High speed mid drive hub as a gyroscopic stabilizer?

[Indubitably]

I've been toying with the idea of coupling my high speed 5302 hub to a front limited slip differential drive train robbed from a small quad ATV via a gocart gearbox to power a long travel rear suspension all wheel steering delta trike, and it occurred to me that there is nothing really stopping me from mounting the motor horizontally.

My thinking is that if the motor is positioned correctly it should act as a sort of gyroscopic stabilizer at high speeds to help discourage the bike from rolling. I plan to make the rear wheel base pretty wide, and the rear steering will have a much less extreme range than the front, so it shouldn't be wanting to roll anyway, but I like the idea of being able to really lean into it and have some counter balanced to offset my weight. I'm also thinking that this would be an interesting way to conserve energy in a stop and go driving environment, since I could kick the gear box into neutral and let the motor spin like a top, or maybe even shift into a lower gear to spin the motor up like a mechanical version of regen braking.

Does anyone see any critical flaws in my reasoning here? Will I need to upgrade bearings in the hub or anything of that sort? Is the gryoscopic effect going to be more than I bargained for (or perhaps barely noticeable)? It will obviously complicate the process of coupling the bicycle crank to the hub motor, but with a differential in the equation (you pretty much can't get a lightweight chain drive differential at a reasonable price, so I'll be using something with a drive shaft who's plane of rotation is normal to the bicycle crank) I figure that is pretty much inevitable at this point anyway.

 

[Indubitably]

The other, far less exotic, complicated, expensive, and functional, alternative is just to buy a complete swing arm chain drive rear end from a generic chinese mini atv. The wheels wouldn't have independent suspension, and I wouldn't be doing any rear wheel steering, but it probably would be lighter, have a differential, and if/when it died, I would be able to more less just straight up swap the whole thing out for another rear end instead of hunting for rare replacement parts and the like.

 

[cal3thousand]

horizontally?

I think gyroscopes work on the right hand rule and would stabilize and balance vertically in the normal wheel orientation. At least that is how I understand bicycles to work. Maybe I'm misunderstanding you?

Got a picture?

 

[cal3thousand]

Also, reading the rest of the power storage part (flywheel), makes me think that the hub would have to be able to freewheel and it would have to be somewhat massive to have a benefit. OR it would have to spin ridiculously fast to be beneficial.

 

[d8veh]

Be careful, you might find that you can't turn. I think you need twin gyros to stop rolling but still be able to steer.
Here's a link to that motorbike that can't fall over.
http://www.youtube.com/watch?v=bWxRV4jZWeY&feature=related

 

[Indubitably]

Cal3thousand:

Hmm... well, to the best of my knowledge the "balancing force" would be normal to both the axis of rotation and the direction in which the bike leans. My thinking was that it would want to hold the bike upright in the same way that a spinning top is held upright under precession. I could be wrong though, it has been a while since I looked at that material.

As for mass, you might be right now that I think about it, if it was the copper spinning you'd have some pretty decent momentum. but the magnets and the casing don't weigh all the much. Then again, kinetic energy goes as the square of velocity, so you might just get enough spin in there to take a little of the bite out of bring the bike back up to speed so long as you weren't stopped for too long.

 

[Miles]

It won't work with a rigid set-up.... It's a bit more complicated than that....

The dynamic stabilization of a monorail car or two-wheeled automobile requires that a torque acting
on the car from the outside be neutralized by a torque produced within the car by a gyroscope. The
gyroscope here is used as an actuator, not a sensor, by using precession forces generated by the gyroscope.
When torque is applied to an axis normal to the spin axis, causing the gyroscope to precess, a moment
is produced about a third axis, orthogonal to both the torque and spin axes. As the vehicle tilts from
vertical, a precession-inducing torque is applied to the gyroscope cage such that the resulting gyroscopic
reaction moment will tend to right the vehicle. The key idea is that motion of the gyroscope relative to
the body is actively controlled in order to generate a stabilizing moment.

Ref: http://www.umich.edu/~arclab/max/media/gyrovehicle.pdf

http://www.endless-sphere.com/forums/viewtopic.php?p=465729#p465729

http://www.endless-sphere.com/forums/viewtopic.php?f=7&t=31949

 

[Indubitably]

Be careful, you might find that you can't turn. I think you need twin gyros to stop rolling but still be able to steer.
Here's a link to that motorbike that can't fall over.
http://www.youtube.com/watch?v=bWxRV4jZWeY&feature=related

Yeah, I was just thinking about that, stopping is like applying a force to the gyroscope in the direction opposite movement (after all, the gyroscope doesn't know its moving once you're at speed), and could potentially yank the front end around. Being on three wheels might help, but if it makes more problems than it solves I may be better served going a different rout.

 

[cal3thousand]

Makes me think of the experiment that I first learned about gyroscopes in my HS Physics class. The teacher had someone sit in a chair that rotated on it's seat while holding a bicycle wheel that was retrofitted with handles extending the axle. With a spinning wheel, the person is able to rotate in the chair by simply varying the orientation of the wheel, thus changing the angular momentum.


EDIT:

Here's youtube I found of the same thing:

[youtube]4EiL7eIpGmg[/youtube]

 

[Indubitably]

It won't work with a rigid set-up.... It's a bit more complicated than that....

The dynamic stabilization of a monorail car or two-wheeled automobile requires that a torque acting
on the car from the outside be neutralized by a torque produced within the car by a gyroscope. The
gyroscope here is used as an actuator, not a sensor, by using precession forces generated by the gyroscope.
When torque is applied to an axis normal to the spin axis, causing the gyroscope to precess, a moment
is produced about a third axis, orthogonal to both the torque and spin axes. As the vehicle tilts from
vertical, a precession-inducing torque is applied to the gyroscope cage such that the resulting gyroscopic
reaction moment will tend to right the vehicle. The key idea is that motion of the gyroscope relative to
the body is actively controlled in order to generate a stabilizing moment.

Ref: http://www.umich.edu/~arclab/max/media/gyrovehicle.pdf

http://www.endless-sphere.com/forums/viewtopic.php?p=465729#p465729

http://www.endless-sphere.com/forums/viewtopic.php?f=7&t=31949

Yeah, that does seem to make sense, although I think d8veh may actually be right in that so long as I have two on gimbles that are at oblique right angles to each other I should be able to balance the bike manually. Of course, that does make it difficult to get power from the hub to the ground, but I could probably righ something up along the gimble axis. Getting it out magnetically would work, but then I would need another set of motors.

I suppose if I was actually going to do this I would go back to a 2 wheel (perhaps with hollow hubs, and a gyro in each hoop) design, and try to find some way to use my batteries as a fly wheel. Then slowly spin the battery fly wheel up via a light weight low power hub that has nothing to do with driving the vehicle and run the power out along the axle with brush contacts or something. The gyro hubs would pull off however much they needed to keep the batteries spinning, and the rest would get pumped to wheels. I can't vouch for efficiency, but it would be a pretty smooth ride.

 

[cal3thousand]

You have a good theory. And that's why I think they are using it in the Lit C-1. But that thing is operating at a larger scale of an enclosed motorcycle. It's also patented, so you might be stepping on some IP.

 

[AussieJester]

The other, far less exotic, complicated, expensive, and functional, alternative is just to buy a complete swing arm chain drive rear end from a generic chinese mini atv. The wheels wouldn't have independent suspension, and I wouldn't be doing any rear wheel steering, but it probably would be lighter, have a differential, and if/when it died, I would be able to more less just straight up swap the whole thing out for another rear end instead of hunting for rare replacement parts and the like.

Pretty sure the rear ends are solid axle no diff..

KiM

 

[Indubitably]

The other, far less exotic, complicated, expensive, and functional, alternative is just to buy a complete swing arm chain drive rear end from a generic chinese mini atv. The wheels wouldn't have independent suspension, and I wouldn't be doing any rear wheel steering, but it probably would be lighter, have a differential, and if/when it died, I would be able to more less just straight up swap the whole thing out for another rear end instead of hunting for rare replacement parts and the like.

Pretty sure the rear ends are solid axle no diff..

KiM

Some are straight live axle, some are locking differential. I just need to make sure that I find the right one. I did however find this...

http://www.northerntool.com/shop/tools/product_35768_35768

Its not a limited slip differential, but it should do the job as long as I don't loose traction.

 

[AussieJester]

^^^Came across the exact diff when i was building trikes, they are for ride on lawnmowers apparently, they
also come in differing lengths and axle size, i have a link somewhere to a place that stock them all..

KiM

 

[Indubitably]

^^^Came across the exact diff when i was building trikes, they are for ride on lawnmowers apparently, they
also come in differing lengths and axle size, i have a link somewhere to a place that stock them all..

KiM

Let me know if you can track it down, I'm thinking if I can find a source of cheap double cardan joints the suspension trike can be done for a fairly reasonable price. I'm also thinking a 1 inch solid steel shaft is over kill for this application, aluminum probably isn't going hold up but sufficiently thick chromoly tube should do the job.I'm planning to build the frame out of brazed chromoly anyway, so I'll probably have some handy.

 

[AussieJester]

^^^Came across the exact diff when i was building trikes, they are for ride on lawnmowers apparently, they
also come in differing lengths and axle size, i have a link somewhere to a place that stock them all..

KiM

Let me know if you can track it down,

http://farmex.now.tc/catalog/index.php?cPath=22_168_663&osCsid=39b5c43cd773837e7f2c43421cdf9061

:wink:

KiM

 

[Indubitably]

http://www.prutchi.com/2012/03/09/d-i-y-gyroscopic-camera-stabilizer-that-really-works/

The more I thought about how I'd go about sticking fly wheels (on gimbles at 90 degrees to each other) in a hollow-hub style wheel, the more it seemed like it realy should be feasable, so I did a search to that effect, and this is what I found...

http://www.prutchi.com/2012/03/09/d-i-y-gyroscopic-camera-stabilizer-that-really-works/

So it looks like I'm not entirely crazy after all (or as innovative as I might have liked to think, but hey, you take what you can get), people have been using almost the exact same design for years to stabilize cameras. I mean, the camera is sitting on top of the "X", where as I was planning to sit between the gyros recumbent style, but its the same basic idea as a bike; you've got a lot of weight distributed along a "forward facing" axis that you want to keep more or less level along that axis. After a little more digging, I stumbled across this....

http://www.rchelicopterfun.com/heading-hold-gyro.html


So it looks like stabilizers can be had for a fairly reasonable price, if you are so inclined. These are designed to controll the heading of an rc helicopter but with a little tweaking I'm sure we could get them to do our bidding. Personally I am of the mind that on a bike this would be better handled by a rider becoming accustomed to the gyro effect and simply countering by shifting his own weight the way a camera man would with a camera, but it might be fun to play with some stabilizers all the same.