Architecture Modeling - SPES 2020

Architecture Modeling
provided interfaces on the ECUs and the required interfaces on the sensors limit the solution
space. This data can be transformed automatically to be used by solving algorithms for finding
a solution. This solution is transferred back into the model itself to generate architecture out of
requirements and physical constraints.
In Addition to architecture generation this technique can also be used for design space exploration.
For different existing alternatives the minimal existing cable length can be calculated
and compared. This approach differs from the typical design space exploration techniques since
the metric for comparing designs is not based on the design that has been created until the run
of the test, but on the quality of the solution that is possible to be designed in the future, based
on the design decisions already made.
This use case demonstrated that the geometrical perspective can be used as a valuable input
for architecture generation and design space exploration. Furthermore the close relations
between perspectives were demonstrated.
3.2.5.2 Identification of particular risks
On the geometric perspective a particular risk analysis (PRA) can be performed in order to
identify safety impacts of geometric installation decisions for a technical system under design.
In the PRA failures that are external to the technical system are identified and analyzed in the
geometric context of the system. The SAE-ARP 4761 defines particular risks as “events which
are outside the system(s) concerned but which may violate event independence claims because
they ’may influence several zones at the same time”’ According to EASA CS25 Book 2 subpart
F particular risks are “those events or influences, which are outside the systems concerned. [...]
Each risk should be the subject of a specific study to examine and document the simultaneous or
cascading effects or influences, which may violate independence.” Therefore, these events are
failures in the geometric perspective that implicate safety risks for the technical system under
design. Technical components that are verified in a functional hazard analysis (FHA) to be
functionally independent can fail together because all of them are involved into the effects of
failures on the geometric perspective. Thus, functional hazards can be reached because of the
geometric installation of components which are located in a way that they are impacted together
by a particular risk. The PRA allows the identification and classification of such risks. Based
on the results of a PRA the geometric installation of a system under design can be optimized in
order to prevent functional hazards.
Particular risks on the geometric perspective Relevant Particular risks for a system under
design depend on the geometric context in which the system operates. Common particular risks
are explosions, fire, heat, lightning, hits by foreign parts or leakage leading to evacuation of gas
or liquids. For an individual system the particular risks are specific. I.e. for a space vehicle
the effects of radiation or the impact of space debris have to be regarded. Tire burst, bird strike
or engine burst are particular risks that can lead to the evacuation and the impact of fragments
that damage or even destroy installed technical components of an airplane. According to EASA
AMC20-128A when analyzing the burst of an airplane engine there can be different fragments
which are single one third disc fragment, intermediate fragment, small fragment and fan blade.
Performing a particular risk analysis on a geometric model In order to perform a PRA
a model of the system under design in the geometric perspective must exist. Components of
a technical perspective are allocated to geometric components of this model. The geometric
components have geometric locations within the system under design. Therefore, the effect
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