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New inverted robot coming up–2 new ballbots!

May 24, 2011

Don’t know what a “BallBot” is? It’s the latest fad, apparently. Since any wheeled balancing device generally balances in only one dimension, it’s been an interesting time watching as people come up with 2-dimensional balancing bots. One such device is the Carnegie Mellon-produced ballbot, the first of its kind.

This has been (one of the many) causes of my lack of recent blog posts: making one in the NXT system. Unfortunately, I only have an accelerometer, so it’s not going to be as good as the real thing… but I’ve made two. Testing time…

EDIT: as it turns out, you really need to have omni-wheels for this kind of project. Sadly, I lack these. Well, I’ll get some (hopefully) when I can afford them. . . .Β  😦

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8 Comments
  1. will fix up this post soon… gotta eat dinner now, so it was thrown together really quick. as aws this comment. 😦

    • sorry… my HTML screwed up there – this is what I tried to say: so kinda like Aswin’s sidbot (http://nxttime.wordpress.com/) ? I think he’s using three accelometers to keep track of where he’s going (might be gyros too).

      • Hmm, quite so. Except, I don’t have a gyro 😦
        Also, I don’t have Omniwheels (those things are expensive!).

        I’m working more like this design. Except, I’ve done two revisions of it, one is mostly the same structure-wise (but includes a missing feature that severely limits the initial design), and the other is much more compact and universal (fits different balls), but lacks the “extra feature”. More details soon.

        P.S. I’m going to try and get my hands on either 3 1-axis gyros or 1 3-axis gyro, whichever is cheaper. or like 2 2-axis gyros. πŸ˜›

        • “those things are expensive!” I know right! when they came out I wanted to get some right away — then it turned out they were in Australia and 50 bucks each… And an “extra feature” — sounds promising! πŸ™‚

  2. Please forgive the brevity, as I am attempting to post this from my phone. Anyways… The “extra feature” is this: a control-moment wheel. What this means, in layman’s terms, is simply a horizontal wheel on top of the ballbot. When this wheel is spun, the Law of Conservation of Angular Momentum dictates that the force with which the wheel would turn is equally and oppositely applied to the base (in this case, the bot). In even simpler terms, this means that when the wheel spins clockwise, the bot spins counterclockwise. This allows the bot to turn, which is a feature that was lacking before.

    • oh. wow. that’s a special feature allright πŸ™‚ so basically kinda like gyros in space? I saw this video of it once where this person has a spinning bicycle wheel in her hand, and, depending in which direction she made it turn, she spun the opposite way herself. It’s an interesting feature, and I don’t think anybody tried it on NXT yet. Did you get it to work?

      • Yep, that’s exactly right, and it works wonderfully. I’m actually working on a double-pendulum balancing device (think a segway on top of a second one, and you have to balance both) that uses a similar theory for momentum. And I have indeed gotten it to work.

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