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AP Question

Discussion in 'Model S' started by lovingit, Jan 5, 2016.

  1. lovingit

    lovingit Member

    Dec 22, 2015
    Orange County, CA
    How does AP work? If I am driving and accelerating and a car cuts me off, will it automatically brake so I don't rear end the car?

    Or or if I am driving toward a car, will it sense it and automatically brake so I don't rear end it? Or do I have to be on cruise control for it to do that? Are there limits on how slow or how fast I have to be driving within for it to automatically brake?
  2. blanche

    blanche Member

    Jun 30, 2015
    Leesburg, Virginia
    Yes, to both questions. AP includes multiple technologies including TACC, so yes, the car will slow down to let someone else cut in front of you and it will also slow down if the car in front of you slows down.

    If you see a car completely stopped in front of you, you may want to take over at that point. AP/TACC will only slow down at the last moment and this may be uncomfortable / unnerving for you.
  3. Jool

    Jool Member

    Jun 26, 2015
    San Diego, CA
    Autopilot is a combination of traffic-aware cruise control and auto steering. Traffic-aware cruise control is always on when auto steering is activated, so the car will slow down once it detects another car ahead of it and is within a certain distance. You can adjust the distance with the cruise control stalk on the steering wheel.

    However, if a car does cut you off relatively close to your vehicle, I would recommend manually braking just in case your car doesn't adjust fast enough. I haven't had any issues with that, but it's better to be safe than sorry!

    I plan to make a video detailing the use of the autopilot functionality later this month, to help clear up any confusion about the system :smile:
  4. ecarfan

    ecarfan Well-Known Member

    Sep 21, 2013
    San Mateo, CA
    @lovingit, I see you are located in the SF Bay Area so you are likely near a Tesla showroom. Call them and schedule a test drive and experience yourself, and have them explain it to you.
    AP is amazing. You won't regret taking the time to try it out. Warning: you may end up spending a large amount of money after the test drive. Be prepared.
  5. mikeash

    mikeash Active Member

    Oct 26, 2014
    Fairfax, VA, USA
    There are two different kinds of braking you might encounter.

    The first is part of TACC (traffic-aware cruise control). This automatically brakes to match the speed of the car in front of you. If someone cuts you off, it will slow down to match their speed, and gradually back off to a safe following distance. If they speed up, it will speed up too up to the speed you set. Note that this requires cruise control to be on. If you have it off then none of this happens.

    The second is automatic emergency braking. If the car detects an imminent collision then it will brake for you. According to the wording in the manual, it brakes to mitigate damage, but not to avoid the collision entirely. I'm not sure if it's really likely to hit anyway or if this is just lawyerly wording to avoid lawsuits, but either way this is an emergency function that you should never count on, and if it does save you from a collision you should count that as something going seriously wrong but you were lucky to come out of it OK.
  6. Patrick W

    Patrick W Active Member

    Mar 17, 2015
    SLC, UT
    I could of sworn there was a thread a while back (which I can't find now) where someone was going to rig a "soft obstruction" and see how the car reacted to it.

    If memory serves the obstruction was something like a piece of aluminum foil suspended from string over a street with the idea being to run the car at it to see how it reacted when (if) it detected the foil.

    Anyone here remember that? Was the experiment run?
  7. robert774

    robert774 Member

    Mar 21, 2015
    Katy, Texas
    The follow setting you use in TACC is very important as well, especially in potential stop-and-go traffic. In Houston, where you can be moving along at 50+ mph only to come up on a bumper to bumper traffic jam that is stopped, if you use a follow setting of 1 or 2 you will very likely experience very hard braking and potentially an accident. I was using this setting for a while and had several very close calls. I then put it back to 4 and found that automatic braking is much safer.

    S4WRXTTCS Active Member

    May 3, 2015
    Snohomish, WA
    The thing about AP is nothing is guaranteed.

    If someone cuts you off the car might save you're bacon, or it might not catch it in time.

    Generally speaking the car will see a stopped car in front of you, but I would never trust my life on it.

    Mostly I see it as "assistive". Like someone that has my back, but not someone who can't be foiled.

    The same is true for false positives. Extremely rarely it will stop/slow for things that are NOT there.
  9. nctalkinghead

    nctalkinghead Member

    Dec 25, 2015
    Raleigh, NC
    The tab on the touchscreen to access AP is labeled DRIVER ASSISTANCE...not driver REPLACEMENT...let's be reasonable about AP.
  10. Max*

    Max* Charging

    Apr 8, 2015
    I thought it was just people speculating how to trick the AEB into kicking on. Someone mentioned foam (which the radar wont see), and someone else mentioned putting foil over the foam to get a reflection from the radar.

    I don't think the experiment was actually run though. Could be wrong.
  11. Vitold

    Vitold Active Member

    Aug 10, 2015
    #11 Vitold, Jan 6, 2016
    Last edited by a moderator: Mar 13, 2016
    Here's how Subaru did it 2 years ago (they make their own system, don't use mobileye):

    Tesla avoiding taxi:

    Also here, and here.

    Just for fun, here's how Volvo did it in 2011:

    <a href=";v=9X-5fKzmy38" target="_blank">
  12. LetsGoFast

    LetsGoFast Active Member

    Oct 13, 2014
    Bjorn had a video where he tried and failed to get AEB to activate with dummy targets.
  13. aaron0k

    aaron0k Two failed MCU's on a S40 & S70D; both at 84k.

    Apr 1, 2013
    On the opposite end of CA traffic moving at 10mph, I've found it's best to set it at 1; which helps tracking the car in front and aids considerably with auto-steering; when setting it to 3/4 it it seems to favor the lane lines, and auto-steering jerks and sways a lot more.

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