Servo control apparatus that performs learning control by changing reference axis

A servo control apparatus for a machine that performs machining by driving and controlling a servomotor on the basis of a position command and by causing a plurality of synchronizing axes to operate cooperatively in synchronized relationship with a plurality of reference axes, the servo control apparatus comprising:

• a processor to perform the following steps:
• calculating a position error between the position command and a detected position of the servomotor;
• acquiring positions of a plurality of reference axes;
• selecting one reference axis on the basis of a machining condition of a driven body from among the plurality of reference axes whose positions have been acquired, a machine condition is acquired by using a workpiece changing signal;
• and
• a plurality of learning control processors for performing learning control using an angle synchronization method, on the basis of the position error and the position of the selected reference axis,
• wherein the plurality of learning control processors performs the following steps:
• sampling the position error at a predetermined sampling frequency;
• converting the position error from time reference to position reference;
• filtering the converted position error;
• storing the filtered position error in a delay memory;
• converting the position error stored in the delay memory from position reference to time reference;
• and
• outputting the position error as correction value,
• wherein the plurality of learning control processors is changed in synchronized fashion when the reference axis is changed by selecting a different one of the plurality of reference axes from the reference axis previously selected, and
• wherein the plurality of learning control processors correspond to the plurality of reference axes.