Robot hand wins at rock, paper, scissors every time (w/ Video)

Jun 28, 2012 by Bob Yirka report

(Phys.org) -- What do you call a robot hand that wins at rock, paper, scissors every time? Some would say a cheater, but others more in the know would call it the Janken robot, built by Japanese researchers from the University of Tokyo. They’ve built a robot hand that when combined with a camera and tracking software is able to beat people at their own game every time it plays. But only because it cheats.

When two people resort to using rock, paper, scissors to resolve a conundrum, they first ball their hands into a fist, then pump two times before throwing down their choice: rock (a fist), paper (open flat hand) or scissors (two fingers simulating a pair of scissors). Because there is no one hand formation that can always beat the other two, the game is considered one of chance, though many insist there is a definite psychological twist as both participants attempt to guess which formation the other is going to use, and then make their decisions based on that.

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With robots though, there’s no trying to psyche someone out; instead it’s, as always, about brute force, or in this case, speed. The Janken (the Japanese name for rock, paper, scissors) robot has a camera attached to it that feeds it information about what is going on with the hand of the opponent. Software running on the attached computer is able to discern which part of the picture is a human hand and then orders the tracking part of the system to follow its movements. Thus, the robot hand closely watches the human hand as it does its fist pumping, and then as it goes for the throwdown. As soon as it recognizes which gesture the hand is forming, its software calculates a winning gesture and orders the hand to throw it down, all so quickly that to us mere humans, it appears as if the robot is able to guess which gesture the human is going to use, every single time.

When two people play, if one tries to hold back on their throwdown to figure out what gesture the other is going to play before throwing down their own, anyone watching can see what’s going on and the person is labeled a cheat. When a robot does it though, is it really cheating? Because cheating is a human construct after all, and implies a degree of deception. The isn’t trying to deceive anyone, it’s just doing what it’s been programmed to do by human beings, which suggests that it’s still people who are doing the cheating after all, albeit in a much more advanced way.

Thus a robotics experiment meant to advance the science by mastering a simple game played around the world, has evolved into a philosophical debate regarding not just the nature of man, but how robots might fit into a future where both will likely be expected to coexist in a peaceful and productive way.

Explore further: SRI microrobots show fast-building factory approach (w/ video)

More information: www.k2.t.u-tokyo.ac.jp/fusion/Janken/index-e.html

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User comments : 15

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CaliforniaDave
1.3 / 5 (7) Jun 28, 2012
So stand with your back turned to the robot and it's advantage vanishes. Not really that impressive an invention IMHO.
antialias_physorg
4 / 5 (8) Jun 28, 2012
Not really that impressive an invention IMHO.

Wait till they expand its capabilities to hand-to-hand combat. You won't be able to land a single blow.
Temple
3.8 / 5 (4) Jun 28, 2012
@antialias_physorg: "Wait till they expand its capabilities to hand-to-hand combat. You won't be able to land a single blow."

I would think that a robot would be largely unconcerned with dodging hand-to-hand combat blows. Instead it would most likely ignore any blows you direct at it, and simply shatter the bones in your head, chest, etc with one swing.
Deadbolt
4 / 5 (4) Jun 28, 2012
It's the fact that it cheats so fast you can't SEE it cheat (unless you look at the slowed down footage) that makes it special.

Shape recognition and reaction in 1ms, with a very fast robot hand moving into to position just a few milliseconds later is a pretty useful demonstration, imo.
Valentiinro
1.8 / 5 (4) Jun 28, 2012
@antialias_physorg: "Wait till they expand its capabilities to hand-to-hand combat. You won't be able to land a single blow."

I would think that a robot would be largely unconcerned with dodging hand-to-hand combat blows. Instead it would most likely ignore any blows you direct at it, and simply shatter the bones in your head, chest, etc with one swing.


That depends what materials the robot was made of, and what sort of armor the person was wearing. In theory, with prediction of what the other person was going to do, you could make the robot out of lighter, cheaper, more easily damaged, materials and still have it not get hurt because it can dodge and counter your moves faster than you can react.
rwinners
1 / 5 (1) Jun 28, 2012
Just ordered another box of double O buck... seein as how I'll have to deal with land based robots as well as them sky thingies...
Temple
1 / 5 (1) Jun 28, 2012
@Valentinro: "In theory, with prediction of what the other person was going to do, you could make the robot out of lighter, cheaper, more easily damaged, materials and still have it not get hurt because it can dodge and counter your moves faster than you can react."

Oh yeah, because developing the hardware and software for a robot to recognize and adapt that quickly is *far* less than the cost of using materials that a bare hand cannot damage. *painfully over-emphasized eye-roll*
antialias_physorg
3.7 / 5 (3) Jun 29, 2012
Oh yeah, because developing the hardware and software for a robot to recognize and adapt that quickly is *far* less than the cost of using materials that a bare hand cannot damage.

It is far less. You only need to develop that type of software once but you would need to buy expensive/durable material for every single robot you construct.
Investement in good software tends to pay for itself rather quickly in the real world (and failure to invest in good software engineering tends to be VERY expensive).
Magus
not rated yet Jun 29, 2012
This is gonna get kinda weirdTwo robots. Do they get in a infinite wait loop?
I guess we will have to use our robot friend to keep us from having to take out the trash, when our robot wife asks us to so.
Bowler_4007
1 / 5 (2) Jun 29, 2012
This is gonna get kinda weirdTwo robots. Do they get in a infinite wait loop?
I guess we will have to use our robot friend to keep us from having to take out the trash, when our robot wife asks us to so.
Each bot will only pick one move per match and both use an rng (random number generator) to choose first move of the match (or perhaps they'll choose at the same time), the one that chooses a move first will then be watched by the other so that it can try and counter it, this will work because rngs won't run at a fixed rate and even if they choose a move at the same time it won't matter because a proper match will have been done
ODesign
not rated yet Jun 29, 2012
Robots are not people and therefore can not compete competitively in any national or international RPS sanctioned tournament (with the possible exception of Alaska which refused to sign the treaty on fair play in human competitions sports).

At most this should be considered a training tool similar to an automatic baseball pitching machine. I feel certain the committee will rule any attempts to disguise this robotic competitor as a real human hand to be grounds for immediate disqualification and possible banishment from the competitive Rock Paper Scissors leagues.
antialias_physorg
2.5 / 5 (2) Jun 29, 2012
Robots are not people and therefore can not compete competitively in any national or international RPS sanctioned tournament

Can a corporation (with a robot as proxy) compete? Corporations are people... or so I heard.
pubwvj
1.5 / 5 (4) Jun 30, 2012
Wow. Totally lame.
Aloken
not rated yet Jul 02, 2012
I wonder if the predictive software makes just one guess or several. How do you beat a cheater? You cheat too. So what if you pretend you're going for scissors by starting to extend just two fingers and then extend them all for paper.
antialias_physorg
3 / 5 (2) Jul 02, 2012
Wow. Totally lame.

You've obviously never tried to do image recognition. At that speed and at that success rate that's pretty good.

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