Ideas to model traffic lanes?

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Fred Kan asked Apr 18, '19 Fred Kan commented Apr 24, '19

Ideas to model traffic lanes?

Hi I'm tasked with creating a model that takes traffic into consideration and wanted to ask if the community had any ideas as to how I may approach this problem.

I've thought about creating a web of network nodes to represent every possible location a vehicle can travel towards, however that seems impractical.

I'm trying to avoid using free traveling task executors and A*Nav because I'd like traffic to flow more orderly.

I'm currently pursuing the idea of using conveyors placed side by side each other to represent driving lanes, however in doing so I find it awkward to create vehicle merges (i.e. changing lanes). I've used the move object command when a vehicle arrives at a decision point, however that results in the vehicle (flow item) effectively teleporting from one conveyor to another, after which the flow item appears to be stuck.

Does anyone have ideas I can try out?

Thanks!

Software Version:

FlexSim 18.1.2

conveyors task executors modeling questions design

· 4

Joshua S commented · Apr 19, 2019 at 07:14 PM

Are you trying to model city traffic, or traffic within a manufacturing plant?

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Fred Kan commented · Apr 22, 2019 at 04:54 PM

Traffic within a manufacturing plant. I imagine it's less chaotic than city traffic.

There are multi lanes but all single direction, and they would merge to designated pick up and drop off locations before leaving. The decision for when a flow item should merge appears to be a challenge. Say for example if the destination is processor 2, should the flow item attempt to merge right before it arrives at processor 2 or should it merge well before processor 1. If it merges too soon it will have to wait and queue behind the flow item in front of it.

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image-01.jpg (248.4 KiB)

David Seo Fred Kan commented · Apr 22, 2019 at 08:27 PM

@Fred Kan

Have you used the NetworkNode object in your model? I am not sure what is your doing, but the networknode can solve your issue.

You can control the passing way using networknode.

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Fred Kan commented · Apr 22, 2019 at 09:31 PM

Thank you all three for the replies.

@Seung Yong Seo I initially tried a web of network nodes, one for every possible stop for the vehicles, but I stopped pursuing that method because I was under the impression that I was getting lost in the woods and that there must've been a better way.

@Claire K Incidentally I was looking into the tutorial for using AGV networks as well since that has a built-in process flow. I tried using area acquire/restrict using triggers with decision points on conveyors with differing results. I'll try AGV's ctrl points and area and see how that goes.

Thank you

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Answer 1 · 2019-04-23T15:33:39Z

Isaac Litster answered Apr 23, '19 Fred Kan commented Apr 24, '19

Hi @Fred Kan

I am not sure if I am understanding correctly, but have you tried adding entry transfers to the conveyors? This will make it so the flow item doesn't get stuck.

conveyor-transfer.gif (2.1 MiB)

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Fred Kan commented · Apr 23, 2019 at 09:20 PM

@Isaac Litster Thank you for the reply and the gif! I'll have to figure out how to make gifs because they seem very useful.

I haven't tried that approach, I didn't know that you can put an entry transfer on the side of a conveyor. I've been going through the manual to try to find how to do it but haven't been able to locate it. Did you create a very thin conveyor to connect the two? My conveyor approached looked a lot like your gif using DPs to decide whether an item should be moved. I used process flow to move object but when the object was moved it was located at the end of the conveyor and it had stopped being conveyed.

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Isaac Litster Fred Kan commented · Apr 23, 2019 at 09:33 PM

You can make a gif using the ScreenToGif app. It's pretty useful!

There is kind of a work around to get an entry transfer. Usually I add a queue next to a conveyor, connect it with an A-connection, and then right click on the entry transfer and remove connections. Then I delete the queue. This way you can select the destination of the Move Object to be the entry transfer.

Hope this helps!

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remove-connection.png (509.9 KiB)

Fred Kan commented · Apr 23, 2019 at 10:14 PM

@Isaac Litster

Thank you for the tip, that will be handy. Screentogif looks very useful and the empty queue trick is clever. I created a model with the side transfer however it appears to let a few boxes through. I'm not sure why, I'll look into it. Thanks again.

transfer1.gif

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transfer1.gif (183.6 KiB)

Answer 2 · 2019-04-22T20:46:15Z

Claire Krupp answered Apr 22, '19

We tried AStar and it worked well except where you want to define specific lanes as you mention. My next approach was to use an AGV Network. That is a much better way to do it. You can easily have merging paths and use Control Points and Control Areas to limit the number of vehicles in a particular segment or area of paths. We used it for Trucks, Buses and People Flow and it works for all cases. (For people you have to "Create Person" at a location which is a Control Point.)

Use the 3D "Task Executer" to represent your vehicles, and just give it an appropriate name and visual that makes more sense than the AGV shown. You also need a different "AGV Type" (in the Network Properties menu) to give different speeds to each type of traffic.

The basic AGV tutorial will get you started.

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