Elevator's redirect CP cannot work

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Steven Chen asked Jul 28, '21 Steven Chen commented Jul 29, '21

Elevator's redirect CP cannot work

Dear everyone,

As you may see in the attached model and picture, the TaskExecuter1 AGV marked as red cannot get into the elevator after being redirected, but the other can work ordinarily. I have connected a dispatcher and the two elevators with the ElevatorRedirectCP and ElevatorFloorCP functions.

I do not know how to fix although I have tried many ways. It will be great if you may offer any suggestions or methods.

Thank you for your time and patience

Test Model of AGV Elevator.fsm

Software Version:

FlexSim 21.0.6

agv flexsim 21.0.6 agv elevator redirect

1627438969275.png (227.3 KiB)

test-model-of-agv-elevator.fsm (82.8 KiB)

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

Answer 1 · 2021-07-28T11:21:02Z

Felix Möhlmann answered Jul 28, '21 Steven Chen commented Jul 29, '21

The issue is that the AGVs will always want to travel to control point 11, as that is the closest one connected to Queue4 from Queue2. Because they are connected to a dispatcher, the elevator process flow assumes that both elevators allow travel to the same destination, which is not true.

The control point at which the AGV will exit an elevator is based on the distance to the destination cp. When elevator2 is acquired, its closest elevator floor cp to cp11 is actually the one on the top floor! As as result, the AGV will exit the elevator again on the top floor, reevaluate the original travel task and then travel to Queue4 via the vertical connection.

Either create a connection between the paths on the bottom floor so both points can be reached from both elevators or delete the dispatcher to force the AGVs to use the correct one.

In the latter case they will always use the first one though, because it is the closest route between the queues. To fix this, you could add separate queues to each path on the bottom floor that connect to one central queue and send the items from Queue2 to one of the possible destinations by some logic (Round Robin would be a simple example).

separatequeues.png (211.5 KiB)

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Steven Chen commented · Jul 29, 2021 at 02:08 AM

Hello Felix,

Thank you for your clear explanation and helpful method.

After applying your solution, my model can work now, with elevators correctly transporting AGVs to their destinations through their control points.

Since connecting a dispatcher with AGVs in such a model is one tutorial on the official website, I think this may be a common issue that people who try to do simulations like this may encounter.

Assumably, the elevator process flow might be designed for a closed-loop AGV path. That's because the problem will be gone if the two paths on the bottom are connected, as you mentioned previously.

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