Measurement of axial and radial error motions on a rotating shaft by a three-channel laser Doppler vibrometer

This paper introduces a novel 3D method using a multi-channel Laser Doppler vibrometer (LDV) to measure axial and radial error motions in high-speed rotating motor shafts. The approach utilizes three orthogonal LDVs to accurately capture 3D displacements from the shaft's surface. This enables the measurement of error motions along both the axial (sensitive to motion parallel to the shaft) and radial (sensitive to motion perpendicular to the shaft) directions. The collected rotational motion data undergoes post-processing to obtain the synchronous and asynchronous components of the axial and radial error motions. Experimental results demonstrate that the shaft's rotational speed significantly influences error motions in both the axial and radial directions, as evidenced by measurements at different speeds. Moreover, analyzing the data facilitates detecting potential damage in the rotating shaft. Finally, an analysis quantifies the combined overall uncertainty in error measurements using this new method.