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My MS thought a 45mph road was 5mph and tried to reduce my speed to 10mph

Discussion in 'Model S' started by GasKilla, Sep 13, 2016.

  1. GasKilla

    GasKilla No Gas Know Peace

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    I was using autopilot on a road I travel daily, in the right hand lane on a three lane (each side 3 lanes 6 total) highway. I was very confused as to why my car was slowing down with no cars in front of me, that's when I noticed the dash said 5mph speed limit and auto steer was limited to 10mph.

    What does AP use to determine speed limit? GPS or the camera? Like I said I travel this road daily and never had a problem before. Posted speed limit is 45mph.
     
  2. GoTslaGo

    GoTslaGo Learning Member

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    Interesting. I had the opposite experience. 45 mph speed limit sign at night. The 4 is an add-on number and for whatever reason unable to be read by AP, so it sees it as 5 mph and posts it on the dash.

    I had AP (Autosteer & TACC) driving at 55 mph (previous speed limit), remembered that the car sees this sign as 5 mph, so waited to push the accelerator. Nothing. The car showed the 5 mph on the dash, but maintained it's 55 mph speed.

    I wonder if it has something to do with what speed you were traveling at. Were you at the speed limit (45 mph)?

    I recall @Garlan Garner had a long post on the difference between Autopilot vs. Automated safety features and some correlation with speed (AEB will come to a full stop below some speed, but will only increase brake strength at higher speeds for example). Wonder if this is a manifestation of that...
     
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  3. Patrick W

    Patrick W Member

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    Pretty sure it mainly uses the camera.

    But sometimes when I get on a road without a speed limit sign in that area it displays the correct speed so I'm guessing it may also go on memory from a previous trek along a different stretch of that same road where a speed limit sign is posted.
     
  4. GasKilla

    GasKilla No Gas Know Peace

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    I have my offset at +5mph so I was going 50mph when the car switched that to 10mph and started to slow down
     
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  5. EVie'sDad

    EVie'sDad Member

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    happened on a small road undergoing a lot of reconstruction, a 35 mph sign was interpreted as a 5 mph sign and yes, it slowed down but fortunately no other traffic in the vicinity and did not cause me much concern or surprise.
     
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  6. msnow

    msnow Active Member

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    First it tries to use the camera if it can't see it, it goes to a database based on location.
     
  7. hybridbear

    hybridbear Member

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    During my cross-country road trip I had a number of experiences like this. A number of stretches of interstate 90 have had their speed limits increased in recent years. As long as the speed limit signs were fairly close together the car was okay. But if there was a long stretch of no speed limit sign then the car would revert to the GPS data and think that the speed limit was lower. Sometimes it would think it was so much lower that it would give me the "autosteer speed reduced" message and start slowing down. Quite often the next speed limit sign would be very close by after that and the car would begin to speed up again before I could take over.

    The car also cannot handle roads that have now become variable speed corridors. We drove on one of those along the Trans-Canada highway in BC and also along part of I-90 in Washington. The car just uses GPS data there and sometimes would not allow us to drive even the speed limit with autosteer on because the new variable speed limit was so much higher than the old posted limit.

    One stretch of road we drove in Canada had a speed limit of 120 kph. The car didn't read a single one of those signs correctly. Sometimes it read them as 20 kph and sometimes as 100 kph. Fortunately that road is classified in such a way that it didn't result in an autosteer speed restriction.
     
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  8. glh280

    glh280 Member

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    I am wondering if it does both. I-275 in Tampa was recently redone (and moved slightly). As a result the navigation keeps thinking we are on side roads while going south. Because of this it does try to slow the car down to 30ish mph in that area. There are no signs pointing to that speed limit, so I must assume it is GPS based. I always have to mute the GPS in that section, and manually press the accelerator for about half a mile until it realizes it is really on the highway and picks back up.

    I am surprised that the GPS doesn't update more frequently. The crosstown expressway was in for years before the navigation noticed it as an available route.
     
  9. roblab

    roblab Active Member

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    The nice thing is that you can turn it off or over ride it while it's learning.

    We have a place, left turn out of traffic, where all the traffic slows down because of the bottle neck caused by the left turners. Funny thing is, even late at night, no traffic, PA remembers and slows down quite dramatically. It's easy to click it off and then resume a hundred yards down the road. We are smarter than PA.
     
  10. Garlan Garner

    Garlan Garner Active Member

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    This is extremely interesting. Thanks for the post. Very informative.

    I do wonder which system reads signs. Is it AP or Automated safety.
     
  11. green1

    green1 Active Member

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    I used to say that it got speed limits right less than 50% of the time. I've discovered recently that that's EXTREMELY generous.

    But don't worry, Tesla has done everything right, and was absolutely correct to tie the maximum speed of AP to their perfectly functioning speed limit detection algorithm. If you don't like it you should sell your car. (If you don't get the sarcasm, read the far too serious posts in every other thread where I bring up this ludicrous limitation added to cars after purchase)
     
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  12. msnow

    msnow Active Member

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    Again, the camera attempts to read the sign (sometimes as noted above it gets it wrong). If it can't see a sign it goes to the location based data.
     
  13. msnow

    msnow Active Member

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    You should qualify that 50% statement. As we've discussed over the past year your situation is somewhat unique to your locale. In my case I can only recall three or four misidentifications of speed limit signs.
     
  14. green1

    green1 Active Member

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    Why should I qualify it? My location is printed right below my avatar on the side of the page like everyone else.

    I think you need to stop assuming that everything that works "acceptably" in California will work well worldwide, and that tying an autosteer limitation to such a horribly faulty system was a poor idea that decreases safety and pisses off owners.
     
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  15. RogerHScott

    RogerHScott Active Member

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    This doesn't add up. The autosteer speed limit only applies on non-divided ("suboptimal") roads, so you should never see it on an
    interstate.
     
  16. msnow

    msnow Active Member

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    Because a 50% error rate is not common, its unique to your particular situation.
     
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  17. RogerHScott

    RogerHScott Active Member

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    If it really does have both of these sources available (I've never seen it come up with a speed limit in a location where one wasn't posted,
    but maybe I just live in a GPS info desert here) then it seems like a fairly obvious and easy fix to the read-route-number-as-speed-limit
    problem would be: if you (think you) detect a "surprising" (let's say, more than 10mph) change in the posted limit, check the database
    and see if the limit you thought you detected happens to be identical to the number of the road you're on; if so, assume you misread
    a route marker and ignore it. If this is too "generous" it could be refined to only kick in after you've seen the limit return to the previous
    non-route-number value.
     
  18. RogerHScott

    RogerHScott Active Member

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    To be fair, you don't have enough data to draw that conclusion. The most you can say is that it is inconsistent with what you've heard
    from others, mainly on these boards.
     
  19. Zybd1201

    Zybd1201 Member

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    I get it all of the time when I am on an interstate and the navigation thinks I am on a neighboring road. Let me know if you want videos and I will provide them.
     
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  20. green1

    green1 Active Member

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    [citation needed]

    And if you claim that the issue is my particular car, Tesla disagrees. I've brought this to their attention on many occasions, not once have they suggested that this is related in any way to my particular vehicle. In fact, they fully admit it's their speed limit recognition system that's at fault. Unfortunately they don't seem to actually have any process in place to fix it.

    Not to mention, Tesla should have thought about that before they made the limit apply to EVERY situation.
     

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