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Autopilot bobbing side to side

Discussion in 'Model S: Driving Dynamics' started by ShadowR55, Jul 5, 2019.

  1. ShadowR55

    ShadowR55 Member

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    I have a Model S and X, both are running 2019.20.4.2 but the Model S has a serious safety concern when autopilot is engaged on the highway. This started happening about two months ago and I have had several software updates since it started and nothing has fixed the issue.

    When going around 80 on the highway with autopilot engaged, the car will start swaying side to side slowly at first and then it speeds up and sways harder to the point that the car will start going over the left and right lane lines. Holding the steering wheel, autopilot will disengage itself because it’s trying to turn instead of going straight. Attached is a short video showing what happens. I was holding the steering wheel tightly because there were cars around me so I was trying to keep it going straight. You can see at the end of the video that it was about to go off the road and autopilot disengages because of my grip.

    The service center says they sent a note to engineering and that they will release a fix once it is completed. Feel like they don’t know how to fix the issue and are crossing their fingers that a future software update will resolve the issue.

     
  2. acoste

    acoste Member

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    It does look like a software issue, which is beyond the capabilities of the technicians to debug or fix it other than updating the software.

    I would however ask them to check the suspension system for tightness and also test the power steering motor. A control system can go unstable if there is an unintended delay in the loop. Such delay can be some loose hardware (in suspension) or a slow response time of the motor for example. And again, slow response time may be the motor's fault or it receives the command delayed which would point to communication or computer issues.
     
    • Informative x 1
    • Like x 1
  3. Tam

    Tam Well-Known Member

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    Does that means there's no problem with Model X at 90MPH on Autopilot?


    Does it happen at a slower speed too? Such as 70MPH, 55MPH?
     
  4. DoubleE

    DoubleE Member

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    I've used AP at 90 before.
     
  5. ATX37

    ATX37 Member

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    It happened with my MS 75D (2019.20.4.2) at speed 75 mph or higher
     
  6. powaking

    powaking Member

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    Have you received 20.4.3? I wonder if the most recent update would help with this. I haven’t experienced this ping pong effect at high speeds but curious if it resolves your issue.
     
  7. DanCar

    DanCar Member

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    What are the details of your Model S & X? How old is the Model S?
     
  8. ShadowR55

    ShadowR55 Member

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    It doesn’t happen with the Model X

    It does happen at slower speeds but not with the same increasing effect it has o higher speeds.
     
  9. ShadowR55

    ShadowR55 Member

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    It’s on 20.4.2 my Model X just received the 20.4.3. I will update the S and see if it resolves the issue.
     
  10. ShadowR55

    ShadowR55 Member

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    2017 S and 2017 X
     
  11. ATX37

    ATX37 Member

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    2017 MS 75D HW 2.0 SW 20.4.2 (problems occurred on 20.4.1 also).
    It occurs more frequenly on Interstate highway vs state highway. I suspect that the wider lane on interstate highway aggrevates the problem.
     
  12. ucmndd

    ucmndd Active Member

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    My Dec 2016 S75 has had the same sort of ping-ponginess for several months as well, though not that bad (that said I haven't tried it at 90 to see if it gets worse with speed - I'm usually going between 75-78).

    Keep waiting for a software update to fix it. Thought it could be alignment related, but an alignment in May had no effect. Tires have less than 10k on them and are wearing evenly. Been contemplating a service visit to have it looked at but I'm out of warranty and have little desire to pay $200 for them to do nothing or tell me to wait for the next update.
     
  13. ATX37

    ATX37 Member

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    I scheduled a service from the phone on this issue but the Austin, TX SC cancelled the appointment. However they contacted me and asked for the time and place. I gave them the information. The latest reply was "this is still undergoing technical review"
     
  14. ATX37

    ATX37 Member

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    Got a text message from the SC saying that they found no problem. The SW on my MS 75D has been updated to 28.3 now but I have not done any test on this issue yet.
     
  15. ucmndd

    ucmndd Active Member

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    This behavior improved for me with 28.2. Wouldn't say it's completely gone, but it's much less jerky than it was before.
     
    • Like x 1
  16. eyedrop

    eyedrop Member

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    After owning AP1 MS for 1.5 years, I can say each software version improves one thing then "breaks" another. Overtime however, the autonomy has improved tremendously.

    I also believe it has off days due to possibly glare from the sun, or just having a bad day. Dont forget we are essentially teaching a child how to drive. Then it phones home to mommy with its LTE and gets taught a "lesson" with her updates.
     
  17. Bullpup

    Bullpup New Member

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    I have been having the same issue for the last three weeks on a 2017 AP2 MS75, coil suspension. For me it started after a tire rotation- I have re-rotated, had an alignment and balance done all to no effect. Like the OP, autosteer will depart a highway lane when engaged above 70MPH after a series of increasing amplitude turns. Below 70 it is noticeable but not as severe.

    This has been a continued issue with my car - every couple of months it will appear again. 2/4 times it was related to tire changes or rotations. It has been SC aligned many times, had the triple camera replaced, and been recalibrated multiple times.

    The tires will need replacing in another few months, so I'm tempted to do it now to eliminate a variable, but I have an upcoming appointment with the SC as well. I'm out of warranty, but have a record of this issue (without full resolution) and still have undelivered FSD capability that is obviously not compatible with the current behavior, so I'm hopeful this won't cost too much.

    Any other ideas?

    Thanks-
     
  18. ShadowR55

    ShadowR55 Member

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    Let me know how the test goes, I’m on 28.2 and I still have it but’s less noticeable. Still an issue though.
     
  19. ATX37

    ATX37 Member

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    Went out and test my car (MS75D HW2.0 SW 2019.28.3) at 80 mph on I35 and the bobbing reduced significantly but it is still there. Before my wife as a passenger got motion sickness. She did not feel the bobbing now. At least I know that it is the software, not the car.
     
  20. ATX37

    ATX37 Member

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    Here's a youtuber with the bobbing problem on 2019.28.3. I believe it is on a model X.
     

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