Method and apparatus for detecting hot rail car surfaces
In one embodiment of the present invention, an apparatus for detecting a hot rail car surface comprises: an infrared sensor for acquiring an infrared signal from a rail car surface of a rail car and transducing the infrared signal into an electrical signal; a rank filter for filtering the electrical signal to produce a filtered array; a first peak detector for detecting a maximum filtered value of the filtered array; and a first comparator for comparing the maximum filtered value to a detection threshold to produce a filtered alarm signal.
1. An apparatus for detecting a hot rail car surface comprising:
an infrared sensor for acquiring an infrared signal from a rail car surface of a rail car and transducing said infrared signal into an electrical signal;
a rank filter for filtering said electrical signal to produce a filtered array;
a first peak detector for detecting a maximum filtered value of said filtered array; and
a first comparator for comparing said maximum filtered value to a detection threshold to produce a filtered alarm signal.
2. The apparatus of claim 1 wherein said rank filter has a rank of about one-half.
3. The apparatus of claim 1 further comprising:
a wireless transceiver for acquiring rail car surface characteristics from a wireless tag mounted on said rail car; and
a filter parameter calculator for calculating a filter length and rank of said rank filter as a function of said rail car surface characteristics.
4. The apparatus of claim 1 further comprising:
an unfiltered signal buffer for buffering said electrical signal to produce an unfiltered array;
a second peak detector for detecting a maximum unfiltered value of said unfiltered array;
a second comparator for comparing said maximum unfiltered value to said detection threshold to produce an unfiltered alarm signal; and
an alarm comparator for comparing said unfiltered alarm signal to said filtered alarm signal to produce a censored false alarm signal.
5. The apparatus of claim 4 wherein:
said censored false alarm signal comprises a binary signal having a true value when said unfiltered alarm signal differs from said filtered alarm signal and a false value otherwise; and
said apparatus further comprises a counter for counting said false values to produce a censored false alarm count.
6. The apparatus of claim 5 further comprising a failure isolator for diagnosing a failure mode from said censored false alarm count.
7. An apparatus for detecting a hot rail car surface comprising:
an infrared sensor for acquiring an infrared signal from a rail car surface of a rail car and transducing said infrared signal into an electrical signal;
a rank filter for filtering said electrical signal to produce a filtered array;
a first peak detector for detecting a maximum filtered value of said filtered array;
a first comparator for comparing said maximum filtered value to a detection threshold to produce a filtered alarm signal;
a wireless transceiver for acquiring rail car surface characteristics from a wireless tag mounted on said rail car;
a filter parameter calculator for calculating a filter length and rank of said rank filter as a function of said rail car surface characteristics;
an unfiltered signal buffer for buffering said electrical signal to produce an unfiltered array;
a second peak detector for detecting a maximum unfiltered value of said unfiltered array;
a second comparator for comparing said maximum unfiltered value to said detection threshold to produce an unfiltered alarm signal; and
an alarm comparator for conspiring said unfiltered alarm signal to said filtered alarm signal to produce a censored false alarm signal.
8. The apparatus of claim 7 wherein:
said censored false alarm signal comprises a binary signal having a true value when said unfiltered alarm signal differs from said filtered alarm signal and a false value otherwise; and
said apparatus further comprises a counter for counting said false values to produce a censored false alarm count.
9. The apparatus of claim 8 further comprising a failure isolator for diagnosing a failure mode from said censored false alarm count.
10. A method for detecting hot rail car surfaces, the method comprising:
acquiring an infrared signal from a rail car surface of a rail car;
transducing said infrared signal into an electrical signal;
filtering said electrical signal using a rank filter to produce a filtered array;
detecting a maximum filtered value of said filtered array; and
comparing said maximum filtered value to a detection threshold to produce a filtered alarm signal.
11. The method of claim 10 wherein said rank filter has a rank of about one-half.
12. The method of claim 10 further comprising:
acquiring rail car surface characteristics from a wireless tag mounted on said rail car; and
calculating a filter length and rank of said rank filter as a function of said rail car surface characteristics.
13. The method of claim 10 further comprising:
buffering said electrical signal to produce an unfiltered array;
detecting a maximum unfiltered value of said unfiltered array;
comparing said maximum unfiltered value to said detection threshold to produce an unfiltered alarm signal; and
comparing said unfiltered alarm signal to said filtered alarm signal to produce a censored false alarm signal.
14. The method of claim 13 wherein:
said censored false alarm signal comprises a binary signal having a true value when said unfiltered alarm signal differs from said filtered alarm signal and a false value otherwise; and
said method further comprises counting said false values to produce a censored false alarm count.
15. The method of claim 14 further comprising diagnosing a failure mode from said censored false alarm count.
16. A method for detecting hot rail car surfaces, the method comprising:
acquiring an infrared signal from a rail car surface of a rail car;
transducing said infrared signal into an electrical signal;
filtering said electrical signal using a rank filter to produce a filtered array;
detecting a maximum filtered value of said filtered array;
comparing said maximum filtered value to a detection threshold to produce a filtered alarm signal;
acquiring rail car surface characteristics from a wireless tag mounted on said rail car;
calculating a filter length and rank of said rank filter as a function of said rail car surface characteristics;
buffering said electrical signal to produce an unfiltered array;
detecting a maximum unfiltered value of said unfiltered array;
comparing said maximum unfiltered value to said detection threshold to produce an unfiltered alarm signal; and
comparing said unfiltered alarm signal to said filtered alarm signal to produce a censored false alarm signal.
17. The method of claim 16 wherein:
said censored false alarm signal comprises a binary signal having a true value when said unfiltered alarm signal differs from said filtered alarm signal and a false value otherwise; and
said method further comprises counting said false values to produce a censored false alarm count.
18. The method of claim 17 further comprising diagnosing a failure mode from said censored false alarm count.