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I have ever seen a gambling machine, that dices could be controled by the machine.
It means the machine could decide the result after throwing dices.
Do you know how it work?
How to make it?

Appreciated.

Perhaps you could clarify your question David.
Have you googled your inquiry?

my question is "how to decide the value of dice after throwing".
I guess maybe there is magnet in the dice.

But, the dice has 6 faces.
How to use magnet to decide which dice toward upside?

So you're trying to make loaded dice?
Google that.

No, he's asking how to tell which side of the die is up AFTER it's been thrown. It's an interesting question.

The first thing that comes to mind is IR-transparent (but visible-opaque) dice that have an IR led and a 6-position 3-axis encoder inside. The die would flash a code depending on which position was active (which side was down). Could be done with some clever machining and a ball-bearing inside.

Alternately, I guess you could try for some eddy-current detection thing where each face of the die was made from a different alloy or simply had grids of metal with different spacing on each side. That would make for much cheaper dice. But I'm getting out of my league here

Other thoughts?

well, I'm not sure if we are talking about your standard dice or not....

if we are talking Hacked dice... you could put accelerometers in the dice to tell what side is up and slap a RF device to it..should do the trick. This is similar to Engineer1138 idea. I have never seen anything like this..

If you are talking about reading the result of a standard dice "looking straight down on it" i would try image processing with some edge detection. Doing it this way could be very interesting... you could use the same project for other neat designs..

To answer your question better david we would still need more information.. do you have a link on what you saw?

If this is a real machine, I would think they use a small camera to look at and score the dices. The same way they score the pins in a bowling machine. Doesn't take too much software to recognize the result, with proper filtering.

TOK

I repeat my question again.

I have ever seen a gambling machine in casino when I was a child.
This gambling machine is trick, dices result could be decided BEFORE throwing.
It means the dices could be decided which side is up by computer, gambling machine.

I have ever seen a special and accident situation that the dices (5 dices) rolling down on the flat table, one of dices reserves to opposite side, such as 1 to 6.

It seems that the dices were controlled by magnetic material.
But, I wonder magnet only has North and south pole, how to use its principle to control dice that has 6 faces.

david753:

Here is an idea using your magnets:

Each die could to be loaded with 3 elecrtro magnets. Each electro magnet would have its axis normal to opposing die faces and would need to be remotely switched on or off. The table surface would also need to be magnetized with polarity reversible.

Here is how it might work: For example, if the computer decides that a six needs to be rolled, it sends a signal to turn on the elctromagnet aligned normal to the six face. Then it sends a signal to activate the elctromagnetic surface of the table, with the table surface polarity switched to be the same as the polarity of the 6 face. When the die is thrown it should roll with the six face up and the opposite face pulled down to the table. Then the computer would need to quickly (say 5 seconds after die is thrown) send a signal to deactivate the magnetic fields.