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Another NHSTA Unintended Acceleration Complaint

Discussion in 'Model S: Driving Dynamics' started by yobigd20, Oct 16, 2013.

  1. yobigd20

    yobigd20 Well-Known Member

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    A few weeks ago, an unintended acceleration complaint was filed with NHSTA and picked up by a few media outlets such as http://green.autoblog.com/2013/09/25/tesla-model-s-involved-in-unintended-acceleration-incident/. this was discussed here http://www.teslamotorsclub.com/showthread.php/21920-Unintended-Acceleration-Complaint

    However, a few days after that, another unintended acceleration complaint was filed. I didn't see this discussed here yet. this owner basically says he knows how to drive (lol, so does everyone else. that's why we have whats called a "drivers license"... well that could be argued though HAHA). anywho he has "driven over 10k miles with the MS" and basically says no doubt this was def an unintended acceleration incident. he also says Tesla employees are not allowed to speak to him " TESLA INSTRUCTED THEIR STAFF TO NOT COMMUNICATE WITH ME ABOUT THIS ACCIDENT." .... weird ...

    most if not all unintended acceleration complaints are proven to be user error so I have my doubts of course.

    2ndcomplaint.png
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    Are they required to type in all caps?
     
  3. stopcrazypp

    stopcrazypp Well-Known Member

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    First thing I noticed too. But it seems other complaints have the text in all caps too. The person did provide a VIN number, so that gives more credibility than one without.
     
  4. AnOutsider

    AnOutsider S532 # XS27

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    Hmm. I, too, typically dismiss these as user error, but for it to be someone who has driven the car for 10k miles and says he RAISED his foot (not pressed the brake and it accelerated) does seems to warrant some investigation. Not sure why broad daylight matters here (maybe he was ruling out "you didn't see the other car" arguments), but if Tesla did instruct the staff not to speak with him, it could be for legal reasons while they examine the logs.
     
  5. Lloyd

    Lloyd Active Member

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    This seems wrong.... The car is designed to have the brake pedal override the accelerator. He does not mention even trying to put his foot back on the brake.
     
  6. ckessel

    ckessel Active Member

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    Certainly sounds much more legitimate than the other complaint. I've always been suspicious of drive by wire since god knows I've written enough software bugs in my time. Tesla can look at the logs, but the problem with the logs in a drive by wire is they'll show what the computer thought happened, the pedal depressed, which may or may not correspond to him actually pressing the pedal.

    I certainly hope it's not true, but it could be hard to ever know.
     
  7. Tommy

    Tommy Member

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    I wonder if creep mode was turned on without the driver being aware of this fact. The car does move forward on it's own in this mode and maybe took the driver by surprise. Though the speed is so slow, I can't imagine hitting another car unless he/she was already very close to the car. Case in point, I drive with creep mode off, however creep mode is always enabled by Tesla employees when my car is being serviced. I presume the employees do it so they can maneuver around in tight spots and have their foot on the brake. The first time I picked up my car from the SC, I wasn't aware that creep mode had been turned on and it did startle me because I didn't expect the car to move forward on its own. I now know to resent my preferences before driving off from the SC.
     
  8. stopcrazypp

    stopcrazypp Well-Known Member

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    Immediately pressing the brake would be the natural reaction of most people, but it's also the same one that leads to claims it's user error (pressing the wrong pedal).
     
  9. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    You can have your foot overlapping the pedals, and roll it to the right, at which point the car senses you have released the brake and stepped on the accelerator. If you're sloppy with your footwork, this can happen in any car.
     
  10. rdrcrmatt

    rdrcrmatt Member

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    Agreed. I know I can two foot drive my car, ride the brake and use the accelerator, but I've only done it once and not to any extreme amounts on either pedal.. I could accelerate with the brake lightly pressed.

    I sort of wonder if it is possible to do a brake stand in the car.
     
  11. Discoducky

    Discoducky Active Member

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    If the driver was on a severe decline and had creep on I could see it being pretty quick. But why not release the brake slowly and put more pressure back on the brake?

    Or if on the severe decline, something could have fallen onto the throttle, but the car lets you know when both pedals are pressed with a visual/audible warning where the brake takes precedence.

    Again, this sounds like user error and I hope no one was hurt.
     
  12. tander

    tander Member

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    Yikes and here I like to think that all those systems are just perfectly put together. Scary to think that something like that could happen, scarier to think that the log wouldn't show what actually happened, although I'm sure that is a very rare combination.
     
  13. ckessel

    ckessel Active Member

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    Well, I don't want to overstate it. There are things that can be done, it's just whether they have. For example, you can measure at various points in the sequence. The computer logs the end result, an intermediate sensor logs the signal from the pedal, then another independent sensor attached to the pedal itself. That sort of thing, then you can compare results at each step and see whether or not you got an erroneous signal at the computer. But you've got to design this stuff in up front. It's there in some medical devices, probably in airplanes, and such.

    I wouldn't be surprised if Tesla has that redundancy. Then again, I wouldn't be surprised if they didn't in some areas as there's a TON of electronics in cars and it's easy to deprioritize redundancy for cost or schedule reasons if, at the time, it seems impossible for it to be an issue for some particular spot. We'll probably never know. I'm sure Tesla is going to do their best to figure it out and did their best designing things ahead of time, but any endeavor can have mistakes or an oversight. I think the most likely explanation is user error, but you can never dismiss a software/hardware failure either.

    When I was in the medial industry, every time a patient died we had to have an investigation. We weren't ever at fault because medical monitors (what I worked on) are attached to patients that die all the time, but you've got to investigate each and every one just in case it could have been a hardware/software issue (e.g. failing to alarm when we should have).
     
  14. Doug_G

    Doug_G Lead Moderator

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    A huge number of cars on the road have drive by wire throttles, and most people likely don't even know. The designs are generally very straightforward and robust. There are two potentiometers in the pedal assembly. One increases in resistance as you push, the other decreases. The two have to move in synchronicity or the system detects a mismatch and disables the throttle.

    As for software, we're not talking about complex computers with operating systems. Only the two screen computers use Linux. These things run "bare metal" with pretty simple software and hand-coded interrupt service routines. Personally, if I were designing a throttle system I would use a dedicated processor and keep things as absolutely simple as possible. Or better yet, I'd implement the functions in an FPGA as hard logic and forgo software altogether.
     
  15. roblab

    roblab Active Member

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    Can someone explain to a dummy why a brake pedal push could not negate a power pedal push? ie: pushing on power, accidentally hit brake. Brake goes on, power goes off. Worst happens is you slow down.

    Sure, now if you hit both, you can overpower the power pedal with the brake, but it is slow. If I am braking to keep from hitting the vehicle in front and my fat foot hits the power pedal at the same time, it gets scary. Why not have the brake just cut out the power whenever it's pushed?? This always seems to happen when trying to brake, not when trying to go.

    I'm sure there must be a good reason why they make it this way, but I don't see it.
     
  16. NigelM

    NigelM Recovering Member

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  17. lolachampcar

    lolachampcar Active Member

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    rob,
    The brake pedal does "over ride" the throttle request in MS. You will even get the chime and a warning on the dash that you are pressing both (while the car stays put).

    WRT processing torque demand from the accelerator pedal, all systems use two processors. The first is the primary that (normally) handles engine functions like timing, mixture and the like. The second is a dedicated watchdog processor. In most cases, both processors not only handle the "opposite swing" potentiometers on the pedal itself but they also compare Mass AirFlow (MAF) against throttle position and torque demand. If the perceived throttle blade position does not agree with the airflow and torque demand, the system is shut down. By shut down, I mean that power is pulled from the bridge driver for the throttle butterfly and the return spring snaps it shut. The throttle butterfly also has "opposite swinging" potentiometers which are resolved by the main and watchdog processors.

    Tesla is way too smart not to have implemented a similar system that tracks motor current in place of MAF as current is directly proportional to torque. Normally, the ONLY way you can have an unintended acceleration issue is if there is a mechanical issue with the pedal assembly that prevents it from returning to zero when released. Creep is also an option but I would think most anyone would have enough time to react to unexpected creep.
     
  18. yobigd20

    yobigd20 Well-Known Member

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    thanks to whoever rated me down for posting this.
     
  19. roblab

    roblab Active Member

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    Well, if you say so. Seems that when I tried to stop behind the Suburban quickly, it was barely quick enough. The chime was going, both pedals pushed, and I was cramming it to the floor, actually slowing down instead of speeding up, so I guess the brake was actually being pushed. It just didn't seem like it was fast enough, tho I didn't hit him. If they made it so the speed pedal actually cut out whenever the brake was pushed, that would eliminate a lot of this, but you say it already does that. Just didn't seem like it. I had heard that the brake is stronger than the power and that was what was happening: They were fighting each other, but brakes won. You say not. But when you're down to the last two feet, it seems like the power is still fighting the brake.

    Having size 15 D feet doesn't help, either.

    That's partly why I like to keep a lot of distance between me and them other guys.
     
  20. NigelM

    NigelM Recovering Member

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