3 ms·

They already do, and in a very intuitive way - it is called a properly implemented brake pedal. For example, on Teslas, hitting the brake pedal to the floor au

They already do, and in a very intuitive way - it is called a properly implemented brake pedal. For example, on Teslas, hitting the brake pedal to the floor automatically overrides any other input and cuts off motor torque, and iirc they have quite a few redundant mechanisms to ensure that this actually happens. You can even press both the acceleration pedal and the brake pedal, and nothing will happen. It operates perfectly as expected, even if the car computer is rebooting/not working.

jacquesm 3y ago
How does that work? Mechanical disconnect of battery power?
- filoleg 3y ago
  No idea honestly, but reading the NHTSA report[0] on the whole unintended acceleration debacle, they seem to corroborate what I said. Relevant quote: “In the few cases where the brake and accelerator pedal were applied at the same time, the brake override logic performed as designed and cut motor torque.” 0. https://static.nhtsa.gov/odi/inv/2020/INCLA-DP20001-6158.PDF https://static.nhtsa.gov/odi/inv/2020/INCLA-DP20001-6158.PDF
  - jacquesm 3y ago
    So, that's not what I meant then. That kill switch as listed above works by releasing the current that holds a relay that keeps the mains power connected, break the loop and it will take a lot of doing to get it back up again. There is no 'logic' involved, no electronics and there are no semiconductor bits & pieces in a typical e-stop chain (at least: there wasn't when I was working on stuff like that), just a plain electromechanical device. The only way in which it could theoretically malfunction is if the contactors of the mains relay had fused.
extraduder_ire 3y ago
By "to the floor", do you mean depressed as hard as one can, or that it actually fully depresses? Never operated a tesla, but I can get nowhere near the floor on a normal brake pedal, with the hydraulic force I'm pushing against.
- filoleg 3y ago
  I meant depressed as hard as one can. A very valid question, so i think you might find this teardown[0] interesting. It goes over the braking system and the brake booster they use (so you don’t really need to fight against the hydraulic force). 0. https://www.marklines.com/en/report_all/rep1863_201905 https://www.marklines.com/en/report_all/rep1863_201905

jacquesm 3y ago

How does that work? Mechanical disconnect of battery power?

filoleg 3y ago
No idea honestly, but reading the NHTSA report[0] on the whole unintended acceleration debacle, they seem to corroborate what I said. Relevant quote: “In the few cases where the brake and accelerator pedal were applied at the same time, the brake override logic performed as designed and cut motor torque.” 0. https://static.nhtsa.gov/odi/inv/2020/INCLA-DP20001-6158.PDF https://static.nhtsa.gov/odi/inv/2020/INCLA-DP20001-6158.PDF
- jacquesm 3y ago
  So, that's not what I meant then. That kill switch as listed above works by releasing the current that holds a relay that keeps the mains power connected, break the loop and it will take a lot of doing to get it back up again. There is no 'logic' involved, no electronics and there are no semiconductor bits & pieces in a typical e-stop chain (at least: there wasn't when I was working on stuff like that), just a plain electromechanical device. The only way in which it could theoretically malfunction is if the contactors of the mains relay had fused.

extraduder_ire 3y ago

By "to the floor", do you mean depressed as hard as one can, or that it actually fully depresses? Never operated a tesla, but I can get nowhere near the floor on a normal brake pedal, with the hydraulic force I'm pushing against.

filoleg 3y ago
I meant depressed as hard as one can. A very valid question, so i think you might find this teardown[0] interesting. It goes over the braking system and the brake booster they use (so you don’t really need to fight against the hydraulic force). 0. https://www.marklines.com/en/report_all/rep1863_201905 https://www.marklines.com/en/report_all/rep1863_201905