| 摘要 |
A method and an apparatus for determining the existence of an in-range failure of a speed sensor involves sensing the speed of a moving device at three consecutive instances in time, wherein the time intervals between these instances in time are preferably equally spaced, and wherein each time interval is relatively short in duration to thereby correlate in time to the waveform characteristics of most anticipated in-range speed sensor failures. The sensed speed at each of these three instances in time is utilized in an excursion formula, preferably implemented by programmable logic, that calculates the total sum of the change in speed between the three instances in time. The excursion formula is defined to be the difference between the sensed speed at the first most recent instance in time and the sensed speed at the second most recent instance in time, with this difference being added to the difference between the sensed speed at the first most recent instance in time and the sensed speed at the current instance in time. The absolute value of this sum is the resulting output of the excursion formula. The calculated total sum of the change in speed is then compared against a predetermined reference value and if the calculated sum exceeds the reference value, an in-range failure of the speed sensor is determined to exist.
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