https://x.com/PicturesFoIder/status/1832940173400699255
(apologies -- not sure of the best Twitter passthrough to use)
If not, what's stopping a "traditional" (ICE) car from (mis)behaving in a similar fashion in some catastrophic circumstance that would damage its computer?
An ecu has a far more complicated control algorithm than a electric motor controller. If it were suddenly damaged it’s more like that the engine would fail to run at all then run out of control because the ecu needs to control the airflow, fuel and spark position for the engine to run, if any of those fail to work, or stop firing at the right the exact time they are required the engine will just stop or run very poorly. I actually think this is true of electric vehicles too, it’s far more likely to stop the motor working than to have it run out of control, unless a wheel speed sensor is damaged or something.
A petrol car can be placed into neutral if all else fails, the engine will run out of control but the car wont. Also the gearbox controller is typically a different computer from the ecu.
The brakes on any car should be able to over power the engine. This is not a challenge for 99% of petrol cars because the torque they output is tiny compared to what a brake system can apply to the wheels. If you slam on the brakes the engine doesn’t even come close. Idk about other countries but in Australia this also applies to electric cars that are road legal, it’s a requirement.
the ecu is usually located in the passenger cabin or sometimes next to the battery quite deep inside the engine bay.
The only thing that would cause a petrol engine to really go out of control would be if it was fly by wire throttle and that throttle position sensor was broken in the particular way that it’s reading as full throttle. Idk if manufacturers do this but it wouldn’t be hard to design a fly by wire throttle that when it fails the ecu will see it as closed not open.
Anyway I don’t think it’s much of a concern for electric cars either tbh.
More like 25 years ago, at least in France. The 2001 Renault Clio 2 I'm driving has throttle-by-wire, the newest car I personally know of with a mechanical throttle is a 1998 Peugeot 205, the last model year of a car that debuted in 1982. I doubt any European car manufactured after 2001 has a mechanical throttle, if only because of European emission standards.
> The only thing that would cause a petrol engine to really go out of control would be if it was fly by wire throttle and that throttle position sensor was broken in the particular way that it’s reading as full throttle. Idk if manufacturers do this but it wouldn’t be hard to design a fly by wire throttle that when it fails the ecu will see it as closed not open.
On the Clio 2 car, there are two redundant linear potentiometer tracks. If the dual measurements don't match or if either sensor is disconnected, the ECU will default back to a slightly higher than idle throttle.
That’s really neat. I was thinking something along the lines of having a microcontroller with a good adc right next to the throttle pedal and its angle transducer (hall effect would be better) and having that microcontroller send a digital signal. If the ecu can’t make sense of the digital signal or it is missing, just set the throttle to idle. That’s a solution that would be reasonably cheap today though but not 25 years ago.
Anyway in my experience most Japanese and Korean cars didn’t have fly by wire until the 2010s
Same for the steering. BMW for example has a method where the steering wheel is physically connected but the computer can add corrections to it via a clever set of gears. See here: https://en.wikipedia.org/wiki/Active_steering
If the computer (or electric steering motor) fails the steering wheel still works.