The position of the point under measurement in accordance to the spindle is determined by using mobile centrode that determines geometric position of instantaneous centres of velocity in the moving body.
The graph of mobile centrode also depends only on the displacement of flat figure and does not depend on chosen centres [O.
Assessment of radial error of rotation by centrodes
Centrodes can be used for this purpose as they unambiguously determine a movement of flat figure.
The trajectory of the spindle is evaluated unambiguously according to the centrodes.
The centrodes can be calculated in the measuring plane according to the displacement of two eccentrically situated roundness standards in the same plane.