AS/RS with crane simulation - best approach

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Marian C asked Mar 27, '19 Fred Kan answered Apr 23, '19

AS/RS with crane simulation - best approach

Hello all,

Has anyone made a simulation for a triple deep as/rs crane installation ?

In case you need to pick the pallet from C location how is it possible to program the as/rs vehicle to remove pallet A and B and move them to a buffer or a closer location and then take pallet C.

triple-deep.jpg

Thank you.

asrs

triple-deep.jpg (80.2 KiB)

Answer 1 · 2019-03-29T04:53:35Z

Joerg Vogel answered Mar 29, '19

I assume you use several racks on each aisle side. If you use a 3D model logic and a dwell time in the rack your request is really difficult, because of the events by the dwell time. The events have been already set to release the items. If you move an item by a taskexecuter it creates additional events again to be released in the future. Your simulation looks faulty because the item jumps back to the rack whenever a release event occurs.

The approach in such cases is to set a dwell time to 0 and hold the item in the rack. You do this by the Send To Port picklist option Do Not Release Item. Then you can release the item by the command releaseitem(obj item, num port). You release the item when the dwell time elapse or you need to get to an item deeper in the cell.

Your logic will cover which output port number the item is released to in your model.

Leaving the rack aisle
Sending the item to another cell in the same rack
Sending the item to another rack in aisle

Point 2 needs a queue object on the ASRS vehicle which uses a transport (ASRS) with the option preempt only and the highest priority in your rack aisle. The item is released to the output port directing to the queue on the ASRS vehicle and then this queue sends the incoming item to the rack again.

Another logic will set cells to stay empty in the involved racks until an item is unloaded to the right cell.

Answer 2 · 2019-04-23T06:38:12Z

Silai Zeng answered Apr 23, '19

I'm developing a multi-deep AS/RS model. I think this model can answer your question. I didn't use @Jörg Vogel's approach, but his answer helps me a lot. Thank you Jörg.

You can get useful information in Send to Port, Place in Bay and Place in Level(rack). Sorry I use Chinese so that will be some mistakes if you open it with English version.

multideep.fsm

multideep.fsm (40.6 KiB)

Answer 3 · 2019-04-23T21:32:24Z

Fred Kan answered Apr 23, '19

I'd like to add my thoughts; it would be possible to program a shuffling algorithm, however that would be a function of the composition of your inventory. I.e. current state.

I think that how you model this problem is dependent on what you're interested in and what question you're trying to answer. If you're interested in crane performance, I would imagine that you could get away with a simple delay with variance built in.

I hope that helps.

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