Truck versus Trailer

[Bernd Welter]

Hi there,

a player wants to use com.ptvgroup.xserver.xload.PackBinsRequest to modell the transport via a truck/trailer combination, so he would use two com.ptvgroup.xserver.xload.BinType objects and the items should be dispatched over the bins by xLoad.

• Does it make sense to use the unloading sequence for the com.ptvgroup.xserver.xload.Stop ?
• In an older post I mentioned that the unloading sequence does not work with more than one bin. Is that correct?

From my understanding the purpose of the unloading sequence constraint should ensure that the unloading of a particular bin maintains two (or more) independent stacks: I don't want to unload items from BIN(i) to get access to the next delivery item (in the same bin) and then reload the blocking items.

Bernd

[Yann Bartesch]

Hi Bernd,

Indeed, it is not possible to use an unloading sequence constraint with several bins.
Actually there are several possible behaviours for this constraint.
Considering 2 bins, these 2 behaviours can be expected:

1/ we could want to get all first items in the first bin ; all the others in the second bin.
For exemple:

• Bin 1 > Order 1, Order 2, Order 3
• Bin 2 > Order 4, Order 5, Order 6

What if the order 3 can not completely fit into Bin 1 ? Should it be splitted between bins ?

2/ we could want that the algorithm take care of the sequence, whatever the bin
For exemple:

• Bin 1 > Order 1, Order 4, Order 5
• Bin 2 > Order 2, Order 3, Order 6

In the current implementation, the behaviour of the unloading sequence with multiple bins is undefined.
That's why, it has been restricted to the use of 1 bin.

[Bernd Welter]

Well, thanks for the answer, Yann.

I also wondered whether some item (or group of items) would have to be partitioned. Sounds similar to tour optimization:
If "40 palettes" do not match a single truck one would have to cut the overall number of palettes into smaller chunks via client logic.

At least I now know that the unloading sequence story does not work with multiple bins.
I'll share that with the partner in crime,

Merci beaucoup!

Bernd