一种振测数据最佳分析长度的确定方法

Method for Determining Optimal Analysis Length of Vibration Data

数据分析长度的选取是提取结构振动特征信息的关键,人为选取信号分析的数据长度会导致其计算结果存在一定误差,为减少主观因素影响,提出一种基于改进多尺度排列熵(improved multi⁃scale permutation entropy,简称IMPE)的振测数据分析长度的方法。对于获得的振动信号,将一维的时间序列数据多尺度化后进行粗粒化处理,确定其相空间重构参数。选取不同长度的振测数据,分别计算多尺度排列熵(multi⁃scale permutation entropy,简称MPE)熵值,发现熵值对数据长度的变化敏感,随着数据长度的增加而变化,最后趋于稳定值。定义该稳定值为标准熵值,满足标准熵值97%精度的熵值作为有效熵值,选出满足精度要求的熵值,将其所对应的最短数据长度定义为振测数据的最佳分析长度。将该方法应用于仿真信号和具体泄流工程振动信号的最佳数据长度选取中,可为结构监测选取准确的数据分析长度,有较好的普适性。

The selection of data analysis length is the key to extracting structural vibration characteristic informa⁃tion,and the artificial selection of the data length for signal analysis will cause certain errors in the calculation re⁃sults.To reduce the influence of subjective factors,an improved multi-scale permutation entropy(IMPE)meth⁃od is proposed to analyze the length of vibration data.IMPE method has a strong advantage in dealing with non⁃linear and non-stationary signals,so the vibration measurement data of the measured structure can be obtained by placing sensors.For the obtained vibration signal,the one-dimensional time series data is multi-scaled and then coarse-grained to determine its phase space reconstruction parameters.The vibration data with different lengths is selected and the multi-scale permutation entropy(MPE)entropy value is calculated respectively.It is found that the entropy value is sensitive to the change of the data length,changes with the increase of the data length,and finally it is going to stabilize.Here,the stable value is defined as a standard entropy value,and the entropy value satisfying standard entropy value of 97%is used as the effective entropy value.The entropy value that meets the accuracy requirements is selected,and its corresponding shortest data length is defined as the opti⁃mal data analytical length of the vibration data.This method is applied to the selection of the optimal data length of the simulation signal and the vibration signal of discharge engineering,and the accurate data analysis length can be selected for structure monitoring,and it has good universality.