Process Flow with AGV

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kkkk asked Jul 16, '23 Julie Weller commented Jul 20, '23

Process Flow with AGV

Hi~ I will like to ask some questions about the process flow of my model. I didn't use the AGV template because I will need to add some other functions into my model afterwards.

About my model, I've created two list (ItemsReadyForDelivery, ItemsReadyForSink), and I grouped up the processors according to the lane.

Below is what I want to achieve：

After the source create the box, it will be pushed to the list ItemsReadyForDelivery
AGV will start to load the box to the processors, and if processors in the same lane all have requirements than the AGV will send all at once (ex. If processor 1 and 3 both have backorder, they are both at lane1 so the AGV will load the box to both processors) and the 2 items will be pulled out from the list ItemsReadyForDelivery. In my process flow's first travel, I used the case method hoping that the AGV will get to whatever lane that have requirements, not sure if this will work.
After the processors finished processing the box, it will be pushed into the list ItemsReadyForSink.
After the AGV successfully send the box to the goal processor, it will check if the same lane has box to take to the sink. If there are items to take the AGV will take all the boxes that need to be take in the same lane to sink and the the items will be pulled out from the list ItemsReadyForSink.

Hope to get some suggestions~ thanks!!!

My model: 0716_pf.fsm

Software Version:

FlexSim 23.0.9

agv grouping procees flow

1689519815061.png (39.1 KiB)

1689519857194.png (36.9 KiB)

0716-pf.fsm (108.1 KiB)

· 3

Joerg Vogel commented · Jul 17, 2023 at 04:38 AM

@kkkk, please use AGV Template! It is tested, approved and has an all implemented transport job management. But nobody ever said you aren’t allowed to customize this template for your needs. If you are build a new logic layer dealing with primary conditions, you might forget secondary goals, which you work on later, but which needs at the end a totally new model. Currently it seems you need to customize in an AGV template a management of priorities to achieve what you want to do. If you would ask about such a variation this results in a thread which would help other users to customize themself such a template in the future. Thank you for considering my suggestion. Joerg

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kkkk Joerg Vogel commented · Jul 17, 2023 at 05:57 AM

Thank you for your suggestion! The reason that I didn't use agv template is based on the default setting of the template. That agv goes to every control point to see if there's work to do. But what I am trying to do is to let agv understand what it is going to do at the very beginning, since it'll need to carry multiple item at the same time. And I also want it to follow the adjusted job sequence from the list. That's why I am trying to build process flow on my own. I'll be appreciated if there's any suggestion of building the process flow. Or any suggestion that can change the agv template default setting! Thank you for any of your assistance!

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Julie Weller commented · Jul 20, 2023 at 02:04 PM

Hi @kkkk, 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 · 2023-07-17T08:38:17Z

Jason Lightfoot answered Jul 17, '23 Jason Lightfoot edited Jul 17, '23

The AGV template may be easier because it has many things in place with which you may struggle to provide your own implementation - especially if you're new to FlexSim. Also it avoids the question of sequencing your deliveries and finding a best route by simply telling the AGV to follow and route and check if there is anything to load or unload at each point along the route. In some systems there could be room for improvement there and it's a good exercise to build your own AGV logic from scratch, especially if you need to customize the logic but there are some basic principles you should understand before undertaking this task. For this reason I advise you do all the tutorials. It could be that you will decide a few tweaks to the template will work for your case.

There are numerous issues in your model, as you probably know since your posting here, and the first in my mind is the formentioned issue of knowing which object is invoking which process. Note that the AGV template is an object based process flow, not a general process flow, and that the AGV is the object invoking the process (creating tokens), not the flowitems requiring transport. You've elected to use lists for the push/pull mechanism that determines which processor an item should visit. This should be distinct from the transport process which uses different lists. Not only that, you've added an Event triggered source to detect the arrival of items in Queue1 and push those to the list, as well as pushing to the same list on the queue's send to port. The only reason you don't see two entries per item is that the default option of the list is to not allow duplicate values on the list.

Once you have an item in the AGVWork list (which you need to add by the way since you're not using the AGV templates) then you need to have the AGV pull from that list. For that I would use an object process flow where the AGV travels to the queue before pulling from the list - that way only one AGV is pulling at once since only one can be at the queue at any given time. From there you need to come up with some logic on which items to pull for a given trip, and how to sort them (it's pretty standard) ready for drop off.

You're missing some logic in your description - for example how will finished boxes be taken out of the lane in the case where all processors in that lane are finished and waiting for the finished box to be collected? In this case no processor will pull a new item and therefore the AGV will not visit the lane so your model will stall.

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