the characteristics of wind tunnel tests, a position measurement system that can minimize the effects on the flow of simulated wind must be established. In this study, a motion-capture camera was used to measure the displacement responses of structures in a wind tunnel test, and the applicability of the system was tested. A motion-capture system (MCS) could output 3D coordinates using two-dimensional image coordinates obtained from the camera. Furthermore, this remote sensing system had some flexibility regarding lab installation because of its ability to measure at relatively long distances from the target structures. In this study, we performed wind tunnel tests on a pylon specimen and compared the measured responses of the MCS with the displacements measured with a laser displacement sensor (LDS). The results of the comparison revealed that the time-history displacement measurements from the MCS slightly exceeded those of the LDS. In addition, we confirmed the measuring reliability of the MCS by identifying the dynamic properties (natural frequency, damping ratio, and mode shape) of the test specimen using system identification methods (frequency domain decomposition, FDD). By comparing the mode shape obtained using the aforementioned methods with that obtained using the LDS, we also confirmed that the MCS could construct a more accurate mode shape (bending-deflection mode shape) with the 3D measurements.

Highlights

To more accurately evaluate wind loads, each country’s design code, including ASCE standard 7, requires or allows wind tunnel tests, which have gained recognition as an indispensable test in the field of civil engineering [1,2]
A displacement measurement motion-capture system (MCS) represents the values of the marker movements (Y-direction) obtained from the motion-capture camera installed at the top of the pylon (M1), and the laser displacement sensor (LDS) measurements represent the values of the movement of the highest point, which was obtained from the LDS (L1)
We have proposed a remote sensing system to measure position using motion-capture cameras for wind tunnel tests used to measure the deformation of a target structure subjected to a wind load

Summary

Introduction

To more accurately evaluate wind loads, each country’s design code, including ASCE standard 7, requires or allows wind tunnel tests, which have gained recognition as an indispensable test in the field of civil engineering [1,2]. The development of a measurement system has allowed wind tunnel test equipment to measure the actual loads on buildings more accurately. SM-PSS tests can output the vertical profile of the moments and shear force accurately as well as all of the information that can be obtained using the HFBB test. These measurement systems are primarily used to evaluate wind loads and are limited to the calculation of the root mean square (RMS) displacement through a spectrum obtained from the aforementioned methods [9]. Measuring and evaluating indicators, such as the drift of structures by wind loads, are essential to estimate the safety of buildings and to evaluate the structural performance of a building

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