Research On Data Acquisition And Gaussian Filtering Method In The Surface Roughness Measurement System

The surface roughness measurement is an important content in geometricmeasurement field, which is directly related to the evaluation of the workpiecequality. In the measurement of surface roughness, according to different forms ofsensors, there are two forms, one is the contact measurement and the other one isnon-contact measurement. But no matter which kind of forms, data acquisitionsystem is needed to obtain the datas of the surface profile. After obtain the datasof the surface profile, according to international standards ISO11562, that isneeded to use Gaussian filter to deal the datas in order to build the surfacecontour line and separate the surface roughness profile. Gaussian filter is thesmallest frequency bandwidth product filter, its structure of Gaussianfiltercomplex to implement is very difficult. The designers are mostly done bysoftware Gaussian filter. This kind of design method make the signal processingspeed is reduced. When the amount of information being processed is too large,the efficiency of data processing will be reduce. For many areas that should behard to accept.This article designs a set of surface profile data collection system based onFPGA, Including the minimum FPGA system, USB interface circuit, the ADconversion circuit and the design of the power circuit, etc. Besides the softwarepart using Verilog language for programming, Completed the design of the ADinterface module, USB interface module design, the FPGA design of mastercontrol program, etc. At last, through using the simulation software complete thewhole system debugging.Based on the FPGA hardware platform,this designrealizes the surface profile of Gauss filter signal processing. Through the study of Gauss filter approximation design methods,determined the approximation methodfor cascaded moving average filter,and the design of FIR type Gaussapproximation filters. In the FPGA chip is realized by hardware and algorithmsimulation of the filter algorithm, verify the design process.Data acquisition system adopts the anti aliasing technology which uses theanalog filter and digital filter and it effectively eliminates the noise of the surfacesignal. Through the collection of actual surface profile, the algorithm of Gaussianfilter based on FPGA hardware finished the extraction of surface contour line,And it effectively isolates the surface roughness profile, lying the groundwork forthe surface roughness of the follow-up evaluation. The system algorithm isreliable and it has high efficiency calculations in the same time Improving thespeed of data processing, so it has a certain practical popularize value.