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How to safely override automatic braking?

Discussion in 'Model S' started by whitex, Sep 12, 2016.

  1. whitex

    whitex Member

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    #1 whitex, Sep 12, 2016
    Last edited: Sep 12, 2016
    We all know that while driving with AP activated, we have to be prepared to take over any time. So, keep you hands on the wheel and keep your foot ready to brake any time. What if the car is slamming on the brakes because it determined it's about to hit something (say the car in front kicked up a mini cloud of aluminum foil fragments which on radar may appear as the landing UFO mentioned in the 8.0 post), how is the driver supposed to safely take over? Hitting the accelerator doesn't seem like safe option (nor do I know for a fact that it would even work), hitting the brakes will just make things worse - increase the chance of getting rear-ended. Is Tesla accepting full liability if my car slams on the brakes for an insufficient reason causing a pile up, or will the standard "driver should have taken over" line apply here?

    The reason I started thinking about it of course is the 8.0 announcement of switching to radar as primary collision detection system plus a more aggressive braking policy, which seems to me has a higher chance of unintended braking.
     
  2. Brunton

    Brunton Pontificating the obvious

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    When TACC is active on a non-limited access highway and someone down the road a bit slows to turn right, my car begins breaking heavily way before such action is needed. I simply put my foot on the accelerator to maintain speed or slow down slower. Foot on "gas" pedal effectively overrides automatic braking.
    If anti-collision braking is engaged, I don't know if it would do that or not. I don't really want to find out.
     
  3. ArtInCT

    ArtInCT Always Learning

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    #3 ArtInCT, Sep 12, 2016
    Last edited: Sep 12, 2016
    We will have to see if Tesla has implemented an adjustment parameter to collision detection. I would hope they would because I think this feature will be "active" even if AutoPilot features are not being used or invoked to "ON" status.

    My radar is in the lower grill as are all of the Pre-Facelift Model S cars. That said, the radar is very susceptible to all sorts of winter weather debris coating the concave surface (snow, ice, salt spray and even plastic bags, bugs, etc.) One wonders how the AP collision detection system will behave in those conditions when the radar sensor is compromised to something less than 100%? Will it warn us that it is in OFF mode?

    For instance, I have had my TACC become inoperative due to a build up of snow slush on the radar gun. The system did warn me that TACC was not available even though I was not using it at the time. I forget the actual message now... sorry.

    BTW, this question is pertinent to Facelift Model S cars as well, the radar gun on Facelifts is well hidden but still can be compromised to some extent. The fact that Tesla Motors moved the radar gun is evidence that its initial placement in the lower grill was not optimal for certain situations.

    BTW, I spray my lower grill with RAIN-X every once in a while to try and mitigate this issue... My Volvo XC60 (which has the Mobileye system and radar) has a convex covering on the radar gun in a position about 1 foot higher than the Model S's. It is also a heated cover so that ice and snow do NOT build up on it. And the active HID headlight lenses have washers too. Volvo thinks of such things.

    That heating element is part of the Volvo cold weather package.... Hint Hint to TESLA... our SUB-ZERO package should provide the same for the Model S radar gun.
     
  4. mikeash

    mikeash Active Member

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    If you want to accelerate instead, press the accelerator. If you want to brake, press the brake. Note that you don't have to slam on the brake, any press will disengage AP and then you'll be in full control of braking. If you want to disengage AP but not do anything else then press the cruise control stalk forward.
     
  5. whitex

    whitex Member

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    How does this work to cancel non-AP emergency braking? When driving without the AP your foot it already on the accelerator or brake, so this action should cancel the emergency brake before it even begins, no? Or do you think you need to floor the accelerator in order to cancel emergency braking?

    Also, if you're in traffic and the car starts rapidly braking, the last thing you want to do is to be looking for the AP stalk to prevent the guy behind you from driving into you. Hitting the brake seems counter intuitive in this situation (may work, just not something someone would do instinctively) and hitting the accelerator a little dangerous - if you hit the car in front of you, it's your fault, if the guy behind you hits you, it's his fault unless he has dashboard footage showing your car slamming on the brakes (but I guess then you could use that footage as leverage to get Tesla to pay for everything;)).
     
  6. mikeash

    mikeash Active Member

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    I thought you were referring to normal AP braking, not AEB, since you limited your scenario to AP.

    For the AP scenario, you should know where the AP stalk is and be able to activate it without looking or thinking too hard. It's a useful control and one we use a lot.

    For the AEB scenario, if you don't want to brake then hit the accelerator. If you need to finesse it just right to avoid hitting the car in front of you and avoid being hit by the car behind you, well, you're probably screwed. Pay more attention to the car in front, and slow down when being tailgated.
     
  7. sillydriver

    sillydriver Member

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    #7 sillydriver, Sep 12, 2016
    Last edited: Sep 12, 2016
    Copied from the 7.1 car manual p. 86 ...

    When Automatic Emergency Braking has reduced the driving speed by 25 mph (40 km/h), the brakes are released. For example, if Automatic Emergency Braking applies braking when driving at 56 mph (90 km/h), it releases the brakes when the speed has been reduced to 31 mph (50 km/h).
    Automatic Emergency Braking operates only when driving between 5 mph (8 km/h) and 85 mph (140 km/h).
    Automatic Emergency Braking does not apply the brakes, or stops applying the brakes, in situations where you are taking action to avoid a potential collision. For example:
    • You turn the steering wheel sharply.
    • You press the accelerator pedal.
    • You press and release the brake pedal.
    • A vehicle, motorcycle, bicycle, or pedestrian, is no longer detected ahead.
     
    • Informative x 3
  8. whitex

    whitex Member

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    I used to use it too, but usually have to think for a second which stalk it is (even though it's been over a year since I got a car with the new switched stalk configuration). I've actually hit the wrong one in the past in an emergency, so started tapping the brake instead. Then again, I stopped using AP except for stop and go rush traffic as it requires more of my attention to watch for it misbehaving (which doesn't happen much, hence the difficulty staying focused on it) than just driving without it.

    That might happen unintentionally if the car is suddenly braking hard and you already had your foot on the accelerator, so that makes me wonder, how much beyond the current point one has to press the accelerator to cancel AEB (since at the onset of AEB the accelerator was pressed to some level to sustain cruising speed, so it's expected that some additional accelerator press would be involuntary with an unexpected deceleration and as such it should not cancel AEB).

    I always keep my distance in front as I almost never brake hard (hardly ever use anything but regen >15mph) - a very old habit from the days when I was driving a 2 seater sports car to school and often had books on the front seat - I learned pretty quick that hard braking means books all over the dash, no problems with acceleration though ;) As for slowing down when tailgated, I used to that too but found that it causes road rage in some tailgaters, especially if you slow down below the speed limit because they won't stop tailgating. I also used to do a little trick where I would tap by brakes just enough for the brake lights to go on and hit the accelerator at the same time, but you cannot do that with modern cars with drive-by-wire anymore.

    Yep, the screwed part is what worries me. I have a 5000+ mile trip coming up towards the end of the year, and a little worried about the 8.x having increased chances of erroneous AEB. I am tempted to see what would happen if a bunch of shredded aluminum foil was thrown in front of my car just to set my own expectations for the trip. I may actually try it (while there are no cars behind me of course) when 8.x comes. Then again, given 8.x was just mentioned and there isn't even a first release deadline set by Tesla, so chances are I won't have to worry about 8x on my car this year.;)
     
  9. whitex

    whitex Member

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    It sounds like this is already an issue with Firmware 7.1 but only while using AP and higher speed (I wouldn't know as I stopped using AP at speed much). With an even more aggressive braking policy and switch to radar as primary collision predictor, I'm worried there are some AP/AEB induced rear-end collisions on the horizon. :(
     

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