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Christoph G5 avatar image
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Christoph G5 asked Joseph Gillespie commented

What´s wrong with my AGV NextLookForWork ControlPoints

I do my first steps for working with the AGV-Module for a larger project.

In my model enhanced, I try to build a small AGV-model like in the Tutorial 4.2.

I have 3 Sources with 4 types auf Items and 3 Queues with 3 different possibilities to transport the items (push, pull, A-connection). In the Tutorial 4.2 the NextLookForWork CP are from AGVEntryPoint to the different MainDropOff / PickUp -Point (in a circle). I try to do this in my model but it doesn´t work. After the first transport the AGV´s receives no more jobs?! What´s wrong in my model.

agv-first-step-gr.fsm

FlexSim 19.2.0
agv module
agv-first-step-gr.fsm (122.8 KiB)
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1 Answer

Joseph Gillespie avatar image
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Joseph Gillespie answered Joseph Gillespie commented
@Christoph G5

When using the AGV Process Flow, AGVs have a specific way of operating when looking for work. They:

1. Follow "NextLookForWork" connections until they find an item to pick up.

2. They load the item.

3. They travel to the item's destination.

4. They unload the item.

5. They follow "NextLookForWork" connections again in search of work to do. (Back to Step 1 really)

If an AGV unloads an item and has no "NextLookForWork" connections to follow, it won't do anything.

In your model, AGVs are getting stuck at these control points (in red squares) because they have no "NextLookForWork" connections away from those points:

If you add "NextLookForWork" connections to connect them back to the "NextLookForWork" loop (as shown in the picture with the red arrows), your model should work fine.


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Christoph G5 avatar image Christoph G5 commented ·

Thank you @Joseph Gillespie ,

now I understand what´s my mistake with the comparison to the tutorial - I have not used a MainDropOff-Point! When I use a MainDropOff-Point instead of a SingleDropOff-Point (DropOff1...3) the model works or rather, after drop off the item the AGV´s get new tasks.

But the model doesn´t work fine! Because the AGV´s are not take the right DropOff-Points. And that´s the same problem in the "Tutorial 4 - Automatic Guided Vehicles / 4.4 - Custom AGV Settings", I have asked view days before (but till this day I have no reply), here is the link:

https://answers.flexsim.com/questions/71691/whats-wrong-with-my-agv-template-model-form-the-tu.html

What´s wrong?

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nextlookforwork-001.jpg (253.2 KiB)
Benjamin W2 avatar image Benjamin W2 Christoph G5 commented ·

Hi @Christoph G5,

It looks like you are still missing the NextLookForWork connections that Joseph mentioned in his answer. It also looks like you created A-connections between the MainDropOff-Point and the Queues. This means that the AGVs will unload to those Queues from the MainDropOff-Point.

Here is a gif of how it works if you add the NextLookForWork connections.

nextlookforwork.fsm

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nextlookforwork.fsm (122.6 KiB)
nextlookforwork.gif (2.1 MiB)
Christoph G5 avatar image Christoph G5 Benjamin W2 commented ·

Thank you @Benjamin W2

yes, the model works fine in this way. That is to say the tutorial description, mentioned above, is wrong too? Because in the Tutorial 4.4 the DropOff-Points has no Locations, only the MainDropOff-Point has Locations.

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