
Raspberry Turk - sohkamyung
http://www.raspberryturk.com/
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dagss
Thanks for the reference to Edgar Allan Poe's essay on the Mechanical Turk,
that was a fun read. So right about some things and so wrong about others :)

""" The Automaton does not invariably win the game. Were the machine a pure
machine this would not be the case — it would always win. The principle being
discovered by which a machine can be made to play a game of chess, an
extension of the same principle would enable it to win a game — a farther
extension would enable it to win all games — that is, to beat any possible
game of an antagonist. A little consideration will convince any one that the
difficulty of making a machine beat all games, is not in the least degree
greater, as regards the principle of the operations necessary, than that of
making it beat a single game. """

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joey_meyer
Wow, my project is on the front page! Happy to answer questions if anyone has
them.

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prashnts
It looks amazing! How is actuator travel distance which compensates
differences between the heights of the chess pieces implemented?

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joey_meyer
It's hard-coded at the moment. I just measured the height of each piece and
stored the values.

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mentos
To me it looked like the clearance height was the same for all pieces. Is it
actually dynamically calculated for each move?

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joey_meyer
Ah yes clearance height is the same for all pieces, the servo raises the piece
to the piece height + the "resting" height. Relevant code can be found here:

[https://github.com/joeymeyer/raspberryturk/blob/master/raspb...](https://github.com/joeymeyer/raspberryturk/blob/master/raspberryturk/embedded/motion/gripper.py#L54)

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rposborne
The documentation on this is an awesome read! What were the costs associated
with this build? What would you do differently the second time around?

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joey_meyer
The robotics components were the pricey part. The breakdown is something like
this:

    
    
      - Table (w/ paint, wood, pipes, lights, etc): less than $50
      - Electronics (Raspi, camera, cables, electromagnet, microcontroller, etc): about $150
      - Robot arm (structural components + servos): $350
    

It's hard to say what I would do a second time around since there are aspects
I still want to work on, I want to write my own chess engine for it!

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GauntletWizard
I've been talking for a long time about making one of these - though my idea
was to put magnets in the pieces and drag them across the board from
underneath. Any advice on getting started with robotics? I'm fairly
comfortable moving servos attached to wheels around, but I'm a little more
hesitant when it comes to things with fixed range of motion.

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c22
What will you do when a knight needs to jump over a row of pawns?

As for advice, I'd look into implementing an xy table with an electromagnet.
You can find many open designs from the 3d printer world. You will probably
want hard limit switches at the end of each axis for alignment.

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GauntletWizard
My plan was to space the pieces out so I could move the Knight down the lines
between the pieces. Inelegant, but simple.

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amelius
Very nice documentation.

I notice that your confusion matrix for piece classification contains about
10-20% error still. Is that a problem in practice? And any ideas how to
improve upon it?

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joey_meyer
The error was too high so I haven't integrated it into the actual code base
yet, so it hasn't been a problem in practice yet! Ha. Yes I think the best
thing I can do will be to collect more data, I am hoping that will close the
gap a bit more. Also, I haven't spent that much time tuning hyperparameters.

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ljw1001
Thank you for such a fun and cool project, but please do take into
consideration the comments others have made about being sure it's safe: at
least if you plan to make a bunch of them and sell them :)

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joey_meyer
Glad you enjoyed it! I don't have plans to make more and sell them, but the
robot is safe–like I mentioned in the other comment it actually moves slower
than the speed it does in the video and the servos aren't powerful enough to
significantly injure someone.

