Seeking advice to automate counting of objects on pallets

As a "paper exercise," weighing pallets is a reasonable approach. Assuming you know the individual case weight and non-case weight (e.g., pallet, cardboard, etc.), calculating number of cases from scale weight is straightforward.

In the "real world" you will have to deal with scale performance -- accuracy and repeatability -- over the range of gross pallet and case weights to verify if you can reliably resolve an individual package. Then there is problem of knowing the case weight -- will this be provided by the supplier, and be reliable, or will you have to take one off the pallet and weigh it? And then pallet and other packing variables. And calibration.

There is also installation of a platform scale. Will it be level with the floor? If so, it must be capable of the total weight that may be driven over it: maybe the full weight of a forktruck, depending on where and how it is installed. If raised, it is at risk to be hit by a pallet or other object.

In my experience, assuming you cannot get suppliers to provide assistance such as RFID tags, weighing pallets may be your least worst option. Machine vision will be tricky if having to deal with the variation shown in the original picture.

@ Mispeld,
In this case unloading from the truck will be done via conveyors, the "Book Idea" is to integrate the scales(Sensors) in the conveyor and measure weight of individual pallet.

I think availability of material data should not be a problem where high end Warehouse Management System is installed.

Hoverer said:

@ Mispeld,
In this case unloading from the truck will be done via conveyors, the "Book Idea" is to integrate the scales(Sensors) in the conveyor and measure weight of individual pallet.

I think availability of material data should not be a problem where high end Warehouse Management System is installed.

Click to expand...

This sounds like a "check weigh" application, but on a scale (size) larger than my experience covers. There are off-the-shelf solutions from companies like Mettler-Toledo, which may have been mentioned earlier. These can be very effective if designed for the range of weights and footprints. The latter should not be too much of an issue because you should know the largest pallet size.

Again, accurately knowing the case and tare weights will be important, particularly if variation is on the order of the individual case weight. I guess I just have less confidence in the information provided by suppliers.

There would be a so called "Master Data" where the ideal weight is saved and which would be the benchmark against which the actual weight would be compared to.

Here the possible issue would be,
Pallet matching the overall weight and variations with respect to case.

Even this is not identified in manual counting process,
If am not wrong !!

IF:

1. the height of the skid is known and
2. the height of the stack can be determined (vision system or height measuring equipment?) and
3. it is known how many items are loaded on each level for a given product,

it would be simple math to get a total of items per skid.

.02

Doug-P said:

IF:

1. the height of the skid is known and
2. the height of the stack can be determined (vision system or height measuring equipment?) and
3. it is known how many items are loaded on each level for a given product,

it would be simple math to get a total of items per skid.

.02

Click to expand...

Yes, in my experience item #2 is less complicated and expensive than check weighing; for example using a fixed-mount laser displacement sensor over the conveyor.

And I would consider skid height (#1) and layer height & count (#3) more reliable Master Data than corresponding weights. But this last point is debatable depending on the industry and suppliers involved.

.04

After doing a bit of research,
Height detection by MLG - 2 sensors from SICK,
Weight detection by Siemens PLC series which converts weight to number of cases, the only problem with weight detection is the varying weight of wooden pallets.
--
Any idea how to dynamically detect weight of wooden pallet ?

Thanks

Hoverer said:

Any idea how to dynamically detect weight of wooden pallet ?

Thanks

Click to expand...

Not really, unless weighed prior to loading and tracked throughout.

If (Maximum Pallet Weight - Minimum Pallet Weight) < Load Unit Weight then you could ignore the pallet weight differences.

Are there different pallets for different products? Is it something like oak pallets vs. pine?

The most reliable way to do it would be to have the pallet weighed prior to filling by the other company, and have the weight data encoded in the product barcode or similar. But that doesn't really look feasible based on your previous statements.

Go with barcode and scale

Install a barcode reader to ID the product as it rolls on scale.
Weight the pallet
Subtract the average empty pallet weight.
Divide the result by the known weight of 1 box.
Result is number of boxes on pallet.

NOTE; This works as long as someone updates the database of products, which don't usually happen.

You can use laser distance sensor and measure from fixed top position. If you are using EURO pallet, it is standardized, and your product has fixed height, so it should not be a big problem.