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Adaptive Cruise Control (TACC) Annoyance

Discussion in 'Model S: Driving Dynamics' started by Karen in MN, Sep 10, 2017.

  1. Karen in MN

    Karen in MN Member

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    Does anyone else get bothered by how little the cruise control looks ahead? I love using it in traffic, but too often somebody ahead of me pulls out of my lane leaving a largish gap to the apparently unseen next car - then my Tesla speeds ahead and I end up breaking (stopping the TACC) because I can see the car in front of me is slow or stopped. It feels very inappropriate. This happens in stop and go traffic, or on speedy side roads where someone changes lanes before a red light.

    If I'm doing something wrong, please let me know. :)

    Karen
     
  2. kdday

    kdday Member

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    I believe the range on the Bosch radar is 160 meters, so depending upon the distance of next car in front, your car simply can't see it via radar.

    The cameras are uses to track the lane lines and maintain the car between the lines, while the radar is used for object detection in the lane.

    While the camera can see further than 160m, the radar can't, so that's that.
     
    • Like x 1
  3. Karen in MN

    Karen in MN Member

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    Thanks for the info, kdday. So 160m is 1/10 mile or maybe approximately a city block. Boy, it seems like I'm within that zone when this happens, especially on the side roads. I'll pay more attentions to see if my radar is malfunctioning.
     
  4. hacer

    hacer Member

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    Usually the Tesla radar is able to track the car ahead of the car in front of you IF it is moving. Stopped vehicles, especially stopped vehicles obscured by a car in front of you are very difficult for any radar to distinguish from all other stationary "clutter" (e.g. the road surface, signs, lamp posts etc, etc. If the stopped vehicle is reasonably close, the camera may detect it and the car will brake (often harder and later than a lot of drivers would) to avoid hitting it, but you should take action yourself anytime the car in front changes out of your lane if there is a stopped car in front of it.
     
    • Like x 2
  5. RLC3

    RLC3 Member

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    I see behavior like you describe as well. It happens even when the further obstacle is MUCH less than 160 meters ahead. I believe it is a limitation of the control algorithm, and that they have a little more work to do on that. :)

    It appears to see that the car it is following has left the lane, then initiates speeding up to the set speed since there is no obstacle slowing it down. Then rapidly decides that there is another vehicle in front and starts to slow again.

    I have never been worried it would hit the second car - but the experience would be much more like a human driver if the speeding up was done AFTER taking into account the further obstacle and closing the gap at a reasonable rate. It's just too aggressive as it is.

    This is probably one of those refinements that will come along in future releases, along with things like moving a little to the left in the current lane if there is an 18 wheeler in the lane to right.

    Tesla, I hope you have long lists of these little things you need to do to make it great!
     
    • Like x 1
  6. Karen in MN

    Karen in MN Member

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    Thanks, Hacer. I'm probably about to show how clueless I am, but shouldn't the radar bounce back off of some hard object stopped ahead in my lane, therefore my car should stop?
     
  7. Karen in MN

    Karen in MN Member

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    Glad I'm not alone in noticing this, RLC3, thanks. I've scared passengers with this behavior, and worry that a car in another lane won't be expecting my speed and will cut in front of me, so I usually break before TACC does.
     
  8. Karen in MN

    Karen in MN Member

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    Partial solve! I hadn't used my car since March (leg break) and just started using it again this month. I realized I hadn't checked the distance between cars setting, and when I did saw it had gotten set to a 1. I've reset this at 6 which I'm sure will help.
     
    • Like x 2
  9. RLC3

    RLC3 Member

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    Could be, although I seem to see this behavior no matter what following distance I set.
     
  10. hacer

    hacer Member

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    Imagine there is a hill in front of you. The radar will bounce off the road (the hard object stopped in front of you). You of course don't want to brake for the hill since you won't hit it (in a car; if you're in a plane and the radar sees the hill - pull up!). Unfortunately, you don't even really need a hill because the ground is very, very large and there is a lot of radar energy bouncing back at all distances from the stationary ground, buildings, bridges, signs, etc. It even appears from the wrong direction(s) due to the (inevitable) side-lobes of the antenna (i.e. it appears to be directly in front of you when it is actually off-axis.)

    Since the radar nearly always sees big stationary objects in front of you, it has little choice but to mostly ignore them. When something is moving, it becomes easily distinguishable from the all the stationary things around you.
     
  11. NSX1992

    NSX1992 Member

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    I am still amazed by how well the car accelerates slowly when a car leaves my lane and then slows down again when reaching the next car. There has been a big improvement since Autopilot was first released.
     
  12. Karen in MN

    Karen in MN Member

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    Thanks for additional comments.

    Hacker, your post motivated me to try to understand things a little more. This was interesting from Tesla: Upgrading Autopilot: Seeing the World in Radar. Interesting, lots to learn and think about.
     
  13. Quick2Judge

    Quick2Judge Member

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    I have mine set to 4 car lengths and love the feature. I have never noticed the inappropriate decel/Accel. Maybe I am lucky?
     
  14. kutkuzak

    kutkuzak Patrick

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    I have a daily commute w/ 2-5 lanes of traffic with speeds ranging from 70 to stopped. TACC is wonderful but semis in lanes to the left or right of me have caused some seemingly 'random' brake episodes that have me on edge. I've started putting my foot on the gas ready to hit it just in case it brakes so that I don't get rear-ended. 98% of the time, it's great - but that 2% is kind of adrenaline inducing.
    I have other cases where it 'slows down' for no obvious reason leaving way more than the set gap but at least it doesn't aggressively slow down or brake.
    Given how random the traffic speeds up and slows down during my commute though, in general, it's a great feature.
     
    • Informative x 1
  15. Karen in MN

    Karen in MN Member

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    kutkuzak- that's scary. Sometime around when I first got my car in January, mine suddenly slowed a couple of times when driving on a Sunday in the express lane. No cars in front, an unfortunate pickup in back. Second time I did it he pulled out of the lane and passed me rapidly in an understandably annoyed manner. Guy at Tesla told me it was due to a software upgrade that didn't have the kinks worked out yet. He said sometimes the radar won't recognize an overhead sign and, playing it safe, it will stop. Unfortunate that you are still having those effects.
     
  16. kutkuzak

    kutkuzak Patrick

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    Things like overhead signs could possibly be an issue as well but it's seemingly random enough and scary enough when it happens that I'm more worried about making sure nobody is going to hit me, etc. before I can try to figure out what might be common about prior occurrences or location. Only going on 2+ weeks with the car so I'm sure over time I'll figure it out. Those recent occurrences definitely 'seemed' to be related to the semi next to me. I almost want to say it was a semi without the side flaps along the trailer and it almost seemed to think it was 2 cars all at once - just the right angle or something. Not sure. :(

    Patrick
     
  17. brianman

    brianman Burrito Founder

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    Just another data point...

    If you're in traffic that is between 20-40 mph on a 60+ mph limit area, drop TACC to 20-40mph. Less stress and nausea.

    Yes I wish they would improve this, but the workaround is decent.
     
    • Like x 1
  18. kutkuzak

    kutkuzak Patrick

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    My problem hasn't been it not slowing down or stopping for cars in front of me, but slowing down slightly or so,etims aggressively for no obvious reason.
     
  19. Karen in MN

    Karen in MN Member

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    I've thought about doing that and I'm glad it works ok.
     
  20. Karen in MN

    Karen in MN Member

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    Is your car new? You might want to talk to dealer about this.
     

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