Spherical Wheels

[Johnny Pneumatic]

Say what you will about the movie I Robot(I liked it), but you have to admit it had some neat vehicle ideas. My favorite is the spherical wheels that most cars, buses and "semi-trucks" of the future have. My question is this. Could that actually work well? How could the wheels have shock absorbers? Could off road high clearance versions be made? How would the "wheels" be steered and spun up to speed?

 

[MRC_Hans]

And what would be their purpose?

Hans

 

[neutrino_cannon]

You could... but it wouldn't be particularly useful. Granted, the mass to moment of interia would be a little more efficient, so your car would roll down hills better, but I can't think of any other advantage.

 

[Matabiri]

You could... but it wouldn't be particularly useful. Granted, the mass to moment of interia would be a little more efficient, so your car would roll down hills better, but I can't think of any other advantage.

They might handle rough terrain better - consider a normal (flat) wheel hitting a kerb at an oblique angle, and a spherical wheel doing the same - the flat wheel is more likely to suffer damage.

Also, there would probably be fewer steering linkage limitations, so you may be able to parallel park by sliding sideways into a gap only millimetres bigger than the car.

I'd assume the wheels could be steered and spun up to speed by having a powerful permanent magnet inside, and some control electromagnet coils around it. Alternatively you could have a small driven rubber wheel in contact with the spherical wheel inside (like in a computer mouse), which could rotate to provide steering.

 

[richardm]

They might handle rough terrain better - consider a normal (flat) wheel hitting a kerb at an oblique angle, and a spherical wheel doing the same - the flat wheel is more likely to suffer damage.

This was the principle behind Dyson's BallBarrow, which was a wheelbarrow with a ball for the front wheel. It worked very well on soggy ground too.

I haven't seen I, Robot so I dunno exactly how similar that is...

 

[Matabiri]

This was the principle behind Dyson's BallBarrow, which was a wheelbarrow with a ball for the front wheel. It worked very well on soggy ground too.

I haven't seen I, Robot so I dunno exactly how similar that is...

The future can't have been designed by Dyson. Everyone knows the future is white and gleaming chrome/dark, rainy and neon-lit*, not made of brightly-coloured plastic.

*Delete as appropriate.

 

[Rolfe]

Are these things set up as castors?

Rolfe.

 

[richardm]

Are these things set up as castors?

Could be very handy for parallel parking.

 

[HarryKeogh]

I always found cars of the future to look pretty dorky

 

[Johnny Pneumatic]

And what would be their purpose?

Hans

What!? You've never had to spin your car around really fast to fling androids off your car? It would be oh so fun to drive down the road sideways. But really the reason to do it would be faster parallel parking and turning your car around in tight spaces.

 

[scribble]

I always found cars of the future to look pretty dorky

Funny, I find them to look like the of <a href=http://www.nissanusa.com/vehicles/MediaGallery/0,,38045,00.html> today, but with plastic wheel covers.

There's only one <a href=http://www.bttfmovie.com/> future car</a> for me.

As for spherical wheels -- you'd get much worse acceleration and be horribly prone to slipping all over the road -- no traction, see. Much less surface area in contact with the road.

 

[BillC]

If the wheels are spehrical and capable of spinning in any direction, kind of like a mouse ball, I can't see how you would steer the vehicle. Wouldn't turning the wheel housing leave the wheel trying to continue to spin in its original plane due to gyroscopic forces?


ETA: My personal choice of future car whips anyone else's. The 200mph speed makes motorway cruising a breeze, even if the backward-facing driving position does make parallel parking a little difficult in town.

 

[Johnny Pneumatic]

As for spherical wheels -- you'd get much worse acceleration and be horribly prone to slipping all over the road -- no traction, see. Much less surface area in contact with the road.

Tires really don't have that much surface touching the road at any given time; only a few square inches(sorry metric people).
What I wonder though is what would the tread pattern look like? Round rubber numbs all over? Maybe hexagons whose edges are raised more than the center. Or something.

 

[H3LL]

The spherical wheel sums up the whole movie for me...balls.

Although a fun action movie, it was just another Frankenstein Complex movie that presented the exact opposite of what Asimov was trying to illustrate in his stories.

Daniel Chandler:

Isaac Asimov, a prolific American writer of science fiction whose background was as a professor of biochemistry, saw technophobia - a fear of technology - as an understandable but regrettable suspicion of whatever was new. He himself harboured an optimistic faith in technological progress, and admitted that he was a technophile. He variously defined one kind of technophobia as 'The Frankenstein Complex', by which he referred to 'the unreasoning human fear of robots' and - since robots are computer-controlled - of computers (Asimov, Warrick & Greenberg 1985, pp. 1, 6). Asimov did not have this fear and disapproved of those who did.

Back to the wheels, what movie/show was it where each axle hub consisted of three, almost spherical, tyres set in an equilateral triangle configuration with a centre pivot? As it hit a bump/rock the triangle of wheels would rotate. Hard to describe but difficult to find a picture without remembering the movie/show.

 

[Yahweh]

As for spherical wheels -- you'd get much worse acceleration and be horribly prone to slipping all over the road -- no traction, see. Much less surface area in contact with the road.

Actually, solid spherical wheels have a slightly lower moment of inertia than a wheel of the same mass, resulting in a faster acceleration (at least since the last time I did an experiment with spheres and cylinders). And friction doesnt rely on surface area.

But the problem I have is trying to figure out how to steer spherical wheels.

 

[Matabiri]

But the problem I have is trying to figure out how to steer spherical wheels.

You could also have a flywheel in the car to offset the gyroscopic effect.

 

[exarch]

Originally posted by Yahweh
But the problem I have is trying to figure out how to steer spherical wheels.

I think it's probably something that won't work without electromagnets, and a computer controller to steer it (turning the wheels is possible, but would render the purpose of your wheels being ball-shaped void. So course changes would have to be made by slightly rotating the balls sideways, sort of spiraling). Perhaps steering could be done by means of a stick, just like a plane, only with the ability to allow control over the sideways motion of the car, perhaps by rotating the stick. Spinning out is no longer that big a problem either.

One good thing though is that your tires will last longer as the entire surface of the ball should theoretically wear evenly, not just the flat surface as with normal tires. How to get air into them is another matter though. That will probably have to be replaced by some kind of foam or something that can't leak out ...

 

[Bruce]

I'm surprised no one has mentioned this yet, but with a tire, you have a rectangular strip of surface area from each tire touching the road. With spherical wheels, you would have a spherical surface area touching the road.

Centering your weight on a single point would not only cause more wear and tear on the wheel, but as mentioned earlier, you would have considerably more trouble with steering and slipping.

The best "wheels" are tank treads. Maximum surface area, and you still have the ability to steer. Those military guys are way ahead of us. I wander why there aren't any vehicles with tank tread available to the public?

 

[Matabiri]

The best "wheels" are tank treads. Maximum surface area, and you still have the ability to steer. Those military guys are way ahead of us. I wander why there aren't any vehicles with tank tread available to the public?

Bad ride, and they're really bad for the roads.

 

[exarch]

Originally posted by Bruce
I'm surprised no one has mentioned this yet, but with a tire, you have a rectangular strip of surface area from each tire touching the road. With spherical wheels, you would have a spherical surface area touching the road.

A circular area actually, but I don't see how this would be a problem. In fact, a circular area would provide equal friction in all directions, while a rectangular area gives far less friction in the direction the wheel is rolling compared to the sideways friction, which is why emergency breaking can make your wheels start sliding.

Centering your weight on a single point would not only cause more wear and tear on the wheel, but as mentioned earlier, you would have considerably more trouble with steering and slipping.

On a single point, yes, but tires are slightly elastic, which would make the point expand to a circular area, with probably about the same surface area as a normal tire. In effect, a cylinder centers the weight on a line, and touches that line every full revolution of the wheel. Also, it only touches the running surface, while a cyllindrical wheel would touch the same point on the tire less frequently, but the 'side' of the wheel is also a running surface. I'm sure wear on the tires would be spread out over a larger area of tire than on a conventional cyllindrical wheel that only wears the running surface.

The best "wheels" are tank treads. Maximum surface area, and you still have the ability to steer. Those military guys are way ahead of us. I wander why there aren't any vehicles with tank tread available to the public?

Tank threads produce far too much sideways friction when turning. Even ordinary car wheels already create quite a lot of friction when being turned. And threads have way too much surface area for what a normal car really needs for normal road use. Look what happens when you only increase the tire width without increasing the weight: less traction because the vehicle has less weight per surface area than a thinner tire, which is deadly on a wet and slippery road. Also, more effort is needed when turning the wheel while standing still (i.e. during parking and other manouvers).

The reasons tanks have threads is because they mostly run on unpaved surfaces, where ordinary wheels are of no use (like mud and rough terrain). Tanks are also really heavy, which is why a tank thread is ideal for spreading all that weight out over a larger area.
By the way, tank threads roll on a set of wheels