Study on Measured Data Processing Method of Model Test for Relative Motions between Two Side-by-Side Replenishment Ships in Waves

Abstract:

The method to process measured data of ship model test with contact measurement to study the characteristics of relative motion between two side-by-side ships was investigated. The reference co-ordinate systems and the relative motions of two side-by-side replenishment ships were defined. Then the integration transform method which combines Fast Fourier Transform(FFT) with Empirical Mode Decomposition(EMD) self-adaptive filter was applied to transform measured acceleration signal into displacement. The EMD adaptive filter is designed, and the integration results from acceleration to displacement with and without EMD adaptive filter were compared, which shows that the EMD adaptive filter can effectively eliminate the noise embedded in the measured data. At last, the relative motions are acquired, which are consistent with the practical situation.

• Periodical: Applied Mechanics and Materials (Volumes 239-240)
• Pages: 1089-1094
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.239-240.1089
• Online since: December 2012
• Authors: Ping An Shi, Jia Wei Ye
• Keywords: Acceleration, Empirical Mode Decomposition (EMD), Frequency Domain Integration, Relative Motion, Side-by-Side

References

[1] M.C. Fang and G.R. Chen. The relative motion and wave elevation between two floating structures in waves: Proceedings of the eleventh(2001) international offshore and polar engineering conference, Stavanger, Norway, pp.361-368

[2] M.S. Kim, H.S. Jeong, H.W. Kwak, B.W. Kim and J.K. Eom. Improvement method on offloading operability of side-by-side moored FLNG: Proceedings of the twenty-second(2012) international offshore and polar engineering conference, Rhodes, Greece, June 17-22, 2012, pp.921-926

DOI: 10.1115/omae2012-83312

[3] B.J. Koo, M.H. Kim. Hydrodynamic interactions and relative motions of two floating platforms with mooring lines in side-by-side offloading operation: Applied ocean research 27(2005), pp.292-310

DOI: 10.1016/j.apor.2006.02.001

[4] G.R. Chen, M.C. Fang. Hydrodynamic interactions between two ships advancing in waves. Ocean engineering 28(2001), pp.1053-1078

DOI: 10.1016/s0029-8018(00)00042-1

[5] J.M. Godhaven. Adaptive tuning of heave filter in motion sensor: Proc. OCEANS, 1998, pp.174-178

[6] J.C. Liu, Q.H. Xu, J.X. Cha. Method of vibration displacement measured with acceleration sensor. Modem radar, 29(5), 2007, pp.69-71(In Chinese)

[7] P. Flandrin, G. Rilling, and P. Gonçalvés. Empirical Mode Decomposition as a Filter Bank. IEEE SIGNAL PROCESSING LETTERS, VOL. 11, NO. 2, 2004, pp.112-114

DOI: 10.1109/lsp.2003.821662

[8] N.E. Huang, S.R. Long, M.C. Wu, et al. The empirical mode decomposition and the Hilbert spectrum for nonlinear and nonstationary time series analysis. Proc. R. Soc. London, Series A, 1998(454), pp.903-995

DOI: 10.1098/rspa.1998.0193

[9] Z. Wu and N. E. Huang, A study of the characteristics of white noise using the empirical mode decomposition method, Proc. R. Soc. Lond. A (2004) 460, pp.1597-1611

DOI: 10.1098/rspa.2003.1221

[10] F. Cai, D.Y. Wang, H. Zhang, Q.M. M. Study on signal integration method based on EMD self-adaptive filter. Journal of ship mechanics, 11(4), 2007, pp.528-532 (In Chinese)