Method and device for measuring the center of rotation of a rotating

Abstract

Three non-contact type displacement sensors are positioned at the vertices of an equilateral triangle and disposed in opposition to an optical flat attached to the tip of a rotating shaft, while the optical flat is rotated at a slight tilt away from parallel. Undulation components synchronized with the rotation are detected from among signals indicating the relative displacement between the optical flat and displacement sensors during rotation, and the individual phase differences are found for two adjacent displacement sensors among the three synchronized components. As a result, three circles can be drawn through the positions of the centers of (two) adjacent displacement sensors, and the position of the center of rotation of the shaft coincides with the coordinates of the point of intersection of the three circles. Using a high-speed calculating device that finds the equations of two circles and their points of intersection from the output of the phase-difference detector, a display that displays the points of intersection of the circles, namely the coordinate position of the center of rotation, and hard-copy printers and the like, the position of the center of rotation can be detected quickly and automatically, displayed and provided as output.