A METHOD OF CONTROLLING A COORDINATE POSITIONING MACHINE FOR MEASURMENT OF A WORKPIECE

A coordinate positioning machine is equipped with either an optical probe or a contact measuring probe. Movement of the head of the machine to enable the probe to scan an unknown surface is controlled by predicting the position of a subsequent point to which the head of the machine is to be driven upon the basis of three most recently measured points, P.sub.1, P.sub.2, P.sub.3. The prediction of the subsequent point P.sub.4 is performed by machine control in real time.