Research On Evaluation Method Of Surface Topography Based On New GPS

Surface Topography is a very important content in novel GPS (Geometrical Product Specification and Verification) system. Surface Topography which is microstructure profile error with minor wave pitch of the surface in a workpiece has an immediate largely effect on technical characteristic and practical function of the component. With the development of manufacturing, the surface quality measurement technique of geometrical product was required. Some traditional methods used to measure the surface quality do not meet all the demands of modern precision of geometrical product. In this dissertation the surface topography characteristic signal is described and the key method to extract the surface topography characteristic signal is researched. Filtration operator is compiled to separate surface topography from surface roughness. It is calculated the evaluation value of profile parameter to solve the issue which causes by inconformity specification with certification. The main contents and creative points are as follows:The tradition methods of evaluation are researched for the surface topography parameters. The definition of relevant parameter of surface profile is stated. According to the surface profile, the algorithm of least square fitting is given. Based on the novel GPS system and filtering masterplan of relevant international standards, the equation and character of liner profile filters are introduced. The weight function and transition function of Gaussian filter are analyzed. Realization process of Gaussian filtering algorithmic is given to measure signal of surface for example. The influence of boundary effect and fantastic characteristic signal are indicated in filtering process.The method of wavelet transform is realized to evaluate the parameters of surface profile. According to the composition of surface topography, its mathematical model is established. Based on the wavelet analyze of relevant theories, B Spline wavelet is proposed to analysis the surface topography. According to the construction of wavelets, we use B Spline function to construct the B Spline wavelet basis. Based on the wavelet model of surface topography, It is realizes the method of B Spline wavelet to evaluate the parameters of surface profile by use the Mallat arithmetic. Meanwhile, how to ensure the decomposition number of wavelet and how to select the wavelet basis are discussed in this dissertation.The feasibility of B Spline wavelet is validated to estimate the parameters of surface profile. The paper uses the traditional methods, wavelet analysis and B Spline wavelet to analyze the paramteres of surface profile. An engineering example is introduced to test the proposed method. Based on the novel GPS system and relevant international standards, the prototype system to evaluate the surface profile parameters is exploited using MATLAB7.0. This system not only realizes parameters evaluation of roughness profile, but also displays the components of surface profile respectively.