question

Samuele C avatar image
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Samuele C asked Fiorenzo A answered

Crash with MTBF/MTTR

@Jason Lightfoot If I try to implement MTBF/MTTR at the 3 stations, after a certain number of cycles the simulation crashes when a failure happens to the Oring station. I attach the new file pro-failure.fsm

FlexSim 22.0.1
mtbf mttrcrash
pro-failure.fsm (96.7 KiB)
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Felix Möhlmann avatar image
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Felix Möhlmann answered Samuele C commented

The Robot3 process flow doesn't properly deal with the case that the Oring station still has an item on it when the next one is due to be moved into it (because of a failure on the station). This then causes Robot3 to move it to the next station. But that label is not present on the station, as the transport is supposed to be done by a separate robot, causing the error. (Does the model actually crash for you (FlexSim closing)? Because I only get the error and the model stops)

You can fix it by adding a second condition to the decide activity, checking that the next station is not Oring.

1658992676532.png

You could also use a separate decide activity for this, in case you want to wait until the item is removed before Robot3 starts the unload movement.

pro-failure-fm.fsm


1658992676532.png (13.3 KiB)
pro-failure-fm.fsm (97.2 KiB)
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Samuele C avatar image Samuele C commented ·
Ok, thank you
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Fiorenzo A avatar image
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Fiorenzo A answered

Hi,

there is a problem at time 643.86s. The Oring station has got an item and the token of "Robot3 Process" processFlow goes in the right flow at decision "HasItem?". When it enters in the assign labels the value "token.item.destination.nextStation" doesn't exist becouse on the oring station this label not exists.1658993827483.png


So the problem could be solved adding a condition in the decide. You could add an extra condition to the previous one to check if the value "token.item.destination.nextStation" exists.


I hope this is useful for you!

I attach the model.

Model.fsm



1658993827483.png (12.2 KiB)
model.fsm (97.2 KiB)
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Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.