| 摘要 |
PROBLEM TO BE SOLVED: To monitor an abnormality of a detector and a signal-processing circuit simultaneously with measuring velocity by obtaining an acceleration signal from the velocity signal of a velocity-measuring apparatus and comparing the signal with the maximum acceleration of a preliminarily set mobile body. SOLUTION: A rotary body 1 is rotated, and an a.c. signal of a frequency proportional to the rotational speed, or a pulse signal is outputted from a rotational speed detector 2, which is shaped to a more perfect pulse waveform by a comparator 41. A rotational speed operation circuit 42 counts pulses per unit time, obtains a rotational speed of the rotary body 1 and outputs as a speed signal 60. A rotation acceleration operation circuit 51 obtains the absolute value of an acceleration which is a change of the speed signal 60 per unit time. When any of the detector 2, a signal line of the detector, the comparator 41 and the rotational speed operation circuit 42 (that is, a rotational speed- measuring apparatus 9) fails in outputting the speed signal 60, the absolute value of the acceleration exceeds a preliminarily set maximum value. Therefore, an acceleration abnormality judgment circuit 52 can judge an abnormality of the rotational speed-measuring apparatus 9.
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