that would make it much harder.
Ok, so what you’re suggesting to a student here is that as soon as he gets his budget he should blow it on a Wii. Come on, we all know what Students are like, and a student with a Wii isn’t going to end up with a 12,000 word essay at the end of it!
Suspension cranks. The only practical place to insert suspension in a unicycle subjected to impact is in the cranks. A crank with a section cut out and replaced with stiff, leaf-spring material.
Yeah and it would be nice if you got a set of all the different splined cranks and tested them to see which are the strongest, that would help us too because then less people would be posting their opinions about everything and there would actually be data to back it up.
Until I learn how to ride, I have no way of knowing:D
How about a crankset that eliminates the dead spot at 6/12? That seems to be where I am struggling.
how about a gyroscopic geared hub? as the wheel spins faster the gear ratio gets bigger.
A possible project would be a way of monitoring a unicycle during the slow boards race to verify that the unicycle never pauses and never makes even a minute backwards correction. It’s a project that has been tried before but without practical success. Should be able to find info on the past attempt.
The past attempt was mechanical in nature.
Another way to do it would be to mark the tire and have a camera and computer analyze the marks to make sure they never pause or move backwards.
But a project that measures the strains and stresses on a seatpost would be more practical in improving unicycling equipment. How much stress does a unicycle put on the seatpost? Where are the forces and in what directions?
Or the same for the cranks and hub.
You’re thinking of the quill style bicycle stems.
A quill is also a type of pen (an old style pen made from a feather that you dip in ink) so that’s where you’re getting the words confused.
An example of a quill style bicycle stem is here.
The quill stem is based on definition #10 for machinery here.
The Wii controllers are fab, and super easy to work with assuming you have a bluetooth dongle / bluetooth laptop that interfaces with them. I’ve done some work with them. They’re pretty cheap, and you don’t need a Wii to use them (although you should have one, they’re oh so good).
But, the accelerometers whilst surprisingly accurate, are limited to 3g of deceleration / acceleration measurement (in practice in the vertical plane because of gravity affecting the device, you get 4g one way, 2g the other).
That’s an interesting idea.
There are bicycle crank setups available that adjust (mechanically) the angle of the cranks whilst riding so that there’s never a total deadspot. Not sure all riders like them so much but they definitely exist - a uni using (an adaptation of) this system could be rather cool!
A full suspention muni. I still think it’s possible to do inside the wheel, and I still can’t quite see how suspention cranks would work to an overal benefit.
This has already been discussed at length here:
Electric assist, for climbing hills. Similar to how they do it on some comfort bikes. You could always pedal faster to go faster, and to suddenly slow down put backpressure on the pedals (but you’d be fighting against the power of the motor), apply your brakes or shut off the motor. Also maybe a veryable power lever.
A geared unicycle that has a goot shifting thing…Also, something that could balance the unicycle a bit better a high speeds (high rpms)
I always smile when I read the out-there design ideas when the entire budget is £250.
This would be fun, though I’m currently trying to pass a proposal to remove the Slow races from the list of points events at NAUCC because there’s no accurate way to judge them. The past method was a little box with a magnet on it, that you stuck to the back of the unicycle above the wheel. A long wire switch stuck out and rubbed on the tire. Rearward motion of something like 1-2cms would set off a “BEEP!” Nobody could ride it, even at walking speed, without setting it off.
So you could allow a larger amount of “play” in the wheel, officially taking the event farther from where we thought it was (or redefine it). That would be the easy solution. I could get you in touch with the guy who made those boxes (in 1986). I’m pretty sure he’s still involved in unicycling, at least a little bit.
I’d say interesting, but probably not really cool. Apparently they did not turn out to be the best thing since sliced bread, anyway. I’ve never seen any in person. Though they might have some use to help beginners, I can only imagine they would be really annoying for riding fast. And weak.
Make sure it offers enough “assistance” to account for its own weight. Problem is the weight would still be there when the thing’s turned off.
I think the hard part with that setup would be figuring out the drive system to not interfere with the rider. It would be an interesting problem to solve, and create the world’s first hybrid unicycle! Check out this wacky thing I saw at Unicon XII in Japan. I never saw anyone attempt to demonstrate it, and I never got around to finding anything out about it.
The word “cockamamey,” however you spell it, comes to mind. Plus the tendency for some people to not read or comrehend entire posts.
The problem there is that it was probably monitoring both wheel movement and frame movement. It’s OK for the frame to move back and forth (change angle) and is part of staying balanced on a unicycle. Gotta isolate that from the wheel movement.
It would be interesting to find out just how slow it is possible to ride a unicycle with no pausing of the wheel. Be funny if turned out to be walking speed.
I really meant “cool” in an engineering sense, not in a “really useful” sense
Yes, I’ve had the impression that on bikes they’ve not gained popularity, although presumably some like them… I get the impression that many serious bikers generally regard anything “weird” involving their cranks with a bit of suspicion.
It wouldn’t have to be a weak mechanism, though - no weaker than a geared hub. The smarts wouldn’t have to reside in the cranks, they could presumably be in-hub, for instance. Of course, this would possibly exceed the requirements of the final year engineering project…
I’m not sure whether they’d be useful to beginners or not… would it be helpful, or distracting? One thing it could be handy for is possibly steep hill-climbing, or muni, where the dead spot can be a real problem. Perhaps it would avoid step-by-step jerking when the rider’s speed drops too low.
I seem to remember seeing videos of a uni with electric assist + pedals (i.e. not the eunicycle). Can’t remember what it was called though…
I was going to suggest something involving solid state accelerometers, but hadn’t thought about the Wiimote. I looked in my local GAME shop today, they were selling them for 32 pounds.
There seem to be both Windows and Linux based methods of getting data out of them, and much of the basic functionality seems to work. It looks as though you may be able to get useful data out of them without using the “sensor bar” (which is actually just a bunch of LEDS, no sensors).
It would be interesting to see if it’s possible to make e.g. a “cycle computer” based on Wii accelerometers and some numerical integration. Inertial navigation would be really cool, of course [particularly if it could recalibrate based on GPS data]. Most of this is just software, and might not be too painful to implement. The flip side is that it might be difficult to get working and I have strayed rather far from the world of unicycles
Isn’t this stuff great? Shows that there will always be room for new ideas, tinkering & improvement.
On the “Rotor” cranks idea (speeding up the cranks at the top & bottom of the circle), that was a subtle refinement on the efficiencies of the pedalling circle. It was tried in many ways before, most popularly with the odd-shaped “Biopace” chainrings and the like. Eventually unicyclists might benefit, but we have more fundamental issues before us.
On the idea of adjustable length crank arms on the fly, also remember that you would need the seatpost to go up or down simultaneously, in order to maintain the same seat-to-pedal distance. I don’t recall that issue being discussed, but maybe I missed it.
I’m interested in a variable gear ratio transmission. Not just 2 speeds like Schlumpf (current state-of-the-art), but having a range of ratios from 1:1 to 2:1, changeable on the fly with a simple handlebar lever. Oh how I wish it could be done with just a few hundred dollars and a few hundred hours!
I’ve spent quite a lot of time programming with the wiimote, I don’t think this is possible. Accelerometers are great, but really limited in terms of integrated accuracy. The wii accelerometers have theoretically ±.1% accuracy I think, and you get a 16 bit level between -3g+3g, but this isn’t enough to get accurate position data out, when you’re moving it around there’s a fair bit of noise. You also have to do quite a nasty integration to attempt to ignore tilt, plus filter as the accelerometers have a little bit of noise on stopping/starting moving. Finally you can’t detect the yaw angle (rotation around the vertical axis) as it’s only an accelerometer, not a gyroscope.
What it is great at doing, is detecting tilt, with a wii controller a pair of stepper motors and a controller it’d be possible to make a segway style vehicle, or even possible a one wheeled balancing vehicle. That would be so cool, and I don’t think anyone has yet made a proper one wheeled balancing vehicle (existing ones either put the weight below the wheel axis, or only did front/back balance, so still required unicycle skills to ride). Probably way beyond your budget though, motors and batteries aren’t cheap, and not in any way practical. The hassle with the wii controller thinking about it, is that you’ve still got a slight bluetooth delay (apparently something like 2ms), which might make real-time control dodgy.
It occurs to me, that if you wanted to do something involving acceleration / positioning, the Lego Mindstorms NXT might be more practical, as you can get wired sensors for it that give you acceleration, compass heading etc. and it all plugs into a nice little programmable box. http://www.mindsensors.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=57&MMN_position=24:24