Study On Evaluation Of Standard Ellipse Device Surface Based On Wavelet Analysis

This dissertation aims at studying de-noising methods based on roundness data, expanding the application area of wavelet analysis. Most of the work is described as follows.The fundamental theories of filtering are discussed, as well as analog filter, digital filter and their frequency characteristics, common types of filter and their application conditions. The definition of roundness and its four common evaluation methods and principles are introduced. The working principle of roundness instrument is given, as well as the problems that should be focused on in measuring roundness.The fundamental theories of wavelet analysis are discussed in detail. Continuous wavelet transform, discrete wavelet transform and dyadic wavelet transform are introduced. The fast algorithm of discrete dyadic wavelet transform is given. The mathematical properties of wavelet bases are studied.The principles of wavelet transform modulus maxima de-noising method are introduced in detail. Some de-noising methods based on wavelet shrinkage threshold are discussed, a combining de-noising algorithm is presented, and the simulation testing is done. Shrinkage threshold based on generalized cross validation (GCV) is discussed and adapt Bayes Shrink threshold is presented, its simulation work is done. The methods for de-noising of roundness data based on wavelet analysis are discussed.