Suggestion to start simulate a high density storage

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Emily K asked Dec 15, '21 Jeanette F commented Jan 7, '22

Suggestion to start simulate a high density storage

Hi, I have tried build a kiva model according to https://answers.flexsim.com/articles/107103/example-kiva-system-model.html

I am doing research about high density storage, and trying to evaluate its performance using flexsim. I will start with A* and floor storage. The allocation of cart is almost same as the example, but number of aisle will decrease to increase space utilization of warehouse.

There are some rule:

1. Planning path before AGV start moving

2. Choose a path that AGV will move the least carts that blocking the way of target cart to work station

3. AGV could not move the blocking carts in the way of target cart

I wonder if it is feasible in flexsim. Any suggestion or advice is much appreciated!

Thanks!

Software Version:

FlexSim 21.2.4

agv kiva robot high density storage

· 2

Connor A commented · Dec 28, 2021 at 05:20 PM

Hi @Emily K, was Jeanette F'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.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

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Jeanette F ♦♦ commented · Jan 07, 2022 at 07:54 PM

Hi @Emily K, was one of anthony.johnson's answers helpful? If so, please click the "Accept" button at the bottom of the one that best answers your question. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

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Answer 1 · 2022-01-04T19:33:13Z

anthony.johnson answered Jan 4, '22 anthony.johnson edited Jan 4, '22

Attached is a very quick and rough cut of how you might go about it. I assume that your main goal is to implement digging, but optimized for the least amount of digs. This model is a starting point for doing that.

It implements its own internal A* algorithm for defining the "path" by which you should dig out items (CalculateLeastDigPath). As part of this algorithm, it implements a high cost if the path goes through an item that is in storage, i.e. it must dig to get to the item. Thus, it should find the item that results in the lowest cost.

Once I have calculated the path, I have AGV2 dig it out. Then AGV1 picks the item. Then AGV2 puts the dug items back in their original spot.

To get it done quickly, I am minimalist on logic for where to place an item that you dig out (just one location, i.e. overlapping items), where to put the dug items back when the pick is finished (the same spot where they were) and how to put the picked items back into storage (I just destroy them). You'll need to figure out how your algorithm should do those things. One thing you'll need to keep in mind is to keep AGV2 out of the way of AGV1. Sometimes AGV1 will get stuck because AGV2 is idle and in AGV1's way, so when AGV2 goes idle you should move it out of the way.

I would suggest using object flows instead of global process flows. Object flows are, in my opinion, more intuitive for implementing the logic of a smart Agent/robot in your system.

I also changed out your queues for a floor storage object, as I believe that's a much easier way to store items.

211206-demo-modified.fsm

211206-demo-modified.fsm (1.1 MiB)

Answer 2 · 2021-12-21T15:44:57Z

Jeanette F answered Dec 21, '21 Jason Lightfoot commented Jan 4, '22

Hello @Emily K,

I do not have experience creating a Kiva system however there are many example model and questions about Kiva systems in the forum. If you search "Kiva" you will find several. This particular post you might find helpful.

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Joerg Vogel commented · Dec 28, 2021 at 06:26 PM

There exists a dev talk video on youtube

https://youtu.be/3AQ-cjOS9tY

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Emily K commented · Dec 31, 2021 at 08:30 AM

Thanks @Jeanette F and @Joerg Vogel ,
I have searched all the topics related to kiva and tried to simulate the model according to the video before I asked this question.

The rules stated were reference from a paper studying high density storage. I would like to simulate its rules using flexsim, but I have no idea where could I start...211206_DEMO.fsm Attachment is a simple model using logic above.

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211206-demo.fsm (1.1 MiB)

Jason Lightfoot ♦ Emily K commented · Jan 04, 2022 at 01:51 PM

You might find that you need to use the Astar API. @anthony.johnson may be able to provide you with a better idea of how to proceed.

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