Parameters Identification in Offshore Platform Using ARMA Model and Technology of Extracting Free Vibration Signal
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摘要: 用随机减量方法提取海洋平台结构在随机环境荷载非白噪声输入下的自由振动信号和用ARMA(Auto Regressive Moving Average)模型对自由振动数据建模。为了消除平台输出信号中有色噪声的影响,在随机减量系统中加人了一个虚拟系统,并采用导通条件和前导点技术使自由振动提取过程仍在有色输人的状态下进行。同时为了消除参数识别的多值性,提出了采用MA系数修正技术识别海洋平台结构的频率和阻尼动力参数的方法,最后用该套技术对海洋平台结构试验模型进行了参数识别,结果表明该方法具有较好的效果和在线识别使用价值。Abstract: A procedure for identifying the dynamic parameter of offshore platform is presented. The present procedure consists of two key features.Fist uses random decrement (RD) technology to extract free vlbration signal in strong noise environment in which it may not white noise. Second technology which called autoregressive moving average (ARMA) is used to model the data treated by the random decrement method.In order to get rid of the color noise in the output signal response from the offshore platform an imaginary system is added in RD system and make the course of extracting performed under the state of color input by choosing the breakover condition and lead time. For elintinating multi-values of parameters identified, an updating moving average method is used. The dynamic parameters of structure under arbitrary input are identigied.Example of the method as applied to a scale-model offshore platform is used to evaluate the technology of efffciency and the value of on-line.
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