One AGV stays parked, why?

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Peter W8 asked May 22, '22 Jason Lightfoot commented May 28, '22

One AGV stays parked, why?

I'm having difficulties managing my AGV:s. In my model there are 18 stations. The AGV:s should transport the flow items from station 1 to the last station (17) which is connected to a sink. I’m using takt time for the stations meaning that the stations wait for each other before beginning work. So once the last station is ready to receive a flow item an AGV should travel to station 16 and bring forward the flow item to the last station. Now station 16 is ready to receive so another AGV should bring a flow item from station 15. This should repeat itself until all stations have received and are ready to process the flow items. This actually works in the model I've built. What doesn't work is that I've noticed that all agvs are not used at the same time, instead one is parked at a parkpoint for the majority of the time.

For instance, AGV1 has just picked up a processed flow item at station 10 and is now en route to station 11, this means that station 9 is ready to send its flow item to station 10 for processing. AGV1_3 is travelling back to a work forwarding point so he's not yet available for tasking. AGV1_2 is at a parkpoint and available and should travel to station 9 but that doesn't happen. Instead, he stays put. After a long time AGV1_2 activates and begins to transport flow items, however, when this happens on of the other agvs goes into a parkpoint. It's like there's a hidden limit set for 2 active agvs. When I look at a State chart in the dashboard it's clear that AGV1_2 is not utilized nearly as much as the other two.

What am I doing wrong?

EAMR_Base_v_1.5.fsm

Software Version:

FlexSim 22.1.2

agv utilization parking point activacion parked agv

agvs-not-working.png (181.3 KiB)

eamr-base-v-15.fsm (2.1 MiB)

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Jason Lightfoot ♦♦ commented · May 28, 2022 at 10:05 AM

Hi @Peter W8, was the answer or last model 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 · 2022-05-22T21:21:08Z

Jason Lightfoot answered May 22, '22 Jason Lightfoot commented May 24, '22

The job to perform the move to the next station is only generated when the next station's item has been unloaded.

You could try adding a pickup location (queue) after each station and have that generate the transport job.

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Peter W8 commented · May 24, 2022 at 12:19 PM

Hi Jason,

I'm realy grateful for your assistans! I tried adding pickup locations as suggested by you and now it works better. all AGVs activate as they should. However, when I added the pickup locations,I'm having issues with the takt time of the stations. This is something you've recently helped me with. I reused your code & processflow and applied it to this model. It seems that the token label "station" in the processflow does not update, It always stays on "Station_2". This leads to that when the AGVs have transported items from the first three stations all stations automatically sends their flow items to the next station without waiting for the AGVs. Any suggestions to whats causing this? I've attached my model if you could take a look.

EAMR_BASE_1.6.fsm

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issue-with-token-label-not-updating.png (144.0 KiB)

eamr-base-16.fsm (2.1 MiB)

Jason Lightfoot ♦♦ Peter W8 commented · May 24, 2022 at 03:53 PM

The idea of adding a queue between the stations as a pickup location was to decouple the stations and have all the move jobs presented at once. I think you've interpreted that as having pickup locations for the agvs which is not the same thing.

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Peter W8 Jason Lightfoot ♦♦ commented · May 24, 2022 at 08:40 PM

I tried adding queues after each station as you suggested in your first post. that did not work. But now when I read your latest reply your saying that I should use one common queue for all the stations? The latest model I uploaded is based of this tutorial https://docs.flexsim.com/en/22.1/Tutorials/TaskLogic/Tutorial4AGVs/4-2AGVsUsingProcessFlow/4-2AGVsUsingProcessFlow.html. I tried to replicate the use of pickup points in my model. Now everything works except the takt time for the stations. I don't get why that got messed up due to me changing the pick up points? This is the only thing I've got left to solve before being finished with the model. Please help

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