Path display apparatus considering correction data

1. A path display apparatus that displays a path of a tip point of a tool of a machine tool, to which correction data including backlash correction and pitch correction is applied, that controls the position and posture of the tool by a plurality of drive axes, the path display apparatus comprising:

a position command acquiring unit that acquires a first position command, generated by a numerical control apparatus, for a plurality of motors that drive the plurality of drive axes, respectively;

a position feedback acquiring unit that acquires first position feedback of each of the plurality of motors, from a plurality of position detectors that detect the respective positions of the plurality of motors every predetermined control cycle;

a correction data acquiring unit that acquires correction data generated for each of the plurality of motors;

a position command calculating unit that subtracts the correction data from the first position command to calculate a second position command;

a position feedback calculating unit that subtracts the correction data from the first position feedback to calculate second position feedback;

a command path display unit that displays a command path of the tip point of the tool, based on the second position command calculated by the position command calculating unit; and

a feedback path display unit that displays a feedback path of the tip point of the tool, based on the second position feedback calculated by the position feedback calculating unit.

2. The path display apparatus as defined in claim 1 , further comprising a correction data calculating unit that calculates second correction data including control delay, using the correction data acquired by the correction data acquiring unit and a transfer function indicating responses of respective position loops of the plurality of motors,

wherein the position feedback calculating unit calculates the second position feedback by subtracting the second correction data from the first position feedback.

3. The path display apparatus as defined in claim 2 , wherein the correction data calculating unit uses a first-order lag filter corresponding to a position gain, as the transfer function.

4. The path display apparatus as defined in claim 1 , wherein the first position command is generated by adding the correction data to a position command read from an operation program of the machine tool.