AGV feature forklift - using AGV module

[christoph_gruber]

[ FlexSim 19.1.2 ]

Hi all,

I´m using the AGV module with TaskExecuters in the libary (a AGV not a Transporter). But my AGV´s need the behavior like a forklift (like a Transporter travelling backwards). So my question: How can I edit this behavior at my AGV?

[joshua_s]

If you set the path to being two-way, it will travel backwards depending on how you set it up, but can you give a diagram or sample model to show more what you are trying to do.

[christoph_gruber]

Hi @Joshua S

sorry for misunderstanding. I need an AGV with a fork. Because my AGV should pick up a pallet from a conveyor (1m high). In my model enclosed there is another problem - the AGV (unfortunately without a fork) doesn´t pick up the pallet from the conveyor. There is no flag “use Transport” on a conveyor or on a DC-Point.

Flexsim Version 19.2.4

agv-handover-conveyor.fsm

[ralf_gruber]

Christoph,

I did not look into the model, but the flag will be found on the exit transfer of the conveyor.

Ralf

[joshua_s · Accepted solution]

@christoph gruber

I made some changes to the model. You can actually replace the AGVs with Forklifts, but due to the kinematics of the AGV system, they won't lift or drop their forks, you have to add animations in order to do this. I've added the necessary changes, but for some reason when I replace the AGVS you had with forklifts, or even just normal AGVs, then model gets stuck, so I don't know what else you did or other connections or references to the AGVs the model needs to get it running right. I can help again on the animation part if you need it.

23990-agv-handover-conveyor-2.fsm

[christoph_gruber]

@Ralf Gruber

I don´t have a exittransfer of the conveyor. I put the item on a list with a DC-Point.

Chriss

[christoph_gruber]

@Joshua S

In my model enhanced, only with the queue in front of the conveyor and normal AGVs, the model don´t stuck!

agv-handover-conveyor-1.fsm

Maybe there is a misstake in your AGVs with fork you built, even the two AGVs are different. One AGV drive with the fork backwarts (it´s ok) and one with the fork in front!?

[joshua_s]

With your model the AGVs rotate themselves, and so will the forklifts. You need to set the paths to only travel forward to get them to do that.

[christoph_gruber]

@Joshua S

ok, thank you for the hint. I canged the parths and the AGVs now going the right direction.

But nevertheless I´m totally confused!

Now I delete all unimportant objects in my model enhanced to find the problems! The model contains only the 3 Handovers and the 2 Pull-Queues. See the picture below.

• 1.Problem: If I disconnect your Source (Lift and Drop in the AGV module) the model don´t stuck. If I connect your Source there is an error message “AGV doesn´t find the destination” – I can´t understand, because the AGV is on the right place and the queue (Handover_56) is connected to the CP-Point (DropOff55) as a location! (Also the fork doesn´t work until this time!?)
• 2.Problem: Suddenly the Transporter1 doesn´t pick up items from MatGenerating_Process2 – I don´t know why? (normally FIFO) ; Because of the conveyor?
• 3.Problem: Suddenly one of the AGV is at the parking position and do nothing while a lot of items are in the handover queues! I only use the standard AGV-Modul and a pull-logic as described in the tutorial.

agv-handover-conveyor-2.fsm

[tanner_p]

@christoph gruber,

I apologize for the lack of activity on this question for the last couple weeks. I'm not sure if you still need help, but @Joshua S is out of the office so I thought I'd add my input.

I think the first problem is happening because the Source is creating two tokens for each arrival that happens at DropOff55. The second token is unable to travel to where it needs to because the first one has already completed the task. That's about all the help I can offer on the first one.

As far as I can tell on the second problem, Transporter1 is picking up items from both MatGenerating_Process1 and MatGeneratingProcess2. It stops eventually because everything gets blocked, though.

The last problem might happen because of the waste handling part that has been added to the Process Flow for AGVs. Otherwise, I don't see why the AGV is not being pulled from the list.

[christoph_g5]

Hi @tanner.p

thank you for answering. Sure, I still have problems to find the right solution for my problem and to use the AGV module.

Regarding Pos. 1, what is the solution, to destroy every second token?

Regarding Pos. 2. I´m not really understand why Transporter 1 only work for MatGenerating_Process1 since all handovers are not available! The item from MatGenerating_Process2 was totally ignored also if one of the handovers is free! Is it why MatGenerating_Process1 has a higher rank in the tree?

Regarding Pos. 3. No, the waste handling part could not be the reason! If you delete this part you have a standard agv-module and the problems are the same! Much more, I figure out, the problem is that only one queue (Queue_pull_1, process for cylinders) are pulling items from the list "ReadyToTransport_List"! And so only one after one order is push to list "Local Partitioned Load List"! That´s it. But I ask myself, if the pull logic is described in the tutorial usable for the agv-module? In my case, a lot of items waiting on the handovers, you have two AGVs, but only one is working - this could not be!

Thanks for helping in advance

[tanner_p]

@Christoph G5

I think the reason why only one Transporter was functioning is linked to why the MatGenerating_Process2 wasn't sending items. Fixing one thing seemed to fix the other.

I found that adding a "Round Robin" pull logic in each of the queues allowed both of the MatGenerating Processors to work. This forces the queue to alternate which processor it is pulling from when the queue becomes available.

I think that you were right and that the queues were pulling based on the input port rank.

Additionally, I think that the problem with Transporter57 was possibly because the items were blocked in the Handover area. By adding the Round Robin pull logic, both transporters now work all the time. Maybe one of the items was supposed to be allocated to Transporter57, but it couldn't. I'm not sure. Hopefully this little updated model helps, though!

agv-handover-updated.fsm