TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

TACC failed to brake at stop, nearly accident.

Discussion in 'Model S: Driving Dynamics' started by Lintrix, Apr 13, 2015.

  1. Lintrix

    Lintrix Member

    Joined:
    Dec 4, 2014
    Messages:
    39
    Location:
    Chicago, IL
    #1 Lintrix, Apr 13, 2015
    Last edited by a moderator: Mar 13, 2016
    I was showing a friend TACC and how it works/performs over the weekend and during a mundane red light stop, the TACC failed to brake properly and we almost ended up rear ending the car in front of us. Needless to say, she was less than impressed.

    I have a dash cam and recorded it here: P85D TACC fails to brake at red light. Almost accident. - YouTube



    It's hard to tell but we were going at a decent but manageable speed and was following the blue Prius in front of us. The TACC was on and i did not manually step on the brakes at all, even until the end. Had I not swerved to the right, we would have rear ended the car. It appears that at that situation, TACC might have thought the road curved to the right given that the vehicle in front of me started going towards the right and also the lane opens up as well. It did not take notice on all the vehicles that have stopped and also the vehicle in front of us that has been stopped.

    So guys, be careful using TACC, especially if the car in front of you is leaving the lane. It seems that TACC does not track or does not like to track anything beyond the vehicle in front of you.
     
  2. mibaro2

    mibaro2 Member

    Joined:
    Dec 2, 2012
    Messages:
    958
    Location:
    Georgetown, ON
    Wow.
    I guess TACC thought you were going to continue to follow the blue car.
    Thanks for the video.
     
  3. Matias

    Matias Active Member

    Joined:
    Apr 2, 2014
    Messages:
    1,590
    Location:
    Finland
    No collision warning either? Did the car brake or you?
     
  4. Lintrix

    Lintrix Member

    Joined:
    Dec 4, 2014
    Messages:
    39
    Location:
    Chicago, IL
    The collision warning came up right before the emergency braking happened. I started to swerve as soon as the collision warning came up.
     
  5. Stoneymonster

    Stoneymonster Active Member

    Joined:
    Jan 8, 2013
    Messages:
    1,554
    Location:
    Aptos, Ca
    Please communicate with Tesla. They can't improve this if they don't know about it.
     
  6. GregTexas

    GregTexas Member

    Joined:
    Apr 8, 2015
    Messages:
    223
    Location:
    College Station, TX
    Infinity claims their Q50 system looks at the car in front of the car that is in front of you to see what it is doing.
     
  7. Matias

    Matias Active Member

    Joined:
    Apr 2, 2014
    Messages:
    1,590
    Location:
    Finland
    Just to make sure I understood it right: car made emergency braking, you didn't step on breaks?
     
  8. Lintrix

    Lintrix Member

    Joined:
    Dec 4, 2014
    Messages:
    39
    Location:
    Chicago, IL
    Is there an email address I can use to send to Tesla so they can review?
     
  9. Stoneymonster

    Stoneymonster Active Member

    Joined:
    Jan 8, 2013
    Messages:
    1,554
    Location:
    Aptos, Ca
    That seems ambitious. Is the Q50 tall enough to always see over the car in front?
     
  10. JohnSnowNW

    JohnSnowNW Active Member

    Joined:
    Feb 13, 2015
    Messages:
    1,397
    Location:
    Minnesota
    Interesting.

    Does anyone know if the system learns from events like this. As in, was this data collected and uploaded to Tesla, to further enhance TACC. I kind of assumed drivers are basically guinea pigs for the TACC system...but is that true?
     
  11. Lintrix

    Lintrix Member

    Joined:
    Dec 4, 2014
    Messages:
    39
    Location:
    Chicago, IL
    I did not brake at all, even at the end. I wanted to show my friend the TACC so I literally let it do its thing. The only thing I did was swerve to the right. I cut the video off, but after the vehicle stopped, it started moving forward again so I applied the brakes to turn off TACC.
     
  12. Matias

    Matias Active Member

    Joined:
    Apr 2, 2014
    Messages:
    1,590
    Location:
    Finland
    Ok. At least the automatic emergency breaking worked :smile:
     
  13. doug

    doug Administrator / Head Moderator

    Joined:
    Nov 28, 2006
    Messages:
    15,914
    Location:
    Stanford, California
    I believe this is done by glancing radar on the road underneath the car in front of you to see further ahead. I'd guess the Tesla hardware has this capability, though not sure if they're using it. I also wonder how that works when all cars are using a similar system.
     
  14. GregTexas

    GregTexas Member

    Joined:
    Apr 8, 2015
    Messages:
    223
    Location:
    College Station, TX
    I think it looks under and around.
     
  15. Stoneymonster

    Stoneymonster Active Member

    Joined:
    Jan 8, 2013
    Messages:
    1,554
    Location:
    Aptos, Ca
    Insane!
     
  16. JMG

    JMG Member

    Joined:
    Feb 26, 2015
    Messages:
    546
    Location:
    NE Texas
    That's very interesting, and a little scary.

    So bottom line, the TACC still needs to be babysat just as if you were doing the driving yourself. Sounds like the only thing it saves is a little calf-fatigue of the constant breaking and accelerating, not that I was going to be reading a book in traffic, but I thought it would be a little more fool proof than this. Hoping Tesla continues to fine tune it and prevent things like this.

    Kudos to you for avoiding the accident and the resulting headache of getting it fixed.
     
  17. green1

    green1 Active Member

    Joined:
    Mar 25, 2014
    Messages:
    4,105
    Location:
    Calgary, Alberta, Canada
    Looks to me like TACC didn't stop because it didn't switch radar lock from one vehicle to the other when the first vehicle turned off, however Emergency braking did work.

    I know you state that you would have hit the vehicle in front, however in the video it appears that the emergency braking managed to stop you just short (though I'll admit it wasn't a comfortable distance)

    Seems to me that TACC could switch vehicle radar lock faster, but that emergency braking worked properly.
     
  18. LetsGoFast

    LetsGoFast Active Member

    Joined:
    Oct 13, 2014
    Messages:
    1,342
    Location:
    Virginia
    Not making excuses for the TACC, but this is a fairly standard failure mode for TACC. The same thing would happen if you came up in cruise control to a stop light where a car was parked for the red. In other words, had the blue car not been there at all, you would have run into the stationary white car anyhow. TACC does not see stationary objects and it would happily plow into the back of it until emergency braking kicked in. That is essentially what happened here. The blue car cleared your lane so TACC thought it was free to accelerate to cruise speed and TACC will not stop for the stationary white car. Had the white car still been moving, it would have locked onto it and stopped.

    It does appear that emergency braking would have managed to stop the car before contact was made, but just barely.
     
  19. Stoneymonster

    Stoneymonster Active Member

    Joined:
    Jan 8, 2013
    Messages:
    1,554
    Location:
    Aptos, Ca
    TACC does not see stationary objects? That's not been my experience. That also means stop-and-go traffic wouldn't work, which it does.

    - - - Updated - - -

    That's always going to be the case, no matter how good it gets. The difference is you have more attention to spend on your surroundings if you aren't wasting effort modulating car inputs.
     
  20. Lump

    Lump Active Member

    Joined:
    Mar 31, 2013
    Messages:
    2,101
    Location:
    So. Cal.
    #20 Lump, Apr 13, 2015
    Last edited by a moderator: Mar 13, 2016
    I assume the ability to read brake lights & stop lights will help in this situation in the future, Tesla is using Mobileye

     

Share This Page