Graph fitting test method for the interpolation error of moire fringe

In order to realize the fast test for the interpolation error, the graph fitting test method for the interpolation error of Moire fringe is put forward in this paper. Firstly, the triangular wave Moire fringe photoelectric signal of the encoder whose phase difference is 90deg are sampled to get the Lissajous graph of the two signals. Secondly, the single wave represented by the founded subsection function is used to fit the practical Moire fringe Lissajous graph. Then, the fitting result is tested to verify whether it satisfies the accuracy requirement. Lastly, the founded subsection function instead of the practical wave function is used to calculate the interpolation error. Using the graph fitting method to sample the Moire fringe single of 15-bits photoelectric encoder to get the interpolation error curve, the tested maximum interpolation error is 70rdquo and the minimum error is - 69rdquo. Comparing with the interpolation error which is received from traditional test method, the change trend of the interpolation error curve is similar, and peak-peak value is almost equality. The results of experiment indicate that: the equipment is convenient and the examination method is efficient and feasible. The measure speed is fast and the manifestation result is intuitionistic. The system can be used in the working field. The method can avoid the speed influence and realize the dynamic interpolation error measure, which is significant for the research of encoder´s dynamic accuracy characteristics.