Wait for AGV before processing

Question

question

Peter W8 asked Sep 8, '22 Jeanette F commented Sep 14, '22

Wait for AGV before processing

Hi,

I want to prevent a processor (VF100) from processing an item if there is no AGV at a specific control point (StartPoint_AGV). I've experimented with process flow and the wait for event task, but I can't get it to work. I've also tried to use triggers without any success. Any suggestions? I've uploaded the model (Wait_for_AGV_before_proc) to the file sharing site.

Software Version:

FlexSim 22.2.1

agv processor controlpoint wait waitforevent

wait-for-agv-before-proc.jpg (76.1 KiB)

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Jeanette F ♦♦ commented · Sep 14, 2022 at 02:51 PM

Hi @Peter W8, was Jason Lightfoot'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.

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Answer 1 · 2022-09-08T18:36:30Z

Jason Lightfoot answered Sep 8, '22 Jason Lightfoot commented Sep 9, '22

You just need to change the Queue_Release process to detect the sendtoport of the upstream queue and override it to not release when there is no AGV to pull and release the item when it pulls one. Then add a wait for event to coordinate the loading task with the item being ready in Queue_Others.

There seem now to be errors with this model - what other changes have been made?

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Peter W8 commented · Sep 09, 2022 at 08:08 AM

Which tasks would you use in process flow in order to

detect sendtoport of upstream queue
override it not to release when there is no AGV

I've done a couple of changes,

Connected PIGG_Final1 & PIGG_Final2
Added more AGVs, from 6 to 31.
Added a new processor called QG_PIGG_EPT to handle EPT & PIGG items
There was an issues with processor "DUAL" being blocked in the model you sent me so I added a new recieving processor called QG11.
All three processors named QG_XXX are, in reality, the same operation, So I added a ControlArea to limit the number of AGVs to 1 in order to prevent all three from processing at the same time.
Added creation restrictions at "Source_Main". The items are now created according to a predefined percentage but also have limitations per variant dictating how often a specific variant may be created. For example, the variant AMT_EXT_ULC should be 7% of all items created but may not be created more often the every seventh item.
Added a Dashboard that displays the creation of items in order to monitor the percentage and restrictions at the source

I've noticed that there are errors and expetions in the system console but the model seems to be working anyway.

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Jason Lightfoot ♦ Peter W8 commented · Sep 09, 2022 at 08:50 AM

I would probably get a reference to the upstream queue directly unless there's a change you will duplicate VF100. So in the existing Queue_release event driven source, sample the upstream queue and change the event to "Send To Port".

I would probably override the release using the queue's own trigger using the option for "Do not release item" and then always release the item in the process flow. When doing this it's important to release through port 1 (or any non-zero port) to prevent the object's trigger from firing and holding the item again.

Attached the model with that change - I'll look into the errors.

Wait_for_AGV_before_proc_jl.fsm.pdf

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wait-for-agv-before-proc-jlfsm.pdf (294.1 KiB)

Peter W8 Jason Lightfoot ♦ commented · Sep 09, 2022 at 09:06 AM

There's something wrong with the file you sent me. Can't open it.

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Jason Lightfoot ♦ Peter W8 commented · Sep 09, 2022 at 09:18 AM

I see you've reintroduced connections for some reason and I worry that you've added processors where there should only be one resource. The data driven approach to defining the process should have prevented the need to do this.

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