4 ms·

Lexus is already doing steer by wire, they used it to make a vehicle with a yoke that didn't suck to operate (as much anyway): https://www.motortrend.com/review

Lexus is already doing steer by wire, they used it to make a vehicle with a yoke that didn't suck to operate (as much anyway): https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-by-wire-yoke-review/ https://www.motortrend.com/reviews/2023-lexus-rz450e-steer-b...

alistairSH 3y ago
What happens if the engine shuts off (and the alternator stops spinning)? Does the steering just run off the 12v system?
- vostrocity 3y ago
  That Lexus is an EV.
- jimt1234 3y ago
  Engineering Explained did a really good video about this: https://www.youtube.com/watch?v=agMrewRJTow https://www.youtube.com/watch?v=agMrewRJTow
  - dkjaudyeqooe 3y ago
    To save going through that whole video for the answer: they have redundant power supplies (3 batteries total) and redundant actuator motors. But the fact is if there is a bad enough electrical/wiring fault, especially as the car gets older, you are toast and you have no steering. Of course the same thing can happen with mechanical steering (eg a broken linkage) it comes down to the quality of the design and build.
    - HPsquared 3y ago
      The whole design will be such that a single electrical fault can't make it fail. It probably has at least 3 channels. Probably won't even allow you to start the car if one of them is faulty. This kind of thing will almost certainly be designed to comply with ISO 26262.
    - sfjailbird 3y ago
      I've had the power steering cut out on me in a traditional ICE car, you're pretty much hosed in that situation, too, as far as steering is concerned.
65a 3y ago
Hasn't VAG had steer-by-wire for nearly a decade now?
- dharmab 3y ago
  Only as part of four-wheel-steering systems in combination with mechanical steering for the front wheels. Nissan has steer-by-wire with a backup mechanical system.
- HPsquared 3y ago
  I had a BMW from 2007 that had something called "active steering", where an electric motor in between the steering wheel and the rack-and-pinion sort of "adjusted" the steering, which gave it a variable steering ratio (add according to speed) and also stability control interventions (it would countersteer in a slide even if I didn't turn the wheel). The stability control part is probably the biggest safety benefit of this steer-by-wire system. Other manufacturers have had similar levels of electronic steering "augmentation" of one kind or another for a long time (e.g. electronically steered rear wheels). In this kind of thing, the safety case is probably that the system only provides small adjustments so that: 1. The driver can overcome any errors in the electronic augmentation system using the main steering system 2. If the system fails, it can switch off and the driver can still steer the old-fashioned way.
- harambae 3y ago
  Yes as well as some BMW’s, McLarens, at least some of the electric Hyundai/Kias and I’m sure a bunch of others I’m not as familiar with. The shock over it on HN is just because of how few people here work in automotive.
  - dharmab 3y ago
    In those systems the steer by wire works in cooperation with a mechanical system. Other cars have had backup mechanical steering systems that engage if the steer by wire fails. What's new about the Cybertruck is it _only_ has a steer by wire system with no mechanical linkages at all. But this is being misreported as the first steer-by-wire system which doesn't cooperate with a mechanical linkage- Nissan has done that for quite a while in some models.
oceanplexian 3y ago
Sounds like a terrible idea to me, honestly. Even Boeing aircraft still have a mechanical linkage. And Cybertruck won’t be a fighter jet no matter how much Elon proclaims it so, it’s just worlds away in terms of maintenance and safety engineering compared to what happens on an aircraft. Not saying it will be common but some sucker will eventually be killed by this.
- masklinn 3y ago
  > Even Boeing aircraft still have a mechanical linkage. Airbus has been FBW for nearly 40 years now. And recent Boeings are FBW as well, the mechanical linkages are only between the yokes, something which is not relevant on a car.
  - ikekkdcjkfke 3y ago
    When i hear fly-by-wire i think of wire rope going from the flaps the cockpit
  - rich_sasha 3y ago
    I think aeroplanes are not a good point of comparison. For one, mechanical steering is still very complicated, with many meters (miles?) of hydraulic hoses, actuators, pressure control systems etc. Two, aerospace is healthily paranoid about QA and failure modes. I'm sure a steer-by-wirw can be extremely safe when done with that mindset. But Im not sure if that's the car industry's mindset, let alone Tesla's. Finally, fly-by-wire offers enormous safety benefits in aeroplanes, because of what it enables. But I have no idea what steer by wire enables for a car.
    - s3p 3y ago
      This answer seems to generate its own proof. >For one, mechanical steering is still very complicated Yes, and digital steering is by nature even more complicated. >aerospace is healthily paranoid about QA and failure modes. I'm sure a steer-by-wirw [sic] can be extremely safe when done with that mindset What? So if we have the right 'mindset' then we can ignore any complexity and adapt anything we want. Why even let users drive cars now? Make their fleet 100% autonomous. Just do it with a mindset of QA and safety!
iainmerrick 3y ago
Yikes! Even assuming it all works correctly and safely, who actually wants a steering wheel like that? What's the upside? The only possible advantage I can think of is that when you start the car up again after having reverse parked, it'll be more obvious what way the wheels are currently pointing, so you can straighten up. But that's such a trivial problem.
- gambiting 3y ago
  >>What's the upside? A much easier to manouver car, because you can get true variable speed ratio steering. It's explained really well here: https://www.youtube.com/watch?v=agMrewRJTow https://www.youtube.com/watch?v=agMrewRJTow Tbh I still think it's a bit of a silly idea. But it's not completely without its merits(the one done by Tesla was though - that was completely entirely pointless).
  - iainmerrick 3y ago
    I just meant the yoke -- variable ratio steering would still work with a wheel, right? I'm skeptical but I can see the potential benefits of drive-by-wire, definitely. The yoke, nope (except maybe for racing drivers).
    - gambiting 3y ago
      Oh I guess it's just that once you elimited the need to ever turn the steering device more than 90 degrees, it doesn't need to be a wheel anymore - same reason why bicycles don't have steering wheels but handlebars.
    - kllrnohj 3y ago
      The yoke is to make visibility of the dashboard better. You can deal with rectangular screens easily then instead of needing to force things into a curve. Not necessarily a good enough reason, but it's not entirely frivolous.
  - drcongo 3y ago
    Forgive my ignorance, but is "variable speed ratio steering" not what the Citroen SM was doing 50 years ago? https://en.wikipedia.org/wiki/DIRAVI https://en.wikipedia.org/wiki/DIRAVI

alistairSH 3y ago

What happens if the engine shuts off (and the alternator stops spinning)? Does the steering just run off the 12v system?

vostrocity 3y ago
That Lexus is an EV.
jimt1234 3y ago
Engineering Explained did a really good video about this: https://www.youtube.com/watch?v=agMrewRJTow https://www.youtube.com/watch?v=agMrewRJTow
- dkjaudyeqooe 3y ago
  To save going through that whole video for the answer: they have redundant power supplies (3 batteries total) and redundant actuator motors. But the fact is if there is a bad enough electrical/wiring fault, especially as the car gets older, you are toast and you have no steering. Of course the same thing can happen with mechanical steering (eg a broken linkage) it comes down to the quality of the design and build.
  - HPsquared 3y ago
    The whole design will be such that a single electrical fault can't make it fail. It probably has at least 3 channels. Probably won't even allow you to start the car if one of them is faulty. This kind of thing will almost certainly be designed to comply with ISO 26262.
  - sfjailbird 3y ago
    I've had the power steering cut out on me in a traditional ICE car, you're pretty much hosed in that situation, too, as far as steering is concerned.

65a 3y ago

Hasn't VAG had steer-by-wire for nearly a decade now?

dharmab 3y ago
Only as part of four-wheel-steering systems in combination with mechanical steering for the front wheels. Nissan has steer-by-wire with a backup mechanical system.
HPsquared 3y ago
I had a BMW from 2007 that had something called "active steering", where an electric motor in between the steering wheel and the rack-and-pinion sort of "adjusted" the steering, which gave it a variable steering ratio (add according to speed) and also stability control interventions (it would countersteer in a slide even if I didn't turn the wheel). The stability control part is probably the biggest safety benefit of this steer-by-wire system. Other manufacturers have had similar levels of electronic steering "augmentation" of one kind or another for a long time (e.g. electronically steered rear wheels). In this kind of thing, the safety case is probably that the system only provides small adjustments so that: 1. The driver can overcome any errors in the electronic augmentation system using the main steering system 2. If the system fails, it can switch off and the driver can still steer the old-fashioned way.
harambae 3y ago
Yes as well as some BMW’s, McLarens, at least some of the electric Hyundai/Kias and I’m sure a bunch of others I’m not as familiar with. The shock over it on HN is just because of how few people here work in automotive.
- dharmab 3y ago
  In those systems the steer by wire works in cooperation with a mechanical system. Other cars have had backup mechanical steering systems that engage if the steer by wire fails. What's new about the Cybertruck is it _only_ has a steer by wire system with no mechanical linkages at all. But this is being misreported as the first steer-by-wire system which doesn't cooperate with a mechanical linkage- Nissan has done that for quite a while in some models.

oceanplexian 3y ago

Sounds like a terrible idea to me, honestly. Even Boeing aircraft still have a mechanical linkage. And Cybertruck won’t be a fighter jet no matter how much Elon proclaims it so, it’s just worlds away in terms of maintenance and safety engineering compared to what happens on an aircraft. Not saying it will be common but some sucker will eventually be killed by this.

masklinn 3y ago
> Even Boeing aircraft still have a mechanical linkage. Airbus has been FBW for nearly 40 years now. And recent Boeings are FBW as well, the mechanical linkages are only between the yokes, something which is not relevant on a car.
- ikekkdcjkfke 3y ago
  When i hear fly-by-wire i think of wire rope going from the flaps the cockpit
- rich_sasha 3y ago
  I think aeroplanes are not a good point of comparison. For one, mechanical steering is still very complicated, with many meters (miles?) of hydraulic hoses, actuators, pressure control systems etc. Two, aerospace is healthily paranoid about QA and failure modes. I'm sure a steer-by-wirw can be extremely safe when done with that mindset. But Im not sure if that's the car industry's mindset, let alone Tesla's. Finally, fly-by-wire offers enormous safety benefits in aeroplanes, because of what it enables. But I have no idea what steer by wire enables for a car.
  - s3p 3y ago
    This answer seems to generate its own proof. >For one, mechanical steering is still very complicated Yes, and digital steering is by nature even more complicated. >aerospace is healthily paranoid about QA and failure modes. I'm sure a steer-by-wirw [sic] can be extremely safe when done with that mindset What? So if we have the right 'mindset' then we can ignore any complexity and adapt anything we want. Why even let users drive cars now? Make their fleet 100% autonomous. Just do it with a mindset of QA and safety!

iainmerrick 3y ago

Yikes! Even assuming it all works correctly and safely, who actually wants a steering wheel like that? What's the upside? The only possible advantage I can think of is that when you start the car up again after having reverse parked, it'll be more obvious what way the wheels are currently pointing, so you can straighten up. But that's such a trivial problem.

gambiting 3y ago
>>What's the upside? A much easier to manouver car, because you can get true variable speed ratio steering. It's explained really well here: https://www.youtube.com/watch?v=agMrewRJTow https://www.youtube.com/watch?v=agMrewRJTow Tbh I still think it's a bit of a silly idea. But it's not completely without its merits(the one done by Tesla was though - that was completely entirely pointless).
- iainmerrick 3y ago
  I just meant the yoke -- variable ratio steering would still work with a wheel, right? I'm skeptical but I can see the potential benefits of drive-by-wire, definitely. The yoke, nope (except maybe for racing drivers).
  - gambiting 3y ago
    Oh I guess it's just that once you elimited the need to ever turn the steering device more than 90 degrees, it doesn't need to be a wheel anymore - same reason why bicycles don't have steering wheels but handlebars.
  - kllrnohj 3y ago
    The yoke is to make visibility of the dashboard better. You can deal with rectangular screens easily then instead of needing to force things into a curve. Not necessarily a good enough reason, but it's not entirely frivolous.
- drcongo 3y ago
  Forgive my ignorance, but is "variable speed ratio steering" not what the Citroen SM was doing 50 years ago? https://en.wikipedia.org/wiki/DIRAVI https://en.wikipedia.org/wiki/DIRAVI