AGV "on arrival" event trigger does not behave as expected

Question

question

Valentin R asked Mar 28, '23 Jason Lightfoot commented Apr 30, '23

AGV "on arrival" event trigger does not behave as expected

Hi,

We tried to modelize some kind of particular monorail. This one does generate an error which we are not able to explain. The "wait until completed" seems to trigger rather early since the AGV is not yet arrived on the CP. This does not generate an error but, on the same frame, when trying to give a new travel to the AGV the following error is popping. The arrival event seems to fire once and still exist, as if there was two arrival at different times.

  
                 
                  time: 22.930894 exception: Exception Caught in dispatchtasksequence(treenode tasksequence, treenode dispatcher DEFAULTNULL)
                  time: 22.930894 exception: Exception caught in start() of activity New default station/AGV Travel new in process flow "Movers". Continuing throw...
                  time: 22.930894 exception: Exception caught in Executive::processeventinlist().

Do you have any idea about where it could come from or how to resolve such problem ?

Bug3_v2022_5_ReportFlexSim.fsm

FYI : this post follow an older one which was: https://answers.flexsim.com/questions/114343/exception-exception-caught-in-executiveprocesseven.html#answer-139162

Best regards,

Val

Software Version:

FlexSim 22.2.4

agv arrival

· 3

Jason Lightfoot ♦ commented · Apr 26, 2023 at 06:15 PM

This looks like a train model - if so, could you have used trailers for the carriages?

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Valentin R Jason Lightfoot ♦ commented · Apr 28, 2023 at 12:52 PM

This definitely is not a train model. Every shuttle has to be controlled separately...

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Jason Lightfoot ♦ commented · Apr 30, 2023 at 11:20 PM

Hi @Valentin R, was Kavika F's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

0 ·

Answer 1 · 2023-04-24T21:26:54Z

Kavika F answered Apr 24, '23

Hey @Valentin R, sorry for the late reply. I think we've found a few things that added up to make this behavior.

Firstly, I'll talk about recreating Movers. The "Reset_Loops_Movers" code included a section on making or removing movers, starting with a line like

int Missing_Movers=Number_Of_Movers-Number_Of_Movers_in_Model;

and followed by two if-statements. I decided to simplify this process by commenting out that block of code and instead using a Parameter with an "On Set" trigger to "Delete and Copy Group Members":

By adding all Movers to a group (like you had already) and setting this parameter, each reset was sure to copy the original Mover and make copies with the correct connections. This isn't to say that your method didn't work, but I was just covering my bases.

We noticed that some of the AGVs dispatcher code seemed off. For example, the first 5 Movers had dispatcher panels that looked like this:

But the rest (6-20) had "Pass To" fields that instead looked like this:

We found that it was caused by the "passto" node not being toggled to FlexScript like it's sibling node "queuestrategy":

So I changed those to be FlexScript and rebuilt the FlexScript to ensure it executed correctly.

With these two changes, we noticed a change in behavior for the Object Flow. The first Mover was getting stuck at CP "Loop_1_St 01_4" because the order the tokens were created and pulled from the list were not as expected. To counteract this behavior, we added a small offset to the tokens to ensure that they spawned "in order". We took the Mover_Number on each object and divided it by 1000 to achieve this behavior.

Finally, after all those changes, the behavior seems to be as expected (or at least we don't get any errors and exceptions).

Here is a copy of the modified model. bug3-v2022-5-reportflexsim_3.fsm

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1682371191507.png (5.6 KiB)

1682371230929.png (2.1 KiB)

1682371323680.png (15.8 KiB)

1682371530067.png (8.8 KiB)

bug3-v2022-5-reportflexsim-3.fsm (5.5 MiB)