METHOD FOR FINDING FAULT-TO-FAILURE SIGNATURES USING ORDERED HEALTH STATES
First Claim
1. A method for finding a fault-to-failure (FTF) signature for a unit under test (UUT), comprising:
- generating a data matrix by repeating a test sequence with the UUT, said UUT having a degradation control parameter set to a baseline value and then to different degradation levels to generate time samples of one or more data parameters to establish reference values of a healthy UUT and degraded values for a plurality of ordered health states;
for each data parameter, determining with a processor a time-averaged health state metric based on differences between the degraded and references values for each said ordered health state; and
determining with a processor a time window for a data parameter wherein gaps between the time-averaged health state metrics for the plurality of ordered health states are consistent with ordered health states.
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Abstract
A method is proposed for finding Fault-to-Failure signatures using ordered health states. A data matrix including reference values for a healthy device and degraded values for different degradation levels is processed to determine which data parameters, and more particularly which data parameter time windows, vary from the reference values both with an “order” and a “separation” consistent with ordered health states. The time sample at which a minimum gap between ordered health states is a maximum may determine the window end point. The window start point may be determined by walking back from the end point to the time sample at which the minimum gap crosses a threshold. In this manner, the time window starts when an acceptable order among the health states is first attained and ends when the separation is the strongest.
7 Citations
20 Claims
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1. A method for finding a fault-to-failure (FTF) signature for a unit under test (UUT), comprising:
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generating a data matrix by repeating a test sequence with the UUT, said UUT having a degradation control parameter set to a baseline value and then to different degradation levels to generate time samples of one or more data parameters to establish reference values of a healthy UUT and degraded values for a plurality of ordered health states; for each data parameter, determining with a processor a time-averaged health state metric based on differences between the degraded and references values for each said ordered health state; and determining with a processor a time window for a data parameter wherein gaps between the time-averaged health state metrics for the plurality of ordered health states are consistent with ordered health states. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for finding a fault-to-failure (FTF) signature for a unit under test (UUT), comprising:
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performing a test sequence with the UUT to generate time samples of one or more data parameters to establish reference values of a healthy UUT; for each of a plurality of ordered health states, setting a control parameter of the UUT to a different degradation level and repeating the test sequence with the UUT to generate time samples of the one or more data parameters to establish degraded values; for each said data parameter, computing with a processor, a time-average health state metric based on differences between the degraded and references values as a function of the time sample over the test sequence for each of the ordered health states; and gaps between the health state metrics for the ordered health states at the time samples; a minimum gap from the gaps between the health state metrics; and selecting with the processor for a data parameter the time sample at which the minimum gap is a maximum to determine an end point of a time window for the FTF signature; and selecting with the processor the first time sample preceding the end point at which the minimum gap crosses a threshold in a positive going direction to determine a start point of the time window for the FTF signature, wherein the order of the health state metrics in the FTF signature as defined by the start and end points of its time window is consistent with ordered health states. - View Dependent Claims (16, 17)
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18. A method for finding a fault-to-failure (FTF) signature for a unit under test (UUT), comprising:
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performing a test sequence with the UUT to generate time samples of one or more data parameters to establish reference values of a healthy UUT; for each of a plurality of ordered health states, setting a control parameter of the UUT to a different degradation level and repeating the test sequence with the UUT to generate time samples of the one or more data parameters to establish degraded values; for each said data parameter, for each time sample in the test sequence a processor, computing a distance between the degraded and references values for each of the ordered health states; applying a fixed-length moving average filter to the distances to compute a time-average health state metric at the time sample for each of the ordered health states; computing gaps between the time-averaged health state metrics at the time sample for the ordered health states; and a minimum gap from the gaps between the health state metrics; selecting with the processor for at least one data parameter the time sample corresponding to the maximum minimum gap to determine an end point of a time window for the FTF signature; and selecting with the processor the first time sample preceding the end point at which the minimum gap crosses a threshold in a positive going direction to determine a start point of the time window for the FTF signature, wherein the order of the health state metrics in the FTF signature as defined by the start and end points of its time window is consistent with ordered health states. - View Dependent Claims (19, 20)
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Specification