Design of Egg Black Box

wlkoh

Our design lecturer require us to come out with a black box which can differentiate between raw egg and hard-boiled egg. On the black box, there should be one inlet and two outlets (one for raw, the other for hard-boiled).Dimension constraints of the black box is 500mm x 500mm x 500mm. The power source given are 12 AA batteries (only these, no other power source are allowed), while the actuators are 3 motors (specification of the motors is up for us to decide). We have tried several ways to differentiate the eggs. The density of the egg regarding the buoyancy stuff seems not particularly useful as the density of egg is differ from one another. The only effective way we have tested to differentiate them is by spinning the egg. Nonetheless, we can hardly come out with any mechanism to spin the egg by using only three motors (not to mention transport mechanism of the egg that also require the motors). Can anyone please give some suggestions on the way of differentiating the eggs or the mechanism to spin them?

berkeman

Would you get extra credit if you did it without power or motors? Can you think of a way that you could do it without power? I think it should be possible....

dlgoff

12 AA batteries could create a lot of light. Could you tell the difference by the amount of light that can get transmitted through them?

wlkoh

No extra credit would be given, but it would certainly be very nice if able to achieve that.

By the way, the operator is not supposed to interfere with the black box while the process is carried out. In other word, the human/operator can't involved in any part or ways during the process.

berkeman

Do you see where I'm headed with the unpowered mechanism, though?

wlkoh

Not sure if I could get it. Mind to enlighten us?

berkeman

Well, just keep thinking about it.... It's based on the spinning property difference that you already mentioned...

wlkoh

Thanks for your hints. We'll try to figure that out before verifying with you.

wlkoh

Does it utilize gravity during the process?

berkeman

Yes. I'd picture a single ramp in, some tricky passive stuff in the middle, and two ramps out...

wlkoh

Can you mention the components of the tricky passive stuff in the middle there?

Borek

I thought task was assigned to you, not to berkeman

M.D.G

Does the raw egg have to come out of the black box as an unsmashed egg?

Xeplict

You could always try to test the friction of the egg shell

theecoop

what about ohms resistance difference in the 2 types of eggs?

berkeman

The high resistance of the shell would probably dominate, I would guess. Have you tried any experiments? I have some HB & raw eggs in the fridge right now...

wlkoh

We hd tried several other methods. Some of them are mentioned briefly as followed:

Let the eggs rolling down inclined plane - raw eggs roll down faster than hard-boiled one. However this require a long ramp before any significant difference can be observed, which is quite not suitable for our case due to size constraints.

Oscillating the eggs - we hd built a crude model of verge&foliot escapement to oscillate the eggs, and tried to observe the difference in their amplitude. We replace the foliot bar and adjustable weight with only the eggs together with its container(paper cup). Slight difference is observed(hard-boiled's amplitude seems to be A LITTLE BIT larger). But it is uncertain whether there is any difference(No conclusion can be drawn), probably due to two reasons:
-our crude model couldnt gv accurate results
-the paper cup contribute additional moment of inertia in the system

We hd also try to oscillate the egg in pendulum manner, and there is a difference - raw egg stops faster than the hard-boiled. But the string must be long enough, otherwise the difference is not apparent. We r thinking to modify a little on gravity escapement to measure the difference. There r things yet to b overcame, i.e.:
-Method of transferring the egg from the inlet to the pendulum position. After finishing the process, transporting it to the outlet.

Anyone gt any idea fr tht?