Positioning controlling device

A positioning controlling device, comprising:

• a position instruction data storage means for storing therein position instruction data for successively instructing the position of a movable member which is controlled by a control axis of a numerically controlled machine tool for machining a work into a non-circular shape, the position of said movable member being variable with respect to time,
• a first Fourier transformation processing means for Fourier transforming the position instruction data stored in said position instruction data storage means to obtain position instruction Fourier transformation data,
• a movement amount detecting means for operating said control axis in accordance with the position instruction data to successively detect an actual amount of movement of said movable member which varies with respect to time as movement amount data,
• a second Fourier transformation processing means for Fourier transforming the actual movement amount data detected by said position detecting means to obtain actual movement amount Fourier transformation data,
• a correcting means for obtaining corrected position instruction Fourier transformation data from the position instruction Fourier transformation data calculated by said first Fourier transformation processing means, the actual movement amount Fourier transformation data calculated by said second Fourier transformation processing means and ideal position Fourier transformation data calculated from an ideal position which should be assumed by said movable member and which varies with respect to time, and
• an inverse Fourier transformation processing means for inversely Fourier transforming the corrected position instruction Fourier transformation data calculated by said correcting means to obtain corrected position instruction data.