Measurement of 5-DOF Spindle Error Motion Using Fourier Model Based Multi-Probe Error Separation

Abstract

This paper proposes a precise measuring method to evaluate radial, axial and tilt error motions of a rotating device such as a direct drive motor. The measurement system uses eight capacitive probes arranged to detect runout signals of a low precision cylindrical artifact which is located on the center of the rotating device. In order to improve the accuracy of the estimated multi-degree of freedom error motion components, form error signal of the artifact mixed in the runout signals is pre-compensated using Fourier model based multi-probe error separation method. An experimental system is designed and constructed to avoid the harmonic distortion, the major problem of the error separation method, by applying the probe arrangement guidelines proposed in our previous study. 5-DOF spindle error motion measurement is implemented. At first, the cylindrical form error of the artifact is separated. Then, the synchronous and asynchronous components of the radial, axial, tilt error motions are calculated using the runout signals after form error compensation based on the geometric relationships of the experimental setup. As a result of the test, it was confirmed that the compensation of the error motion component and the form error is properly performed. Therefore, it is possible to measure and evaluate high-accuracy error motions using low-cost and low-precision artifact. Furthermore it can be compensated the 5-DOF error motion in on-machine system for high-precision rotational machine.