topic Re: Double Stacker Crane Problem in FlexSim Forum

Double Stacker Crane Problem

hong_seongweon — Wed, 02 Jul 2025 16:03:32 GMT

What would be a good way for Stacker Crane 1 and Stacker Crane 2 to work without colliding?

Re: Double Stacker Crane Problem

FelixMoehlmann — Fri, 04 Jul 2025 08:33:15 GMT

You can check out the post linked below. The answer contain a model that uses the agent system to detect when two cranes are about to collide and preempts one of them to travel in the opposite direction.

https://forums.autodesk.com/t5/flexsim-forum/crane-collision-logic-with-agent-system/m-p/13506971

In this case the position of the ASRS can be identified by the bay they are travelling to (with 0 and 21 being used for the conveyors). So you could also use a more proactive approach and check the other ASRS' position whenever a task involving the rack is started. If the other ASRS is far enough away from the target position, the task can continue as normal. If not, the task is interrupted and the ASRS has to wait for the other to move away. If the other one is currently idle, a task to move out of the way can be given to it.

Re: Double Stacker Crane Problem

hong_seongweon — Sat, 05 Jul 2025 09:38:42 GMT

Thank you very much for the help.
When the Minimum Dwell Time of the Rack is set to 45 seconds, the vehicles collide with each other.
In this condition, the vehicles do not collide when the order of the ‘Slide Retract Delay’ and ‘Update DestBay Label’ activities are reversed.

Re: Double Stacker Crane Problem

FelixMoehlmann — Sat, 05 Jul 2025 09:59:41 GMT

Good catch! Though in the upper block the order should stay the same. The token moves through there when the ASRS is about to return to the conveyor or sink. The label should only be updated when it actually starts to move (meaning after the slide has retracted). Otherwise the other ASRS might start moving too soon.

In the lower block the label needs to updated immediately, as you said. After switching the order the Delay doesn't serve a purpose and can be removed entirely.