Understand the risks associated with Sub-Optimal Diagnostics.
by DSI International Leading Provider of Advanced Diagnostics ModelingWhat is a
“False Alarm”?
The explanation of a False Alarm
inopportunely is dependent upon your particular perspective. In general
context, it is the indecorous reporting of a failure to the operator of the
equipment or system. In tackling the world of possibilities that could
compromise the proper reporting of a failure, DSI has come over one specific
cause and the primary contributor to the experience of False Alarms, which is
the “Diagnostic-Induced” False Alarms, or more simply “Diagnostic False
Alarms”.
Diagnostic
False Alarms
The text book example of a “Diagnostic
False Alarm” is, for instance, when the diagnostic equipment (usually, on-board
BIT) misreports the functional status (test results) of whatever the sensor is developed
to be finding in its Test Coverage. If the sensor itself was really failing
while the “sensed” function was basically correctly working, then this would be
a textbook case of a diagnostic-induced false alarm. These will generally the
outcome when any sensor is in diagnostic ambiguity with the function of the
hardware it was supposed to be sensing. As a result, the diagnostic design was
inadequate and thus unable to isolate the hardware function from the faulty
sensor.
A False Alarm “rate”, like any metric
based upon generating values using a measurement of “rate”, is more suitably considered
using a stochastic means, thus depicting random variables and any vicissitudes
likely to happen over time.
The “Diagnostic” False Alarm rate is a metric that
considers both the diagnostic integrity of the design, and the sustainment
lifecycle by using feigning the eXpress Diagnostic Design of the fielded system
in the STAGE operational support simulation environment.
Although a conventional deliverable of
a Testability or Reliability examination product may give a blushing picture of
a design’s diagnostic, reliability or maintainability shrewdness, the actual
experience in the sustainment lifecycle could be “alarmingly” conflicting. For
instance, designs that are considered as meeting product assessment criteria in
such areas as FD/FI, FA, FSA, MTBF, MTBUM, etc., may lead to disturbing and opposite
outcomes in a diagnostic simulation.
Many findings evolve when diagnostic
restraints are considered in simulation that depiction, for example, the incapability
to isolate between critical failures modes at lower levels of the design, as
discussed above. Given that, there are various intrinsic operational and
diagnostic expectations that are unknowingly overlooked in any design-based
assessment product that fails to consider the diagnostic impact upon the
support of the fielded design over time. The STAGE simulation seamlessly reveals
such limitations, and expectantly early enough in design development to impact
design decisions to augment sustainment effectiveness and value.
When components are being replaced in
any maintenance process, the federation of the design of components may shine
in solving one design goal but may be a major cost stimulant in sustainment.
This generally caused by such corrective actions that resort to replacements of
non-failed components along with “presumed-to-be-failed” components due to lack
of unambiguous isolation means. Diagnostic ambiguity results when the
Diagnostic Integrity of the design (“net” Test Coverage) is not well defined.
In eXpress, the Test Coverage can be exhaustively validated early in design
development or at any time during the product lifecycle(s).
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Created on Dec 20th 2017 01:37. Viewed 259 times.