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Mischa Spelt avatar image
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Mischa Spelt asked anthony.johnson edited

Gap-Optimizing Merge Controller with errors

While reviewing the Gap-Optimizing Merge Controller with a customer I ran into two (separate?) issues.

First of all, we tried to build a simple model with a few lines and a regular merge controller, which worked fine. Then we included the Process Flow template, and quite quickly ran into an issue; at t ~ 88 the gap that should be 1 turns out to be about 0.5: MergeControlllerFailure.fsm. I did find https://answers.flexsim.com/questions/87065/error-when-using-fixed-gap-merge-controller-proces.html but downstream backups don't seem to happen here.

Then we had a look at the demo model Merge Control With PF.fsm and noticed a major difference is that the slug lines have a small curved conveyor going onto the takeaway conveyor. So we tried to copy that in this model: MergeControlllerFailure2.fsm but then FlexSim complains that a slug builder lane has an inline transfer onto a non-slug building conveyor.

So the main question is why the first attached model does not work, with a secondary question on how the demo model got the curved conveyors to work.


FlexSim 20.2.2
processflowflexsim 20.2.2merge controllerconveyor systemgap optimizer
mergecontrolllerfailure.fsm (77.1 KiB)
merge-control-with-pf.fsm (103.1 KiB)
mergecontrolllerfailure2.fsm (79.7 KiB)
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1 Answer

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anthony.johnson answered

The gap optimizing merge controller process flow assumes that all transfers to the takeaway conveyor are inline transfers. If there are side transfers, then the convey time calculation gets messed up. In your first model, the transfers onto the takeaway conveyor are side transfers, so the convey time is miscalculated.

You can fix this without having to have a curved in-between conveyor by increasing the Max Angle For Inline Transfers in the properties of the transfer type. If you increase it to something like 90 degrees, then those transfers will be interpreted as inline transfers, instead of side transfers, and the convey time calculation will work right.

In your second model, the error was Object /Conveyor16 is a slug building conveyor and should not have transfers along its length. The error says what it means. If you have a slug building conveyor, all transfers to/from that conveyor must be exactly at an end of the conveyor. When you placed curved sections, the transfers for those curved conveyors were not exactly at the end of the conveyor.

You need to adjust the ends of the curved conveyors so that they are exactly at the end of the conveyor.


sidetransfer.gif (264.6 KiB)
1600443729547.png (93.3 KiB)
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