Numerical controller performing oscillation cutting correcting spindle tracking error

A numerical controller configured to perform oscillation cutting by superimposing an oscillation instruction on a position instruction, the oscillation instruction including specifying an oscillation frequency and an oscillation amplitude, the numerical controller comprising:

• a position instruction generating unit configured to generate the position instruction;
• an oscillation instruction generating unit configured to generate the oscillation instruction;
• a position speed control unit configured to add the position instruction and the oscillation instruction to generate a synthesized instruction;
• and
• a current control unit configured to control movement of a tool or rotation of a spindle,
• wherein the oscillation instruction generating unit includes:
• a tracking error calculating unit configured to obtain and calculate an actual angle and an ideal angle of the spindle, and
• a frequency recalculating unit configured to recalculate the oscillation frequency as a multiple of a ratio of the ideal angle divided by the actual angle,
• the oscillation instruction generating unit regenerates an oscillation instruction based on the recalculated oscillation frequency,
• the position speed control unit adds the position instruction and the regenerated oscillation instruction to regenerate a synthesized instruction, and
• the current control unit controls the movement of the tool or the rotation of the spindle according to the regenerated synthesized instruction.