Axis Y1, Y2 -- the left and right sides of the slide block are respectively equipped with Italian givi high-precision grating ruler (Y1, Y2), which is used to determine the exact position of the slide block and the workbench. The grating ruler is connected with the workbench through a C-shaped frame, which can eliminate the influence of the deformation of the throat of the rack on the position of the slide block to the greatest extent. The measurement accuracy will not be affected by the elastic deformation of the rack, and the accurate position data will be fed back to the CNC system In general, it can calculate the output servo valve control signals (S1, S2). Thus, the positioning accuracy of the slider is ± 0.02mm, and the repeated positioning accuracy is ± 0.01mm.