Precision measurement of 5-DOF rotational error motion using two multi-probe error separation methods

Abstract This study proposes a new method for the precision measurement of the 5-DOF error motion of rotating machines. The developed seven-probe error separation system uses two measurement units, consisting of an upper four-probe unit and a lower three-probe unit, for the separation of error signals. From the seven probe output signals, the profile signals of the measured surface and the 5-DOF error motion signals, including random components, can be precisely separated. An analysis was carried out to examine the effects of the intersection term by the 5-DOF error motion signals, which is an additional measurement error cause. Furthermore, an effective calculation process capable of calculating a precise surface profile and error motion signal by compensating for the effect was proposed. Numerical validation tests and measurement experiments were performed. This showed it was possible to make accurate measurements by separating the 5-DOF error motions and surface profile signals and using a compensation calculation process. In addition, the effect of the stability error of the probe, which can be a significant factor in increasing measurement uncertainty, on the measurement results was observed and analyzed. Based on the geometric relationship of the measurement system, a process for estimating the expected effect of the stability error of the probe on the measurement result was presented. By applying this process, it is possible to determine the scale of probe stability error to secure the measurement reliability required when selecting a probe used in the system.