关键词: 包络线, 标准互相关函数, 端点效应, 经验模态分解, 模态混叠, 单层多道, 焊道间距, 増材制造

Abstract: In the empirical mode decomposition method (EMD), as a result of the uncertainty of the signal at both ends of the border, the end effect exists in the course of getting envelop of data. The emergence of the effect makes the results of EMD have a serious distortion. On the basis of the existing algorithm, an improved method for EMD based on standardized cross-correlation function is proposed. The standardized cross-correlation function is used for the similarity criterion of the internal signal to find the endpoint waveform which is the smallest amplitude difference waveforms for data extension, instead of this segment waveform to produce the end effect of the envelope. The method not only realizes the smooth transition between extending envelope and original envelope but also reduces the error of envelope near the ends of data. Simulation and experiment prove that the algorithm can effectively solve the end effect, and can restrain mode mixing. The algorithm is simple and easy to implement compared with several other common algorithm.

Key words: Empirical mode decomposition, End effect, Envelope, Mode mixing, Standardized cross-correlation function, Distance between bead, Single-layer multi-bead, Shape metal deposition