基于HHT变换的超光滑加工表面谱特征分析

Hilbert-Huang变换(HHT, Hilbert-Huang Transform)是最新发展起来的处理非线性非平稳信号的时频分析方法,其基本的实现分为两步:多分辨经验模态分解和瞬时频率的求解,获得信号的时频谱.该方法的关键是多分辨经验模态分解(EMD, Empirical Mode Decomposition),任何信号都可以分解为有限数目并且具有一定物理意义的固有模态函数(IMF, Intrinsic Mode Function).用于表面分析,HHT可以将粗糙度曲线分解成不同频率范围的分量,每一个分量都有其独有的物理意义,区分各影响因素,得到Hilbert谱,进而可以分析加工过程中各影响因素的作用.针对超光滑表面的粗糙度谱特征进行了HHT变换分析,并得出了相应结论,对加工有一定的指导意义. 

Application of HHT analysis in surface roughness

HHT(Hilbert-Huang transform) is a new two-step time-frequency analysis method to analyze the nonlinear and non-stationary signal.The key step of this method is EMD(empirical mode decomposition) method with which any complicated data set can be decompose into a finite and often small number of IMF(intrinsic mode functions).The HHT can decomposed curve of the surface roughness into component with different frequency spectrum.Each component has its own physical meaning.So it can distribute all sorts of factor which had an influence on finished surface.As a consequence,the allsided Hilbert spectrum could be got.Based on this spectrum,it can be know how contributing factor function in workpiece process.HHT is used in the analysis of roughness,and the conclusion is helpful to machining.