topic Re: Load elevator from 2 conveyors at different levels in FlexSim Forum

Load elevator from 2 conveyors at different levels

amit_k2 — Mon, 30 Mar 2020 15:22:28 GMT

[ FlexSim 20.0.3 ]

Hello,

I decided to add more complexity to the model that you answered here.In the attached twolevel-pickup-groundlevel-unload-3302020.fsm model, I added another set of conveyors on the ground level and replaced the "travel to location" activity with simple "travel" activity to make the elevator travel to top/ground level depending where the pallets arrive first.

Here is what happens, the first set of pallets from the top level are loaded and unloaded correctly. After that the elevator loads pallets from ground and top level and then delivers downstream. The rule is that two pallets that are loaded must come from the same level. To add this functionality a label "Level" is added to created pallets and my thinking was to push them to the list "Ready for Transport" and then pull from this list by creating a partition named "Level".

What should I change? Also which section of the manual should be referred to get an understanding of loading and unloading destinations options when using these activities in the process flow?

Best regards,

Amit

Re: Load elevator from 2 conveyors at different levels

Brandon_Peterson — Mon, 30 Mar 2020 15:57:38 GMT

@Amit K2

Your pull from list was using the level as the partition ID but all of the pallets were not specifying the partition ID so they all looked the same to the elevator. The solution to you problem is a little more complex than what you were modeling. Before we get to that, I made some other changes to your model that were necessary. First, the pallet wait for event activity needed some changes so that the tokens were only released when their pallet triggered the event. The way you had it set up any pallet would release the tokens. Second, I removed the zone from the pallet process flow. I would handle the situation with an area restriction on the decision points not in process flow.

For the answer I modified your process flow so that the pallets would be put on two lists. A secondary and primary pallet list. This allows the process flow to make sure that two pallets are available on a level before the elevator gets notified. The elevator pulls the primary pallet (2nd to arrive) off of one list and then sets it's level to that pallet before pulling the second pallet off of the other list with the partition ID set to the level.

I hope this helps,

Brandon

answer-tlpuglu.fsm

Re: Load elevator from 2 conveyors at different levels

amit_k2 — Mon, 30 Mar 2020 17:40:31 GMT

@Brandon Peterson

Thanks for the crystal clear explanation! Would you recommend using zones instead of decision points if I were to collect statistics?

Best regards,

Amit

Re: Load elevator from 2 conveyors at different levels

Brandon_Peterson — Mon, 30 Mar 2020 18:05:02 GMT

@Amit K2

The reason for taking the zone out was mainly that it was limiting the number of pallets in the zone to 2. So the model would break if there were two pallets in the same conveyor or on different levels, as it would not allow another pallet to reach the front of the conveyor. So you could use the zones to track stats but you would need to use them in a more complicated way if you wanted to limit the movement on the conveyor with them.

Brandon

Re: Load elevator from 2 conveyors at different levels

amit_k2 — Mon, 30 Mar 2020 18:08:23 GMT

Understood! Thank you!