Now that we have a better idea of the overall system, wouldn't it be simpler to give each player a device on which they could enter the positions of their chess pieces, rather than sense the positions: then illuminate the positions to which the pieces could be moved accordingly?

Simpler, yes. But I like a challenge and it would not work well as there is not even a good notation for positions of chess pieces on 6 combined boards. Also if players make mistakes in entering the positions the whole tracking will become a mess.

 

In the meantime I have also done some brainstorming over drinks with a couple of friends. One acceptable alternative would be giving both players a glove that is wired to one pole, with chess pieces having a metal top section, a piece-defining resistor inside, then a metal ring at the bottom which connects to contacts on each field - which connect to the other pole. The chess boards would be made of PCBs (as they also have small LEDs inside anyway to indicate the available fields for moves) with small magnets on the inside of each field to keep the pieces from falling off. As soon as a player touches a piece, the circuit for the field on which the piece is located will detect a piece-type-dependent current.

Any thoughts on this ?

 

A glove system is never going to be as attractive as one that uses say capacitance / rfid.
I remember a musical device, that had tape loops for each note, it was fantastic, but was very soon replaced by one with a solid state memory, a sampler, now done in software...
https://en.wikipedia.org/wiki/Mellotron

Rfid seems to be the way to go , an antenna under each square, rfid chip in each piece, the magnet is not relevant especially as if mentioned above, its in the centre of the coil on the piece.
or how about putting magnet in each square, with the coil around, and a metal piece !
You don't even need to especially code each piece, provide every piece was unique coded, say a MAC.. then on start up you assume that each piece is in the correct place, and you remember what each ID is then.

Detecting the player touching a piece, how about capacitive sensing ?
https://en.wikipedia.org/wiki/Capacitive_sensing
you should be able to detect the change in RFid signal when a finger is on the metal chess piece,
or use the same coil under each square, to send a different frequency than th eRFid one,
and detect the change as the finger capacitance is applied,
All very doable

 

Yeah, capacitance sensing could work too but it might be more challenging. I'm assuming you mean sensing the piece by parasitic capacitance rather then via electrical contacts between a square and a chess piece. This is the sort of sensing in capacitance touch sensors.

I think you still have to have a coil for each square and then you have to sense 64 different pieces (capacitance values) plus an empty square condition. Adjusting/controlling the capacitance of each piece may prove difficult but can be done. Measuring/differentiating the different capacitance values may also prove difficult. Worth experimentation before diving in.

If you have coils per square anyways... then it may be easier to embed an NFC tag in each chess piece and avoid the complexity of tuning the capacitance of each piece. Regardless, capacitance sensing might do the job.

 

Thanks for all the useful insights. Very busy with other stuff (work, house renovation) right now but will report back when I have made some progress with this.

 

Simpler, yes. But I like a challenge and it would not work well as there is not even a good notation for positions of chess pieces on 6 combined boards. Also if players make mistakes in entering the positions the whole tracking will become a mess.

A wireless 2D bar code reader seems superior to the glove idea. If the squares were coded, the could point at the first, then the second for error free input without the extensive wiring confusion entailed by wiring up each square.

Alternatively, since you said you will have LEDs on each square, you could include an 8-pin SMD MCU driving each LED and include a repeating code that modulates the LED output at high frequency (it wouldn't be visible) then a reader could be placed over the LED on each square, wirelessly sending the move data.

In either case, the piece identification would be based on my previous suggestion. Once the board was (re)set, the processor dealing with the data would be signaled that everything is "home", and it would simply track the changing positions based on knowing what was there already.

The glove idea seems very janky. One problem is that people have a large range of hand sizes, another is that it involves a wire which seems likely to interfere with the board at some point. It also seems extremely inelegant as solutions go.

 

I want to create a chess board that detects where each piece is located. Existing technology from DGT uses small coils and capacitors, but this solution apparently does not work when metal is involved. My chess pieces have a small magnet at the bottom as they are going to be used on a 3-dimensional chess cube. Any ideas on what type of technology to use to make this work would be very welcome. I have looked at RFID but that will not allow the precision I need. Distance between the piece and the sensor would be a couple of millimeters, with metal and magnet between them.
I need to distinguish between black and white pieces and 6 types of pieces, i.e. 12 in total. Also I would need to combine the identification of pieces on each field with a sensor that tells me if a player is touching a piece. If some pressure is required to detect this that would be acceptable. I guess I need to combine several technologies here but if there is one approach that would handle both requirements (touching and identification of the piece) that would be ideal.
Once the identification / location and sensing which piece is being touched are known and transformed into digital signals, a micro processor can handle calculation of target fields that can be reached, making small LEDs on each of those fields light up.

I realize that your chessboard will need to be ferrous metal, to allow magnetic adhesion, but if you can find a way to finesse thr details, a linear Hall-effect sensor might do the job.

 

I realize that your chessboard will need to be ferrous metal, to allow magnetic adhesion, but if you can find a way to finesse thr details, a linear Hall-effect sensor might do the job.

Or the chess piece could have ferrous metal bottoms and the magnet could be embedded in (or beneath) each square I suppose.

 

Or the chess piece could have ferrous metal bottoms and the magnet could be embedded in (or beneath) each square I suppose.

Or magnets on both sides... To force precise alignment.

 

Apply the cheap USB camera and bit witchcraft around the LabView runtime! We did similar about century old vacuummeter logarythmic scae reading. The choice was to buy modern meters (2500 Eur) plus sensors (1300 Eur) multiply to ten complects or to use those old (mesurer nil Eur, sensors 10 Eur) plus camera 5 Eur. Work just brilliant.

 

I know this topic has gone cold but I have been thinking about it a bit more.

I might have missed the info, but I'm wondering about the playing board dimensions... i.e. what are the dimensions on the squares?

Also... what is the total number of unique pieces that you need to detect? I got a little confused by the multidimensional image / construction.

 

Squares are currently about 1 x 1 inch - so that the complete cube can be mounted on an axle inside a pretty standard size bicycle wheel. As for unique pieces to detect: there are 6 different pieces and 2 colours. I doubt that recognising all pieces individually is going to give any advantage. It would mean having 32 x 4 = 128 different IDs.

I have had to pause work on this as life keeps happening, and so does work. I will revisit this topic once I have found some time to experiment with various suggestions. Might be months...