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Cruise Control does not adapt to speed limit changes?

Discussion in 'Model S: Driving Dynamics' started by willcasp, Aug 27, 2016.

  1. willcasp

    willcasp Member

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    Location:
    Bothell, WA
    running firmware 2.32.23 in a 2016 Model S 90D

    I was on WA-520 yesterday. My cruise control is set to +9. Everything worked fine. Speed limit icon was showing 60. WA-520 changes to a 45 mile road when it turns into Avondale. I would expect the cruise control icon to drop to 54 (45 + 9). I noticed that the cruise was still set to 69. The speed limit icon was showing 45, as expected. I disabled the cruise by pushing the stalk forward. It turned grey, but was still set to 69.

    I came to a light, and hit the brake. The Cruise Control icon and auto steer disappeared.

    When resuming, the icons came back. The Cruise Control icon was now showing 54.

    Is this a bug?

    William
     
  2. Cosmacelf

    Cosmacelf Active Member

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    Yes, the operator should not have been using TACC on a road with traffic lights!

    In all seriousness, the car does not adjust the speed you set when you set TACC. You set it, you must modify it as conditions change.

    Do be very extra careful and alert when you use TACC on non-freeway roads.
     
    • Like x 1
  3. willcasp

    willcasp Member

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    To be clear, I had disabled TACC when the road changed from a proper highway to one with traffic lights. I think the designation still technically remains a highway. Disabling it with the stalk is why the icons were greyed out.
    Good to know that it stays steady. I noticed this same behavior with previous firmware while on interstates during speed limit changes.

    With all of the automation and telemetry in the car, this is something they should be able to adjust easily in software.
     
  4. glenhurst

    glenhurst Member

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    What I have noticed is that if one is on a multilane road and the speed limit drops, the TACC does not seem to adjust the speed accordingly. However, if one is on a two-lane road and the posted speed limit drops (and the camera is able to read the speed limit sign) it will drop the speed of the car to no more than 5mph over the speed limit. There's some debate as to whether the TACC should be used on two-lane roads, but I always keep a hand on the wheel and generally drive under the assumption that the autopilot is going to be wrong about a lot of things.
     
  5. BertL

    BertL Active Member

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    #5 BertL, Aug 28, 2016
    Last edited: Aug 28, 2016
    OP, my previous Lexus, MBZ and BMW that each had a "radar cruise control" equivalent to TACC, each operated similar to the way my MS does -- once the speed limit was set, it stayed that way until the driver changed it, or the vehicle was turned off and back on when that vehicle's default went back into effect. I only have my MS today, so I've fairly well adapted to the way it operates except when firmware tweaks are sometimes made. OTOH when I had multiple brand cars at the same time in my garage, the nuances of similar evolving higher-tech capabilities like these were sometimes frustrating at best, especially trying to remember what that particular vehicle would or wouldn't do in emergency situations.

    I suppose one could say (or expect) that a Tesla which has TACC and AP could be smarter in regards to MPH as you suggest, however, from a UI and safety perspective, the first questions that came to my mind as I read your initial post was "What if the car can't determine for whatever reason the speed limit for the existing road? Should the speed then just stay as the driver previously set it and the driver assumes the vehicle has changed it (back down or up?) like it would in more normal conditions? Who's problem would that then be, assuming the owner isn't paying attention to very small images/text on the TACC display?"

    As much as it pains me to say it from a technology and geekie perspective, having consistency in how vehicles perform driver-assist functions, especially in these early days of newer capabilities and autonomous driving. Every driver, not just enthusiasts (like us) that try to keep up with evolving detail and documented caveats, needs to know what to expect the vehicle will do 100% of the time. It's hard enough to get all drivers to read an owner's manual before they jump behind the wheel, and we know drivers of even MS are not always reading (or comprehending) one-time pop-ups that require driver confirmation to enable specialized functions. Designing or dumbing-down for these (few) is bad for us that would love to push the envelope with more automation, but I believe mfgrs have a tough balancing act as new frontiers are explored, beta code becomes available, out-lying logic is refined, and vehicles are put into the hands of the masses -- many of which are not or don't want to be technically inclined.

    Until we have an AI that can take primary driving responsibility away from the driver as our true AutoPilot, IMHO consistency and having a vehicle maintain a driver setting or override like maximum TACC Speed Limit, is best for most drivers today. It's relatively easy to explain, and with less exceptions, easy to remember. Even if it's documented somewhere, it's when the vehicle acts in a way different than the driver expects, when confusion and more accidents happen. Some of the recent MS/MX accidents are examples where the driver thought their vehicle would do something other than it could and did in exception conditions. We each have our POV which is great, but all that to say, I believe it is best for Tesla to not have TACC change the default max speed based on posted or database MPH as it's operating, but it should always reset to the default MPH+offset when the vehicle is turned-off and back on.
     
  6. WannabeOwner

    WannabeOwner Member

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    When the speed limit changes (and the dashboard displays the new limit) you should be able to pull-and-hold the TACC stalk for "half a second" to change (up or down) to the new limit (plus whatever offset you have configured)
     
  7. grichard

    grichard Member De-Luxe

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    I don't think that Tesla's detection of speed limit signs is robust enough for me to even want the car to change its cruise settings autonomously just yet.

    It'd be nice if the system worked the way you expected, and worked well. But I find that the car sometimes reads "truck" or "school zone" speed limit signs as the real things, and sometimes misses real signs. Until that behavior improves, I'd rather that the car didn't take the initiative.
     
  8. LastGas

    LastGas Member

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    That's what the manual says.
     
  9. u00mem9

    u00mem9 Member

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    Can anyone verify this works for them? I checked my manual and you are correct. But this weekend I tried multiple times to get this to work and no joy.
     
  10. WannabeOwner

    WannabeOwner Member

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    Works for me. I come into a (lower) speed limit, once the Icon is displayed pull-and-hold the AP/TACC stalk and it changes TACC down. Come out of the speed limit and for a short while my Speed Icon goes blank, then it shows "national speed limit" and, again, pull-and-hold and it changes TACC up to that new, faster, limit.

    I would NOT have been on AP when I have done this, dunno if that would make a difference. The sorts of roads where I need this aren't AP-suitable!!

    (We have an "End of limit" sign here, unless the speed is changing to a different, but still restricted, limit. So coming out of a speed restricted zone the limit becomes "national speed limit" which varies according to the type of road; single carriage way is 60 MPH and dual carriageway / highway / motorway is 70 MPH)
     
  11. LastGas

    LastGas Member

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    I certainly hope the upcoming 8.0 update will provide an option to ask the TACC to automatically reset the speed when it detects a different limit (at least lower it). I mean, this is supposed to be about safety as well as convenience.
     
  12. WannabeOwner

    WannabeOwner Member

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    I don't think the current system works very well. Sometimes the new (lower) limit pops up the moment I enter the zone, sometimes a handful of yards later. Either way, I am already in the 30 MPH zone and still doing 60 MPH at that point ... the slowing down needs to happen before I get to the start of the limit. So if there will be an option to automatically slow down for a speed limit I reckon it needs to happen earlier than is currently possible.
     
  13. kort677

    kort677 Active Member

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    you need to be interactive and attentive
     
  14. LastGas

    LastGas Member

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    It has GPS speed limits it could refer to.

    I'm not asking the car to be responsible for managing the speed of the car in all circumstances, but it would be great if the car wouldn't barrel into a construction zone if the driver had fallen asleep.
     
  15. WannabeOwner

    WannabeOwner Member

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    Indeed :) The bit that I'm not figuring is how to tell it to slow down. Right now I can't pull-and-gold-stalk to change to lower speed limit until I'm inside it. I suppose I could select & set a general "Reduce speed for all lower limits" option, but would I want to select that for all such instances? I think?? I would prefer that the new limit is offered a short while before reaching it, allowing me to signal a slowdown with a pull-and-hold action or somesuch. But I would have to notice that the dashboard was giving me that advanced warning; on a straight road where I can see the new speed limit sign ahead that's fine, if its around a bend that still might not work very well.

    Perhaps the world should just decide that speed limits have to be adhered to? I'm only a moderately good candidate for that change!!
     

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