Fault detection using averaging filter with variable response time

Claim 1

A fault detection system for a vehicle comprising: a performance monitor coupled to said vehicle, said performance monitor producing a data stream quantifying a performance parameter of said vehicle, said data stream including random error fluctuations; a geometric filter filtering said data stream to produce a plurality of successive average values, said geometric filter characterized by a time constant to produce said average values, wherein said geometric filter is responsive to an initialization signal to obtain a temporary fast response of said geometric filter, wherein said time constant is initialized to a minimum value in response to said initialization signal and is incremented during successive average values to a maximum value; a comparator comparing said average values with a predetermined threshold and generating a fault signal when one of said average values exceeds said predetermined threshold, wherein said comparator utilizes the same predetermined threshold both prior to and following said initialization; and a diagnostic indicator annunciating a fault in response to said fault signal.

Claim 6

A method of fault detection for a vehicle comprising the steps of: monitoring a performance parameter of said vehicle to generate a data stream quantifying said performance parameter; initializing a time constant to a minimum value; filtering said data stream with a geometric filter to produce an average value in accordance with said time constant; comparing said average value with a predetermined threshold; generating a fault signal if said average value exceeds said predetermined threshold; incrementing said time constant by a predetermined step size and then repeating said filtering, comparing, and generating steps; repeating said incrementing, filtering, comparing, and generating steps until said time constant reaches a maximum value; and repeating said filtering, comparing, and generating steps using said maximum value for said time constant until said initializing step is repeated.

Claim 7

A method of fault detection for a vehicle comprising the steps of: monitoring a performance parameter of said vehicle to generate a data stream quantifying said performance parameter; initializing a time constant to a minimum value; filtering said data stream with a geometric filter to produce an average value in accordance with said time constant; comparing said average value with a predetermined threshold; generating a fault signal if said average value exceeds said predetermined threshold; incrementing said time constant by a predetermined step size and then repeating said filtering, comparing, and generating steps; repeating said incrementing, filtering, comparing, and generating steps until said time constant reaches a maximum value; and repeating said filtering, comparing, and generating steps using said maximum value for said time constant until said initializing step is repeated.