General > General Technical Chat
Average car contains 100 million lines of code, The State of Autosoftware
pcprogrammer:
--- Quote from: David Hess on January 27, 2023, 11:04:35 pm ---
--- Quote from: tom66 on January 27, 2023, 03:06:44 pm ---See also: accelerator/brake confusion is common in automatic cars. If a driver presses what they think is the brake and the car goes faster, an instinctive reaction might be to press the 'brake' harder. In a panic, it's very easy to make a mistake, and not everyone thinks rationally.
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I have occasionally made that mistake after getting used to driving a manual. I go to push in the clutch and my left foot catches the edge of the wide brake pedal. The car brakes, which makes me think I have not pushed the clutch pedal in far enough, so I push harder, and harder, and come to a screeching stop.
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This reminds me of our first holiday we had in the states. We hired a car and it was an automatic. Driven only manuals up to that point, so the leaving of the parking lot was a bit shaky me trying to push the clutch that was not there but hitting the brake with force. This because your left foot is used to push with force straight down, where as your right foot is gentle in applying pressure to the brake :-DD
jonovid:
having seen the video. a lot of this is about assumptions. that everybody has your best interest at heart.
the HAL 9000 is integrated software at work.
pcprogrammer:
--- Quote from: josuah on January 28, 2023, 12:28:46 am ---That sounds like a case of making the unexpected even less likely -vs- correctly handling unexpected conditions:
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It takes thorough analysis of the underlying problems to come up with proper solutions and it might be that the analysis phase is skipped more often. You can't catch every condition because otherwise there would be no unexpected, but with cars being in existence for many years most should be known.
--- Quote from: josuah on January 28, 2023, 12:28:46 am ---My impression is pointing the programming language is relevant, but the spontaneous conclusion "replace the language" does not cover the full problem:
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Relying on a programming language to make your code safe is grounds in itself for errors. It should not matter which language you use to write your program, you have to be aware of the logic and perform proper tests to catch the errors and possible unforeseen results. This refers back to proper analysis.
--- Quote from: josuah on January 28, 2023, 12:28:46 am ---1. Non-software problems (power electronics, motor control algorithms in any language, ASIC design) have at least as many footguns as risky programming languages. Is there a Rust for Electrical Engineering, Rust for manufacturing?
2. The real solution might not be a language, but an architecture: having a failure (memory safety among many others) less likely to happen (i.e. through language safety) would not replace blocking the propagation of any failure. i.e. a hypervisor, watchdog timers, redundancy, or simply observing the possible affected parts. Although language safety might contribute in favor of this too
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I know little about how modern car control systems are set up architecturally, but wonder if they have redundant processors like I have seen in early digital phone switching systems. These used three separate control systems with an arbitrator to select the leading answer.
So yes it is not just software that should be analyzed when it comes to safety. Hardware is as much a part of it all. To create something truly safe a proper design of all facets is needed, including a full plan for testing those aspects, both hardware and software. This also means designing tests to test the safety features like the watchdog timers.
And this takes times which is where the problem lies, because that costs money.
--- Quote from: josuah on January 28, 2023, 12:28:46 am ---Some topical analogy would be saying that to take a passenger safely from point A to point B, more safety mechanisms help, but do not replace careful driving. :-)
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The one big problem in this is the human factor. There are so many that think they are the best drivers in the world, but in reality are not. Just look on youtube at the videos about idiot drivers. In 40 years of driving I never had an accident, but avoided quite a few with fast reacting to stupid moves from others.
Berni:
--- Quote from: David Hess on January 27, 2023, 11:04:35 pm ---I have occasionally made that mistake after getting used to driving a manual. I go to push in the clutch and my left foot catches the edge of the wide brake pedal. The car brakes, which makes me think I have not pushed the clutch pedal in far enough, so I push harder, and harder, and come to a screeching stop.
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Yep did the mistake of pressing the 'clutch' in an automatic before. It gets you stopped real quick indeed.
Part of it is also that you never press the clutch pedal gently. You always just stomp down all the way on it. As a result you don't actually have the muscle memory of being gentle on pedal using the left foot. Go ahead and try to use the left foot to intentionally press the brake pedal. Even if you try to press it slowly gently, you end up pressing it quite a bit harder than you intend., not making for a smooth deceleration at all.
After actually owning an automatic transmission car the clutch problem never happened again. Driving a manual again is no problem (apart from forgetting to down shift here or there until the engine reminds me to with being unhappy about its low RPM). But yeah driving in the city is so much nicer with an automatic once you experience both sides of the coin. (And it helps when you have the transmissions computer figured out, so that you avoid doing things that confuse it about what gear it thinks it should be in)
MadScientist:
Given I’ve owned several new cars , I don’t see the problem people are eluding too. Most worked as I expected then including some with elaborate driver aids.
In reality new cars are extremely reliable certainly compared to the rubbish around in my dads time where th engine needed a re-bore after 200,000km and the body rusted away in a few years
Today I get 7 year warranties ( Kia) and very reliable long lived modern cars despite considerable more complexity etc.
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