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2 wheel electric scooter

2 Parallel wheels and gravity make balancing a no brainer
 
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Recent buzz has been created with an expensive device that will "transform the world". You can support changing the world or at least that company by coughing up 5 grand, or build a better version yourself.

Gravity helps a lot. So does high school physics. To balance, all you really need is for the center of gravity to be below the center of the wheels. The lower the better.

Take 2 wheels, say 16" diameter. Mount a wide U shaped chassis I-\______/-I The platform of the chassis should be as low as you can get, but about 3” off the ground.

2 Electric motors will drive each wheel. You can use automotive motors such as a windshield wiper motor, which is geared already, but make sure you have a reversible motor. That will make maneuvering in low speeds better as you can turn in place. Use a joystick to control a high amp dual H bridge connected to both motors.

I think that thing will stand on it’s own and not fall over. Reason is that the center of gravity is below the pivot. It will be like the blow up toy that you can punch down and it stands right back up. Once you stand on it, you may think that you immediately fall, but not so. If you stand above the center of gravity, you in fact contribute to the weight below the center pivot. Leaning forward or backwards will exert vertical force, which would have toppled you down, but humans have a natural self-correcting gravity defeating devices called feet. Your natural instincts will keep you standing upright. Make sure you start the motors slowly and slow down gradually and you will maintain balance. If you must, you can paint it gray, add a supercomputer, a T bar for your paws and a “mind reading” gravity sensor (or surplus gyro from avionics of an Cessna). I say keep it simple.

fogelman, Dec 27 2002

(?) same thing seated http://www.halfbakery.com/idea/UnCycle
[FarmerJohn, Oct 17 2004]

[link]






       Center of gravity...let's see...16" diameter means axle is approximately 8" off the ground, the platform is 3" off the ground...so, if your personal center of gravity is less than 5", you're in business. However, the platform suspended below the axle would certainly be better than above.   

       Having said that, I'd try to ride this. I think it would take some practice, maybe more than a unicycle. If your feet are directly side by side, this is gonna be a tough one. And, I hope you've got some very high resolution motor speed controls in mind for that slow start if it's all manual control.   

       I will withhold my vote on this until I can take a test ride.
half, Dec 27 2002
  

       Since most people's personal center of gravity is about 3 feet from the ground, the wheels would have to be at least 6 feet in diameter to give passive balance.
FarmerJohn, Dec 27 2002
  

       [FJ], how about the average lawn gnome?   

       I think quick braking is going to be the downfall of this idea.
half, Dec 27 2002
  

       Ah, a gutted Segway.
st3f, Dec 27 2002
  

       It is true that the center of gravity of the whole system is well above the axle point of the wheels.   

       But the things to note are: 1) The device will self balance if no one is standing on it, like one of them there toys with a half sphere on the bottom and inflatable doll on top. 2) Humans self balance very well. If you need proof, look at any bicycle rider. Sure there is more at play, gyroscopic muvement etc, but I think it adds up to that the system can work. At no point is it reccomended that one stands under a steamroller to make oneself shorter..   

       I saw a Segway the other day, and it didn't seem like there was any motor involvment in stationary situatuions. Only when moving. that may indicate that balance is achieved mechanically and by the human balance, not fancy technology.
fogelman, Jan 10 2003
  

       I too, (the other day) saw one of these machines on the msn home page. It seems that they employ the use of liquid sensors much like in the ear drum of you or me) that control lightning fast motors to keep the machine in perfect balace. It looks like my old style lawn mower, the kind with no motor, except for that you stand on it. Speed is controlled by hand grips, like a motorcycle. Incidentaly, it is gray, as far as I could tell from the picture. It can be purchased for around 5 G's with a five hundred dollar deposite due imediately. I'm still waiting for the hover board from Back to the Future (although its probably already here as well).
demtangs, Feb 21 2003
  

       There are two problems inherent to all "multitrack" (more than one wheel per axle) vehicles: they always require a path at least as wide as the vehicle's track, and they cannot easily be banked into turns. Single-track (unicycle, bicycle) vehicles can use very narrow paths, and they tilt into corners, keeping lateral forces on the rider to a minimum.
norcal944, Aug 28 2003
  
      
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