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Automatic Emergency Braking Design Point

Discussion in 'Model S: Driving Dynamics' started by BertL, Oct 25, 2015.

  1. BertL

    BertL Active Member

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    I understand if AEB is engaged by MS, it will reduce driving speed by 25 MPH if the car was already going 5-85 MPH. I've searched through a myriad of other TMC threads to no avail. Can anyone provide their POV as to why Tesla has elected to implement what I consider a "partial AEB solution", vs. AEB attempting to bring MS to a full stop if it believes a crash is unavoidable? TACC and Autosteer bring MS to a full stop as a matter of course when necessary, and according to the manual, AEB involves use of the camera and radar even when TACC is off. I'm just puzzled trying to understand Tesla's design choice not attempting to always bring MS to a full stop in emergencies.

    FWIW: My former 2013 Lexus RX450h had their optional Pre-Collision System (which included a more limited sort of TACC), but it would not bring the car to a full-stop in any situation including under radar cruise control -- it would only sound warnings for the driver to take final action at a certain point. IMHO, part of that lack of automation was because of their lagging tech at the time and very conservative nature. OTOH, my former 2014 MBZ SLK with optional Distronic Plus which included what they call Pre-Safe Brake, would attempt to bring that vehicle to a full stop with emergency braking if a crash were imminent between 4-124 MPH. Since MBZ has provided AEB-like function with full-stop for years, it's odd to me that Tesla does not (unless TACC or Autosteer is engaged?)

    Your thoughts are appreciated.
     
  2. LetsGoFast

    LetsGoFast Active Member

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    I've not seen any successful test of the AEB function and I'm a bit skeptical of the "reduce by 25mph" bit in the owner's manual. Like you, I can't see any reason why it should work that way.
     
  3. deonb

    deonb Active Member

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    Because a sensor error that brings you to a full stop could cause an accident.

    I've had collision detection fire 3 times on me over the last year. None of the cases were correct, and all of them would have resulted in me getting rear-ended if my car stopped all of a sudden.
     
  4. cgiGuy

    cgiGuy Member

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    Had an Infiniti with DCA (Distance Control Assist) that would bring you to a full stop, but said it would only use 25% of total braking power to do it. Sounds like they all want to get an early jump on the reaction time, but still require you to be ready to stand on the brake.
     
  5. yobigd20

    yobigd20 Well-Known Member

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    the AEB was only designed to reduce the force of an impact, not prevent one. so you're still going to get into an accident, it's just not going to be as bad as without the AEB.
     
  6. musicious

    musicious Member

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    #6 musicious, Oct 25, 2015
    Last edited: Oct 25, 2015
    They should look at Subaru's Eyesight as the model for the best implementation, it will prevent an accident at ANY speed if within 31mph of the car in front and will come to a complete stop. I had that on my 2yr old Subaru Legacy which I traded in for $17k to get my Tesla primarily because of AutoSteer (the subaru had adaptive cruise but only beeped when leaving the lane without a signal).

    Subaru uses 2 stereoscopic cameras and had the top rated collision avoidance (prevented an accident 3 times for me) of any system out there on their first generation Eyesight. The second generation that came out last year got even better with color vision to see red brake lights for faster reaction and twice the distance and width of vision along with added side to side radar for backing out of a parking space and blind spot protection that can see cars speeding toward you from far back when about to change lanes (which is what Tesla needs for auto lane change).

    Here is an article comparing front crash avoidance, Mercedes hit the dummy car in multiple speed braking tests when the subaru applied brakes in time. Maybe Mercedes has improved since then but Subaru definitely did, I think Tesla should use them as an example.

    Subaru EyeSight crash avoidance system beats Volvo, Mercedes-Benz

    Just noticed Subaru now has lane keeping assist too, probably not full autosteer tho
    Subaru Details Second-Generation EyeSight Driver-Assistance Technology – News – Car and Driver | Car and Driver Blog
     
  7. Discoducky

    Discoducky Active Member

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    Could you please provide a link to the Merc verbiage? Amazing system if it can do that from 124mph.
     
  8. yobigd20

    yobigd20 Well-Known Member

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    Me thinks that if a group of people can implement missile avoidance systems on fighter jets it should be comparatively easier to implement an effective automatic emergency braking system on a car.
     
  9. Discoducky

    Discoducky Active Member

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    Found it: http://www.mbusa.com/vcm/MB/DigitalAssets/pdfmb/ownersmanual/2014_SLK.pdf

    Pre-safe is active in those speed ranges but it does not state how much energy it will mitigate while specifically saying it will not mitigate all the engrgy of a crash and does NOT react to smaller stuff that radar is not good at seeing like people and animals.

    What's great is that is specifically calls out that it could apply full force braking so kudos to that!

    Starting from page 66...
     
  10. BertL

    BertL Active Member

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    I know the MBZ implementation worked for me... Day after I took delivery of my SLK: Three cars took off through a red-to-green light at large intersection -- me as the 3rd behind. Just as I was in the center of that intersection, a guy comes barrelling around the corner on my right against his red and cuts off driver #1. #1 swerved into his left lane of traffic to avoid the idiot, fortunately the cars in that lane swerved. Car #2 ahead of me put on the brakes and went a bit sideways, as did I hit my brakes as fast as I could... But before I knew what was going on, my MBZ had my SLK stopped with the buzzer going off and such. I just remember the brake seeming like it had a mind of its own beyond what I was doing stomping on it. No damage to any vehicle, except a lot of hearts palpitating, but since then, I have a great appreciation for any vehicle that tries to assist in an emergency faster than I can perhaps react. It's why I've become pretty interested in more of the details how some of these safety systems will operate vs the broad brush marketing hype that can sometimes occur.

    My point with this thread was really more about why would Tesla implement AEB still to this day as what I'd term a partial solution that does not fully stop the vehicle, yet then implement Autopilot and TACC with full stop in the same vehicle like my new 90D, and not circle back to make AEB at least attempt a full stop brake if it can vs only slowing down 25MPH and then turn all responsibility back to the driver without any more automated assistance? I get there are many variables, and speed and what is/is not moving ahead makes a difference with sensor and radar capabilities we have today, but if MBZ attempts and can deliver full-stop brake with several-year old tech, is there any reason someone can think of why our MS couldn't do the same thing? Perhaps it is just Tesla not "circling back" to update AEB now that they have the tech worked out with Autopilot, similar to the way some things seem like they are in beta for ages. ;). If so, I'll be the first one to put AEB improvements in as a suggestion for improvement with v7.1 firmware that Elon has asked for input on.
     
  11. epoints

    epoints New Member

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    my thought exactly..

    thats my thought exactly... I am glad you post this... I couldnt get a straight answer from the DS. I wish they would do the same as Subaru. now that doesnt sound right, Elon?
     
  12. JenniferQ

    JenniferQ Member

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    I have a 2014 MBZ GL63 and don't think it has this system. Maybe not available on SUVs? Is it too heavy? It has a bunch of other safety stuff that just seems to overreact and annoy me. Particularly that lane departure warning that jerks the car back into the lane even if I'm steering away to avoid someone on the other side coming into my lane. It beeps a lot when I've already noticed the threat ahead. I've turned it off now. Too nervous for me.
     
  13. Discoducky

    Discoducky Active Member

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    Why do you think that the AEB on Model S currently will not bring the vehicle to a complete stop?
     
  14. BertL

    BertL Active Member

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    The Owner's Manual (V7 pg 81) states: "When Automatic Emergency Braking has reduced the driving speed by 25 mph, the brakes are released. For example, if Automatic Emergency Braking applies braking when driving at 56 mph, it releases the brakes when the speed has been reduced to 31 mph." ...and there is more detail following that in the manual.
     
  15. Carspotter Daily

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    I have personal experiences with AEB and I'll tell you on thing for sure: It works. AEB is designed to help you brake in emergencies, in one instance, I was braking to let someone turn two cars ahead. The people who were supposed to be turning decided it would be a good idea to stop in the middle of a two lane highway. Before the person In front of us crashed into the people ahead, the AEB had already slammed the braked pedal into the floor.

    For a couple of months now, I have been trying to film an example of AEB, but to no avail... I have tried cardboard walls (as big as SUV's) cardboard pedestrians and tarp. I'm not sure why the system does not work with these objects, but works with other vehicles.

    AEB works great in real life, but fails in testing, this baffles me, but I am more confident with this system enabled on my MS.
     
  16. BertL

    BertL Active Member

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    Jennifer, From my experience, packaging and options vary widely on the German Brands and even model-to-model, so it's hard to say without researching the specific options delivered on your GL63. From a quick glance I just did through the 2014 GL manual, it appears the Distronic Plus option was available and included BAS PLUS and Pre-Safe just as I had on my 2014 SLK. IMHO, you likely only have Distrionic Plus if you ordered your vehicle and specified the option -- most new cars available on dealer lots don't come loaded with the $2K+ Distrionic Plus option. One note, (at least IIRC in my former SLK) if you've turned-off Radar perhaps because some other thing it was involved with annoyed you, you may have also disabled some other (safety) systems reliant upon it -- if so, it may be worth your looking into just to be sure you have not unintentionally turned something off, in case one of the systems could help you and your family one day when you're in that MBZ.
     

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