4 ms·

Putting aside gripping strength versus traditional wheels for a moment, it would be interesting to see if this would enable more efficient street geometries. Fo

Putting aside gripping strength versus traditional wheels for a moment, it would be interesting to see if this would enable more efficient street geometries. For example, due to the reduced turning radius, could this open up additional safety buffer space for pedestrians at city crosswalks?

dpark 5y ago
These don’t provide a better turning radius than traditional wheels. The reduced turning radius only happens because the left and right wheels can spin independently, but you can do that with traditional wheels (but not traditional drive trains). I’m not sure that this does anything for pedestrian safety, though.
- ralusek 5y ago
  Wheels like this could literally turn the car 360 degrees in place...
  - dathinab 5y ago
    Yes but only if you stand on a point, not in moving traffic. E.g. if you are on a bike you can have a hyper small turning radius, but only if you mover very very slow (but not too slow ;) ). The problem is requiring such a radius would be a safety hazard, as people would all the time not get the turn due to driving to fast, even if they literally started driving a moment ago due to a red traffic light.
  - dpark 5y ago
    Regular wheels can literally do that as well. Left wheels forward, right wheels reverse will spin a vehicle like a top. Spherical wheels can do it more efficiently because they can do it with less slippage. But regular wheels can absolutely do that maneuver. Even tracks can. Heavy equipment does this all the time.
    - TaylorAlexander 5y ago
      If you have four wheel steering and a large range of steering then even normal wheels can do it without slippage. See for example this Jeep prototype vehicle. https://youtu.be/PBHrtBomLJA https://youtu.be/PBHrtBomLJA
      - dpark 5y ago
        True. If you can steer all wheels independently then you can achieve that with standard wheels. That seems a lot simpler than spherical wheels.
- dragonwriter 5y ago
  > These don’t provide a better turning radius than traditional wheels Spherical wheels provide zero radius for off-original-orientation movement from a stop (and similar but somewhat less benefit at low speed) because you can thrust independently of the direction of orientation. This isn't the same a reduced turning radius, but it has similar effects for certain low speed maneuvers to an extreme reduction in turning radius.
  - dpark 5y ago
    Standard wheels can provide a zero (or rather, minimum possible) turning radius with appropriate drive. Tracked vehicles like excavators frequently turn in place with a minimal radius by turning their tracks in opposite directions. This action does not need spherical wheels. It doesn’t even need 4 independent wheels. The only thing you can get from spherical wheels that you can’t get from standard wheels with comparable drive is sideways motion, which granted, would be kind of awesome (zooming down the highway and switching lanes with no directional change), but also not actually that useful. You can also get a bit of this from independently-steerable wheels, as someone else pointed out. But that won’t get you sideways motion from a standstill if that’s somehow useful.
    - dragonwriter 5y ago
      > You can also get a bit of this from independently-steerable wheels, as someone else pointed out. But that won’t get you sideways motion from a standstill if that’s somehow useful. You can actually get it from independently steerable wheels with AWD if they are mounted and driven independently (practical with an electric power system) rather than off a common axle; I’m pretty sure I recall concept vehicles (or at least designs) from various car companies with that design, for that purpose. The typical highlighted urban use case is zero-approach parallel parking. For autonomous vehicles, especially, it would make higher density but basically random access (and, therefore, not subject to easy blockage by small number of vehicle failures) storage possible > zooming down the highway and switching lanes with no directional change You probably can't get better than AWD with independently steerable wheels on an axle for this, because the limiting factor in how far you can change thrust direction while maintaining control at highway speed is going to be traction long before it is maximum wheel angle.
dathinab 5y ago
You can only reduce turning radius when you also reduce speed. For many cars and ares in the world the turning radius usable on small streets is not really a problem. > open up additional safety buffer space I don't think that matters, we already have very save cross road designs, we just need to use them.

dpark 5y ago

These don’t provide a better turning radius than traditional wheels. The reduced turning radius only happens because the left and right wheels can spin independently, but you can do that with traditional wheels (but not traditional drive trains). I’m not sure that this does anything for pedestrian safety, though.

ralusek 5y ago
Wheels like this could literally turn the car 360 degrees in place...
- dathinab 5y ago
  Yes but only if you stand on a point, not in moving traffic. E.g. if you are on a bike you can have a hyper small turning radius, but only if you mover very very slow (but not too slow ;) ). The problem is requiring such a radius would be a safety hazard, as people would all the time not get the turn due to driving to fast, even if they literally started driving a moment ago due to a red traffic light.
- dpark 5y ago
  Regular wheels can literally do that as well. Left wheels forward, right wheels reverse will spin a vehicle like a top. Spherical wheels can do it more efficiently because they can do it with less slippage. But regular wheels can absolutely do that maneuver. Even tracks can. Heavy equipment does this all the time.
  - TaylorAlexander 5y ago
    If you have four wheel steering and a large range of steering then even normal wheels can do it without slippage. See for example this Jeep prototype vehicle. https://youtu.be/PBHrtBomLJA https://youtu.be/PBHrtBomLJA
    - dpark 5y ago
      True. If you can steer all wheels independently then you can achieve that with standard wheels. That seems a lot simpler than spherical wheels.
dragonwriter 5y ago
> These don’t provide a better turning radius than traditional wheels Spherical wheels provide zero radius for off-original-orientation movement from a stop (and similar but somewhat less benefit at low speed) because you can thrust independently of the direction of orientation. This isn't the same a reduced turning radius, but it has similar effects for certain low speed maneuvers to an extreme reduction in turning radius.
- dpark 5y ago
  Standard wheels can provide a zero (or rather, minimum possible) turning radius with appropriate drive. Tracked vehicles like excavators frequently turn in place with a minimal radius by turning their tracks in opposite directions. This action does not need spherical wheels. It doesn’t even need 4 independent wheels. The only thing you can get from spherical wheels that you can’t get from standard wheels with comparable drive is sideways motion, which granted, would be kind of awesome (zooming down the highway and switching lanes with no directional change), but also not actually that useful. You can also get a bit of this from independently-steerable wheels, as someone else pointed out. But that won’t get you sideways motion from a standstill if that’s somehow useful.
  - dragonwriter 5y ago
    > You can also get a bit of this from independently-steerable wheels, as someone else pointed out. But that won’t get you sideways motion from a standstill if that’s somehow useful. You can actually get it from independently steerable wheels with AWD if they are mounted and driven independently (practical with an electric power system) rather than off a common axle; I’m pretty sure I recall concept vehicles (or at least designs) from various car companies with that design, for that purpose. The typical highlighted urban use case is zero-approach parallel parking. For autonomous vehicles, especially, it would make higher density but basically random access (and, therefore, not subject to easy blockage by small number of vehicle failures) storage possible > zooming down the highway and switching lanes with no directional change You probably can't get better than AWD with independently steerable wheels on an axle for this, because the limiting factor in how far you can change thrust direction while maintaining control at highway speed is going to be traction long before it is maximum wheel angle.

dathinab 5y ago

You can only reduce turning radius when you also reduce speed. For many cars and ares in the world the turning radius usable on small streets is not really a problem. > open up additional safety buffer space I don't think that matters, we already have very save cross road designs, we just need to use them.