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Unintended Accleration

Discussion in 'Model X' started by blake6551, Aug 15, 2017.

  1. blake6551

    blake6551 Member

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    Well, I had a near incident with unintended acceleration that now has me wondering if it could possibly have been the case in a few of the incidents in the news previously.

    I was turning into a friend of mine's apartment complex, street is marked at 30mph and the complex is gated. As I went to make the right turn, my left hand swept the autopilot stalk by accident mid-turn, and the car immediately took off. Luckily I had felt the incidental swipe and was able to slam on the brake immediately. Not sure what would have happened otherwise, but in that moment I was aimed directly at the center divider/guard shack at the front of the apartment complex.

    Might have gotten interesting! Anyone else ever experience this?
     
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  2. Tam

    Tam Active Member

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    Yes, when I intentionally touch the autopilot stalk it would obey my command and accelerate. If I intentionally do not want that, I can tap lightly to the brake pedal and it would stop accelerating any more.

    Please do not hesitate to use your brake.
     
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  3. Adm

    Adm Active Member

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    I don't own a Tesla, but if I should unintentionally touch the resume button of the cruise control and the programmed speed is higher than the current speed, my car will accelerate to that programmed speed. The car is incapable of determining whether the activation of the cruise control (or in your case AP) is intentional or not and therefor assumes you know what you're doing. I think your "incident" demonstrates why we need full self driving cars.
     
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  4. racpuc

    racpuc Member

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    Set cruise control to absolute. If you unintentionally turn on autopilot it will be set to the speed limit.
     
  5. blake6551

    blake6551 Member

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    I didn't realize this was an option...in settings?
     
  6. aesculus

    aesculus Still Trying to Figure this All Out

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    Yep. Immediately new what I did too and either applied the brake or deactivated the TACC. It's a bit startling the first time or two you do it. So far nothing has been in my path that was an issue. You just feel like a DA.:oops:
     
  7. chillaban

    chillaban Active Member

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    One rant I've had about "one pedal driving" is that it leads to the logical fallacy of sitting and doing nothing being the default reaction to the car traveling faster than you'd like. The brake pedal is there for a reason -- don't hesitate to use it!

    The TACC ramp speed is pretty controlled and civil. You should have plenty of time to react and hit the brake to disengage TACC and slow down the car.

    Furthermore, below 18mph, TACC will refuse to engage unless AP thinks you are following another car. That's already a safety feature to guard against unwanted activations during low-speed maneuvers.
     
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  8. blake6551

    blake6551 Member

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    This has nothing to do with intentionally engaging TACC. That's why it would be called an accident.

    The issue is that:

    1. the stalk is very similar to the signaling stalk and protrudes further than similar devices in nearly every other vehicle
    2. the default speed is not the speed limit of the street, but a default depending on the type of road you are on

    I don't think this a huge deal, but I could have seen it resulting in an accident. One that would be impossible to replicate in nearly every other car on the market. Something like limiting the default to the speed you are currently traveling would likely eliminate the issue entirely.
     
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  9. blake6551

    blake6551 Member

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    Yep, I was wondering if the below 18mph has always been there or if that was added after some of the initial incidents. Haven't been around Tesla's long enough to know, but I have seen some of those videos driving right through the parking spot! Likely confusion with brake pedal, but interesting to consider.

    This was definitely an edge case as I must have been going over 18mph as the turn was initiated, and the fact that I was mid turn and the margin for error given my trajectory was nearly zero. In this case, the TACC ramp was anything but civil in the 15' I had before ramming the guard shack! :)
     
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  10. deonb

    deonb Supporting Member

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    The 18mph (30kph) thing was added about 25 years ago by Mercedes Benz, which is where Tesla got the stalk from.
     
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  11. Tam

    Tam Active Member

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    I agree that if the drive is frozen and does not use the brake pedal or worse, by using the wrong pedal, the accelerator!

    It's just basic driving skill. Driver needs to be in control of the car whether the car is classic or with bells and whistles full of technology.
     
  12. AnxietyRanger

    AnxietyRanger Well-Known Member

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    I would say there are now at least half a dozen of cases on TMC where I suspect exactly this happened, some near misses, some crashes.

    Here is one:

    sudden acceleration

    The design (I know, Mercedes inherited) of the cruise stalk setting current speed by flicking it e.g. up makes right-hand turns especially dangerous as a steering hand coming from down to up on the left side of the wheel can hit the cruise control stalk, e.g. mistaking it for the blinker stalk, if blinker is initiated late in the turn process... some don't even realize they flicked the cruise instead of blinker...

    My recommendation to Tesla would be to find another way of setting the cruise speed than flicking up/down when the cruise is not engaged. This clearly seems one of those usability problems that keeps coming up. If the cruise speed could only be set in some other manner, this specific case could be moved away from the mistake-prone-zone.

    Frankly, I think even making it so that only downward flick engages cruise would help, considering the stalk placement makes upward flick the more error-prone one IMO. On perhaps require a long flick for cruise engagement (similar to long pull needed for AP engagement), that might help too.
     
  13. AnxietyRanger

    AnxietyRanger Well-Known Member

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    Or better usability in our manually driven ones...
     
  14. ShockOnT

    ShockOnT Quickish

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    Turning on cruise control in a parking complex is not recommended.
    The car will start to accelerate to cruising speed, which is probably faster than comfortable in that environment.
     
  15. Ames

    Ames Member

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    I have fallen into the bad (and lazy) habit of using what some people call "Tractor Beam Mode" where I switch on TACC while slowing down behind stationary cars so I don't have to bother pressing the brake pedal and disturbing my one pedal driving zen.

    The problem with that behaviour is that you often forget TACC is engaged and sometimes it starts resuming a preset speed - hence the sudden unintended acceleration.
     
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  16. RRM998

    RRM998 Member

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    I move the Auto Pilot control instead of the turn signal (and vice versa) every now and again. I think having the TACC make a noise when it engages like auto steer does would help alert drivers to this mistake. Not having the up and down motion engage TACC would also be a big safety plus.

    I note that the Model 3 has Auto Pilot on the right side of the steering wheel. Seems like a good idea to me.
     
  17. blake6551

    blake6551 Member

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    I knew they took the stalk from MB, didn't realize they took all the cruise programming as well re:18mph.

    I'll give an example from this am, I was on a two lane road marked at 40mph, default TACC was 60mph. I slowed to 21mph to make a right hand turn, mid-turn doing that speed my TACC was still set to default to 60mph.
     
  18. MasterT

    MasterT Member

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    You keep saying "default" - TACC does not have a "default" speed. Default means a predefined value selected in absence of other criteria. TACC speed is always derived from either traveling speed or posted speed limit (if detected) +/- offset. You can change the offset in settings to 0 to make TACC set to speed limit/traveling speed.

    Also, TACC activation in a turn does not result in immediate acceleration as on straight line - there is initial slight acceleration, but then it tapered almost completely off - I think because the cart knows it's in a turn and only after a sec or so traveling straight, the acceleration resumes.

    I think the current controls setup is just fine and if TACC activation would be moved anywhere else - people would still find ways to accidentally activate it and complain
     
  19. MasterT

    MasterT Member

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    What's wrong with that? That's how I would expect TACC to behave - it needs to remember the last set speed for the resume function. If you imply that activating TACC at that time would result in speeding up to 60mph - that is also correct, why wouldn't it? BTW, if the local speed limit (+/- offset) at the time of activation is less than the resume speed, TACC will reduce its set speed appropriately.
     
  20. bak_phy

    bak_phy Member

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    This has happened to me at least once. I had plenty of time to hit brake but I can see that if someone panics and hits wrong pedal things cold go wrong really fast.
    It would seem that having to pull stalk back to re-engage TACC would eliminate this issue. If not then preventing re-engagement if difference between current and set speed is too great (e.g. >20mph?)
     

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