Method and apparatus for feature extraction from internal combustion engine ignition waveforms
First Claim
1. A method of extracting features from an engine ignition waveform for diagnosis in real time comprising the steps of:
- sampling the waveform at a first sampling rate to produce a first sequence of sample values;
choosing one sample value out of every N sample values from said first sequence, where N is an integer, to produce an input sequence of sampled data values, each sampled data value having a magnitude and a time of occurrence;
searching said input sequence for a firing peak with height to indicate a spark plug firing event by finding a plurality of adjacent sample values with magnitudes at least twice the magnitude of other sample values;
determining an actual firing peak height as the greatest magnitude of said adjacent sample values;
comparing the actual firing peak height to a predetermined minimum height threshold value and reporting an anomalous firing event when said actual firing peak height is less than the minimum height threshold value;
comparing the actual firing peak height to a predetermined maximum height threshold value and reporting an anomalous firing event when said actual firing peak height is greater than the maximum height threshold value;
comparing the actual firing peak height against a cylinder'"'"'s running average firing peak height and reporting an anomalous firing event when the actual firing peak height differs from said running average firing peak height by more than a predetermined amount;
said running average firing peak height formed by adding a cylinder'"'"'s current firing peak height to the sum of its previous firing peak height, said sum divided by predetermined number.
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Abstract
The invention is a method and apparatus for extracting and analyzing features in real time from primary or secondary ignition waveforms, including engine probes, sampling device, and a processor that extracts from the waveform features such as peak firing height, firing line duration, firing line slope, firing line noise, post firing line duration, primary oscillations, and dwell interval duration and compares them against fixed thresholds and running averages to detect anomalies. Anomalies are reported as they occur allowing diagnosis of transient events as well as steady conditions. Waveforms with or without anomalies may be stored and retrieved as needed.
44 Citations
16 Claims
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1. A method of extracting features from an engine ignition waveform for diagnosis in real time comprising the steps of:
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sampling the waveform at a first sampling rate to produce a first sequence of sample values; choosing one sample value out of every N sample values from said first sequence, where N is an integer, to produce an input sequence of sampled data values, each sampled data value having a magnitude and a time of occurrence; searching said input sequence for a firing peak with height to indicate a spark plug firing event by finding a plurality of adjacent sample values with magnitudes at least twice the magnitude of other sample values; determining an actual firing peak height as the greatest magnitude of said adjacent sample values; comparing the actual firing peak height to a predetermined minimum height threshold value and reporting an anomalous firing event when said actual firing peak height is less than the minimum height threshold value; comparing the actual firing peak height to a predetermined maximum height threshold value and reporting an anomalous firing event when said actual firing peak height is greater than the maximum height threshold value;
comparing the actual firing peak height against a cylinder'"'"'s running average firing peak height and reporting an anomalous firing event when the actual firing peak height differs from said running average firing peak height by more than a predetermined amount;
said running average firing peak height formed by adding a cylinder'"'"'s current firing peak height to the sum of its previous firing peak height, said sum divided by predetermined number. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for extracting features from an engine ignition waveform for diagnosis in real time comprising:
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engine probe means responsive to primary or secondary engine ignition signals for producing electrical signals representative of said engine ignition signals; sampling means, with output, coupled to the engine probe means for sampling said electrical signals at predetermined times and producing a first sequence of sample values, choosing one sample value out of every N sample values from said first sequence, where N is an integer, to produce an input sequence of sampled data values, each sampled data value having a magnitude and a time of occurrence; processor means responsive to the output of said sampling means for; searching said input sequence for a firing peak with height to indicate a spark plug firing event by finding a plurality of adjacent sample values with magnitudes at least twice the magnitude of other sample values; determining an actual firing peak height as the greatest magnitude of said adjacent sample values; comparing the actual firing peak height to a predetermined minimum height threshold value and reporting an anomalous firing event when said actual firing peak height is less than the minimum height threshold value; comparing the actual firing peak height to a predetermined maximum height threshold value and reporting an anomalous firing event when said actual firing peak height is greater than the maximum height threshold value comparing the actual firing peak height against a cylinder'"'"'s running average firing peak height and reporting an anomalous firing event when the actual firing peak height differs from said running average firing peak height by more than a predetermined amount;
said running average firing peak height formed by adding a cylinder'"'"'s current firing peak height to the sum of its previous firing peak height, said sum divided by predetermined number;communications means coupled to said processing means for reporting anomalous firing events. - View Dependent Claims (15, 16)
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Specification