| 摘要 |
PROBLEM TO BE SOLVED: To accurately find a rotation speed of a rotary member for support-fixing an encoder just after start-up, irrespective of whirling motion of the encoder based on a shift between the rotation center and the geometric center. SOLUTION: A sensor for detecting the rotation speed outputs a detection signal expressing a speed superposed with an actual rotation speed d<SB>d</SB>and a fluctuation component d<SB>n</SB>based on whirling. A canceling signal y for canceling the fluctuation component d<SB>n</SB>is calculated by an adaption filter 17 using a signal self-generated from the signal from the sensor as a reference signal x, and the canceling signal is subtracted from the detection signal d. Since a signal e expressing substantially the rotation speed d<SB>d</SB>is obtained as a result therein, the rotation speed of the rotary member is calculated based on the signal e. A time required until a filter coefficient of the adaption filter 17 is converged is shortened by imparting an initial value to the filter coefficient of the adaption filter 17 so as to solve the problem hereinbefore. COPYRIGHT: (C)2006,JPO&NCIPI
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