4 ms·

Tesla vehicles are not drive by wire, but have a direct mechanical linkage.

frosted-flakes 5y ago
Of course it's drive-by-wire, it's an electric car. How could it possibly be drive-by-cable? Cars have been largely drive-by-wire since the early 2000s.
- ternus 5y ago
  The confusion here is between throttle-by-wire (which, as you point out, is now ubiquitous) and steer-by-wire, which Teslas still aren't. There was some hope that the newest yoke-equipped Model S would be, but my understanding is that it's still a direct mechanical link, i.e. wheels still turn if you move the steering wheel when the car is off. The driver-assist functions use motors to move the steering linkage.
  - throwawaygh 5y ago
    Right; the whole conversation re: "what is drive by wire anyways?" is a massive red herring. That's really my bad. The operative question is just "what happens if the primary chip fails?" If the answer is "nothing bad, yet, but maybe something bad when we ship FSD" then Tesla's approach here seems reasonable (modulo not informing customers, which will probably catch them a fine in at least some of these jurisdictions, but in my book is more like a "mild breach of commercial contract" issue than a "fundamental consumer rights" issue). If the answer is "something bad" then this is a big deal and could be bad news for Tesla.
  - frosted-flakes 5y ago
    Wouldn't steer-by-wire that reduce steering feedback even more? Compared to my old (somewhat unreliable) Jetta with hydraulic power steering, every electric steering-assist car I've driven has terrible steering feel, like I'm driving an RC car. I feel so disconnected from the road, as if I'm merely aiming the car rather than actually driving it.
- PlanckMeasure80 5y ago
  It can be drive by cable in a multitude of ways. One way is that your foot moves a plug in and out that physically connects the batteries to the motor. There are other ways that are real, too.
throwawaygh 5y ago
Is that really true? I know that there's a mechanical connection, but the existence of a mechanical connection doesn't necessarily mean that the system is not effective drive by wire (for the purpose of reasoning about system safety). I guess the operative question is: if the controller fails, what happens? If the answer is "loss of operator control", then saying that the car isn't drive by wire is the worst type of "technically true". Just like it was, in a silly sort of way, technically true that the 787-MAX's flight characteristics weren't changed in a way that required retraining... What is the safety-critical use case of the steering column controller? Just interrupting the ADAS?

Of course it's drive-by-wire, it's an electric car. How could it possibly be drive-by-cable? Cars have been largely drive-by-wire since the early 2000s.

ternus 5y ago
The confusion here is between throttle-by-wire (which, as you point out, is now ubiquitous) and steer-by-wire, which Teslas still aren't. There was some hope that the newest yoke-equipped Model S would be, but my understanding is that it's still a direct mechanical link, i.e. wheels still turn if you move the steering wheel when the car is off. The driver-assist functions use motors to move the steering linkage.
- throwawaygh 5y ago
  Right; the whole conversation re: "what is drive by wire anyways?" is a massive red herring. That's really my bad. The operative question is just "what happens if the primary chip fails?" If the answer is "nothing bad, yet, but maybe something bad when we ship FSD" then Tesla's approach here seems reasonable (modulo not informing customers, which will probably catch them a fine in at least some of these jurisdictions, but in my book is more like a "mild breach of commercial contract" issue than a "fundamental consumer rights" issue). If the answer is "something bad" then this is a big deal and could be bad news for Tesla.
- frosted-flakes 5y ago
  Wouldn't steer-by-wire that reduce steering feedback even more? Compared to my old (somewhat unreliable) Jetta with hydraulic power steering, every electric steering-assist car I've driven has terrible steering feel, like I'm driving an RC car. I feel so disconnected from the road, as if I'm merely aiming the car rather than actually driving it.
PlanckMeasure80 5y ago
It can be drive by cable in a multitude of ways. One way is that your foot moves a plug in and out that physically connects the batteries to the motor. There are other ways that are real, too.

throwawaygh 5y ago

Is that really true? I know that there's a mechanical connection, but the existence of a mechanical connection doesn't necessarily mean that the system is not effective drive by wire (for the purpose of reasoning about system safety). I guess the operative question is: if the controller fails, what happens? If the answer is "loss of operator control", then saying that the car isn't drive by wire is the worst type of "technically true". Just like it was, in a silly sort of way, technically true that the 787-MAX's flight characteristics weren't changed in a way that required retraining... What is the safety-critical use case of the steering column controller? Just interrupting the ADAS?