| 摘要 |
PROBLEM TO BE SOLVED: To detect abnormality in a high-accuracy signal outputter and in a low-accuracy signal outputter. SOLUTION: The rotational angular velocity of a pinion 3 and that of a main wheel 4 are calculated based on respective output signals from the high-accuracy and the low-accuracy signal outputters 5 and 6. When the calculated rotational angular velocity of the pinion 3 stands at abnormal values consecutively n-times (n is an integer not smaller than 2, for example), it is determined that an abnormality has occurred in the signal outputter 5. When the calculated rotational angular velocity of the main wheel 4 stands at abnormal values consecutively n-times, it is determined that an abnormality has occurred in the signal outputter 6. A difference is found between the calculated angular velocity of the pinion 3 and a value obtained by multiplying the calculated angular velocity of the main wheel 4 by the reciprocal number of the reduction ratio of the main wheel 4 to the pinion 3. When the difference exceeds a predetermined permissible difference value, it is determined that an abnormality occurs in at least one of the signal outputters 5 and 6. COPYRIGHT: (C)2004,JPO&NCIPI
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