基于FFT-FS频谱细化技术的船模耐波性试验测量信号分析方法研究
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摘要
针对FFT频率分辨率受限制且精度不高的缺点以及船模对波浪的运动响应频率是低频且窄带的特点,采用FFT-FS方法对测量的运动响应信号在其对应的窄带频段内进行频谱细化获得更细致准确的信号频域特征;通过对该算法的运算量及分析精度的研究表明该算法是一种运算效率高、分析精度高且受信号本身信噪比影响小的频域分析方法;通过对船模运动响应的仿真信号和实测信号的分析表明该算法确实能有效地用于船模耐波性试验测量数据的定量分析。
The frequency components and spectrum characteristics of ship models motion signals measured in seakeeping test,whose response frequencies are low and in a narrow bandwidth,can not be effectively analyzed by FFT owing to its low frequency resolution.Thus,a method based on FFT-FS was put forward to improve the frequency resolution.The calculation efficiency and analysis precision of FFT-FS were dis-cussed and are presented to be high.The results also show the analysis precision of FFT-FS is less influ-enced by the snr(signal-noise ratio) of the signals.Simulation and test signals of ship model motion re-sponse were analyzed by FFT-FS,and the results show that it is an effectively analytical method in frequency domain and can be applied to analyze measured signals of model seakeeping test.
The frequency components and spectrum characteristics of ship models motion signals measured in seakeeping test,whose response frequencies are low and in a narrow bandwidth,can not be effectively analyzed by FFT owing to its low frequency resolution.Thus,a method based on FFT-FS was put forward to improve the frequency resolution.The calculation efficiency and analysis precision of FFT-FS were dis-cussed and are presented to be high.The results also show the analysis precision of FFT-FS is less influ-enced by the snr(signal-noise ratio) of the signals.Simulation and test signals of ship model motion re-sponse were analyzed by FFT-FS,and the results show that it is an effectively analytical method in frequency domain and can be applied to analyze measured signals of model seakeeping test.
引文
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[2]赵霞,熊小伏,郭珂.用细化频谱技术分析断路器操动机构振动信号[J].电力系统自动化,2003,12(27):37-41.Zhao X,Xiong X F,Guo K.Application of zoom spectrum analysis to circuit breaker operating mechanism vibration[J].Electric Power Systems,2003,12(27):37-41.
[3]程佩青.数字信号处理教程[M].北京:清华大学出版社,2001:144-146.Cheng P Q.A Course in digital signal processing[M].Beijing:Tsinghua University Press,2001:144-146.
[4]王兰炜,赵家骝,王子影.频率细化技术在超低频/极低频电磁信号检测中的应用[J].地震学报,2007,26(1):59-66.Wang L W,Zhao J L,Wang Z Y.Application of zoom FFT technique to detecting EM signal of SLF/ELF[J].ACTA SEISMOLOGICA SINICA,2007,26(1):59-66.
[5]Cheng Junsheng,Yu Dejie,Yang Yu.A fault diagnosis approach for roller bearings based on EMD method and AR model[J].Mechanical Systems and Signal Processing,2006,20:350-362.
[6]何宏斌,席泽敏,刘峰等.基于FPGA的高斯噪声实时产生方法[J].舰船电子工程,2008,6(28):124-125.He H B,Xi Z M,Liu F.Real time Gauss noise generate method based on FPGA[J].Ship Electronic Engineering,2008,6(28):124-125.
[7]Mircea Grigoriu.Control of time delay linear systems with Gaussian white noise[J].Probabilistic Engineering Mechanics,1997,12(2):89-96.
[8]南利平.通信原理简明教程[M].北京:清华大学出版社,2000:43-44.Nan L P.A Concise course of communication principle[M].Beijing:Tsinghua University press,2000:43-44.
[9]Dong W C,Liu Z H.Experimental study on the hull form of high-speed air cavity craft[J].The Ninth International Conference on Fast Sea Transportation,2007:264-269.
[10]许勇,欧勇鹏,董文才.基于低通滤波和经验模态分解的舰船耐波性试验信号分析方法研究[J].船舶力学,2009,26(1):59-66.Xu Y,Ou Y P,Dong W C.Study on the measured signal analysis method based on low-pass filtering and EMD for ship seakeeping test[J].Journal of Ship Mechanics,2009,5(13):712-717.
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