Digital Subdivision Technology Of Grating Moire Signal Based On Amplitude Sampling

Grating measurement technique is a high precision measurement technique based on the Moire Fringe.It has been widely used in precision instruments,coordinate measuring machines,high precision machining and so on.As an important technical support for the application of grating,the subdivision of Moire signal has been an important research content of grating measurement.At present,the main methods include four subdivision,resistance chain subdivision,phase locked frequency multiplication subdivision,carrier modulation subdivision,and amplitude segmentation.There are extensive and deep research on the various methods,but the research level and the degree of industrialization,the foreign research status should be far ahead of the domestic level,the vast majority of the products market is also occupied by Germany,the United States,Japan and other countries.Through the analysis of the research status of the Grating Moire signal subdivision technology,this paper presents the research of the digital subdivision technology of Moire Signal based on amplitude sampling,the main research contents as follow.(1)Based on detailed description of the principle of the digital amplitude method of Moire signal,starting from the function of basic method,this paper illustrates the construction of amplitude subdivision linear function,the method of dividing the interval,the thickness division and the fine division,the principle and the method of operation,and the principle of the CORDIC.The feasibility and convenience is proved in the scheme.(2)On the basis of introducing FPGA design framework and development process,the logic function development of the FPGA chip is based on the requirement of the subdivision of the grating Moire signal.After setting up the circuit of grating signal subdivision,the correlation between the parameters of circuit system and the effect of subdivision result will be analyzed and researching.Finally the optimal parameters are selected to achieve a 1024 subdivision of the Moire signal with a cutoff frequency of not less than 40 KHz.(3)The Quantization Error CORDIC(OQE)is studied,and the OQE algorithm is analyzed.The simulation and circuit experiments are carried out according to the basic principle of CORDIC algorithm,and the key parameters and error components of OQE are analyzed.(4)The relationship between the equal amplitude,the sine,the DC level drift and the subdivision accuracy of the Grating Moire signal is analyzed.On the basis of establishing the relationship model of the orthogonal and subdivision multiple,the compensation scheme is presented,which is based on FPGA to implement.And the validity of the error compensation scheme is proved by experiments.In order to further verify the effect of the orthogonal compensation,the orthogonal compensation function is introduced into the subdivision system,and the cut-off frequency is raised to 93% above the maximum value for different segments.In this paper,the research results are provided for the development of grating sensor displacement measurement technology in the field of precision measurement.