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Cruise Control Bug?

Discussion in 'Model 3' started by pipplo, May 8, 2018.

  1. pipplo

    pipplo Member

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    I noticed some weird behavior, can anyone confirm?

    Normally when I enable cruise control it defaults to the speed limit or my current speed if it is above the speed limit. (This is slightly different than most cars)

    But, today I was enabling the speed warning, and I set it to a relative offset. I wanted to be warned when i went 15mph over the speed limit.

    After I did that, cruise control now defaults the speed to speed limit + relative offset from the speed warning! I was on the highway goign 60 and enabled cruise, then cruise speed was set to 80! If i change the relative offset it changes the cruise speed default.

    If I change the warning to absolute speed the cruise still seems to be using the last relative offset value.

    I'm not sure how to report this weird behavior to Tesla?
     
  2. animorph

    animorph Active Member

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    That's normal, for S and X, warning and initial cruise speed are tied together.
     
  3. TT97

    TT97 Active Member

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    That is how the TACC works:

    Cruising at the Speed Limit
    Traffic-Aware Cruise Control makes it easy to cruise at the speed limit. You can cruise at the speed limit that is currently being determined by Speed Assist (see Speed Assist on page 79). To do so, move the gear lever fully down once then release. When you release, your cruising speed is set to the speed that is determined by Speed Assist, taking into consideration any offset you have specified. If you are already driving faster than the speed limit when you pull the lever, the set speed does not adjust to the speed limit—it adjusts to your current driving speed.
     
    • Informative x 1
  4. flying_things

    flying_things Member

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    that's normal.
     
  5. pipplo

    pipplo Member

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    Well, good to know it's intentional I guess. It doesn't make any sense to me. Especially since it applies the offset even though the UI elements don't even show the offset. Why hide the relative offset UI element if it's still relevant and being used for something?
     
  6. EVnut

    EVnut EV #5

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    I realize this thread is five months stale... but I agree with pipplo on this! And I'll go one step further.

    Why is there no way for me to begin cruise control UNDER the speed limit? If I'm pulling a trailer, my speed limit in CA is ten MPH below the posted limit. If I need to drive for range, I need to go below the limit. But when I tap for cruise control, it accelerates me inappropriately to either the speed limit or my "alert" offset. And that's insane behavior, IMO.
     
  7. intjester

    intjester Member

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    You can flick the right thumb wheel up/down to manually add/subtract speed in 5mph units or tick it slowly for 1mph increments. No reason you can't dial in any target you want, but the underlying UX assumption is you would want to be going at the limit if you were unobstructed.

    For most drivers in most situations this is true and thus sane behavior.
     
  8. EVnut

    EVnut EV #5

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    I can't dial in a target, because this can only be done AFTER activating CC, and AFTER the acceleration begins. Like firing a gun, and THEN putting up the silhouette. If it could be pre-set, the problem would be solved. That is exactly what I'm after. Having the system assume that I want the speed limit is fine... but just like follow distance, let me pre-select a different speed before I activate CC. If I want 55 mph, and the speed limit plus offset points to 75 mph... this is far from optimal. Especially considering how quickly the car tries to achieve the set speed. That there is no way to dial in this different before activation is the issue.

    For me personally, it is not sane. Do you have reference numbers or citations that point to "most" drivers and situations desiring this behavior? Maybe what you say is true. And that would speak volumes about the confusion about what "speed limit" means. And really, who doesn't want to set the CC at the current speed of the vehicle? Obviously we assume that if the speed limit is being exceeded that the driver wants that speed set. Why not the other way as well?
     
  9. intjester

    intjester Member

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    It's Traffic Aware cruise control.

    Literally, its best use case is IN TRAFFIC. So, I'm cruising along driving manually and I hit a patch of bumper to bumper traffic.

    Bing, on goes TACC at 15mph or whatever the crawl is at. Now the traffic abates and cars can resume 65mph.

    In your view, I should be stuck at 30mph, because who doesn't want to set the CC at the current speed of the vehicle?

    The answer is anyone in traffic.
     
  10. ecarfan

    ecarfan Well-Known Member

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    And on the S/X you can engage TACC and it will maintain the speed at which it was engaged.

    The 3 is different. I prefer the way S/X TACC engages.
     
  11. EVnut

    EVnut EV #5

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    I can see the confusion, but no. In my view, you should be able to set it at whatever speed you'd like your max speed to me. That could be the current speed, below the speed limit or above speed limit. And I'm OK with the default being the speed limit... just let me spin the wheel to adjust before engaging (the same way that I can pre-adjust the follow distanced by pushing left or right).

    To me it sounds like you'd like drivers to be limited to the choice that Tesla made, and the choice that you enjoy. I hope that I am also misunderstanding your view.

    My bad. I should have said, "who never wants the option to set the cruise control speed at the current speed?"

    As configured, a driver can set it at the current speed as long as he is exceeding the speed limit and/or exceeding the pre-set "alert" offset. But there is no way to set it below the posted speed limit until after allowing it to start accelerating you to the higher speed, and then manually dialing it back down. There's no logical nor practical reason to avoid offering the choice.
     
  12. pipplo

    pipplo Member

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    Yeah I'd really at least like an option to set to current speed. Every other car I've ever driven before has that as the default behavior and it seems more sane to me. Especially considering multiple roads in my area have the wrong speed limits set.

    My bigger concern is the really hidden way the 'relative speed' settings impact the cruise control.
     
  13. EVnut

    EVnut EV #5

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    Agreed! That whole offset thing (grayed out because I have it set to "no alert") surprised the heck out of me. And then I found that there's no way to change that while driving. So if you get that wrong, you're stuck with it until the next time you're off the freeway and stopped.

    There's a pretty simple change here that could make everybody happy.

    The next question that pops into my mind... If Auto Pilot was not purchased, does that mean that the default cruise control speed setting is the current speed?
     
  14. SpaceCarFan

    SpaceCarFan Member

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    The UI around speed warning and Autopilot engagement speed are dangerously bad. I hope Tesla revisits this.

    1. It is extremely confusing to link a speed warning to the autopilot speed limit. These are entirely separate logical concepts that can exist without each other and deserve separate inputs in the UI.
    2. Autopilot should default to engaging at the current speed, even if it is below the limit, unless the user sets a custom behavior. Not only is this how every other car in the world works, but there are legitimate safety reasons to travel below the limit sometimes such as inclement weather.
     
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