Trajectory measuring device, numerical control device, and trajectory measuring method

A numerical control device comprising:

• a servo control unit that performs, on a machine that moves a moving target by using three or more movable axes, feedback control by using command signals for the movable axes;
• a trajectory measuring device that measures a moving trajectory of the moving target, the trajectory measuring device comprising:
• a display-target-axis designating unit that designates two movable axes, as display targets, out of measurement target movable axes that are the three or more movable axes;
• and
• a trajectory calculating unit that:
• calculates the moving trajectory, on the basis of
• command conditions for the moving target including a radius of a circular command, an inter-axis phase difference among the movable axes, and feed velocity used in measuring the moving trajectory,
• command signals for the measurement target movable axes common to the measurement target movable axes generated as a sine wave signal that has an amplitude equal to the radius of the circular command and that has a frequency equal to a value obtained by dividing the feed velocity by the radius, and
• feedback signals indicating positions of the measurement target movable axes when the movable axes are being controlled by using feedback such that the positions of the measurement target movable axes follow the command signals,
• extracts, during the calculation, the command signals and the feedback signals for the two movable axes,
• adjusts timing of one movable axis of the two movable axes such that the inter-axis phase difference of the command signals for the two movable axes is 90°,
• calculates an adjustment time of the timing, and adjusts timing of the feedback signal of the one movable axis by using a time that is the same as the adjustment time so as thereby to calculate the moving trajectory, and
• a display control unit that causes an external display device to display the moving trajectory calculated by the trajectory calculating unit on a plane defined by the two movable axes designated by the display-target-axis designating unit,
• wherein movement of the moving target is controlled based on the displayed moving trajectory.

A trajectory measurement method for measuring a moving trajectory of a moving target in a machine that includes three or more movable axes for the moving target, the trajectory measurement method comprising:

• designating two movable axes as display targets out of measurement target movable axes that are the three or more movable axes;
• calculating the moving trajectory, on the basis of command conditions for the moving target including a radius of a circular command, an inter-axis phase difference among the movable axes, and feed velocity used in measuring the moving trajectory,
• command signals for the measurement target movable axes common to the measurement target movable axes generated as a sine wave signal that has an amplitude equal to the radius of the circular command and that has a frequency equal to a value obtained by dividing the feed velocity by the radius, and
• feedback signals indicating positions of the measurement target movable axes when the movable axes are controlled using feedback such that the positions of the measurement target movable axes follow the command signals,
• extracting, in the calculating, the command signals and the feedback signals for the two movable axes,
• adjusting timing of one movable axis of the two movable axes such that the inter-axis phase difference of the command signals for the two movable axes is 90°,
• calculating an adjustment time of the timing,
• adjusting timing of the feedback signal of the one movable axis by using a time that is the same as the adjustment time so as thereby to calculate the moving trajectory;
• displaying the calculated moving trajectory on a plane defined by the two movable axes designated by the display-target-axis designating step;
• and
• controlling movement of the moving target based on the displayed moving trajectory.