151–160 of 335 posts
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It is very troubling development when doing something so trivial even requires a computer. That's a matter readily solved by a PID controller made of a few dozen 74XXX parts. Possibly made n-times redundant. Even a more fancy LP solver probably wouldn't need a fully fledged computer.
Ah the classic HN "just use this things I just came up with". https://xkcd.com/793/
Disclaimer up front: I work for GM. I don't work on chips or components for my day job. What follows is solely my own opinion. Some things to emphasize: OEMs (GM, Ford, Toyota, VW, etc) do not design components, and they do not want to. They design specifications for components, and then get suppliers to bid. This is great for efficiency in established ecosystems, not great for agility. To my knowledge, GM did not ca…
>40-60V system What makes that voltage a better trade off?
So to minise weight/wire size, use the highest voltage possible (and thus the lowest current). Losses are purely related to current (I^2*R) so the incentive is to squeezee the current (so needing to increases the voltage).
There's a reason the high-voltage overheads are 432 kilovolts (or more); 10 amps at 432kV = 4.3MW (MegaWatts) while 10amps from a stock AC outlet is 1.2KW (KiloWatts). The wire thickness required for both is the same (though the HV wires need to be better insulated, out of the way of crazy fools etc).
So a 60V system for a car carries 1/5 the current of a 12v system, and the wires can have 1/5 the cross-sectional area.
(yes, I know there are caveats when it comes to AC).
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> "I wonder if the balance is shifting towards taking action." I can't find a public source, but some actions are being taken. Bear in mind that any major shifts would happen in a new product, that is, something 5-7 years out.
Fundamentally, what is it that prevents the established auto makers from making changes mid lifecycle? Seems like Tesla keeps pulling it off; why can’t GM? Is it that the component specification+acquisition cycle you describe is optimized to take as long as the development cycle of a new car?
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Sure but that's not related to the point I'm making. The point is that not following software design best practices can leave you open to liability, or at least put you in such a weak legal position that you are compelled to settle. If/when Tesla gets hauled into court over its software flaws, any lack of adherence to best practices will make the company appear negligent.
This is a risk adverse culture then. Tesla is spending gobs of money specifically on building safer if not the safest cars out there.
> “We were able to substitute alternative chips, and then write the firmware in a matter of weeks,” Musk said. “It’s not just a matter of swapping out a chip; you also have to rewrite the software.” https://www.theverge.com/2021/7/26/22595060/tesla-chip-short...
Tesla is much better at writing software than most of their competitors. That's how they can adapt so quickly. They also do a lot more in house than their competitors. That means they can optimize their development processes, and align with chip suppliers across different components. If you have to work with a multitude of suppliers that each ship their own hardware and software, life is a lot more complicated. Chang…
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There are cars where the enthusiast scene burns their own ECU EEPROMS to compensate air:fuel calculations after installing larger injectors, better flowing intakes, etc. Edit: There's also some "universal ECUs" from companies like Haltech. They sell a single ECU plus some adapter cables to make that single ECU run on a broad variety of cars from the 90's. Possible since the 90's cars all have the same rough types/num…
Yeah, but I think those enthusiasts are mostly just fixing up calibration values, not changing the actual control software.
But they do actual control software too, though that's less common. https://en.wikipedia.org/wiki/MegaSquirt
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Are they better at writing software or do they just care less about how safety critical it is?
I think you underestimate how poorly software development is done in traditional industries. Practice makes perfect and they mostly practice writing reports not software.
This feels like lack of planning. The semiconductor industry was a known entity for many years before this level of integration came to vehicles. They should have known this would happen. Ultimately the industry will have to maintain their own production for consistent silicon.
As mentioned above there are folks who's entire job is maintaining the spreadsheet for said plan.
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It is very troubling development when doing something so trivial even requires a computer. That's a matter readily solved by a PID controller made of a few dozen 74XXX parts. Possibly made n-times redundant. Even a more fancy LP solver probably wouldn't need a fully fledged computer.
ECUs are simpler to build than the mechanical components they replaced and do things impossible to do mechanically (given the space and weight limits of a car). Jadon Cammisa has a great series on this stuff. Here's just one episode on one topic, drive by wire throttle control: https://youtu.be/gKsCHx5NOMM
The carmakers have been making the wrong call for the past decades.
One of their suppliers has eclipsed their impact on society, marking one of the first times in something like ~70 years that things didn't bend over to meet their needs.
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And before you ask. Yes i would rather have a pace-maker with triple redundancy and thrice redesigned.