The problem is that there will be inductive coupling between the antenna so no amount of switching is going to isolate one token.

So if the muxes are used to select the transmitter in column 'B' and the receiver in row 'B' what you are saying is that the transmitters in columns 'A' and 'C' will also fire and the receiver will see multiple tags is that correct?

Is there no way round this by say reducing the transmitter power (the rfid tags will be right on top of the transmitters) and by grounding the transmitters that are not supposed to fire?

Phew, I thought this was going to be an electronic nose project.

You are not planning on strapping the Arduino to an ankle are you? There may be algorithms published already for this, you should search for them. Otherwise do it empirically, gather data when walking, jogging, sprinting, climbing stairs etc. look for a pattern in the data that characterises each motion then write software that looks for the pattern. You are going to get differences in acceleration and frequency of motion for one thing.

Have to start working on this.. It will be a challenging task for me specially when come to the design of antennas by moderating sensitivity and signal strength(at most 1cm) by considering the dimension of standard Chess Board.

I would test the theory by using one transmitter and one receiver at right angles with firstly a single rfid above the intersection , then with rfids also on adjacent squares.

One problem might be the transmitter firing rfids other than the one at the intersection. You might be able to make the rfids more directional by placing tin-foil caps over them so that they only "see" downwards.

Hi Palliser, Your mathworld link seems clearer. It gives the possible states as; (8! 3^{8} 12! 2^{12})/( 2^{.}3^{.}2)=43,252,003,274,489,856,000

I can sort of see where the equation comes from. There are 8 corner mini-cubes each of which have 3 colors, and there are 12 edge mini-cubes each of which have 2 colors - so that is where the numerator comes from. I am not sure about the denominator.

Anyway its clear this is a very big number so brute force to precalculate solving the cube is not on. And yet any cube can be solved in at most 20 moves!

There are algorithms for solving the cube so that bit of the project can be done, though I expect most use far more than 20 moves.

The LED solution would be a lot more achievable but not nearly as exciting as seening a cube move, particularly if external wires could be avoided.

Well that pins it down to all cubes being solved in at most 20 moves.

I don't understand how they are calculating the number of states though;

Quote

The original (3×3×3) Rubik's Cube has eight corners and twelve edges. There are 8! (40,320) ways to arrange the corner cubes. Seven can be oriented independently, and the orientation of the eighth depends on the preceding seven, giving 3^{7} (2,187) possibilities.

How can there be 40,320 ways to arrange the corers but only 2,187 possibilities?

Like I said I think this is an excellent idea, but there are enormous practical problems. Boffin1 is right bout the servos, a fair bit of force is required to move the faces.

Can anybody say how many states a rubik's cube actually has? In other words how many unique combinations can one be scrambled into.

Also don't you wish you had a real talent and skill like this;

Polymorph's idea sounds plausible and, assuming it works, you get unique identification of each piece.

Another way with the reed switches is to have an extra 7 squares off to the side of each player (14 in total) on which players are obliged to place any major pieces they capture. That way it becomes possible to determine if a player has decided to promote a pawn to a queen, rook, bishop or knight. This means though that you need magnets in all the pieces plus 78 squares fitted with reed switches.

However if polymorph's idea is correct you could uniquely identify each piece and have much simpler code. You would need RFIDs in each piece (and cheap passive ones would probably be best), plus 8 transmitter coils and 8 receiver coils. This seems like the prime candidate to me.

A Rubik's cube 'appears' to be made of 3x3x3 smaller cubes. However there is no central cube so that reduces to 26.

Of these cubes there are;

8 corner cubes

3 faces visible each

24 faces total

12 centre of edge cubes

2 faces visible each

24 faces total

6 central cubes

1 face visible each

6 faces total

26 cubes total

54 faces total

That sounds a lot but of course the cubes are not really free to move at random. Maybe it would be possible to brute force the cube and calculate in advance the shortest path from any starting point?

Here is a chess set that says it is magnetic. Still not sure how it works though. What is the pillar at the back left of the board? How does the computer figure out what piece is on what square? [url][http://www.chessbaron.co.uk/chess-CMD2002.htm/url]

I presume the chess men are all passive? Is there some kind of reader under each square and how can it tell one piece from another?

Maybe I am making too much of this, perhaps you don;t need to "read" the identity of each piece, how about this;

If you have a fairly strong magnet in each piece and a magnetic reed switch under each square you probably don't need to know by reading which piece is which. Instead you just make the assumption that the players set up the board correctly, that white makes the first move and that all the moves are legal. Then, with a knowledge of the rules, the computer can calculate what is on each square.

Pawn promotion is a snag though because you cannot assume it will be a Queen and, even after it moves, you still might not know what it is. i think manual input for promotion might be required.

will the wire be clamped in position during cutting

will you know the wire has been cut

is the cut wire removed

Will you use a PC to provide the interface to the Arduio e.g. to tell it what length you want cut, how many pieces and the wire dia?

The mechanical aspects of this project are probably the difficult bit. You probably will not need much IO and the control logic should be relatively simple, but you should firm up the physical design first.

Also you should say what skills you and your son have. Have you done anything like this before are you good at building machines and working with electricity, do you have programming and electronics experience.

There are sites on the internet that let you load pictures then you can post a link to them. The other thread posted a picture and it makes it a lot clearer to people what you are trying to do.