空間フィルタを応用した回転速度変動センサ

抄録

Though the measurement of minute fluctuations in rotational speed is involved in various fields of engineering, eccentricity error unavoidable in practical situations poses limits on accuracy. This paper proposes a method for providing high accuracy while easing the setup procedure.
The principal configuration of the instrument is that the image of a radial stripe pattern attached to the rotating shaft of interest is projected by a lens onto the polar-coordinate-type spatial filter. Undesirable fluctuation caused by the eccentricity of the pattern is canceled by the differential operation afforded by a number of elements of the spatial filter.
The primary advantage of the proposed method is its high accuracy in the order of 0.02% of the average, while employing relatively crude components. Also featured is the sensor housing separated by about 20cm from the rotating pattern, thus providing safety at high speeds.
Two examples of tortional vibration are evaluated: cogging of a motor, which could not be directly evaluated so far; and a planetary gear mechanism rotating at speeds as high as 15, 000rpm, which could not be traditionally treated because of the mechanical limitation of bearings.