question

José Antonio MD avatar image
0 Likes"
José Antonio MD asked tannerp answered

A*: Deallocation Time Offset

allocation-astar.fsm

Hello,

I have a problem using A* and Deallocation Time Offset in an AGV problem. (I cannot use paths).

My problem is the distance between AGVs: AGVs in movements have a minimum distance (I can solve this using the time offset), and if an AGV stops the others must stop in the closest node.

The problem is when AGV1 stops, AGV2 works fine, but AGV3 stops too far away because AGV2 does not do the deallocation.

Thanks in advance.

FlexSim 19.1.2
agvastar navigatorallocations
allocation-astar.fsm (24.9 KiB)
5 |100000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

1 Answer

tannerp avatar image
0 Likes"
tannerp answered

Hi @José Antonio MD,

AGV1 deallocates the node because it has completed its travel activity. For AGV2, the travel task is still underway, but it's been interrupted. With that distinction, we can assume they will behave differently.

That said, if you need to adjust the distance at which AGVs will stop in relation to each other, you could maybe try adjusting the node spacing or turning off collision detection altogether. I don't think the current situation would change the model behavior that much.

Is there a reason you can't use AGV paths? There's more flexibility for deallocation there...

· 4
5 |100000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

José Antonio MD avatar image José Antonio MD commented ·

Hi @Tanner Poulton,

Thank you for your help.

I know the advantages of using AGV paths (I usually use it). However is not possible in this case, because A* system is similar to the real behavior of AGVs and a customer requirement.

This is a simple example, but my problem is the distance between AGVs in movement have to be larger than parked.

For example, they should have 6 meters for security in movement (so when AGV1 starts its movement, AGV2 must wait until the distance will be enough) and they can stop together (if AGV1 stops (loading, collision, etc.), AGV2 can stop next to the AGV1). I am not sure if the results will be affected, but visually it can be a problem.

This logic can be implemented in AGV path system, but It is possible in A*?

Thanks in advance.

0 Likes 0 ·
Benjamin W2 avatar image Benjamin W2 José Antonio MD commented ·

Hey @José Antonio MD,

Can you post your model so we can take a closer look? I think we will be able to help you better if we can see it.

0 Likes 0 ·
tannerp avatar image tannerp José Antonio MD commented ·

Hi @José Antonio MD,

I apologize that I never got back to this question and it fell through the cracks. To answer your question: The behavior you're looking for isn't easy to achieve in A*, and I'm not sure it's even possible.

If the customer is set on using A* instead of the AGV system, they must understand it well enough to know the behavior. My recommendation is to go with A* if you want the visuals and go with AGV if you want the results.

0 Likes 0 ·
José Antonio MD avatar image José Antonio MD tannerp commented ·

Hi @tanner.p,

Thanks for your reply! As you know, sometimes it is challenging to transmit some limitations, but I will continue with your advice. Thanks again!

0 Likes 0 ·