The Tesla spokeswoman says the company has the ability to update its vehicles over the air. “Unlike other vehicles, Tesla is uniquely positioned to address more corner cases over time through over-the-air software updates, and it continually does so to improve factors such as stopping distance,” she says.
I'm curious the mechanism that makes that possible, or if it's just BS.
Maybe they have a system for warning owners about these sorts of updates?
I'm also not sure what the alternative you're imagining here is. Take it in to a shop just to have them install the update for you? I also don't see how this is any different than changing worn out brakes on an old ICE car. I had the brakes changed in my old '97 Accord, and the difference was noticeable when I pulled it out of the driveway. I think you need to give people a little more credit...
Also, the Whats Changed prompt literally takes up the entire 17in touch screen. It's sort of hard to miss.
I didn't propose an alternative but there's a huge difference in awareness between a physical in-person "update" vs an OTA update.
For something as serious as changing brake handling, I'm sure they would have some sort of prominent display/cannot continue until you agree prompt but there's always going to be people who do not read things in their entirety. For something that can be destructive as a car, I don't find that acceptable.
Def changed the way the car drove, can't say that I minded in that case though.
I suspect you would get used to it fairly quickly.
They can probably update the settings for the brakes as well, as long as the underlying mechanicals support it.
So the goal is not regenerate the battery (and it doesn't matter if the driver was "an electric neophyte"), it's to brake hard and to repeat the process a couple of times to see if you get brake fade.
From the article: Our testers get a car up to 60 mph, then slam on the brakes until the car comes to a stop. They repeat this multiple times to ensure consistent results. Between each test, the vehicle is driven approximately a mile to cool the brakes and make sure they don’t overheat.
[1] https://www.engadget.com/2016/11/16/tesla-p100d-software-per...
Edit: why downvotes?
[1] http://www.documentcloud.org/documents/4458000-Waymo-Driverl...
Signing updates and checking signatures is established technology to certify that updates come from the right place and are not tampered with.
That and the updates are likely >10 GB, so you wouldn't want to download them over mobile data anyway.
That's just odd.
It's possible that the tesla software either isn't applying the extra assistive force, either due to incorrect tuning or a bug.
The Model 3 (3,800lbs for the long range model) is a fat pig of a car compared to other, conventionally powered cars in its class (3,300lbs for a BMW 3 Series) but this is countered by Tesla fitting them with relatively enormous brakes (14" rotors up front, 13.5" in the rear, larger rotors have more heat absorbing capacity for the pads).
If I had to guess the root cause for this problem, I'd say it is likely down to Tesla's focus on minimizing aerodynamic drag causing a lack of airflow within the wheelwell and across the brakes out the wheel itself. Either that or they chose an absolutely terrible brake pad compound but that just doesn't seem likely in this modern era. Either way, the brakes are getting so hot after a single stop that CR's cooling procedure (a reasonable one I might add) is inadequate to keep the brake pads from drastically overheating. This also explains why braking performance was still compromosed after letting the car cool overnight. The work hardened surface will perform poorly until it is literally ground off from further heavy use of the brakes.
That's actually a very reasonable explanation. I can't say I'm a car expert, but your logic at least sounds correct.
As for expense, brakes are simple and the parts generally cheap, at least for mass-market cars. You can get a full set of pads and rotors for less than $100 from Autozone.
They are a lot cheaper today but the cost of rotors varies tremendously depending on the manufacturer and their volume. I gather they turn rotors a lot less than they used to because they're so darn inexpensive to replace, but I'm pretty sure it's still economical for some of the higher-end stuff.
Conceivably, the car's weight may mean that aerodynamic down-force produces a relatively smaller impact on grip, and air resistance a relatively smaller deceleration. But I'm not sure that's enough to account for the difference.
But most consumer tires have coefficient of friction of less than 1. ~.9 for higher end stuff, but it could be as low as ~.5 or so. Which mean 2-tons of car will lead to LESS than 2-tons of acceleration / deceleration / turning force.
In effect, "more weight is more advantage" is only true if you have a coefficient of friction greater than 1.
Since F=MA, A=F/M. Assuming the braking force (F) is μ (coefficient of friction) * Mass * Gravity, thats F=μMG.
Combining those equations you get:
A = μMG / M
And the M's cancel, giving:
A = μG
Therefore the braking distance due to road friction alone (and ignoring aerodynamic downforce effects) is independent of the mass of the vehicle.
According to theory, the width of a tire has zero effect on tire grip. Race cars and high-performance cars prove this is incorrect: there's a reason they have wide tires (which also cause poorer fuel economy through extra friction). Tires and their interaction with the road are a lot more complex than some simple physics equations.
Its like the whole "area" doesn't matter as well. I can't help but think that maybe the Newtonian friction model is overly simple sometimes. Surely weight and surface area would have an effect?
But perhaps not really. Or at least, not in a way that's very measurable.
Alternatively, there's also "let the human do it". (Aka: threshold braking), but most people prefer to have the computer do this task during an emergency.
This algorithm has been used in anti-lock brakes for decades at this point. I'm not sure why it would need an OTA update to improve. Once this algorithm is properly implemented, then the only thing left is to buy better tires and use better rubber to get better grip.
This CR report suggests that Tesla's braking behavior is suboptimal. There's no reason for a smaller, lighter Model 3 to have a worse braking distance than the freaking F-150 truck.
That's not to say Tesla haven't decided to re-solve it / implement it themselves anew. The rest of the auto industry has been doing ABS much longer than Tesla has existed.
It's also not a prescriptive algorithm. ABS systems don't stay within the static coefficient of friction; they repeatedly retest the boundary between static and dynamic friction (hence the judder). It's a bit like optimising TCP window size for those familiar with it. There are a bunch of parameters you can tune.
Typical ABS systems typically perform far worse on gravel or sand than non-abs systems for example. It turns out on gravel locking the wheels is usually a better solution because then you start to plough deep into the gravel.
No ABS system could determine that beforehand, since it isn't to know if the gravel is deep (allowing ploughing deep into it) or shallow (where staying on the boundary of static/dynamic friction works better).