Curve interpolating method

A method of generating a smooth curve from a commanded sequence of points by a numerical controller for a multi-axis machine tool having three linear axes and two or more rotary axes to perform interpolation along the generated curve, comprising:

• (1) the step of calculating interpolation points between points of a commanded sequence of points and setting the calculated interpolation points as geometrical command points;
• (2) the step of noticing respective points of the geometrical command points one by one so as to select a noticed point and geometrical command points located before and behind the noticed point and the number of which has been decided in advance;
• (3) the step of resolving each of the geometrical command points into component of three linear axes and component of two or more rotary axes;
• (4) the step of generating an approximated curve for linear axes with regard to the component of three linear axes;
• (5) the step of moving the component of three linear axes toward the approximated curve for linear axes so as to obtain corrected command point for linear axes;
• (6) the step of generating an approximated curve for rotary axes with regard to the component of two or more rotary axes;
• (7) the step of moving the component of two or more rotary axes toward the approximated curve for rotary axes so as to obtain corrected command point for rotary axes;
• (8) the step of synthesizing the component of three linear axes of the corrected command point for linear axes which has been moved and the component of two or more rotary axes of the corrected command points for rotary axes which has been moved so as to obtain a synthesized corrected command point;
• (9) the step of repeatedly executing the above steps (2) to (8) with regard to the respective geometrical command points;
• (10) the step of generating a curve passing through a point sequence of the synthesized corrected command points;
• and
• (11) the step of interpolating the generated curve.