homer
Member
Registered: Jan 2000
Location: Twin Cities, MN
Posts: 1683 |
quote:
It's more along the lines of holding the bat vertical with sheer forearm strength. If the bat starts tipping, you can actively straighten the bat without moving your hand just by twisting your wrist in the opposite direction.
aha! I'll admit that the above WOULD work IF:
1) The wheels were affixed securly to the pavement (these tires would have to have some AMAZING traction).
2) The electric motors had enough torque to counter a 200lb object on a 3 ft fulcrum travelling at 12mph. (It's been a LONG time since I took physics...does anyone have the formula for the total force that this would equate to?)
So, MAYBE it can do that, but these would have to be some monster motors and some truly amazing tires.
quote:
If it can balance a rider while standing still (as evidenced on the GMA segment I saw on Monday morning), it certainly can balance while in a pothole.
I don't think it is standing still. It's making very minor adjustments. Try standing still. You'll notice that your body is making very fine adjustments. It may appear that you are standing still, but you are moving.
That said, if there IS a stablizing gyro in the segway, when standing upright, the gyro MAY have enough mass to act as a physical stablizer.
quote:
Your bicycle theory about the wheels being gyros is not true. It's the combined center of gravity (rider and bike) and forward motion that keeps a bike upright. The next time you're riding, lean out to once side as far as you can... those wheels aren't going to keep you vertical or prevent you from falling.
Bicycle wheels certainly are gyros. What do you think a gyroscope is? It is a wheel with an axle. Is the mass of a bicycle wheel enough to balance a human alone? Certainly not.
And that's my point. There is no way that there is a gyroscope in the Segway massive enough to stabilize a 200 lb human by itself. It may help, but I believe it's sole purpose it to act as an intrument so that the wheels can keep you stabilized.
quote:
Take one of those industrial floor polishers with the big, round pads. Tilting it forward makes it move backwards and vice versa. That's what the gyros on the Segway are doing...
A floor polisher is also a gyro...a very MASSIVE gyro. A floor polisher is considerably bigger, and much more massive than a segway. Also, try standing on a floor polisher and lean forward. It does NOT have enough mass to keep itelf upright.
quote:
As for keeping itself vertical without moving the wheels, it's the torque of the drive system that accomplishes that, not the wheels themselves.
This is the same argument as Dick-Richardsons and it is a valid theory. However, the mass of the device has to be MORE than the object riding it. And this simply isn't the case with the Segway.
It can only balance itself if it can balance the center of gravity with forward (or reverse) momentum. If this was an issue of torque only, then the Segway would be at absolute verticle at all times, as it would be most efficient for the motors that way.
quote:
I maintain that you can replace the wheels with blocks and still have the unit maintain a vertical position.
If you're sticking with the toque argument, then the blocks would be a better solution than wheels (more traction + mass).
So let's go with torque. If you lean forward on the Segway, what happens? The segway attemps to pull the fulcrum back to pull you upright. However, since the mass/friction on top (the 200lb rider in motion) is more than the mass/friction on bottom (65lbs on wheels) the torque ends up moving the wheels forward to be in alignment with the fulcrum.
This, actually, is the same thing. The difference in our arguments is when this wheel gets stuck in a pothole. If I just set the segway in a pothole and wedge the tires in so that they can not move, then I agree with both of your arguments that the torque of the motors would be able to up a slightly off-axis 200 lb object. But, since it would be extremely rare for a wheel to wedge itself so snug and the fact that 200 lbs moving at 12mph puts significantly more force on the fulcrum I simply do not see it being able to remain upright.
And, EVEN IF IT COULD, keep in mind that you would hit that handlebar at a force of 24mph. That would hurt.
quote:
Little irritates me more than not getting my idea across. I really hate having to explain things. Everyone should just understand what I'm saying the first time.
I blame my ADD. I end up using simply awful metaphors. They make sense to me, but I tend to forget a few key elements when explaining it and the whole logic of it falls apart.
Plus, it's hard to explain things with text only. Pictures work so much better.
That and I just like arguing. 
(which is obvious for all of us, I suppose...why else would we spend our time arguing the physics of a complicated transportation device in a discussion board on Visors?)
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12-06-2001 01:46 AM
What do you mean you haven't heard an argument as to how it does it? My entire previous post described how it could work. Where is the confusion coming in?
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