Patent ID: 9046362
Filing Date: 2015-06-02
Classification: G01C

Abstract:
1. A method for a measuring instrument, the measuring instrument comprising at least one rolling-element bearing, comprising a plurality of rolling elements and a first and a second bearing lane, and an instrument body controllably rotatable about at least one rotational axis by at least one rolling-element bearing, for determining angular deviation of the at least one rotational axis from a corresponding true rotational axis due to bearing imperfections, the method comprising: detecting the rotary position of the at least one rolling-element bearing; determining angular deviation of the at least one rotational axis from a corresponding true rotational axis in a plurality of rotational positions of the instrument body, wherein the instrument body is rotated a plurality of successive full or partial revolutions about the at least one rotational axis such that a plurality of sets of angular deviation values, each set of angular deviation values corresponding to a respective revolution, are generated; and on basis of the rotary position of the at least one rolling-element bearing and comparison between at least two sets of angular deviation values of the plurality of sets of angular deviation values, determining angular deviation of the at least one rotational axis from a corresponding true rotational axis related to any surface irregularities in at least one bearing lane of the at least one rolling-element bearing and angular deviation of the at least one rotational axis from a corresponding true axis related to any difference in size of rolling elements of the at least one rolling-element bearing relatively to each other.