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Let's say I have a bag full of sugar candy. Some will be whole, some will be dent, some will be broken (in part, or half, etc). Let's say I have a device with an input box where I empty the bag, and the device has two output boxes where it start placing the whole candies in one box, and all the dented/broken one in the other box. What principle of the physic could use the device, to be able to tell the whole candies from the dented/broken ones?

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closed as off topic by Waffle's Crazy Peanut, Manishearth Dec 20 '12 at 7:37

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This reads like a homework question. – user1504 Aug 21 '12 at 14:10
Instead of Physics, you could use Artificial Intelligence in Computer to identify your candies... – Waffle's Crazy Peanut Aug 21 '12 at 14:28
It's a real case scenario, and I will need mostly to build a mechanic device (or with some simple electronics) able to handle this job. I get the big bags from the wholesaler, but during the shipping of the bags, some of the candy broke or get dents. before selling them to my customer, I need to keep only the whole ones. – Terix Aug 21 '12 at 15:50
The problem with this questions, as I see it, is that it is not fundamentally a physics problem. You need to talk to a industrial engineer. ::pauses for everyone to make their favorite joke at the expense of industrial engineers--even the civil engineers:: Yes you, said "What principle of the physic", but the fact is that the problem isn't identifying the physics (it's just weight and shape after all), but figuring out an efficient, accurate, functional and cost effective way to do it. – dmckee Aug 22 '12 at 3:52
up vote 2 down vote accepted

The mechanism you would use to identify the candies would be one of computer vision (which is off topic for this site try However, the exact mathematical method you would/could use to determine the broken candies from the okay ones depends on the shape of these candies. Lets say for arguments sake that they were spherical; in this case you would use the Hough Transform to determine which once were broken etc.

I hope this is of some help.

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For the broken ones, weight will work. For the dented ones, you have a much harder problem, particularly if you consider arbitrarily small dents.

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For the broken ones, weight works, as Jim Graber says. For the dented ones, you should design a slide that rolls the candies along, and separates the ones that roll smoothly into a track and the ones that don't into a separate track. The rolling requires some symmetry of the candy, but it will snag the bad ones.

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