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Build Your Own Self-Balancing Unicycle
CaptainKaos[DOH!] writes "Robot hacker Trevor Blackwell is at it again, this time with a self-balancing Eunicycle. Blackwell writes, 'Some time ago I built a self-balancing two-wheeled scooter. Since then I realized that two wheels are redundant, and only a single wheel is needed to make a ridable vehicle. A vehicle with a single wheel is much smaller and lighter. It weighs under 30 lbs and is easily carried with one hand when going up stairs or on public transportation.' Trevor's previous 'Segway' type two-wheeler was mentioned on Slashdot."
One wheel good, two wheels bad!
You can find a torrent for the video here: Park-all.lowbw.mpg.torrent
I misread that as a eunuchcycle. clicky
"I have a strong bias towards building products that people buy for their own use." -Trevor
I too support people killing themselves. But, really - couldn't we find a more effective method?
Here's another person with "too much time on their hands." The yuppie sophisticates will no doubt complain that people who invent "have no life" and really should be sitting in their $28,000 bought-on-credit living room watching celebrity bug-eating in high definition surround sound. [/sarcasm]
Then everyone else will bitch and gripe because the new invention didn't live up to the media hype and dismiss it all as the equivalent of a circus act. The fact they made it a circus act will, of course, be forgotten in time for the next "you could have this if you had a job" advertisement for something else to buy on credit.
People who spend their time doing anything except shoveling money into the local yuppie grill or sipping white wine while they watch prime time commercials occasionally interrupted by a screaming carnival barker are routinely criticized by our society because society has nothing but contempt for imagination and vision, unless it involves some dramatic amount of money.
Business isn't willing to pay for products, innovation and careers, so we get brands, mortgage commercials and layoffs.
Trevor mentions that you control speed by leaning forward/backward and steer by twisting your body. This is appropriate for low speeds.
But as with a bicycle or motor cycle, at higher speeds you can steer by leaning. For instance:
- Lean right.
- Force on the axle is translated to motion 90 degrees offset in the wheel's direction of rotation, causing the wheel to gradually precess to the right, gradually turning the vehicle.
Twisting continues to work but differently - in reverse and one stage of integration removed:
- Gently push forward on the right handlebar, as if turning left. (There should be a body-twisting motion to produce an equivalent on the unicycle.)
- Force on the axle is translated to motion 90 degrees offset in the wheel's direction of rotation, causing the wheel to gradually precess to lean progressively more to the right. (Stop pushing the handlebars when you're tilted as much as you want.)
- Tilting the wheel moves the center of gravity to the right, causing the vehicle and rider's weight to apply a force on the axle, as with the "lean right" case above.
- When you've turned far enough, gently push forward on the LEFT handlebar (or do the opposite body-twist) to undo the lean.
This only works at moderate-to-high speeds, when the gyroscopic effect is adequate. And it works at much lower speeds on a motorcycle than a bicycle due to the greater gyroscopic effect from the heavy wheels. (It's hard to get a bike going fast enough to do this.)
Try it out on a motorcycle: Find a nice flat, straight, country road with good pavement and no traffic. Get moving maybe 25 MPH, and balanced well enough that you can open your hand around the handgrip and steer by leaning. Once you've got that working, try just barely touching the back of one handle to push it forward.
Once you get the hang of it you can use it to perform extremely abrupt turns on the 'cycle. A stiff push causes the cycle to suddenly drop into a steep bank and begin a tight turn. A stiff push the other way pops it back upright and traveling straight. The banking is just right to keep you stuck to your seat and turning at a constant rate while applying no twisting force to the handlebars. Very relaxed while performing extreme manouvers, since the only muscular effort is used when you CHANGE your RATE OF TURN. (But don't overdoit and break traction or you'll go down.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
http://66.102.7.104/search?q=cache:4K9GC46wUkAJ:tl b.org/eunicycle.html+&hl=en
Turning by leaning does require gyroscopic force, but not in the way you describe. It is required to allow you to change your center of gravity by leaning. On a bike with no centrifugal force (a stopped bike), you cannot change your center of gravity by just leaning without turning the handlebars. If you could, it would be easy to sit upright on a stopped bike.
When gyroscopic force enters the equation, it does allow you to change your center of gravity by merely leaning your body. Once you lean to the right and move your center of gravity to the right, you start falling over to the right. The reason you don't fall over completely is that the wheel also turns to the right of its own accord, which turns you and brings it back under the moved center of gravity. But the main reason for the turning not gyroscopic force; the real reason is the fact that the turning axis for the front wheel is not vertical. This means that when the bike is leaning to the right, the front wheel has a natural tendancy to turn right, even when stationary. Imagine a bike on its kickstand; the wheel is always turned in the direction of the lean, right? That's not a coincidence. This is the reason why you will never see a bike with a straight vertical rod connecting the front wheel to the handlebars. (or if you do see one, it will be quite hard to ride, and look stupid to boot...) Gyroscopic force also has an effect here, but it is not the main player.
I found a cool site that explains it all: Motorcycle stability and steering.
main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}