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Self-balancing center of gravity shifter system

  1. May 15, 2012 #1
    I should say that while I've taken some physics courses, I should probably be considered a layman or hack as I haven't done any real world engineering. I'd love to hear some more expert feedback on this topic.

    I'm sure that there are many approaches to this concept. For this project, my goal is to find an elegantly simple, low maintenance system that is also rugged, shock-resistant and relatively low cost. I prefer a solution that is passive requiring no external power supply but this may not be possible I understand.

    Other constraints:
    -Dimensions - Total height of the outer box/cage can't exceed about 10". The shorter the better. width and length of inner box determined by external factor and not defined yet.
    -Wear resistant materials a plus for low maintenance.
    -Preferably non-conductive (electrically) or reactive materials. Inner 1000lb box is probably going to be an aluminum box.

    This is what I have initially come up with. Excuse the crude mock up conceptual drawing here:

    Questions I have:
    What is the best possible latency in the restorative force I could expect in a hydraulic system like this?
    Are ball bearings best for low friction and low clearance? Are plastic/synthetic ball bearings rugged enough for this weight?
    Am I totally missing some basis concept here? Does this idea make sense?
    Is electronic control necessary to have a more responsive system, ie: less latency?

    I considered a robotics approach, using gyroscope etc, but again, was hoping to solve this in a purely mechanical fashion, ie: the "dumb" way.

    Thanks for your comments.
  2. jcsd
  3. May 15, 2012 #2


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    This might be the stupidest question in the history of humanity, but just what on Earth is this thing supposed to do? It looks like a very expensive teeter-totter. I'm probably missing something, but that's my first impression. No offense intended.
  4. May 15, 2012 #3
    Haha, a fancy teeter-totter. Well, if it did its job, it wouldn't be a very good teeter totter because it wouldn't let you teeter or totter. That's the point. The idea is to have a weight to counteract the acting force. Maybe I didn't explain very well.

    This same idea is used in skyscrapers I'm told so that when the wind causes the building to sway, there is a weight to counteract the wind force and brings the building back to some equilibrium.

    Anyway, this is actually not a representational drawing, it's conceptual, so I'm not surprised that it might not be clear how this kind of technology would apply in real world.
  5. May 20, 2012 #4


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    Oh, okay... a mass damper.
    Taipei 101, which is one of the tallest buildings in the world, uses the same concept. It is considered to be as close to earthquake/typhoon-proof as is currently possible. It has a 660 tonne pendulum hanging down the core, which counteracts the sway of the building under adverse conditions.
    The immediate problem that I see with yours is that it is 2-dimensional. You would have to stack 2 of them at 90° to each other in order to cover your butt in all directions.
    Keep in mind, though, that I'm uneducated; the forgoing is just an observation that might not be valid in your case. In fact, my browser quit displaying your diagram, so I'm not ever sure that I'm remembering it correctly.
  6. May 21, 2012 #5
    Hey Danger, yeah that's what I'm talking bout.

    I took down the image because I think it was misleading and not a very good demonstration of the idea. I'm working on another one that I'll upload to see if it make the idea clearer and allows people to give input easier.

    I'm only working in the x-y plane because the third axis gets taken care of by mounting it onto four independently adjustable corners which move in the z-axis. So the moveable weight only needs to shift in x-y which causes a z tilt.

    I'm finding it's hard to draw this idea out.
  7. May 22, 2012 #6


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    Do you mean that there will be one of these units mounted on each corner of a building? I can see some incredible problems arising from such a concept. The first is that you could end up with something similar to tidal forces. If these things don't agree with each other, they could get into a tug-of-war that will shred your building.
    Please keep posting about this. You have some good ideas, and it's interesting. I probably can't contribute any more, but I'll love to see where this leads.
  8. May 22, 2012 #7
    It's funny because at first when I pictured it in my head, I didn't see this tug of war issues you're referring to, but after I tried to draw it out, it became clear that in order to have things NOT fight with each other, that each axis of movement needed to be independent from the others. Because of the need to have a box within a box within a box to connect these cages together, the drawing became difficult to read. So, here's a much more simplified version of the idea. Hopefully this makes more sense. I can't easily draw in 3D, so we're just looking at X-Y plane and Z axis is in/out of the page. Hopefully this is more intelligible.

    EDIT: This drawing obviously doesn't show the "negative reinforcement" hydraulic system that would cause movement in one direction to move the weight in the opposite direction, which was sort of the point of this thread. But, it was clear from my initial post and drawing that it was too confusing, so better to go step by step. This drawing shows what the concept is. The other drawing will address the issues of the actual system I'm engineering. As time permits, I'll get to drawing up a detail.

    Feedback appreciated

    Attached Files:

    Last edited: May 22, 2012
  9. May 24, 2012 #8


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    Aha! Your new picture shows that I misinterpreted your meaning about the corners. I thought that you were going to put a complete damper system in each corner of a building, whereas you actually meant that each corner of the single system is independently sprung. Sorry about the misunderstanding.
    That does bring up another thought, though. Keep in mind that I'm way out of my element, and into my Scotch, so I'm once again rambling. Given the purpose of this thing, I can't help wondering whether or not some sort of pantographic mounting might be more efficient than gas shocks. My reasoning is that it would keep the platform horizontal under all circumstances, so gravitational action upon the counterweight wouldn't be an issue.
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