Technology ConnectionsMay 25, 2023

New video comin' out soon.

I'm torn between two titles: I'm discussing a problem which is made obvious by electric cars, and I spend a lot of time discussing the specifics of the problem. Most of the video's runtime is spent dealing with electric cars and one-pedal driving.

However, the problem affects pretty much all new cars these days - electric or not.

Should I stick with "Electric cars prove..." in the title for the clicks, or is it better to go with "New cars prove..." ?

"Electric"
35.1%
"New"
64.9%
Poll ended at .
Show threadDouglas KilpatrickMay 25, 2023

@TechConnectify if it's about destroying physical controls, you can blame Tesla ... That's pretty rage-clicky

I dislike blaming EVs for things not even specific in general: idiots will actually do things that will slow down adoption/etc. But the no-physical-controls thing is clearly Tesla's fault for starting, and they deserve to be called out for it.

Show threadDouglas KilpatrickMay 25, 2023

@TechConnectify Now that I've watched it ... Your clickbait title might be

"The one thing Tesla (might) have gotten right!". Worth A/B testing that?

Show threadDouglas KilpatrickMay 25, 2023
@TechConnectify (I'm also required to point out that the accelerometer the Bolt uses isn't extra or added just for this. ABS requires accelerometers in each wheel for normal function, so you car already has 4. Using them for the brake-lights then becomes "just software", and has no per-unit costs)
Show threadTechnology ConnectionsMay 25, 2023
@kilpatds Do you know that for a fact? It seems somewhat questionable to me to allow a body control module to talk to the ABS module like that
Show threadDouglas Kilpatrick
@TechConnectify I am not a citable source, no. Lemme see if I can find you one.
May 25, 2023 at 4:00pmMastodon for Android
Show threadDouglas KilpatrickMay 25, 2023

@TechConnectify but for evidence of the connection: your car throws codes when they fail, so they're obviously connected.

See also "unlock&start your car via the headlight" discourse for a general sense of the isolation of car components from each other (none)

Show threadTechnology ConnectionsMay 25, 2023

@kilpatds Yes, I'm aware they're connected - every module is over the CAN bus. But usually they're limited in what they can say to each other for security and network reasons. While sharing actual sensor data between modules isn't impossible, it doesn't pass my sniff test.

Also... doesn't ABS use wheel-speed sensors?

Show threadDouglas KilpatrickMay 25, 2023

@TechConnectify Yes?

Which you turn into a deceleration (accelerometer) and compare against possible deceleration/expected deceleration to detect a wheel lockup event.

(I checked, I've lost my contact with the Bolt-tied engineer I knew, so I can't get you proof)

Show threadTechnology ConnectionsMay 25, 2023

@kilpatds Oh - see, by my standards that would count as you "knowing for a fact"

(also, quite honestly I've never head anyone refer to wheel speed sensors as accelerometers)

Show threadDouglas KilpatrickMay 25, 2023

@TechConnectify they measure wheel speed rapidly, turn that wheel speed into wheel acceleration, and then figure out if that number's "bad". So they don't measure acceleration directly, no. But they measure (wheel) acceleration as a core element of their function.

Also, I never talked to said Bolt engineer on this topic directly, so by my standards I still don't "know for a fact". :)

Show threadTechnology ConnectionsMay 25, 2023
@kilpatds No, right, understand that I get the theory of ABS 100% - but truthfully I've never heard it described as detecting differences in wheel acceleration. I mean, yes that's literally what's happening but I've always had it in my inner-monologue that the computer is just looking for improbable mismatches in rotational speed.
Show threadbhtooefrMay 25, 2023
@TechConnectify @kilpatds It *can* be done with just wheel speed sensors, if you have a lookup table for how quickly a wheel can decelerate without being locked, but a lot of systems also use accelerometers to detect when a wheel is spinning too slowly relative to the vehicle speed, to better modulate it

also some systems specifically use braking G forces to automatically enable hazard flashers under panic braking, and in some cases even (non-destructively) tension seatbelts
Show threadbhtooefrMay 25, 2023
@TechConnectify @kilpatds oh, and AFAIK, two-wheeler ABS systems (off-topic, but they exist, and are mandated for a lot of motorcycles in Europe, and even exist on bicycles now) basically need accelerometers because with only two wheels that aren't connected by differentials, it's a lot harder to trust that *either* wheel speed is accurate for the vehicle speed (lock both wheels and you'll have a very fast crash, and it can't detect that scenario well without an accelerometer)
Show threadDouglas KilpatrickMay 25, 2023
@bhtooefr @TechConnectify Right. His concern is "does that information get to the computer that controls the brake light?" (and also: yes. Because that's usually the ECU, and the ECU also needs wheel acceleration info for traction control)
Show threadbhtooefrMay 25, 2023
@kilpatds @TechConnectify On modern designs it's a "body control module" that controls things like lighting and locks (with potentially more CAN bus from there to individual light fixtures), not the engine control unit that handles traction control