topic Re: What´s wrong with my AGV NextLookForWork ControlPoints in FlexSim Forum

What´s wrong with my AGV NextLookForWork ControlPoints

christoph_g5 — Fri, 06 Sep 2019 11:43:11 GMT

[ FlexSim 19.2.0 ]

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

Re: What´s wrong with my AGV NextLookForWork ControlPoints

joseph_g3 — Fri, 06 Sep 2019 22:56:58 GMT

@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.

Re: What´s wrong with my AGV NextLookForWork ControlPoints

christoph_g5 — Mon, 09 Sep 2019 10:44:55 GMT

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?

Re: What´s wrong with my AGV NextLookForWork ControlPoints

benjamin_w2 — Wed, 11 Sep 2019 21:55:46 GMT

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

Re: What´s wrong with my AGV NextLookForWork ControlPoints

christoph_g5 — Thu, 12 Sep 2019 05:02:56 GMT

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.

Re: What´s wrong with my AGV NextLookForWork ControlPoints

christoph_g5 — Thu, 12 Sep 2019 05:23:29 GMT

Here is a screenshot from the aerial in the tutorial model that I talk about @Benjamin W2

Re: What´s wrong with my AGV NextLookForWork ControlPoints

joseph_g3 — Fri, 13 Sep 2019 21:17:32 GMT

@Christoph G5

I'm sorry that your other question was missed. I've just answered it:

What´s wrong with my AGV-Template-Model form the Tutorial?

This should explain why you should use the solution I gave earlier. It also explains why you should remove the "DropoffPoints" connections.