Need help with stopping AGV gridlock.

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Claire Krupp asked Jan 18, '23 Claire Krupp commented Jan 19, '23

Need help with stopping AGV gridlock.

I have a large AGV network, and recently added some new spurs for parking. I keep getting gridlock around the area where the parking spurs are. I've tried extra control areas, control points, spacing etc. and this keeps happening:

The AGV on the left has not even reached the next control point, but it has already allocated two path junction points which are further ahead, so that the AGV on the right cannot move out of the spur, even though it has allocated the control point to the right.

Is there any way I can change this "look ahead" allocation behavior? I've tried so many permutations and it just keeps happening!

Thanks.

Software Version:

FlexSim 23.0.1

agv allocation agv gridlock path junctions

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Answer 1 · 2023-01-19T07:33:20Z

Felix Möhlmann answered Jan 19, '23 Claire Krupp commented Jan 19, '23

Anthony's answer to this older post might help with finding a solution.

In short, while the allocation of control points happens on the PreArrival event of the previous control point, the allocation timing of transfer points depends on the "Intersection Stop Point" values that are set for the accumulation behaviour. (The AGV will try to allocate the transfer point at a time, so that i could come to a stop at the specified distance).

Moving the control point at the intersection entry back or reducing the stopping distance so that the control point at the exit is allocated before the transfers should fix the deadlocks.

Alternatively, version 23.0 introduced the possibility of handling deadlocks by returning a 1 in a deadlock "OnAllocationFailed" event.

In this case, you could try to preempt both AGVs to stop at their current control point. Then resuming one and after it has cleared the intersection resume the second one.

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Claire Krupp commented · Jan 19, 2023 at 02:23 PM

Thanks for the explaining how it works @Felix Möhlmann . I'll try to reduce the number of control points and see if that helps.

The deadlock recovery looks possible too, though more complicated!

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Claire Krupp commented · Jan 19, 2023 at 06:26 PM

I took out some control points and moved things around a bit, and now it works perfectly!

Thanks @Felix Möhlmann

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