16 ms·

Electric power assist already allows that. It's probably cheaper, lighter and maybe safer to have no steering column.

m463 3y ago
I meant decoupled variable ratio, not mechanical variable ratio[1], not power assist. sort of like turning mouse acceleration on and off. [1] https://en.wikipedia.org/wiki/Steering_ratio#Variable-ratio_steering https://en.wikipedia.org/wiki/Steering_ratio#Variable-ratio_...
yreg 3y ago
No matter what we think about FSD, Tesla's end goal are robotaxis – eventually probably with no steering wheels. Steer by wire is a stepping stone in that direction.
giobox 3y ago
They almost always only vary the amount of power assistance, not the ratio. The ratio is fixed on virtually all electrically power assisted steering racks ever shipped. There is still a fixed mechanical linkage - decoupling this is what allows the ratio to be dynamically adjusted. To date only a handful of Lexus production cars have had dynamic variable ratio and decoupled steering via drive by wire. Electric power steering is essentially the same in use as traditional hydraulic systems - they just replace the hydraulic assistance with electric motors. The big advantage of decoupling and steer by wire is dynamic variable ratio, as well as packaging - no steering column to worry about making space for.
- inferiorhuman 3y ago
  Nah, there are variable ratio mechanical systems. On a rack and pinion setup, for instance, you vary the spacing of the teeth on the rack. ZF's been doing this for decades.
  - giobox 3y ago
    Generally speaking almost all mechanical steering systems are not dynamic though, you are missing the point entirely. It can't change the spacing of the teeth on the fly - steer by wire effectively does. The number of turns lock to lock on a mechanical system is almost always the same, regardless of speed. With steer by wire, you can easily implement say one turn lock to lock at low speed for easier parking, increasing to 2-3 turns at highway speeds for stability. Which is essentially exactly what the recent Lexus model with such a system does. At low speed it can turn its wheels from one extreme to the other in just 150 degrees of steering wheel rotation - no hand over hand turning etc. 150 degrees is essentially unthinkable on a mechanical rack and pinion system, as it would make the car incredibly twitchy on a highway. > https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-by-wire-yoke-review/ https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-b...
    - inferiorhuman 3y ago
      It can't change the spacing of the teeth on the fly. Geez, Elon really ought to start a goalpost moving company. But hey I'll play: yes, yes it can. That's precisely what BMW's active steering is, yes it's mechanical, yes it varies the ratio depending on speed, and yes it's been around for a couple decades now.
      - giobox 3y ago
        BMW active steer doesn't get remotely close to 150 degrees lock to lock when maneuvering (minimum rotation reached is ~720 degrees/2 turns), or offer the infinite and instant range of adjustability you can get with a drive by wire system. But sure, it's just the same. I couldn't care less whether the system is on a Tesla or not, its just abundantly clear there are some design and packaging advantages when you lose the mechanical link in anything with a steering wheel. The vast, vast majority of rack and pinion systems ever made, both old and modern, don't adjust number of turns lock to lock at all, whereas the ability to essentially infinitely adjust it is inherent in all drive by wire steering systems.
        3y ago
- m463 3y ago
  and you could invert X :)

m463 3y ago

I meant decoupled variable ratio, not mechanical variable ratio[1], not power assist. sort of like turning mouse acceleration on and off. [1] https://en.wikipedia.org/wiki/Steering_ratio#Variable-ratio_steering https://en.wikipedia.org/wiki/Steering_ratio#Variable-ratio_...

yreg 3y ago

No matter what we think about FSD, Tesla's end goal are robotaxis – eventually probably with no steering wheels. Steer by wire is a stepping stone in that direction.

giobox 3y ago

They almost always only vary the amount of power assistance, not the ratio. The ratio is fixed on virtually all electrically power assisted steering racks ever shipped. There is still a fixed mechanical linkage - decoupling this is what allows the ratio to be dynamically adjusted. To date only a handful of Lexus production cars have had dynamic variable ratio and decoupled steering via drive by wire. Electric power steering is essentially the same in use as traditional hydraulic systems - they just replace the hydraulic assistance with electric motors. The big advantage of decoupling and steer by wire is dynamic variable ratio, as well as packaging - no steering column to worry about making space for.

inferiorhuman 3y ago
Nah, there are variable ratio mechanical systems. On a rack and pinion setup, for instance, you vary the spacing of the teeth on the rack. ZF's been doing this for decades.
- giobox 3y ago
  Generally speaking almost all mechanical steering systems are not dynamic though, you are missing the point entirely. It can't change the spacing of the teeth on the fly - steer by wire effectively does. The number of turns lock to lock on a mechanical system is almost always the same, regardless of speed. With steer by wire, you can easily implement say one turn lock to lock at low speed for easier parking, increasing to 2-3 turns at highway speeds for stability. Which is essentially exactly what the recent Lexus model with such a system does. At low speed it can turn its wheels from one extreme to the other in just 150 degrees of steering wheel rotation - no hand over hand turning etc. 150 degrees is essentially unthinkable on a mechanical rack and pinion system, as it would make the car incredibly twitchy on a highway. > https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-by-wire-yoke-review/ https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-b...
  - inferiorhuman 3y ago
    It can't change the spacing of the teeth on the fly. Geez, Elon really ought to start a goalpost moving company. But hey I'll play: yes, yes it can. That's precisely what BMW's active steering is, yes it's mechanical, yes it varies the ratio depending on speed, and yes it's been around for a couple decades now.
    - giobox 3y ago
      BMW active steer doesn't get remotely close to 150 degrees lock to lock when maneuvering (minimum rotation reached is ~720 degrees/2 turns), or offer the infinite and instant range of adjustability you can get with a drive by wire system. But sure, it's just the same. I couldn't care less whether the system is on a Tesla or not, its just abundantly clear there are some design and packaging advantages when you lose the mechanical link in anything with a steering wheel. The vast, vast majority of rack and pinion systems ever made, both old and modern, don't adjust number of turns lock to lock at all, whereas the ability to essentially infinitely adjust it is inherent in all drive by wire steering systems.
      - 3y ago
m463 3y ago
and you could invert X :)