Robot Cheats at Rock Paper Scissors

It is hard enough to beat computers at games like chess. Now robotics engineers at the Ishikawa Watanabe Laboratory in Japan have created a janken robot that wins every time (if you didn’t know, janken is the Japanese name for rock-paper-scissors). How can it win every time? Easy. It cheats.

The janken robot evolved through three different versions. In the first version, the robotic hand would note the human player’s hand with a high-speed camera and then move the hand to a winning counter play with about a 20 millisecond delay. In the second version, the delay was greatly reduced.

However, in the third version, the robot uses a scanning technique to capture an entire field of view and determines what play the human is making. Again, a winning counter play is instantly produced by the robotic hand.

We actually covered an earlier version of the janken robot in 2012. You can contrast the two videos to see how it has evolved over time. If you want to go old school, you can even play janken against a computerized glove. Not quite as cool, but maybe easier to build.

The only question we had: If you are going to go through all the trouble to build this robot, why wouldn’t it play rock paper scissors Spock Lizard?

14 thoughts on “Robot Cheats at Rock Paper Scissors

  1. easy:
    choose scissors
    close your eyes, count to three
    on three, maintain a fist for about 30ms longer than normal.
    computer cheats and makes paper
    finally make scissors, then open your eyes.
    win without cheating.

    1. I don’t think you understand how it works. It watches your hand very closely, very fast. When it sees you start transitioning from rock to paper, it can quickly (way faster than a human) change to scissors. It doesn’t count to 3 (or “rock, paper, scissors, GO) like people do. You can sit there transitioning between every different play and it will look like the robot is instantly playing the winning counter-move.

  2. If you click on ‘rock paper scissors’ at the bottom of the article you will see the same device covered by HaD previously in 2012.
    And this might be the 3rd version, but seriously, do you need a 3rd version? Do you need 3 years to make a new one?

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