How to avoid deadlock between AGVs

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stefano L asked Nov 3, '19 stefano L commented Nov 5, '19

How to avoid deadlock between AGVs

I have set up a model with two AGVs that are supposed to transfer boxes between queues. Unfortunately the model works well at the beginning but it seems to not work as expected after a while due to a deadlock error.

I get a deadlock where the AGV arriving from one branch gets the next control point's allocation, but the AGV from the other branch gets a point on the path, so I get a deadlock error as reported in System Console.

In the Process Flow I try to elude deadlock using "Travel to bypass temporarily deadlock" activity, but it is just a temporary solution to the problem.

I attached the model that eventually shows the error:

deadlock.fsm

Could you tell me if you have an idea on how I can fix the problem in order to avoid this situation?

Thank you.

Software Version:

FlexSim 19.0.0

agv agv network deadlock

deadlock.fsm (59.6 KiB)

5 |100000

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 · 2019-11-04T14:15:34Z

Alessio Merlo answered Nov 4, '19 stefano L commented Nov 5, '19

Hi @stefano L,

to solve your issue I suggest two ways:

1. Create a circular agv path. I never saw an agv system where in a main loop the agv run in both direction. Sure somebody in the forum could disappoint. This is my first solution (deadlock-sol1.fsm);

2. Create an exchange area. This is typical solution to solve this issue, but it isn't easy to configure because for each couple of control point you need to implement a "way point". This is my second solution (deadlock-sol2.fsm).

In the second solution you need to configure the rule to deallocate the control point and the area according to your implementation.

deallocation.png (10.5 KiB)

deadlock-sol1.fsm (60.2 KiB)

deadlock-sol2.fsm (61.2 KiB)

· 1

5 |100000

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

stefano L commented · Nov 05, 2019 at 08:38 AM

Thank you @Alessio Merlo for your precious advices!

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