Picking Items into Tote on a Conveyer

[berkayguz]

Hi everyone,

I’m modelling a very common scenario but got stuck at the picking logic. Any hints or support would be much appreciated. I’ll attach the model file in the forum post.

Goal:

I have a rack with multiple sections, and each section is assigned to a different operator. One operator is assigned to only one section.
There is a conveyor in front of the rack, and totes (representing orders, i.e. BoxIDs) move along this conveyor.
Each tote corresponds to a single BoxID and contains multiple SKUs that need to be picked from the rack.

The idea is:

• As the tote moves along the conveyor, it stops at each station (section) only if it needs to pick something there.

• When it stops, the operator responsible for that section should pick the correct SKU(s) from the rack and drop them into the tote.

• Once all SKUs for that station are picked, the tote should resume and move to the next station.

• The process continues until the tote has completed all picks for its order.

So far I have:

• Built the full 3D layout:

  • FlowRack filled using a Source

  • Five operators (Operator1 to Operator5), each positioned at a different section

  • A conveyor placed in front of the rack (Decision Points on conveyor to be added)

  • A queue that spawns totes (orders) onto the conveyor

• Created ProcessFlows:

  1. A Create Orders PF that:

     • Reads the order table

     • Aggregates SKUs by BoxID

     • Pushes to the order list

  2. A second Picking Operation PF, which:

     • Currently breathes, assigns labels, pulls from list, and creates objects (placeholder for now)

     • Intention is to use it for assigning pick tasks to the correct operator per station

• Created Global tables that contains order data and rack assignments for SKUs.

Where I am stuck:

I’m not sure how to continue from this point and structure the picking logic:

• I planned to create one child token per SKU, and assign it the right station, section, BayNum, etc. using RackPlan lookup.

• But I’m confused about what happens next: how to design both process flow and 3D environment for picking operations.

I’m attaching my model (PickingPractice.fsm), along with another example model (pickingstations.fsm) that is similar to what I’m trying to achieve.

I’m new to FlexSim and have been working hard to learn it, so any help or advice would mean a lot. Thank you in advance!

[moehlmann_fe · Accepted solution]

What I will suggest is slightly advanced, but I think the end result is pretty easy to follow and very scalable.

The first thing I did was add one Decision Point to the conveyor for each section and add a column to the "RackPlan" table that links each row (and thus SKU) to one of the DPs.

To create orders, I generate as many tokens as there are rows in the "AggregatedOrders" table (which I changed to be updated on model reset - see its On Reset trigger). I then loop through the SKU array and create a map that stores which SKUs need to be picked per DP. This map is then written to the created box as a label.

The actual picking is controlled by an Object Process Flow with the Decision Points as instance objects. When an item arrives at a DP, the logic checks if there is an entry in the map for that DP. If so, items with the respective SKU values are pulled and a task sequence is given to the operator (referred to by centerport connection) to load those into the box.

[berkayguz]

Thank you!! This was incredibly helpful and performs exactly what I want. And although I'm a beginner it is easy to follow the logic. I also have a quick follow-up question. If I want to have multiple lines operating in the same way, should I create another object process flow for each line or can I just use the existing one by doing the necessary adjustments in it?

Thanks again! I really appreciate your support!

[moehlmann_fe]

That depends. Would those other lines use the same SKUs? Then you would need to find a way to differentiate between multiple DPs per SKU when creating the order token. This could be done by adding one "DP" column per line to the RackPlan table.

If the SKUs are different, then the model should be usable as is.

The Object Process Flow would not need any adjustment in either case, since it just reacts to what is written on the tote's labels.