4 ms·

I heard a similar story from a coworker. They were interfacing with a car via CAN. They had an engineer from the manufacturer telling them the details of the me

I heard a similar story from a coworker. They were interfacing with a car via CAN. They had an engineer from the manufacturer telling them the details of the message they should be sending to demand a certain speed. Turns out the description wasn’t quite right. The message ID was correct, but not the endianness of the speed demand signal. Thus when they tried to test it they thought they requested a stately 5m/s, but the vehicle thought they were asking it to exceed the speed of sound. Which of course it wasn’t designed to be able to do, but it still tried. That’s why i prefer to have nice hardware e-stops on prototype vehicles.

m463 2y ago
> That’s why i prefer to have nice hardware e-stops on prototype vehicles. Yeah, I kind of wonder if lawsuits/regulation might be the way to get those. Because there will always be some sort of cost with that kind of thing. I'm pretty sure a major reason garage doors have limit and occlusion sensors is because of regulation. (and even those suck - it is common for garage doors to incorrectly sense occlusion in bright sunlight)
- krisoft 2y ago
  > I kind of wonder if lawsuits/regulation might be the way to get those. I’m talking about prototype cars. The solution there to have an e-stop is to ask your technicians to put it on. No lawsuit or regulation is necessary for that. If you are thinking about mandating e-stops on production vehicles then I don’t think that is the right thing to do. It is a complicated analysis but it boils down to that the cases where it would help should be vanishingly small, and even in those people not trained for it would forget to use them. > there will always be some sort of cost with that kind of thing Absolutely. And the cost of the switch is not the major component. Where i work forgetting to reset the e-stop is so common that it is the first thing we ask about when something is weird. And the people forgetting them are skilled engineers with known prototype cars. I imagine the cost of support/service calls would be huge in prod.
bewaretheirs 2y ago
Something similar was at work in the 2018 natural gas explosions in and around Andover, MA: https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosions https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosion... "According to the NTSB's preliminary report, customers in the accident area received gas from a low-pressure (0.5 psi) distribution network which, in turn, was fed from a high-pressure (75 psi) main pipeline via regulators controlled by sensors measuring pressure in the low-pressure pipes. At the time of the accident, workers were replacing some of the low-pressure piping, but the procedure set out by Columbia Gas for doing this failed to include transfer of a regulator's pressure sensor from the old, disused piping to the new. As a result, when the old pipe was depressurized, the regulator sensed zero pressure on the low-pressure side and opened completely, feeding the main pipeline's full pressure into the local distribution network."
- deleted 2y ago
  [deleted]
- echoangle 2y ago
  Interesting that they only had a single regulator, if overpressure is that dangerous, I would expect them to have multiple regulators in sequence or a blowout valve to dump excess pressure.
  - neaanopri 2y ago
    After the accident, the Massachusetts legislature passed a law to require a licensed professional engineers stamp on all gas infrastructure designs of this type
  - lazide 2y ago
    That will be in the postmortem I’m sure. In the mean time, that costs money, and since no one managed to kill people by being dumb in this particular way before….
    - bewaretheirs 2y ago
      The NTSB final report on this accident is here: https://www.ntsb.gov/news/events/Pages/2019-PLD18MR003-BMG.aspx https://www.ntsb.gov/news/events/Pages/2019-PLD18MR003-BMG.a... Unfortunately the shutdown of go.usa.gov broke a bunch of links from that page, but the NTSB recommendations are summarized starting on page 33 (PDF page 44) of https://www.ntsb.gov/investigations/AccidentReports/Reports/PAR1902.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... But the recommendations to the gas company included: > Review and ensure that all records and documentation of your natural gas systems are traceable, reliable, and complete. (P-18-7) (Urgent) > Apply management of change process to all changes to adequately identify system threats that could result in a common mode failure. (P-18-8) (Urgent) > Develop and implement control procedures during modifications to gas mains to mitigate the risks identified during management of change operations. Gas main pressures should be continually monitored during these modifications and assets should be placed at critical locations to immediately shut down the system if abnormal operations are detected. (P-18-9) (Urgent) Edit to add: This page has currently working links to the specific recommendations: https://www.ntsb.gov/investigations/Pages/pld18mr003.aspx https://www.ntsb.gov/investigations/Pages/pld18mr003.aspx
jeffreygoesto 2y ago
Yup. EStop saved is from the fence when a programmer learned that there are "low active" signals on an ECU he war trying to convince to follow our acceleration CAN signals. Adrenaline time...

m463 2y ago

> That’s why i prefer to have nice hardware e-stops on prototype vehicles. Yeah, I kind of wonder if lawsuits/regulation might be the way to get those. Because there will always be some sort of cost with that kind of thing. I'm pretty sure a major reason garage doors have limit and occlusion sensors is because of regulation. (and even those suck - it is common for garage doors to incorrectly sense occlusion in bright sunlight)

krisoft 2y ago
> I kind of wonder if lawsuits/regulation might be the way to get those. I’m talking about prototype cars. The solution there to have an e-stop is to ask your technicians to put it on. No lawsuit or regulation is necessary for that. If you are thinking about mandating e-stops on production vehicles then I don’t think that is the right thing to do. It is a complicated analysis but it boils down to that the cases where it would help should be vanishingly small, and even in those people not trained for it would forget to use them. > there will always be some sort of cost with that kind of thing Absolutely. And the cost of the switch is not the major component. Where i work forgetting to reset the e-stop is so common that it is the first thing we ask about when something is weird. And the people forgetting them are skilled engineers with known prototype cars. I imagine the cost of support/service calls would be huge in prod.

bewaretheirs 2y ago

Something similar was at work in the 2018 natural gas explosions in and around Andover, MA: https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosions https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosion... "According to the NTSB's preliminary report, customers in the accident area received gas from a low-pressure (0.5 psi) distribution network which, in turn, was fed from a high-pressure (75 psi) main pipeline via regulators controlled by sensors measuring pressure in the low-pressure pipes. At the time of the accident, workers were replacing some of the low-pressure piping, but the procedure set out by Columbia Gas for doing this failed to include transfer of a regulator's pressure sensor from the old, disused piping to the new. As a result, when the old pipe was depressurized, the regulator sensed zero pressure on the low-pressure side and opened completely, feeding the main pipeline's full pressure into the local distribution network."

deleted 2y ago
[deleted]
echoangle 2y ago
Interesting that they only had a single regulator, if overpressure is that dangerous, I would expect them to have multiple regulators in sequence or a blowout valve to dump excess pressure.
- neaanopri 2y ago
  After the accident, the Massachusetts legislature passed a law to require a licensed professional engineers stamp on all gas infrastructure designs of this type
- lazide 2y ago
  That will be in the postmortem I’m sure. In the mean time, that costs money, and since no one managed to kill people by being dumb in this particular way before….
  - bewaretheirs 2y ago
    The NTSB final report on this accident is here: https://www.ntsb.gov/news/events/Pages/2019-PLD18MR003-BMG.aspx https://www.ntsb.gov/news/events/Pages/2019-PLD18MR003-BMG.a... Unfortunately the shutdown of go.usa.gov broke a bunch of links from that page, but the NTSB recommendations are summarized starting on page 33 (PDF page 44) of https://www.ntsb.gov/investigations/AccidentReports/Reports/PAR1902.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... But the recommendations to the gas company included: > Review and ensure that all records and documentation of your natural gas systems are traceable, reliable, and complete. (P-18-7) (Urgent) > Apply management of change process to all changes to adequately identify system threats that could result in a common mode failure. (P-18-8) (Urgent) > Develop and implement control procedures during modifications to gas mains to mitigate the risks identified during management of change operations. Gas main pressures should be continually monitored during these modifications and assets should be placed at critical locations to immediately shut down the system if abnormal operations are detected. (P-18-9) (Urgent) Edit to add: This page has currently working links to the specific recommendations: https://www.ntsb.gov/investigations/Pages/pld18mr003.aspx https://www.ntsb.gov/investigations/Pages/pld18mr003.aspx

jeffreygoesto 2y ago

Yup. EStop saved is from the fence when a programmer learned that there are "low active" signals on an ECU he war trying to convince to follow our acceleration CAN signals. Adrenaline time...