Transporter not picking the item based on the arrival sequence table

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Elle asked Mar 30, '23 Elle commented Apr 1, '23

Transporter not picking the item based on the arrival sequence table

Hello!

Could anyone help me point out what's the problem with my simulation here? Current State.fsm

The goal and the issue encountered:

So, each of the sources generates different types of pallets with a given quantity of each type. (I've recently learned about the "Arrival sequence" and that helped me a lot in achieving the desired arrival style.) Two forklift operators then load and unload each pallet corresponding to their assigned floor storage.

The forklift operators are supposed to load 60 pallets of the same type in each floor storage. In cases where the floorstorage is filled all the way to the back, transporter 1 and 2 should then start unloading the pallets starting from the front to the back again until they reach the 60th pallet of the same type. Once they finished 60 pallets of the same type, they should then move on to the next type of pallet/floorstorage.

This logic works for transporter1 and for some time for transporter2 until approximately 17,000 seconds.

As you can see in the picture below, there are still Type 9 pallets at the end of the conveyor belt, but Transporter 2 keeps on loading the Type 10 pallets first for some reason. Also, at about 17,700 seconds, transporter 2 just stopped working.

The issue is a little mystery for me because I tried recreating the same logic in a smaller environment and it seems like it's working fine. Also, source 1 (which is working fine) and source 2 shares the same logic. So, I don't know what's messing with the sequence. I might really be missing something here, if someone can please fill me in on what this is, that would be really great!

Best Regards,

Elle

Software Version:

FlexSim 22.2.2

arrival sequence specific quantity for each type of item wrong pick of pallet

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current-state.fsm (720.8 KiB)

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Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Answer 1 · 2023-03-30T23:11:32Z

Kavika F answered Mar 30, '23 Elle commented Apr 1, '23

Hey @Elle, I think I found your problem. I noticed that you had a lot of tokens waiting to acquire Transporter2 after a Wait for Event activity.

I assume that you wanted to pull items off at the end of the conveyor as they arrive at a Decision Point. Well "Wait for Event" activities will release all tokens that match the specified criteria. In your case, they accumulated at the Wait for Event and then all got released at once when 1 pallet arrived; this made it so the tokens were no longer in "order" and the Transporter would just pick them randomly from the conveyor.

You can fix this by simply adding the "match" operation to the Wait for Event. This will make it so in order for a token to be released, it's "Pallet" label has to match the one on the item that arrived at DP2 (ensuring only the pallet that arrives moves on).

I hope this helps!

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5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Elle commented · Apr 01, 2023 at 04:18 AM

Hello @Kavika,

Your solution worked, thank you very much for your time and help!

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