how to control operator's task priority?

[_3gsimulator]

[ FlexSim 21.2.2 ]

The operator1 does his loading process from "load and send to workstation". When tote in the queque 5 gets empty.yama 1.9.fsm

Model works perfectly, when I use two different operators for those tasks. When I use only Operator 1, I don't know how to set the priority of the task. Operator1 do both tasks in the same time.

Can you please help me to set up, how? Operator 1 must finish his last task in the loading process and then move to the cart and continue together to the AMP zone and load new totes.

[patryk_u2 · Accepted solution]

To use the same operator for multiple tasks, it is best to connect the "Acquaier" blocks to the same "resource" block

I added aquaier and release opertor between subsequent activities so that in a situation where there isn't an item, the operator does not wait indefinitely but performs other activities.

In the attached model, I change the push Trolley logic.

yama-19_3.fsm

[_3gsimulator]

@Patryk thank you, nice clear solution. After your modification I have problem with tote. Queque5 pushes totes into the list: Itemlist1. But in time 324 (after repeats many times) it pushes more items then it includes physicaly on the queque5. Do you know how to solve this? That it pushes exactly the number that exists on the queque5, and operator doesen!t need to search for the item and still from the working operators?

Thank you

[_3gsimulator]

@Patryk since there is no properties on "pushtolist" at queque5, mabye i need to write it in the script of queque? Or change somehow settings for "pullfromlist"? Thank you for your help!

[patryk_u2]

I checked and I don't see an error in 324. In the screenshot you sent too, in my opinion, everything is correct when it comes to the number of totes in the queue, there are 8 of them, on the list 5 and 3 are already taken for loading.

[FelixMoehlmann]

I'm not seeing what you describe when I run the model @Patryk uploaded in his answer. Each tote is correctly pushed to the list once. Did you modify the model since it was uploaded?

I also don't see anything wrong in your screenshot. There are eight totes in the queue. Five are still on the list and three were already pulled by the tokens in the marked "Load tote" activity block.

I saw one thing that caused the operator to move to the stations on the left: When the first plate returns not all "fresh" plates have entered the system yet and the batch logic at the start of the flow is distrupted. Because two of the three plates of the batch are returning ones, the batch does not fill up and the "fresh" plate is not stopped. As a result the operator has to travel to the end of the conveyor to load the items onto it.

This happens around 1900s time when I run the model.

[_3gsimulator]

So sorry, It was in 870 (after it repeats many times) when he starts to steal "tote". The problem is probably with push to the list at queque5, but don't have any idea how to do it.

this is the file yama-19-3_autosave.fsm

[_3gsimulator]

Dear @Felix Möhlmann , in 870 The operator starts to walk away and steal tote from different pallets. Do you know, what is the error? Thank you.

attached the model. Yes i modificated the model, but just in the loading process - operator picks up all item at once. Do you think this can be the problem? yama-19-3_autosave.fsm

[FelixMoehlmann]

The error occurs because you exchanged the "Load/Unload" activities in the subflows, that move the totes into the queue, with "Move" activities. These move all items in the "token.item" label at once, but you still run the subflow as many times as there are items. This leads to the items that get pulled off the list immediately after entering to be pushed to it again, because not all queued "moves" have finished.

Either run the subflow only once or move the items individually by using "token.item[rank]" in the "Object(s)" field of the "Move" activity.

[_3gsimulator]

@Felix Möhlmann thank you. So if I want to run the subflow ony once - what shoul i change in the properties? Thank you

[FelixMoehlmann]

Type a "1" into the "Quantity" field instead of "token.item.length" (which means number of entries in the label "item" on the token).

[_3gsimulator]

Thank you - i did it, and operator stil steal the tote at time 1620

Do you think there is mistake in something else?

yama_3VI_buffer_24.9_autosave.fsm

[_3gsimulator]

@Felix Möhlmann thank you - I changed in "push troley" to do it only once. But operator at time 1620 again stole the tote from process station 😞 Do you know why?

Thank you

yama_3VI_buffer_24.9_autosave.fsm

[_3gsimulator]

@Felix Möhlmann I think it is connected with processflow, when i made operator to walk with trolley twice. In the previous model, where he walks only once, it is correct

I need he walks twice with the trolley (one way takes 8 units) and he needs to deliver 16 in total and then continue work.

Previous model yama-19-3_autosave.fsm

[FelixMoehlmann]

@Lukas Buchta

When you copied the activity block to let the operator get two batches of eight items you kept the setting "Insert at front of" in the Pull from list. This means the second batch will be added to the array label rather than replace the previous one. As a result the first eight items get moved into the queue a second time. When one of them was already pulled, this causes the same problem as before, where they get falsely added to the list a second time.

Changing the option to "Assign to" fixes this.

There also seemed to be some errors connected to your logic that stops/resumes the totes on the conveyor. I changed the logic to be more robust and hopefully still what you want.

The first decision point creates the token. The tote can then move until it reaches the second decision point. Here, the tote will be stopped if the "ready" label is still set at zero (which happens in the queue in front of the conveyor). After the tote is loaded and assigned a station, a message is send to the decision point, resuming the item.

Whether two items from a previous run must be unloaded first is now determined simply by the amount of items on the tote. Using the "ready" label for this, as well as the stopping/resuming caused some problems.

yama-3vi-buffer-249_fm.fsm

[ryan_c10]

Hi @Lukas Buchta,

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If we don't hear back in the next 3 business days, we'll assume you were able to solve your problem and we'll close this case in our tracker. You can always comment back at any time to reopen your question, or you can contact your local FlexSim distributor for phone or email help.