When SRL had a booth at Maker Faire a couple months back, one of the demos we had was a modified a robot arm (dubbed “the littlest arm”), to be a “mumbly peg” bot. But this scarier version of a mumbly peg bot called Knife.Hand.Chop.Bot by 5voltcore.com way outclasses our efforts, as evidenced in their description of the ‘nervous sweta’ feedback loop and thier (intense, white-knuckle-ride) video. Snip:
The Robot is equipped with a knife that the Machine uses to s(t)imulate the test of courage – a kind of game known as “Mumblety-Peg”. The User puts his/her hand into the Machine and starts the knife game at the push of a button. The knife starts to hit the space between the fingers, first slowly then continually getting faster. The Machine knows where to chop by receiving signals of a sensor that guides the knife to the place between the fingers.
Electric contacts are mounted on the support block of the Machine, where the hand is situated. These contacts are activated as soon as the first “nervous sweat” appears that turns the skin into a conductor. Subsequently the computer becomes disturbed by the electric current that is now transmitted via the skin.
This has two effects: on the one hand, sounds are generated by the closure of the contacts (circuit bending) that can either be interpreted as warning or act as an additional source of stress. On the other hand, they can have an effect on the position of the knife which is controlled by the computer and thereby hurt the potential perpetrator of the disturbance.