Yes but you want it in two dimensions. X-Y

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Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com/

 

Are you suggesting that some sheets might have a thickness or other characteristic that will make it so that for some reason or another resistance in two dimensions might not consistently vary as a function of distance? I can't say that such sheets are not popular because I am not familiar with the market. However, I am also aware of no natural phenomenon that excludes material from having a certain resistance levels - including the ones that I'm interested in. Hopefully, someone will be able to direct me to something premade - or some things that are readily available and easily assembled.

 

You're still ignoring the fact that you can't keep track of more than one piece. Keeping track of one piece is already hard enough due to the minimal changes in resistance (and may not be implementable if you can't find a sheet of material with the tolerances you need).

But keeping track of multiple pieces is impossibile, even theoretically. Each set of resistances measured does not correspond to a unique set of positions on the board. It only works with one piece per board.

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Tanaka Sensei (avatar) says: Please spell it "ridiculous" correctly! Not "rediculous". ^^

 

I was thinking about how many possible locations might be identifiable for a given number of game pieces, and how this number of locations could be reduced if how pieces were drug rather than disconnectedly relocated was analyzed - or if the signals communicating locations were timed. I think that a part resembling a sheet could make this project worthwhile, however the resistive properties do not have to be inherent in the sheet – these properties could be an attribute of something else such as the coatings that were suggested earlier.

 

Varying the way you measure resistance between the contacts still doesn't resolve the fact that multiple pieces can be positioned multiple ways to get the same resistance reading becayse all playing pieces still influence each measurement all at once.

Neither does recording the resistance and position of playing pieces in various combinations because all playing pieces still influence each measurement all at once. By the way, there's no difference between dragging a piece across the board while taking measurements or placing it on the board at a slightly different location each time. You can only take discrete measurements at discrete locations, whether or not the playing pieces are moving continuously across the board. Besides, you wouldn't be able to drag it anyways since you would need to let the piece sit still to get an measurement of it's position before measuring the resistance. It's still going to produce a discrete reading either way. The only difference is how far apart on the board each measurement is being taken, and making the distance very small or very large does not solve the core problem:

All playing pieces still influence each measurement all at once. If you can't find a way around this, it's not going to work.

Might I also point out that if you did try to record all position-resistances for just 2 playing pieces and you divided the board up in a measly 10x10 grid or 100 locations, there would be 9900 possible combinations all of which you would have to move through? Increase the number of playing pieces or sectors by any amount and that combination will sky rocket even more. Of course, none of this would change the fact that more than one position is going to give you the same resistance readings.

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Tanaka Sensei (avatar) says: Please spell it "ridiculous" correctly! Not "rediculous". ^^

 

Have you thought of something like ohmegaflex?

 

Let me echo DK at this point. Simple resistance sheeting will not work, it can't do 'multi touch'

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Add to that identify what's placed on it.

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Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com/

 

In order for something like this to work you'd have to use 'smart' pieces. But the play surface itself would have to be a complex grid of resistive branches to provide voltage refrence for X/Y position and a grid of simple conductors to provide the pieces with power (batteries would be stupid)

I have a computerized chess set, it takes a MUCH simpler approach. Each 'square' is a simple membrane type touch sheet. You press the piece you want to move down, pick it up and press it down on the new square, works great. It 'knows' what piece is being moved by the initial starting conditions and has a method to set up pre-set conditions

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Could the location of pieces be identified by how much uniquely spaced conductors on the bases of the pieces uniquely reduced the resistance in the sheet between multiple locations on the sheet, and the location of the pieces be identified by how a circuit in the game pieces incorporating these bases and the sheet were closed at distinct intervals producing unique contributions to fluctuations in one of the electrical connections to the sheet?

 

Would the amount of heat produced and resistance vary if I decreased the spacing of the connections?

 

I couldn’t think of a neat way to identify enough locations by modifying a keyboard to implement a device similar to your chess game. I also wasn’t able to encode signals in a grid with resistive values having a high place values representing distances in one direction and resistive values having low place values in another direction because I haven’t come across resistors with a tolerance that would allow this.

 

Simple X - Y conductive grid lines with each piece having its own unique resistance signature.
At each grid wire crossing a simple non conductive film is placed between them.
By measuring the circuit voltage of each grid line on each axis one at a time a map can be made of whats siting where. Common touch screen mapping technique from way back.
Just add the variable resistance factor in to know what is where.
It will take a micro processor to do the mapping and grid line switching and voltage measuring but it will give what you need.

Think of it as a dot matrix light system only back wards. Instead of telling what row and column and what intensity to put out, you measure rows and columns and what resistance is found at what point.

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"Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech
"Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech
"Your impossibility may just be my day to day routine." -- tcmtech

 

The X/Y conductive grid lines are the hard part. good idea for the piece having unique resistance, can let them be a binary sequence. You'd need 32 bit accuracy for a chess set though...

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As far as grid based games go tick-tack-toe is about as complicated as I get!

I can do checkers but not well!

Chess? WTF?

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"Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech
"Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech
"Your impossibility may just be my day to day routine." -- tcmtech