Abstract
Visualization and characterization of changes in equipment conditions over time based on precise Lissajous curves are discussed. Enhancing the performance of condition monitoring and diagnostic technology based on vibration measurement requires the use of vibration phase information. The commercialized 3-axis high-precision digital vibration sensor, M-A342, combined with the proposed algorithm that suppresses the effects of external interference, make it possible to draw accurate and high SNR Lissajous curves. The trajectories of precise Lissajous curves corresponding to equipment vibrations are observed to be distributed in certain planes in many cases. We propose that the vibration surface angle (θv, φv), which is a vector perpendicular to the vibration surface expressed as an angular component in polar coordinates, can be used as an indicator. The standard deviation of the variation of θv, φv and the fluctuation of θv, φv well reflect changes in the equipment operating conditions over time, indicating the possibility of detecting changes in the operating conditions earlier than conventional methods such as using RMS values. Since these indicators are dimensionless quantities and can be calculated independently of the type and size of the equipment, direct and absolute value comparisons may be performed even if the equipment and measurement location are different.
