alt Hacker News> Steer-by-wire
Thinking back to case-studies around the Therac-25 [0], I would like to pre-emptively highlight the differences between:
1. Technique X is unsafe.
2. Technique X is unsafe because too much can go wrong even with the best intentions.
3. Technique X is unsafe without strong QA and interlocking safety measures, and there's too much economic pressure for the manufacturer to cut corners.
Replies
The obvious problem with steer-by-wire is that in the traditional design, it's not uncommon to lose power assist but not the mechanical connection to the wheels, so you can still steer the car. To completely lose steering control you'd need significant mechanical damage.
If the whole thing goes through the computer then there are lots of new ways to fail. Steering wheel position sensor goes bad on the highway? Computer gets bad data. Control wires get disconnected or damaged? No data. Completely unrelated wires get shorted and fry the computer? No steering. Anything pops the wrong fuse? No power, no computer or steering motors.
Some of those can be mitigated with redundancy but you're still vulnerable to common causes. You have three position sensors and someone dumps their beverage down the steering column, are there any left and do you have any good way to determine which one(s)? The vehicle took some minor damage allowing water to get somewhere it's not intended to, any way to guarantee you're not about to lose both sides of a redundant electrical system the next time it goes through a puddle infused with conductive road salt?
Moreover, Technique X does not actually provide any significant value.
The whole steer-by-wire in CT happened because Musk wanted a yoke as the control system. And a yoke requires progressive steering which is impractical without steer-by-wire.
Safety is a great reason to not do something. Utility and enhanced safety are great reasons to override that reflex. A lot has happened since the Therac 25 incident in the medical world with AI, machine learning, robotic neuro surgery, all sorts of computer aided diagnostics, etc. This stuff undeniably saves lives. The incident did inspire some level of scrutiny of course. But compared to modern medical equipment, that machine is from the stone age.
Steer by wire (which the article highlights) is common on all modern airbus planes for decades. The first ones flew shortly after the Therac incident. Boeing has also started implementing that on their newer models. And of course most of the vtol planes/drones currently starting to operate and progress through certification programs also commonly use steer by wire. Several of these flew without pilots before their first manned test flights. These are computer controlled, pilot directed pretty much by default with that part being optional by design.
Beyond Tesla, there are now several other manufacturers implementing steer by wire in the car industry. Nio, Lexus, Toyota, Mercedes, and a few others each either already have cars on the road for this or are working on new ones. And while Tesla has received quite a bit of criticism on their FSD system, I don't think there have been a lot of incidents implicating the steer by wire in Cybertrucks. It seems to work and drivers seem to mostly like it once they get used to it. The car is controversial of course. But there's a lot of cool tech inside that is being copied across the industry now.
The implied warning "we should be careful with this stuff because Therac-25" is a bit of a cliche at this point. Yes, we need lots of checks and balances when using automation in safety critical systems. And that has been common for decades.