Machine balances pencil on its tip


[Video Link]


In our demonstration, we address the challenging problem of balancing an arbitrary standard pencil, based solely on visual information. A stereo pair of silicon retinas reports vision events caused by the moving pencil, which is standing on its tip on an actuated table. Then our processing algorithm extracts the pencil position and angle without ever using a "full scene" visual representation, but simply by processing only the spikes relevant to the pencil's motion.

Our system uses neurally inspired hardware and a neurally inspired form of communication to achieve a difficult goal. Thus, it is truly a Neural Information Processing System.

Pencil Balancer (Via Make)


  1. Pfffft! I’ll bet NASA could do the same thing for only $500 mil. What did you guys spend, huh? Probably didn’t even let the taxpayers in on it.

  2. I am curious if the machine can achieve quiet equilibrium. This would most likely require the ability to measure the mass of the pencil in the course of corrective actions.

    1. If I understand what you mean by “quiet equilibrium”, I don’t think it’s actually possible in the general case. They said it was an “abritrary standard pencil”, i.e. not one that was specially balanced and sharpened to be exactly balanced.

      It is certainly possible to sharpen a pencil so that it is lopsided which would make that equilibrium (non-moving pencil) impossible. I believe it is probably the most common case by far that a pencil will not have a perfect mass distribution, but I can’t prove this off the top of my head.

  3. Interesting to me because I’m the only person I know who can balance a pencil on my finger tip, everybody thinks it’s a trick,
    I just always have been able to, I can balance anything easier
    (weightier at the top) so still it looks like it glued to my finger, useless but neat.

  4. For their next research project, they’ll be making a machine which can mechanically balance a spoon on their nose…

  5. cool stuff. FWIW, Tobi Delbruck is the son of the late Max Delbruck, who was awarded the Nobel Prize in Physiology and Medicine in 1969.

  6. @kp They’re doing some neat visual processing that only detects pixel changes rather than detecting the actual pencil… They seem to do this to reduce the amount of information from the visual sensors and mimic how real eyes convey information.

    I think that means that the pencil always has to be moving somewhat to generate input to adjust the motion table.

    Other systems out there that use full-frame video and a bunch more processing can statically balance things like double pendulums on end.

  7. In another age this would show up as an executive toy in the Sharper Image catalog next to must-haves like the motorized tie rack and the electric back hair shaver.

  8. I’d like to see a pen installed in the bottom and a piece of paper locked beneath to see what it draws as it keeps the pencil on top upright.

  9. I sometimes wish I had studied engineering at ETH. They keep publishing these videos of relatively simple, useless, but very cool contraptions. Must be fun.

  10. That really brings back memories. Back in 1974 Professor Dertouzos at MIT gave a robotics course. He had two big goals. He wanted a computer to accompany him on a recorder, listening as he played to match his tempo, and he wanted a robot that could balance a broomstick much as this device balances a pencil. The first computers on a chip were just being released. A friend of mine and I did a survey of available, and almost available processors, and both projects were near the hairy edge of their processing power given what we knew about physics and control theory. I remember he had a spec from Toshiba for a processor they were developing and hoped to sell to Ford to control automobile engines. It looked promising. I also remember an awful lot of neat gizmos being built in the lab, and Professor Dertouzos addressing our awkward question, “That’s right. You are probably wondering about getting a grade.”

    It took another year or two before he got his balancing robot. I’m less sure about his recorder companion, though I gather there are such things today.

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