Loading and unloading multiple items by crane using process flow logic

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felicity asked Nov 27, '23 felicity commented Dec 30, '23

Loading and unloading multiple items by crane using process flow logic

I want to load and unload 10 items at once (I want the crane to go down and up again only once) and I have checked several questions here, however none of them seem to work for my model. I'll upload a test model and describe what exactly I want the model to do work as described below:

1) There are 2 types of items. each type must be sent to a specific inventory. Items of type 1 must be transferred to Inv2 and items of type 2 must be transferred to Inv3 and Inv4. Here I would like to know how I can refer to both these inventories in my process flow without having to define them as a resource (So that when other cranes also want to unload items in the same inventories they don't have to wait for the Inv3 or Inv4 to be released)

2) I tried two different methods to load 10 items at a time but they don't seem to work. What is wrong with the model?

Thanks in advance

test- loading 10 items by a crane.fsm

Software Version:

FlexSim 22.2.0

crane load multiple item object referencing process flo

test-loading-10-items-by-a-crane.fsm (73.2 KiB)

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Jason Lightfoot ♦ commented · Dec 04, 2023 at 04:42 PM

Hi @felicity, was one of Jason Lightfoot's or Joerg Vogel's answers helpful? If so, please click the "Accept" button at the bottom of the one that best answers your question. 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 comment back to reopen your question.

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Answer 1 · 2023-11-27T16:28:41Z

Jason Lightfoot answered Nov 27, '23 felicity commented Dec 30, '23

You're invoking your process for each item entering inv1 which is not matching the logic you have following. Either batch those into a single token with an array of items to pick, or create a single token that loops around the process pulling items from inv1's list.

Also at the moment token.item is only ever going to be one item as you're not assigning it the list of pulled items from the list.

Lastly - you can remove the crane's travel tasks - it only does offset travel by default.

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felicity commented · Nov 29, 2023 at 09:50 AM

@Jason Lightfoot Thank you for your answer

I have assigned token.item to the list, but I don't know what you mean in the first paragraph. Can you perhaps take a look at the edited model and tell me what I should do to make it work?

test- loading 10 items by a crane.fsm

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test-loading-10-items-by-a-crane.fsm (72.4 KiB)

Jason Lightfoot ♦ felicity commented · Nov 29, 2023 at 10:30 AM

By invoking a process I mean creating tokens using a source activity - whether that's scheduled or event driven.

In this case think about what that token represents when it is created, and then think about the actions your creating with it. It doesn't make sense for each item to create an action that loads 10 items.

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felicity Jason Lightfoot ♦ commented · Dec 05, 2023 at 10:02 AM

@Jason Lightfoot you're absolutely right!

I hadn't noticed that. I have worked on my model for the past couple of days and changed the structure a bit. I'll upload it here. Instead of items representing a token, the crane is moving through the process flow as a token. I think this model must work if properly set. However I think I'm doing something wrong. Can you take a look?
(I'm not sure if I've filled the puller, push value and assign to fields correctly)

Thanks in advance

test- loading 10 items by a crane- crane list.fsm

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test-loading-10-items-by-a-crane-crane-list.fsm (74.6 KiB)

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Answer 2 · 2023-11-27T16:11:07Z

Joerg Vogel answered Nov 27, '23 felicity edited Dec 6, '23

here is an example: Push items on Itemlist not Tasksequence List in Use Transport of Queue1 -> similar to Tutorial. Process Flow > Batch Item activity > Aggregation: make an Array -> run sub flow activity to load multiple items -> run subflow to unload multiple items.

transport_more_items.fsm

transport-more-items.fsm (39.7 KiB)

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felicity commented · Nov 29, 2023 at 07:07 AM

@Joerg Vogel Thank you for your answer.

I studied my model some more and realized I need the crane to load up to 10 items but can move less items as well. Can I use this logic using batch or do I need to use the list option only?

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Joerg Vogel felicity commented · Nov 29, 2023 at 07:44 AM

@Felicity, you need to aggregate more items or you let the crane wait. You can always decide how you build your logic. A list is only a suggestion, a batch is a suggestion, too. Currently you have for each item to transport a new token. If your logic consists of calling a subflow, you have to aggregate data from single tokens into a structure like an array to call a subflow more often. Or you choose a structure which loads more items to a crane and then you wait until a time interval ends. Then the crane moves. Or the crane has loaded already its maximum capacity and you let the crane continue immediately.

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felicity Joerg Vogel commented · Nov 29, 2023 at 10:06 AM

@Joerg Vogel I see. I want to use lists to move between 1 and 10 items and I saw something similar here:

https://answers.flexsim.com/questions/144978/unloading-items-from-a-task-executor-by-crane.html

But the model doesn't work for me. I uploaded an edited version of my model in my comment above. Is it possible for you to make the changes you're suggesting on the model?

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