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Script for identification of safety goals

medini_1059816043

Sehr geehrte Damen und Herren,

wir benötigen Hilfe zur Erstellung eines Java Scripts.

Wir haben folgenden Aufbau des Medini Files:

Wir haben einen Fehlerbaum der aus den Sicherheitszielen abgeleitet ist

Die Baseevents am Fehlerbaum sind verknüpft mit Malfunction und Failure Modes (Failure Modes
abgeleitet aus Element)

Das ist die unterste Ebene der FTA

Die FMEDA ist mit den HW - Effekten verlinkt. Dem Bauteil werden Fehlereffekte auf HW Ebene zugewiesen.

Des Weiteren haben wir die HW - Effekte der FMEDA zu den Base Events der FTA verknüpft

Hardware Effekte (FMEDA) werden an die Base Events (Failure Modes aus FTA) über Fehlernetz verlinkt

Ziel:

Die Sicherheitsziele müssen den Fehlermodes in der FMEDA zugordnet werden (manuelles setzten
der Checkbox)

Das Sicherheitsziel welches durch den Fehler verletzt wird, ist aber nicht sichtbar in der FMEDA was das setzten der Checkbox erschwert

Abhilfe:

Zusätzliche Spalte im Formsheet: „Safety Goal“

Ist es möglich ein Java Script zu erstellen welches über das Fehlernetz und die FTA die
entsprechenden Sicherheitsziel herausfindet und in dieser Spalte anzeigt. Das würde uns sehr helfen, die richtigen Sicherheitsziele herauszufinden. Aktuell müssen wir manuell bei jedem einzelnen Fehler in der FTA nachsehen, um die Sicherheitsziele herauszufinden

Danke

Grüße

Markus Faltermeier

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medini_1059007410

Hi Markus,

a few clarifying questions:

1) your "short circuit" failure mode is within the FMEDA "Effects" column, right?

2) the base events represent any element in the upward cause/effect chain, so either the failure mode "Wrong current..." or MF052, and the cause/effect chain can have a variable length - is that true? [Having these variables (failure mode or malfunction, position in the chain not predefined) will make the script more complicated, but still doable.] Or is it simpler and the chain length and position is always the same?

Regards,

Nils

medini_1059816043

Hallo Nils,

No short circuit is in the column potential failures. In the column effects there is "wrong current signal". And this is linked to the base event of the FTA. Which is Failure in current sensor.

Another example in the FMEDA:

For the second point.:

This is correct. The way from the base events in the FTA to the safety goals is different (variable length). This depends on the structure of the FTA with its AND / OR gates

Example in the FTA:

Thanks

Regards

Markus

medini_1059007410

Hi Markus,

ok, a misunderstanding in each direction (with variable position in the chain I didn't mean the FTA), but I hope I now got the understanding right. So the failure mode, which is in the FTA (represented by a basic event) is in the "effects" columns of the FMEDA. Then it's easier, resulting in this:

Two steps:

1) Get the events of the effect(s) - in OCL, as this is a very simple modification of the existing similar columns (ISO26262 best practice template/ESL) for the components/failures:

(self.element.oclAsType(safetyModel::Failure).effects.oclAsType(safetyModel::Failure)).mediniGetOpposites('represents')->
 select(c|c.oclIsTypeOf(FTA::Event)).oclAsType(FTA::Event)->reject(e:FTA::Event| ( e.mediniGetOpposites('analyzedEvents')->size() >0))

2) Get the top level events for these events and from these the traced safety goals - in Javascript, as recursion is easier there (at least for me):

var ftaEventsList = self.user_effects_related_fta_event_s_;
if (ftaEventsList) {
 // First find the top event node(s) of the given events
 var topEventNodes = [];
 ftaEventsList.toArray().forEach(function (ftaEvent){
 // start filling topEvents array (can be multiple, due to transfer gates)
 recurseToTopEventNode(ftaEvent.nodes.get(0));

 function recurseToTopEventNode(node) {
 if (("effectiveKind" in node) && node.effectiveKind=="TOP_LEVEL") {
 topEventNodes.push(node);
 } else {
 // recurse on potential parent node
 if (("parent" in node) && node.parent) {
 recurseToTopEventNode(node.parent);
 }
 // recurse on potential target event node - check before
 if (("transferGateTarget" in node) && node.transferGateTarget) {
 node.transferGates.toArray().forEach(recurseToTopEventNode);
 }
 }
 }
 });

 // Then get the related safety goal(s) of these top event node(s)
 var safetyGoals = [];
 var safetyGoalsList;
 topEventNodes.forEach(function getRelatedSafetyGoalsAndAddToArray(topEventNode){
 // traces are from the event, not the node
 safetyGoalsList = topEventNode.event.mediniGetTracedElements(Metamodel.safetygoals.SafetyGoal);
 if (safetyGoalsList) {
 safetyGoalsList.toArray().forEach(function addSafetyGoalsToArray(safetyGoal) {
 safetyGoals.push(safetyGoal);
 });
 }
 });

 // Finally display safety goals (best as list)
 java.util.Arrays.asList(safetyGoals);
}

Names of the profile properties in the above examples as shown here:

Does that fit your use case?

Happy Scripting,

Nils

medini_1059816043

Hi Nils,

thank you for your answer.

Your first sentence is not correct. The base events in the FTA and the "effects" column in the FMEDA is not the same. These HW effects are only used in FMEDA. The base events are only used in FTA.

So we can do the FTA and FMEDA with different teams independently.

After FTA is finished we link the HW effects (FMEDA) to the base events (FTA) via the cause and effect net.

So link from FTA to FMEDA is not the "effects" column. The link is the cause and effect net

Does this script work with this approach?

Thanks

Regards

Markus

medini_1059007410

Hi Markus,

just to avoid further confusion, can you please post example screenshots of FMEDA, Cause/Effect Net and FTA extract (around the base events), which fit together?

Thanks!

medini_1059816043

Hi Nils,

attached you find some example screenshot of Medini

Regards

Markus

medini_1059007410

Hi Markus,

Ok, so one step from FMEDA effect FM to FTA represented FM. That's an easy modification of my previous derived properties. Just modify the first OCL one by another ".effects.oclAsType(safetyModel::Failure)":

(self.element.oclAsType(safetyModel::Failure).effects.oclAsType(safetyModel::Failure).effects.oclAsType(safetyModel::Failure)).mediniGetOpposites('represents')->
 select(c|c.oclIsTypeOf(FTA::Event)).oclAsType(FTA::Event)->reject(e:FTA::Event| ( e.mediniGetOpposites('analyzedEvents')->size() >0))

For that case I'd recommend to rename the respective column with "subsequent effect" (or as you like - you can also hide it and change columns order).

Please try, if it now fits for your purpose.

Happy Scripting,

Nils

medini_1059816043

Hi Nils,

Thank you

Now we have the link to the base event in the FTA. This works good now...

And now is it possible to identify also the TOP Level Safety goal? Which is violated by this effect:

Thanks for your support

Regards

Markus

medini_1059007410

Hi Markus,

The safety goals linked to the top events are identified by the second step in my previous post (Tue, 22 Nov at 10:18 PM), the Javascript one.

So far you have the first step, which should be an OCL property named "user_effects_related_fta_event_s_" (name is used in the second step) - you used the display name of the second property already, might want to correct that to avoid confusion.

The seconds step is the Javascript property named e.g. "user_effects_safety_goals__via_fta_top_event_", to be filled with the script in the 10:18 PM post.

Be aware that your last FTA screenshot doesn't show the top event on the upper right corner, as it is a transfer target, so the tree goes further up via (one or many) transfer gates.