- Volume 18 Issue 4
To estimate structural displacement, a visually servoed paired structured light system (ViSP) was proposed in previous studies. The ViSP is composed of two sides facing each other, each with one or two laser pointers, a 2-DOF manipulator, a camera, and a screen. By calculating the positions of the laser beams projected onto the screens and rotation angles of the manipulators, relative 6-DOF displacement between two sides can be estimated. Although the performance of the system has been verified through various simulations and experimental tests, it has a limitation that the accuracy of the displacement measurement depends on the alignment of the laser pointers. In deriving the kinematic equation of the ViSP, the laser pointers were assumed to be installed perfectly normal to the same side screen. In reality, however, this is very difficult to achieve due to installation errors. In other words, the pose of laser pointers should be calibrated carefully before measuring the displacement. To calibrate the initial pose of the laser pointers, a specially designed jig device is made and employed. Experimental tests have been performed to validate the performance of the proposed calibration method and the results show that the estimated displacement with the initial pose calibration increases the accuracy of the 6-DOF displacement estimation.
structural health monitoring;displacement measurement;visually servoed paired structured light system (ViSP);laser pose calibration
- Balageas, D., Fritzen, C.P. and Guemes, A. (eds) (2006), Structural Health Monitoring, New Jersey: John Wiley & Sons, Inc.
- Jeon, H., Bang, Y. and Myung, H. (2011), "A paired visual servoing system for 6-DOF displacement measurement of structures", Smart Mater. Struct., 20(4), 045019. https://doi.org/10.1088/0964-1726/20/4/045019
- Jeon, H., Shin, J.U. and Myung, H. (2012), "Incremental displacement estimation of structures using paired structured light", Smart Struct. Syst., 9(3), 273-286. https://doi.org/10.12989/sss.2012.9.3.273
- Jeon, H., Shin, J.U. and Myung, H. (2013), "The displacement estimation error back-propagation (DEEP) method for a multiple structural displacement monitoring system", Meas. Sci. Tech., 24(4), 045104. https://doi.org/10.1088/0957-0233/24/4/045104
- Lee, D., Jeon, H. and Myung, H. (2014), "Pose-graph optimized displacement estimation for structural displacement monitoring", Smart Mater. Struct., 14(5), 943-960. https://doi.org/10.12989/sss.2014.14.5.943
- Jeon, H., Myeong, W., Shin, J.U., Park, J.W., Jung H.J. and Myung, H. (2014), "Experimental validation of viSP (Visually Servoed Paired Structured Light System) for structural displacement monitoring", IEEE/ASME Trans. Mech., 19(5), 1603-1611. https://doi.org/10.1109/TMECH.2013.2290020
- Ji, Y.F. and Chang, C.C. (2008), "Nontarget stereo vision technique for spatiotemporal response measurement of line-like structures", J. Eng. Mech. - ASCE, 134(6), 466-474. https://doi.org/10.1061/(ASCE)0733-9399(2008)134:6(466)
- Kim, S., Pakzad, S., Culler, D., Demmel, J., Fenves, G., Glaser, S. and Turon, M. (2007), "Health monitoring of civil infrastructures using wireless sensor networks", Proceedings of the 6th Int. Symp. on Sensor Networks, Cambridge.
- Lee, J.J. and Shinozuka, M. (2006), "Real-time displacement measurement of a flexible bridge using digital image processing techniques", Exp. Mech., 46(1), 105-114. https://doi.org/10.1007/s11340-006-6124-2
- Leith, J.G., Thompson, A. and Sloan, T.D. (1989), "A novel dynamic deflection measurement system for large structure", Proceedings of the 4th Int. Conf. on Civil and Structural Engineering Computing, London.
- Marecos, J., Castanheira, M. and Trigo, J. (1969), "Field observation of Tagus river suspension bridge", J. Struct. Div. - ASCE, 95(4), 555-583.
- Meng, X., Roberts, G.W., Dodson, A.H., Cosser, E., Barnes, J. and Rizos, C. (2004), "Impact of GPS satellite and pseudolite geometry on structural displacement monitoring: analytical and empirical studies", J. Geodesy, 77(12), 809-822. https://doi.org/10.1007/s00190-003-0357-y
- Mita, A. and Yokoi I. (2001), "Fiber Bragg grating accelerometer for buildings and civil infrastructures", Proceedings of the SPIE Smart Structures and Materials: Smart Systems for Bridges, Structures, and Highways, CA.
- Myung, H., Lee, S.M. and Lee, B.J. (2011), "Paired structured light for structural health monitoring robot system", Struct. Health Monit., 10(1), 49-64. https://doi.org/10.1177/1475921710365413
- Nassif, H.H., Gindy, M. and Davis, J. (2005), "Comparison of laser Doppler vibrometer with contact sensors for monitoring bridge deflection and vibration", NDT & E Int., 38(3), 213-218. https://doi.org/10.1016/j.ndteint.2004.06.012
- Olaszek, P. (1999), "Investigation of the dynamic characteristic of bridge structures using a computer vision method", Measurement, 25(3), 227-236. https://doi.org/10.1016/S0263-2241(99)00006-8
- Park, J.W., Lee, J.J., Jung, H.J. and Myung, H. (2010), "Vision-based displacement measurement method for high-rise building structures using partitioning approach", NDT & E Int., 43(7), 642-647. https://doi.org/10.1016/j.ndteint.2010.06.009
- Psimoulis, P.A. and Stiros, S.C. (2008), "Experimental assessment of the accuracy of GPS and RTS for Determination of the parameters of oscillation of major structures", Comput. - Aided Civil Infrastruct. Eng., 23(5), 389-403. https://doi.org/10.1111/j.1467-8667.2008.00547.x
- Thorlabs Inc. (2011), Thorlabs' V21 photonics catalog, http://www.thorlabs.com
- Wahbeh, A.M., Caffrey, J.P. and Masri, S.F. (2003), "A vision-based approach for the direct measurement of displacements in vibrating systems", Smart Mater. Struct., 12(5), 785-794. https://doi.org/10.1088/0964-1726/12/5/016
연구 과제 주관 기관 : Korea Agency for Infrastructure Technology Advancement (KAIA)