Crane offset error when picking up a Flow Item

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Jason Merschat asked Aug 17, '17 Joerg Vogel edited Aug 18, '17

Crane offset error when picking up a Flow Item

The Crane TE has canned logic described as: "If there is an involved flow item for the offset travel task, then the crane travels so that its x/y center and z base arrive at the top of the flow item, or in other words, it increases the arrival z location by the z size of the flow item."

This seems to work for the drop off into a queue, but not from picking out of a queue even when the picking rule for the Queue is LIFO. This seems like a bug...

If this is not a bug but a design flaw can we get that to dev.

In the interim is there a way to set the pick height i.e. the crane hook height to grab the top flow item to the z-value of the top flow item currently in the queue?

Using 17.2 Beta

Software Version:

FlexSim 17.1.4

crane lifo

Answer 1 · 2017-08-18T13:38:16Z

Phil BoBo answered Aug 18, '17 Joerg Vogel edited Aug 18, '17

Can you post an example model or video that shows the issue you are seeing?

Everything seems to be working fine to me. See the attached model showing the crane picking up an item from a lifo queue where the crane travels so that its z base lines up with the item’s z top.

crane-loading-from-lifo-queue.gif (6.8 MiB)

crane-picking-from-queue.fsm (17.4 KiB)

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Jason Merschat commented · Aug 18, 2017 at 03:57 PM

Hello Phil, I have changed the arrival schedule for your model and uploaded. Watch the 1st pick. I am having an issue where I modify the box shape and it acts as if all of my "slabs" are on the bottom level of the queue... crane-picking-from-queue-jam.fsm

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crane-picking-from-queue-jam.fsm (17.4 KiB)

Joerg Vogel Jason Merschat commented · Aug 18, 2017 at 04:24 PM

At the time the first item enters the queue, the queue dispatches the transport tasksequence. And the crane hasn't got a sorting algorithm, which tells him to wait a distinct time to collect transport tasksequences and then work on the last entered tasksequence. He sorts the taskseqeunces in fifo style. If you want to get this done right, you can give the crane on reset something to do and wait 1 second. Then all tasksequences are in the cranes taskseqeuncequeue and you can sort them. If you set the priority ascending of the receiving tasksequences then the crane starts with the tasksequence which is the highest in the tasksequencequeue.

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Jason Merschat Joerg Vogel commented · Aug 18, 2017 at 04:29 PM

OK so essentially, don't trust LIFO setting, just do it through coding. This is disappointing. One would expect that on arrival to make the pick it would assess the queue state. This functionality should be re-written correctly. What other canned functions should I be wary of?

Like you said it's simple, but not at all intuitive or realistic. This is a problem from the developer to user perspective that must be bridged.

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