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Adil M avatar image
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Adil M asked Jeanette F commented

Picking strategy from conveyor and offset travel empty logic

Stnadard work Final Grab 2 and go Stratergy.fsmI created a model to mimic a picking strategy, as boxes are coming down the conveyor they are to be scanned and placed onto a pallet position dependent on label "type".

1. The model runs fine for some time but then gives an error at around 11:40 am. Not sure why its giving an error. The pallet(queue)

2. The pallet(queue) at the end of the conveyor is supposed to get packages that were not "picked" by operators. I've noticed the operators are not picking the packages from that queue even when they are ideal. Is there something I can do to make them pick the packages from that queue and place it onto the correct locations?

3. I'm collecting state statistic for the operators. I was wondering what's the difference between travel empty and offset travel empty? I see that I can deselect the travel offset for load/unload tasks but wasn't sure what that means. When i tried deselecting it I could not see a difference in the operator movement but the state did not show "offset travel empty" anymore. If I want to collect data on how much time was the operator travelling empty, what's the best way to do it?

FlexSim 21.2.4
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stnadard-work-final-grab-2-and-go-stratergy.fsm (75.7 KiB)
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Ryan Clark avatar image Ryan Clark commented ·

Hi @Adil M, 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.

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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Jason Lightfoot avatar image
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Jason Lightfoot answered Jeanette F commented

1. Queue182 is set to use the centerObject for transport but none is connected.

2. The first item enters the queue at 1170.12 secs (created 1132.28secs). It travels down and all operators are busy so do not collect it. Are you saying the operator should take it from the queue also? You have no output puts from the Queue195 at the end of the conveyor.

3. The task sequences are typically comprised of Travel tasks to fixed resources and Load/Unload tasks for items. The travel tasks record the travel time as either Travel Empty or Loaded while the load and unload tasks record travel time as Offset Travel. The navigator determines how to interpret the Travel tasks and the task executer handles the remaining offset travel for load tasks. The switch between the two states is determined by how close the navigator manages to have the TE travel to the "destination" before it hands over travel to the TE. When you select "Do not use travel offsets for load and unload tasks", you'll see the operator walks only part of the journey to the item and then the item is loaded from that position.


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Adil M avatar image Adil M commented ·
Thank you! The idea of the model is to calculate travel time empty v travel time loaded totals. I don't really want the model to separate travel empty and offset time empty separately, similarly for time loaded and offset time loaded I rather have them together. The next phase of my model would be having operators mimicking zone picking where they can only pick packages from a certain zone on the belt. I wanted to compare both the scenarios to see which one is better. Is there a way I can get these states as totals, instead of having them separated?
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Ryan Clark avatar image Ryan Clark Adil M commented ·

Hi @Adil M,

I made some modifications to your model to reflect the notes that @Jason Lightfoot made earlier and to get the statistics the way you want it.

  1. I removed the center port connection from Queue182.
  2. I connected Queue195 at the end of the conveyor to the rest of the queues just as a guess to what you wanted to do. The operators currently wait until the queue reaches a batch of 70 items before letting the operators go pick those boxes, but you can change that as needed.
  3. I added a Process Flow to your model to provide a workaround to get the statistics you wanted. In the Process Flow, I have an Event-Triggered Source that triggers when any of the operators change state. Then, if the new state is Offset Travel, then I have it manually switch the operator's state to the "non-offset" version of travel, so it should be gathering the stats you want now.

I hope this helps! Let us know if you have further questions!

stnadard-work-final-grab-2-and-go-stratergy-rc_2.fsm

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stnadard-work-final-grab-2-and-go-stratergy-rc-2.fsm (90.3 KiB)
Adil M avatar image Adil M Ryan Clark commented ·
Hi Ryan, Thank you so much for going ahead and making the changes to the model to what I requested. I had a few clarifying questions


1.) The packages are going to all the pallet location(queues) instead of the 34 location it should be going to using the percentage breakdown from the inbound table.


2. The throughput for the operators seems to have reduced now. Its around 155(avg) for the model that I shared and only around 130(avg) for the model you shared.


3.) Another point to notice is that once queue 195 fills to the stated number the operators start giving it priority over the packages coming on the belt. I wanted a case where the priority is given to the packages coming on the belt and if the operator is ideal than they should go and pick from queue195.


4.) Even thought the capacity of the operators is set to 2 I'm mostly seeing them picking only 1 package from the conveyor. This is leading to operators missing picking packages as they all picked 1 each and the 5th package ended up in queue 195. Is there something I can do to make sure that a pick-2 and go strategy is more strictly adhered to?


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