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Natural Science Forum / Physics / General Physics / July 2008Feasibility of spherical wheels
We're trying to fit spherical wheels to move a prototype vehicle rather than the conventional circular one for our project. The advantages we see are greater acceleration due to smaller M.I (for the same mass of the wheels) and easy parking. I suggested the electric motor principle for giving drive to the wheels. For steering, i think, by changing the orientation of the field, we could bring about a change in the rotational axis. Is this idea feasible? Im not sure about the steering part. can you people come up with some constructive ideas? | We're trying to fit spherical wheels to move a prototype vehicle | rather than the conventional circular one for our project. The [quoted text clipped - 5 lines] | Is this idea feasible? Im not sure about the steering part. can you | people come up with some constructive ideas? http://www.dyson.co.uk/?sicampaignppc=google&sicampaigntopic=brand > | We're trying to fit spherical wheels to move a prototype vehicle > | rather than the conventional circular one for our project. The [quoted text clipped - 7 lines] > > http://www.dyson.co.uk/?sicampaignppc=google&sicampaigntopic=brand That's just a mono wheel though, not quite what the OP is talking about. Note the tread pattern. | > "Gan" <sganesh88@gmail.com> wrote in message news:3d5e893c-5c18-4731-9185-352bfb53d64e@y38g2000hsy.googlegroups.com... | > | We're trying to fit spherical wheels to move a prototype vehicle | > | rather than the conventional circular one for our project. The [quoted text clipped - 10 lines] | That's just a mono wheel though, not quite what the OP is talking about. | Note the tread pattern. Oh, so he wasn't talking about a spherical wheel. Any idea why he said "We're trying to fit spherical wheels to move a prototype vehicle" instead of "We're trying to fit mono wheels with funny tread patterns to move a prototype vehicle" then I would have known what he was talking about? Tom Davidson got it right, he said ball bearings. I seem to recall those being different to needle roller bearings and sleeve bearings. Note the smooth tread pattern. Pity the Dyson vac wasn't a constructive idea for the steering part he wasn't sure about. Perhaps he's building a prototype tea trolley. How about castors? Or he could do away with wheels altogether and have a hover tea trolley, a step up from the lawn mower. We could even have afternoon tea on the lawn when he's finished mowing it. http://www.blueworldgardener.co.uk/store/images/flymoturbo_Lite_330oscom_tn.jpg Androcles said(This time i get this right) "If you are so stupid as to not know who did then you have no possibility building or designing ANYTHING. " A far-fetched conclusion. Btw, you remind me of Richard Rivers of the Physics community in orkut. | Androcles said(This time i get this right) | "If you are so stupid as to not know who did then you | have no possibility building or designing ANYTHING. " | A far-fetched conclusion. | Btw, you remind me of Richard Rivers of the Physics community in orkut. BTW, you remind me of Stan in Laurel and Hardy. http://www.youtube.com/watch?v=3WpFJJorSi0 > | Androcles said(This time i get this right) > | "If you are so stupid as to not know who did then you [quoted text clipped - 4 lines] > BTW, you remind me of Stan in Laurel and Hardy. > http://www.youtube.com/watch?v=3WpFJJorSi0 Perhaps the OP is promoting the new ball wheel Dyson vacuum clearner? Harry C. @benj "The only useful part of the "wheel" is the band around the center that touches the ground." But you need some mass in-between for torque transmission from the central disc to this "band" right? Roll a sphere and a hoop of same mass down an incline? the one which contains "only the useful band" has lesser acceleration. "Hint: Even if you go with identical mass, Solid Cylinder = 1/2 (MR^2) Spherical Shell = 2/3 (MR^2) Um I believe 2/3 > 1/2 " First of all the wheels used presently aren't exactly solid cylinders. rather they fall under the "Thick-walled cylindrical tube with open ends, of inner radius r1, outer radius r2, length h and mass m" given in http://en.wikipedia.org/wiki/List_of_moments_of_inertia And i'm just talking about a solid sphere. Not a spherical shell. "Why can't I rotate the axle by 90 degrees? I can do it if I want to! As someone mentioned Tea Trolley casters. " We aren't talking about tea trolleys here. Rather something that's much bigger than that. Ever seen a fourwheeler tire turn 90 degrees?? Anyway i guess implementing spherical wheels might help in better and fast steering-might prove critical in collision avoidance- and easy parking. But im confused regarding the methodology of doing that. @androcles "BTW, you remind me of Stan in Laurel and Hardy. " hey i didn't mean anything wrong. Richard Rivers was a great guy there. Had a large fan-following. | @androcles | "BTW, you remind me of Stan in Laurel and Hardy. " | hey i didn't mean anything wrong. Richard Rivers was a great guy | there. Had a large fan-following. Stan was a very funny guy, a real clown. Unfortunately we have too many of them in sci.physics. > We're trying to fit spherical wheels to move a prototype vehicle > rather than the conventional circular one for our project. The [quoted text clipped - 5 lines] > Is this idea feasible? Im not sure about the steering part. can you > people come up with some constructive ideas? Nothing constructive here. I know that all the latest cartoon Sci Fi movie cars all are shown with spherical wheels, but unless I"m mistaken the idea is for them to LOOK cool rather than actually BE cool! First off I seriously doubt the MI is smaller. Consider. How much of a spherical wheel is used? A band right around the center! That means all the mass that makes up the rest of the supporting sphere that never touches the ground is wasted excess! Of course the cool thing about spherical wheels is that you can roll them in any direction (as is amply demonstrated in the aforementioned films). Driving sideways is cool. But I'll note that you can also drive a standard wheel sideways by simply rotating the axle 90 degrees! I can see an advantage of the sphere in some situations, like say a mouse ball where it is to pick up all directions as well as motions, but generally I'd guess that there is a reason cars don't have spherical tires no matter how cool it'd look. I mean the Dyson does look cool, no? But I doubt it drives around the rug any better than my wheeled Hoover. > We're trying to fit spherical wheels to move a prototype vehicle > rather than the conventional circular one for our project. The [quoted text clipped - 5 lines] > Is this idea feasible? Im not sure about the steering part. can you > people come up with some constructive ideas? Which "electric motor principle"? If you mean using the ball as a rotor in your basic electromagnetic motor, I'd think stray fields would be an issue. Also, "changing the orientation of the field" will be more than a little awkward stator-coil-design-wise. Googling for "spherical wheel" finds this among the early hits: http://www.sphericalwheel.com/ing_home.html Notice the ball is held in a sort of "keeper" frame which not only transfers the load vertically but also stabilizes the ball laterally. Of course it isn't a driven wheel, but powering the bearings (I'm imagining a motor per bearing, feeding them power proportionally to the desired direction) and hence the ball should be fairly simple. Whether it would violate the patent, or would be a patentable improvement, is your problem. ;>) Mark L. Fergerson > We're trying to fit spherical wheels to move a prototype vehicle > rather than the conventional circular one for our project. The [quoted text clipped - 5 lines] > Is this idea feasible? Im not sure about the steering part. can you > people come up with some constructive ideas? Ball bearings. The trackball in a mechanical mouse will give you ideas for mounting, driving, braking, steering. Tom Davidson Richmond, VA Androcles said: "First off I seriously doubt the MI is smaller. Consider. How much of a spherical wheel is used? A band right around the center! That means all the mass that makes up the rest of the supporting sphere that never touches the ground is wasted excess!" The M.I is smaller because of the reason you mentioned. Since a considerable mass of the wheel is concentrated closer to the center than that of the circular wheel, the M.I gets reduced. "But I'll note that you can also drive a standard wheel sideways by simply rotating the axle 90 degrees!" No. You cannot rotate the axle by 90 degrees; and when the rotational axis is in line with the direction of motion, friction is no longer static or in other words starts doing work, which we don't want. | Androcles said: | "First off I seriously doubt the MI is smaller. No I did NOT. If you are so stupid as to not know who did then you have no possibility building or designing ANYTHING. > Androcles said: (Actually I said it, not Andro) > "First off I seriously doubt the MI is smaller. Consider. How > much of a spherical wheel is used? A band right around the center! > That means all the mass that makes up the rest of the supporting > sphere that never touches the ground is wasted excess!" > The M.I is smaller because of the reason you mentioned. Since a > considerable mass of the wheel is concentrated closer to the center > than that of the circular wheel, the M.I gets reduced. Your thinking is really fuzzy here. First off your assumption of equal mass isn't practical at all nor a valid comparison. Think about this. The only useful part of the "wheel" is the band around the center that touches the ground. Now given that, we can support it with two hemispheres or a single disk in the center (standard wheel). Which takes more material and which has larger MO? Hint: Even if you go with identical mass, Solid Cylinder = 1/2 (MR^2) Spherical Shell = 2/3 (MR^2) Um I believe 2/3 > 1/2 > "But I'll note that you can also drive a > standard wheel sideways by simply rotating the axle 90 degrees!" > No. You cannot rotate the axle by 90 degrees; and when the rotational > axis is in line with the direction of motion, friction is no longer > static or in other words starts doing work, which we don't want. Why can't I rotate the axle by 90 degrees? I can do it if I want to! As someone mentioned Tea Trolley casters. |
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