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Speed (MPH) needed to deploy Airbags on Model S?

Discussion in 'Model S' started by earlyretirement, Jun 8, 2017.

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  1. earlyretirement

    earlyretirement Model X 90D

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    Do any of you know the minimum speed needed to set up the airbags in the Model S?
     
  2. boonedocks

    boonedocks Member

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    Test it out and let us know. Inquiring minds want to know. J/K.

    On a side note I hit a deer at 55mph and sent that thing sailing through the wind like a batter hitting a home run. No airbags. Just hood and bumper cover replacement. Took forever and costly but no airbags...just cosmetic
     
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  3. earlyretirement

    earlyretirement Model X 90D

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    Thanks for the info about the deer and the airbags not deploying even at 55 MPH. I was just curious if there was a specific MPH that triggers the airbags in the event of an accident. Just curious how the car determines when the airbags should deploy?
     
  4. chillaban

    chillaban Active Member

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    Almost every car uses some combination of shock sensors. There is a central accelerometer in the crash/airbag controller, and panels have pressure sensors that measure the force of impact.
     
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  5. purduelion

    purduelion Member

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    My steering wheel and driver footwell deployed at 5 mph during/after an accident where I rear ended a Ford Expedition. 1 week before AEB released....grrr. Safety first...can't complain about that.
     
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  6. croman

    croman Active Member

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    AEB only active 7-27mph. So, at least that wouldn't have prevented your accident.
     
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  7. earlyretirement

    earlyretirement Model X 90D

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    #7 earlyretirement, Jun 9, 2017
    Last edited: Jun 9, 2017
    Thanks purduelion. This is the type of incident I was curious about. A few years ago I also hit an SUV from behind at very low speed. Probably 5 to 10 MPH at time of impact. Damage to their vehicle was very minor. Dented fender and broken tail light. We really weren't going that fast. I really barely felt anything. The crumble zone in my car absorbed it and the hood got dented.

    No one was hurt at all after the accident. We just exchanged info and went on our way. Now 2 year later I get sued by the person stating they have major injuries and claiming we were going faster than we really were going.

    There was barely any damage to her car and we weren't moving fast. The airbag in neither car went off. That's why I was just curious if there was a set speed it goes off at. Thanks for the excellent responses.
     
  8. Zaphod

    Zaphod Galaxy President (former)

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    It is more about the deceleration rate rather than the overall speed of impact. There is accelerometer that will measure the G-force and depending on the force will determine if the airbags get triggered or not.
     
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  9. purduelion

    purduelion Member

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    There was nothing but minor scratches to their vehicle. Most of the damage to my Model S was caused by their trailer hitch hitting me square in the "T" and riding up the hood about 6 inches and barley into the frunk. The trailer hitch won. As to AEB, I was likely going 10 MPH, I braked, slowed down to about 5, and made contact. It was in heavy traffic routing around another accident...i.e. Lots of confusion. In fact the cop already onsite and witnessed it issued no tickets. If I had AEB, I would be surprised if it wouldn't have activated. Life goes on and after 5 weeks I have my car back good as new and 17.17.17.
     
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  10. earlyretirement

    earlyretirement Model X 90D

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    I didn't have AEB either as this was back in 2013. Yes, it took a LONG time to get my car repaired back then as there is only one authorized repair shop in San Diego. It was really cool to see Tesla's strip down to frame. They let me walk back and showed me. They had many, many being repaired.
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    Other's already pointed it out, but it's based on acceleration/forces rather than speed. Think of this situation: say you are going at 101mph and you tap into a car going at 100mph, very little deceleration. Airbags probably wouldn't deploy despite high speeds.

    Then another situation: say you are at a stop and someone smashes into you at 50mph in your front, or you are going 10mph and you smash into a solid tree. Airbag probably will deploy despite low speeds.
     
  12. John Green

    John Green Banned

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  13. Max*

    Max* Autopilot != Autonomous

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    #13 Max*, Jun 29, 2017
    Last edited: Jun 29, 2017
    Check the statutes of limitations, I know locally it's 2 years to sue someone for a car accident. So if he's over the 2 year mark, you may be in luck.

    Also, the fact that the airbags didn't deploy or that it was a minor accident is irrelevant. You could be in a very minor accident, feel nothing after the accident, have no airbags deploying at low speeds and still suffer a concussion or other injuries and only realize the next day when you wake up. Why it'd take 2 years sue is beyond me, but the speed and damage to the car doesn't imply that the other party is faking their injuries.
     
  14. Rashomon

    Rashomon Member

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    There generally is no minimum speed, but an algorithm programmed into the airbag controller looks at the acceleration trace after some minimum acceleration or change of speed is reached. It has about 20ms to determine whether the acceleration of the vehicle is such that it looks like a collision is developing. Sometimes, when running into something with very concentrated loading, like a pole, the accelerations are relatively low compared to the overall change of speed, and the airbags won't deploy even though the change of speed is significant. Other times, say when hitting a flat wall that eventually breaks away, rapidly rising accelerations look like a serious crash, and the bags deploy though the actual event didn't live up to the initial accelerations. Remember, you only have 20ms to decide to deploy or not!

    And, generally, you don't want the airbags going off. In crashes involving speed changes under 25 mph, you're more likely to be injured by the airbags than helped -- it's just that the system can't accurately judge that the collision isn't that great in the 20ms, and thus is programmed to deploy so it doesn't miss a high-speed crash. And it's the really high speed crashes with speed changes greater than 30 mph or so where the airbags are a benefit.
     

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