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Looks great! Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering ZF's own page about this has a bunch mo

Looks great! Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering ZF's own page about this has a bunch more info https://www.zf.com/products/en/cars/stories/maneuverable.html https://www.zf.com/products/en/cars/stories/maneuverable.htm... Their page also contradicts the Interesting Engineering where it said: "The system further requires an unusually large amount of space in the wheel wells to get that kind of angle, one that can only be achieved in front-wheel drive vehicles." The ZF page states the opposite: "EasyTurn is suitable for vehicles with rear-wheel drive, the usual setup in electric cars. And it is ideally suited for volume segments because the MacPherson axle is compatible with around 80 percent of today's common platforms"

bbarn 4y ago
> Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering First thing I noticed as well. I would imagine it's also possible without it, but you'd likely be losing traction on the rear inside wheel? At slow speeds some cars already do this anyway, even with the differential helping minimize it.
- photoGrant 4y ago
  You use a lovely thing called a haladex
  - jacquesm 4y ago
    Haldex?
    - photoGrant 4y ago
      Aw dangit why do you have to spot the a like that!
  - jjtheblunt 4y ago
    or torsen
- t0mas88 4y ago
  BMW has that on many models, rear wheel steering and variable-ratio at the front. It's an option they call Integral Active Steering. The rear is steered either against or with the front, so it will make a tighter turn on a parking lot and it will "crab" on the highway for extra comfort when changing lanes. The front ratio uses a planetary gear set to give you a higher or lower steering-ratio based on speed, and it allows the stability control to automatically counter-steer a bit when loosing traction at the rear.
throwaway0a5e 4y ago
Considering a) ze German penchant for interesting control linkages and b) the lack of an 80degree CV shaft shown in the demo video I'm assuming this is a RWD thing. If they could pull of an 80deg CV joint, hell even a 60deg one, at a decent price/performance point that would be the real money maker here. Every fork lift made in the last century can turn the wheels near 90, being able to transmit the power there (like you need in a FWD application) is the hard part. Furthermore, work trucks and vans need this kind of stuff a lot more than compact cars do. A tiny car already turns good enough to be not a pain point in practice, the opposite really. People are already highly satisfied with them so making it turn better is just dick measuring. Taking a van that turns bad and making it turn good is a competitive advantage.
- 0xbadcafebee 4y ago
  > A tiny car already turns good. This device would gain us 1-2 more cars per parallel parked city block (if it took off). You simply can't get out of a parallel parked space without extra room due to steering angle.
  - prmoustache 4y ago
    It is more about how much patience do you have than steering angle.
  - _carbyau_ 4y ago
    I find it is mostly about whether I have the patience to find the perfect position/angle of approach, timing of turn etc. Much easier to simply drive along and find a slightly bigger park. Combine this with auto-park though. Could be nice.
- hnov 4y ago
  Maybe the thing to solve this will be individual electric motors that are mounted to subframe as to not add unsprung mass but articulate with the wheel somehow. Or more realistically instead of huge angle on undriven wheels, a bit of an angle on all wheels. It’s been done for a while, in the 90s on Japanese sports cars and now German luxo barges.
robin_reala 4y ago
Yeah, that struck me as well. The demo video uses an i3 which, unless they’ve done some serious reengineering, is a RWD vehicle.
- jcampbell1 4y ago
  This only works for rear wheel drive. The author is terribly confused. To achieve these turns, the torque is applied on the outer rear wheel by braking the inside rear wheel.
darksaints 4y ago
It's gotta be a typo. Front wheel drive gives you the opposite of a lot of space in the wheel wells.
- _yb2s 4y ago
  I agree this must be a typo! The demo car in the video (BMW i3) is a rear wheel drive car. Given that, this whole thing doesn't make any sense to me as a supposed advance. RWD cars have always had tighter turning raidii. Many of them actually have a stop to keep you from turning the wheel 90 degrees such that the tires push instead of roll. I remember adjusting an early 70s Volvo so the front wheel could turn almost 90 degrees just as an experiment, and doing this adjustment was trivial.
  - twawaaay 4y ago
    Well, FWD cars will always have a potential for tighter turning radius. RWD car is essentially pushing on a wheel that is almost perpendicular -- not very helpful, a lot of force needed to start the car rolling, potential to damage the wheel. As you get closer to 90 degrees the force needed becomes higher than available traction and the entire thing stops steering at all. FWD can be thought as "pulling" the car by the front of it, the wheels can be in any position as long as we know how to transfer power.
    - ryukoposting 4y ago
      Sure, it's true that "FWD cars will always have a potential for tighter turning radius." In practice, that's not the case for conventional front-engine layouts. Most RWD cars mount their engines longitudinally, so the transmission sticks out the back of the engine. This means there isn't a whole lot of "stuff" sticking out to the left and right of the engine. That means more room for wheel articulation. One problem with FWD is space. Since the engine is usually mounted transversely, the transmission has to go under/beside the engine, taking up space that would otherwise be usable for larger suspension components / wheel articulation. The other problem with FWD is, as you mention, power transfer. It would be extremely difficult to design a shaft that could transfer power to a wheel that articulates up to 80 degrees. Keep in mind that such a shaft must snake its way through suspension components, too. If I understand it properly, the demo is using torque-vectoring-by-brake during turns (basically braking the inside drive wheel). Most modern cars can do this, it's just not typically necessary for low-speed turns. I suspect that the BMW i3 was featured in the video for a lot of reasons: 1) It's RWD, which leaves room for extreme wheel articulation. 2) It's electric, so there's less stuff up front in the first place. 3) The i3's tires are super skinny, meaning less resistance on those super tight turns. 4) The i3's short wheelbase means the outside rear wheel doesn't scrub too badly during tight turns.

bbarn 4y ago

> Couldn't help noticing the video appears to show the demo car also has 4WS with rear wheels also steering First thing I noticed as well. I would imagine it's also possible without it, but you'd likely be losing traction on the rear inside wheel? At slow speeds some cars already do this anyway, even with the differential helping minimize it.

photoGrant 4y ago
You use a lovely thing called a haladex
- jacquesm 4y ago
  Haldex?
  - photoGrant 4y ago
    Aw dangit why do you have to spot the a like that!
- jjtheblunt 4y ago
  or torsen
t0mas88 4y ago
BMW has that on many models, rear wheel steering and variable-ratio at the front. It's an option they call Integral Active Steering. The rear is steered either against or with the front, so it will make a tighter turn on a parking lot and it will "crab" on the highway for extra comfort when changing lanes. The front ratio uses a planetary gear set to give you a higher or lower steering-ratio based on speed, and it allows the stability control to automatically counter-steer a bit when loosing traction at the rear.

throwaway0a5e 4y ago

Considering a) ze German penchant for interesting control linkages and b) the lack of an 80degree CV shaft shown in the demo video I'm assuming this is a RWD thing. If they could pull of an 80deg CV joint, hell even a 60deg one, at a decent price/performance point that would be the real money maker here. Every fork lift made in the last century can turn the wheels near 90, being able to transmit the power there (like you need in a FWD application) is the hard part. Furthermore, work trucks and vans need this kind of stuff a lot more than compact cars do. A tiny car already turns good enough to be not a pain point in practice, the opposite really. People are already highly satisfied with them so making it turn better is just dick measuring. Taking a van that turns bad and making it turn good is a competitive advantage.

0xbadcafebee 4y ago
> A tiny car already turns good. This device would gain us 1-2 more cars per parallel parked city block (if it took off). You simply can't get out of a parallel parked space without extra room due to steering angle.
- prmoustache 4y ago
  It is more about how much patience do you have than steering angle.
- _carbyau_ 4y ago
  I find it is mostly about whether I have the patience to find the perfect position/angle of approach, timing of turn etc. Much easier to simply drive along and find a slightly bigger park. Combine this with auto-park though. Could be nice.
hnov 4y ago
Maybe the thing to solve this will be individual electric motors that are mounted to subframe as to not add unsprung mass but articulate with the wheel somehow. Or more realistically instead of huge angle on undriven wheels, a bit of an angle on all wheels. It’s been done for a while, in the 90s on Japanese sports cars and now German luxo barges.

robin_reala 4y ago

Yeah, that struck me as well. The demo video uses an i3 which, unless they’ve done some serious reengineering, is a RWD vehicle.

jcampbell1 4y ago
This only works for rear wheel drive. The author is terribly confused. To achieve these turns, the torque is applied on the outer rear wheel by braking the inside rear wheel.

darksaints 4y ago

It's gotta be a typo. Front wheel drive gives you the opposite of a lot of space in the wheel wells.

_yb2s 4y ago
I agree this must be a typo! The demo car in the video (BMW i3) is a rear wheel drive car. Given that, this whole thing doesn't make any sense to me as a supposed advance. RWD cars have always had tighter turning raidii. Many of them actually have a stop to keep you from turning the wheel 90 degrees such that the tires push instead of roll. I remember adjusting an early 70s Volvo so the front wheel could turn almost 90 degrees just as an experiment, and doing this adjustment was trivial.
- twawaaay 4y ago
  Well, FWD cars will always have a potential for tighter turning radius. RWD car is essentially pushing on a wheel that is almost perpendicular -- not very helpful, a lot of force needed to start the car rolling, potential to damage the wheel. As you get closer to 90 degrees the force needed becomes higher than available traction and the entire thing stops steering at all. FWD can be thought as "pulling" the car by the front of it, the wheels can be in any position as long as we know how to transfer power.
  - ryukoposting 4y ago
    Sure, it's true that "FWD cars will always have a potential for tighter turning radius." In practice, that's not the case for conventional front-engine layouts. Most RWD cars mount their engines longitudinally, so the transmission sticks out the back of the engine. This means there isn't a whole lot of "stuff" sticking out to the left and right of the engine. That means more room for wheel articulation. One problem with FWD is space. Since the engine is usually mounted transversely, the transmission has to go under/beside the engine, taking up space that would otherwise be usable for larger suspension components / wheel articulation. The other problem with FWD is, as you mention, power transfer. It would be extremely difficult to design a shaft that could transfer power to a wheel that articulates up to 80 degrees. Keep in mind that such a shaft must snake its way through suspension components, too. If I understand it properly, the demo is using torque-vectoring-by-brake during turns (basically braking the inside drive wheel). Most modern cars can do this, it's just not typically necessary for low-speed turns. I suspect that the BMW i3 was featured in the video for a lot of reasons: 1) It's RWD, which leaves room for extreme wheel articulation. 2) It's electric, so there's less stuff up front in the first place. 3) The i3's tires are super skinny, meaning less resistance on those super tight turns. 4) The i3's short wheelbase means the outside rear wheel doesn't scrub too badly during tight turns.