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Vadim Fuchs avatar image
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Vadim Fuchs asked Steven Hamoen commented

AGV Tugger - how to use/load/unload correctly?

Greetings,

I am trying to set up a simulation of an AGV tugger line. I create the carts for the tugger as TaskExecuter flowitems in the tugger (also a TaskExecuter) OnReset callback.

So far I have encountered two problems:

1) I cannot get the carts to act as participants in a coordinated task sequence (I was trying to get each one of them to execute TASKTYPE_FRLOAD to "load themselves")..

2) I cannot load anything onto them. I tried using a transporter (forklift) to load from a queue into each cart individually, but the forklift drives to the tugger instead of the cart and the flowitem disappears (visually) instead of being stacked on top of the cart.

I realize I can work around this problem by manipulating the 3d shape of the carts depending on their loaded or unloaded state, however it would be interesting to understand where do I go wrong.

FlexSim 16.0.1
agvtask sequenceproblemtugger
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2 Answers

anthony.johnson avatar image
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anthony.johnson answered Steven Hamoen commented

I'm not sure exactly what your situation requires, but my suggestion is to not use coordinated task sequences at all. Instead, process flow should be able to do all you need to do. I've attached an example model that essentially listens for when an agv loads something, then the moves it into a cart.: agvtrailerexample.fsm. It's not perfect (by the fact that I'm moving things out of the AGV, it thinks it has more capacity than it should), but it gives a general idea of how I would go about it.

Your situation sounds a little different in that it sounds like other actors are loading the items into the carts. Nevertheless, I don't see any big problems with doing it using process flow, which makes it much easier to visualize and control than using coordinated task sequences.


agvtrailerexample.fsm (35.4 KiB)
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Vadim Fuchs avatar image Vadim Fuchs commented ·

@anthony.johnson,

thank you for your reply and for a sample model. Could you possibly explain why it is preferred to replace flexscript with the process flow? Is it being deprecated?

Thank you! Vadim

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michael.smith avatar image michael.smith Vadim Fuchs commented ·

Hi Vadim, we spoke last time I was in NZ at a Simulation Australia event in Auckland.

As Anthony says flexscript is not being replaced but process flow is a new and very powerful addition to FlexSim, we are using it on a number of projects in collaboration with existing FlexSim methods and it's working very well. We are doing some update and new features training at the moment, if your interested let me know.

Mike Smith

FlexSim Australia & NZ

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anthony.johnson avatar image anthony.johnson ♦♦ Vadim Fuchs commented ·

Vadim,

No, flexscript is not being deprecated any time soon (many elements of process flow use flexscript). The reason I suggest using it is simply because it's better. Better for building models, easier to support, better to communicate with. Most people I know who have ever built a really complicated coordinated task sequence would welcome an easier way to do it, and process flow provides that.

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Lincoln Sellers avatar image Lincoln Sellers commented ·

@anthony.johnson

I am interested in your sample model to see how everything works, but I cannot seem to successfully open it. I am using FlexSim 7.5.4. It will open/save the fsm file, but when I open it, all it shows is a blank workspace with errors - it is either giving me a byteblock because of size, or a C++ error. Do you know of any way that I can view this sample model? It would help me tremendously.

Thank you.

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Steven Hamoen avatar image Steven Hamoen Lincoln Sellers commented ·

The process flow module was not available until 7.7. But the model is probably build in version 2016. So I suggest you upgrade your Flexsim version or download the latest express edition to take a look at this model.

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Steven Hamoen avatar image
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Steven Hamoen answered anthony.johnson commented

Why don't you use the AGV module for this? That is what it is designed for. It has standard option to have the loads being tugged by the tugger so you don't have to mess around with coordinated tasksequences.

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Vadim Fuchs avatar image Vadim Fuchs commented ·

Hi @steven.hamoen,

Thank you for your reply. I was using the AGV module. Sorry for not mentioning it explicitly. The simulation I am trying to build is very straightforward: I am modeling a simple replenishment operation where at the loading station totes with boxed goods are loaded manually on pallets, a forklift loads pallets on the carts of the agv tugger, and the tugger transports the carts with the pallets to the storage part of the facility where another forklift unloads them. Simple. As long as I do not try to load goods into the carts, everything is exactly as in the AGV tutorial. I have created a new type of the TaskExecuter flowitem shaped like a cart, and loaded 4 instances thereof into the AGV tugger in the OnReset trigger callback. With a simple tasksequence of traveling along the AGV network from A to B and back to A, the carts follow the tugger beautifully. The problems begin when I try to use the carts as actors in the CTS (under assumption that if they are "TaskExecuter flowitems", they can be used as task executers). I could not get it to work. The second problem that I could not solve was when I tried using a transporter to load the carts. I have configured the new flowitem used for a cart to be a container flowitem and defined a layered packaging strategy. Except the transporter refuses to load the totes into carts. It navigates to the tugger instead (could be because the carts are hierarchically inside the tugger), unloads the totes into the tugger, after which they disappear from view. I was wondering if someone could offer instructions on how to deal with the problems outlined above. I understand that I can simply destroy the flowitems during the loading of the carts and change the 3d shape of the cart to make it look like a loaded cart, but I would prefer to be able to load and unload it naturally, using the TASKTYPE_LOAD and TASKTYPE_UNLOAD tasks.

Thank you!

Vadim

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