Method of and apparatus for copy controlling coordinate measuring probe with rotary table

A method of copy controlling a coordinate measuring probe with a rotary table, for copy measuring the coordinates of an object to be measured using the coordinate measuring probe by installing the rotary table on a platen of a coordinate measuring machine and placing said object on said rotary table to rotate the object by the rotary table, the method comprising the steps of;

• determining a probe speed vector V of the probe when the rotary table is at a rotational angle .theta.;
• calculating the angular velocity .omega. of the rotary table by the probe speed vector V relative to a measuring reference line of the object and correcting said angular velocity .omega. to adjust the lead or retardation due to control error of said rotational angle .theta. from target value so as to keep unchanged a direction of said probe with regard to said measuring reference line of the object;
• calculating a follow-up speed vector V.sub.R that compensates the movement by the corrected angular velocity .omega.;
• and
• issuing as a speed command of the probe the vector sum V.sub.T (=V+V.sub.R) of said follow-up speed vector V.sub.R and said probe speed vector V and issuing said corrected angular velocity .omega. as a speed command of the rotary table,
• whereby one axis copy control owing to the rotary table is incorporated in addition to three-axis copy control of the probe in the case where the rotary table is not employed, to achieve copy operation by simultaneous four-axes control keeping unchanged said direction of the probe with regard to said measuring reference line of the object.