Robot Logic Implementation for Pallet and Box Handling

[Pooja_inde]

Dear Team,

I’ve implemented the logic for handling one box, and it’s working as expected in the model.
However, I’m encountering an error when the robot tries to pick the second box and place it on the next available pallet.

Summary of the intended logic:

• A pallet arrives at the station with 2 boxes.

• The robot picks one box from Station 1 and places it on the first pallet.

• Then, it should pick the second box and place it on the next available pallet.

• These two pallets should be combined at the combiner point station, where the operator will work on them together.

• If no pallet is available, the robot should wait and not pick any box.

• Please do not use a queue, as it leads to accumulation of boxes at Station 1.

I’ve attached a reference for further clarity.
Could you please help identify the issue or suggest a better approach for this logic?

[joerg_vogel_HsH]

A robot is not a processor in meaning of FlexSim’s Class objects. It belongs to the Class Taskexecuter. This means it supports a transport of items from objects to other objects. And this leads to the fact, that if you want to let transport an item, the item must be able to be moved by a task sequence. And this is only possible if your sending object has released the item and a receiving object is capable to let enter this item. So actually not the Roboter decides what to do. It is more a decision of a sending object, if the item will get to a receiving object. 
The restriction of not using a queue is not reasonable, because you can prevent a queue from entering items or restrict number of items being queued. 

[Pooja_inde]

Thank you for the response.

I have developed a model to implement the combiner logic as discussed. In this setup:

• Two pallets transfer into the combiner and align beside each other.

• The robot places one box on each pallet.

• Once placement of both boxes is complete, the cycle time begins.

Currently, I have successfully implemented the logic for one box and pallet.

However, I’m encountering an error when the robot attempts to handle the second box and pallet.

Please find the attached model for your reference.

Your inputs on resolving the issue with the second box would be appreciated.

[moehlmann_fe]

You just need to push all items on the pallet to the list instead of just the first.

Due to how the timing currently works out, the process time of the Combiner and the transport of the second item actually happen in parallel. I moved the "Breathe" and updated the Custom Code activity to be responsible for adjusting the location of the second pallet to fix this.

[Pooja_inde]

Thanks for the response @moehlmann_fe 

Can we modify the model as per below process?

1. Both pallets arrive at the combiner simultaneously (side-by-side).

2. The robot picks and places boxes — one on each pallet.

3. Once both placements are complete, the cycle time starts (e.g., for the operator to work on both units together).

[moehlmann_fe]

1. Create a copy of the pallet flow item that contains with a second pallet as subnode by default.

2. Run the Pull from List -> Load -> Unload flow twice, once unloading to the pallet and once to the first subnode of the pallet (the other pallet)

3. Place a Decision Point ahead of the station and handle loading the boxes there. This is the only way of preventing the operator from being called prior to both boxes having been moved.

[Pooja_inde]

Hi @moehlmann_fe ,

Thanks for your response!

Looking at the current model (as per the image above), I noticed that it only accounts for a single pallet entering the system.

Would it be possible to modify the model to reflect the following process?

• Both pallets arrive at the combiner simultaneously (side-by-side).
• The robot picks and places boxes — one on each pallet during the same cycle.
• Once both placements are complete, the cycle time starts (e.g., for the operator to work on both units together).

This adjustment would better reflect our actual process and help align the simulation with real-world operations.

Note: Since the pallets will separate later in the process, they cannot be modeled as a single flow item (i.e., double pallet). Each pallet should remain an individual entity in the simulation.

Please find attached model.

Let me know your thoughts!

[moehlmann_fe · Accepted solution]

The two pallets are still individual items that can be separated. Otherwise it would not be possible to unload to one or the other specifically. But if you want to keep them as separate items throughout, maybe have a look at the logic in the linked post below. It has pallets move on a conveyor and uses two decision points to wait for two pallets to be available.

https://forums.autodesk.com/t5/flexsim-forum/combine-and-seperate-on-conveyor-station/m-p/13734822#M...

Also, items can't move side by side on conveyors in FlexSim. At least not while retaining proper accumulation that keeps items from overlapping. For that you would have to place one as a subnode of the other.