topic Assigning item to available pickstation conveyor model in FlexSim Forum

Assigning item to available pickstation conveyor model

timon_dj — Mon, 06 Jul 2020 14:36:04 GMT

[ FlexSim 20.1.2 ]

Conveyor pickstation assignment example 20200706.fsmIn my desired model I have a conveyor system with multiple pickstations with 2 pick positions each. A pallet is assigned to a pickstation. It does not matter to which of the two pick positions, as long it is available (zero items at pick position and/or separator).

Two questions:

How can I build this logic?
Is it possible to stack the conveyors going in and out at the pick station on top of each other? In reality it is a two-directional conveyor, so I would like to have the same visual appearance in the 3D model.

The attached model is a simplified version of my actual model, with only 1 pickstation.

Re: Assigning item to available pickstation conveyor model

benjamin_w2 — Mon, 06 Jul 2020 17:10:26 GMT

Hi @Timon de Jong,

Have you tried out the conveyor tutorials? I think they will help you with your model:

https://docs.flexsim.com/en/20.1/Tutorials/AdditionalTools/Tutorial1Conveyors/ConveyorsOverview/

Yes, it is possible to stack the conveyors on top of each other. Just make sure to use the "Join Conveyor" object to connect them to upper or lower levels (I find this the easiest way).

You can also program a 2-way conveyor, although it is a little more complicated. Whenever you want to reverse the direction, simply set the speed to a negative number:

https://docs.flexsim.com/en/20.1/Reference/CodingInFlexSim/FlexScriptAPIReference/Conveyor/#Property-targetSpeed

Re: Assigning item to available pickstation conveyor model

timon_dj — Tue, 07 Jul 2020 15:37:34 GMT

Thanks for your answer. Regarding the first question of mine: I did try out all of the conveyor tutorials recently, but they did not give me an answer for my specific 'problem'. Let me explain it in more detail:

Every pickstation has two exit conveyors running towards it from the main conveyor (called 'pick positions'). If the first is occupied, the logic behind the whole conveyor system should send the item to the second one. Or vice versa. So item x is send to pickstation 1 and when it arrives at the first pick position it should determine if it is occupied or not (that part is clear to me). When occupied it should be send to the second pickposition. How to do that is my actual problem. Can you give me any direction for that?

Re: Assigning item to available pickstation conveyor model

tanner_p — Thu, 09 Jul 2020 16:25:38 GMT

You might try adding a Send Item By Case function on the Decision Point that checks to see if the first pick position is empty. If so, it will send the item to the first station. Otherwise, it will send the item to the second pick position. I added this to your model based on the assumption that the two short conveyors are the pick stations and the logic is correct as shown in the picture below.

conveyor-pickstation-assignment-example-20200706 (1)_1.fsm

Re: Assigning item to available pickstation conveyor model

timon_dj — Tue, 14 Jul 2020 15:15:18 GMT

This brings me one big step closer the final solution, thanks! However, I need one additional condition. To clarify this I modified the model with an extra pickstation (attached).

The Send by Case does check for all passing items whether the connected Pick Position 1 is available or not. If not, it will send it to Pick Position 2. That works great, but it does not check whether the item needs to be at that specific Pick Station. Is it possible to add that condition to the Send by Case or another method? Like this:

IF item label corresponds with Pick Station number

THEN send it to available Pick Position that belongs to Pick Station

ELSE pass item through

Because multiple items with multiple destination Pick Station labels may be on the same conveyor line it needs to check the Pick Station assignment label on the item.

Hope you understand my comments and are able to give me the last help to the final solution.

Conveyor pickstation assignment example 20200714.fsm

Re: Assigning item to available pickstation conveyor model

tanner_p — Tue, 14 Jul 2020 16:47:47 GMT

@timon.dj,

I updated the logic according to what you described. The first thing that the DP looks at is the Pickstation label. If it is 1, it sends it to the first station. If 2, the second. Then, the logic checks to see if that Pickstation is full. If so, it switches it to a different Pickstation.

conveyor-pickstation-assignment-example-20200714_1.fsm