TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

How Does Autopilot Sense "Hands on Wheel"?

Discussion in 'Model S' started by Shinteetah, Aug 21, 2016.

Tags:
  1. Shinteetah

    Shinteetah Member

    Joined:
    Nov 17, 2015
    Messages:
    38
    Location:
    Indianapolis
    I'm not asking this question to get around the system. :) I'm asking because the system seems to ignore me.

    I frequently prop my arm on my knee and hold the steering wheel. This results in little weight/pressure on the wheel but I do have a full grip on it.

    When I use Autopilot -- which is a lot, I just finished a 1300 mile run -- I will keep a hand on the wheel but often propped up as described. Autopilot regularly yells at me to hold the wheel, even though I am. I've found I usually have to jig the wheel a little, wiggling the car in the lane, to turn off the warning.

    This isn't critical, but with all the Autopilot freak-out news (when I was leaving on this run my Dad told me goodbye and not to rely on Autopilot) and reports that Tesla's data showed the driver wasn't holding the wheel, it makes me worry a bit. If someone hit me, but then Tesla's data showed I wasn't holding the wheel, would I be more liable than if I were in a car without Autopilot and someone hit me? And even though I WAS holding the wheel?

    My very informal experiments MIGHT indicate that two hands on the top half of the wheel stave off the warning, but results are inconclusive. Can anyone tell me how to keep my car happy and convinced that I'm paying attention? Thanks!
     
    • Like x 1
  2. mblakele

    mblakele radial cross member

    Joined:
    Mar 7, 2016
    Messages:
    244
    Location:
    SF Bay Area
    It's a torque sensor. You have to resist the car a little, but not enough to deactivate the feature. Try a slightly firmer grip on the wheel. I had the same problem at first. Now I usually keep my hands toward the bottom of the wheel, to minimize fatigue.

    The nag message is, in my opinion, bad design: poorly worded and much too small.
     
    • Like x 2
  3. Kristoffer Helle

    Joined:
    Jan 1, 2015
    Messages:
    50
    Location:
    Norge
    It's not torque sensor. It's a position sensor. Very accurate.
     
    • Dislike x 1
  4. Skione65

    Skione65 Member

    Joined:
    May 5, 2016
    Messages:
    201
    Location:
    Kentucky
    @Kristoffer Helle,

    Can you explain in more detail? To anyone else....I believe what the OP is asking is 'where' on the wheel does the hand need to be? Also....does it need to be 'constant' pressure, or a 'touch' pressure every so often or certain amount of time to cancel out the nag. What exactly is the parameter the sensor is searching for to meet the requirements of the nag (touch, pressure, heat sensor for the hand)?

    Ski
     
  5. omarsultan

    omarsultan Active Member

    Joined:
    Jun 22, 2013
    Messages:
    1,496
    Location:
    Northern California
    I believe @mblakele is correct - the car sense torque on the steering wheel.

    ==UPDATE==

    Quick Googling found this quote:
     
    • Like x 1
  6. TaoJones

    TaoJones Beyond Driven

    Joined:
    Nov 10, 2014
    Messages:
    1,299
    Location:
    The Americas
    Pressing/squeezing the area directly adjacent the left thumb controls makes the nag go away*







    * There's a joke there somewhere...
     
    • Funny x 2
  7. msnow

    msnow Active Member

    Joined:
    Jul 14, 2015
    Messages:
    4,258
    Location:
    SoCal
    No, it's torque.
     
    • Like x 2
  8. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

    Joined:
    Mar 15, 2016
    Messages:
    418
    Location:
    My Model S
    It detects your weight on the steering wheel, i.e. torque sensor.

    1. When it gives you a warning "Hold steering wheel" just try and put a little pressure with your hands, not enough to disengage autopilot, but enough to get rid of the warning.
    2. Also, if you hold the steering very lightly (i.e. full contact, but not putting any weight), it still gives you the "Hold steering wheel" message.

    Autopilot when used properly is BETTER and SAFER than no autopilot. But it is also too easy to not use it properly and not understand it's limitations. So, I feel there is a true danger of Autopilot giving a false sense of security, and the driver may rely on autopilot without understanding it's limitations. Sadly there are plenty of idiots abusing autopilot, and I fear that they will ruin it for all of us.

    Personally speaking, unless it's a more or less straight freeway, I don't let go of the steering wheel. And when when I do, I always keep my eyes on the road. But given that I am not doing the mundane task of watching the lines ahead of me, I feel my brain has more free cycles so I have more situational awareness of the idiots around me, which keeps me safer.
     
    • Like x 2
  9. ecarfan

    ecarfan Well-Known Member

    Joined:
    Sep 21, 2013
    Messages:
    10,381
    Location:
    San Mateo, CA
    I suspect that when you do that you inadvertently apply enough torque to the steering wheel to alert the system that you are in contact with the wheel.
     
    • Like x 1
    • Funny x 1
  10. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,734
    Location:
    Smithfield, VA
    • Like x 2
  11. rscott0

    rscott0 Member

    Joined:
    Jul 26, 2016
    Messages:
    49
    Location:
    Massachusetts
    OK, we've got people who insist it is positioning (e.g. a slight movement of the steering wheel by your hand, the same thing that it detects to know to move the wheels when AP is not used), torque (very similar I believe, seeing how fast the steering wheel is turned), and pressure sensors (your hand is physically pushing slightly on the wheel, such as a tight grip, even if the wheel isn't turning).

    This could be tested by [1] holding tightly on the wheel but not turning it, and [2] not even touching the wheel, but occasionally turning it (preferably in a place where no sensor would likely be). It might take some time to figure it out, though.
     
  12. msnow

    msnow Active Member

    Joined:
    Jul 14, 2015
    Messages:
    4,258
    Location:
    SoCal
    There's no dispute here. Everyone except one post says its torque. What's the issue?
     
    • Like x 2
  13. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,399
    Location:
    San Diego
    I make the nag go away and/or never get the nag by periodically jiggling the steering wheel a bit. I jiggle left and then right against the resistance of the AP controlled steering wheel and then let it fall back into neutral. It doesn't move the car (much), but it is enough to tell the car I'm here. Gripping the steering wheel doesn't do it for me, I have to move it slightly.

    If you do this every few minutes, you'll never get a visual nag, let alone an audio one.
     
    • Like x 1
  14. mikeash

    mikeash Active Member

    Joined:
    Oct 26, 2014
    Messages:
    1,107
    Location:
    Fairfax, VA, USA
    If the car is alerting when you have a hand on the wheel, try adjusting your position a bit so that the weight of your hand pulls the wheel a bit. Rather than holding the bottom, hold the side, for example. This will apply some constant torque and make sure the car knows you're there.
     
  15. ohmman

    ohmman Maximum Plaid Member

    Joined:
    Feb 13, 2014
    Messages:
    4,848
    Location:
    North Bay, CA
    This is what I do as well. Leaving my hand on the side isn't enough, I guess I "follow" the wheel movement enough that it doesn't detect me. Mine nags me all the time, despite having my hands on the wheel all the time. So I have to do this jiggle dance to make sure it knows I'm around.
     
    • Like x 1
  16. ecarfan

    ecarfan Well-Known Member

    Joined:
    Sep 21, 2013
    Messages:
    10,381
    Location:
    San Mateo, CA
    Yes those are the same thing. And torque is the force applied to the wheel that causes the wheel to rotate.
     
    • Like x 1
  17. Max*

    Max* Autopilot != Autonomous

    Joined:
    Apr 8, 2015
    Messages:
    4,883
    Location:
    NoVa
    So now that we all agree that it's a torque sensor.

    I keep my left elbow on the arm rest, and my left hands fingers rest lightly/not-really-grip the area with the volume controls. That weight is enough for the torque sensor to never give me a keep-hands-on-wheel message.
     
    • Helpful x 1
    • Like x 1
  18. Zybd1201

    Zybd1201 Member

    Joined:
    May 30, 2016
    Messages:
    229
    Location:
    California
    I only agree with us saying that autopilot is "better and safer" than no autopilot if we include the caveat that autopilot does some crazy dangerous things that you as the human have to react to immediately or risk harming yourself and others.

    To me, better and safer, requires that it be something which at minimum does not do harm. I think I am experiencing in my first few thousand miles on autopilot what the news stories are showing. Autopilot can be very dangerous and even when used properly as an aid the only reason it is not dangerous is because of human intervention.

    I want it to be better. I do. It just isn't. I think you agree but I just would argue with the "better and safer" comment.
     
  19. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

    Joined:
    Mar 15, 2016
    Messages:
    418
    Location:
    My Model S
    ^^ I agree, Auto-steering especially can unexpectedly do some really crazy things, and there is a real danger of the driver getting desensitized into a false sense of security. At 65mph, milliseconds matter. Auto-steering is just not safe enough at the moment, to allow it unsupervised for more than a few milliseconds, which sort of defeats a great portion of the purpose.
     
    • Like x 1
  20. RDoc

    RDoc S85D

    Joined:
    Aug 24, 2012
    Messages:
    1,569
    Location:
    Boston North Shore
    I just grip the wheel comfortably at the bottom, next to the spoke and let the wheel move my hand. I never get a nag.

    However, there have been several occasions when the car has done something crazed, e.g. steering towards a truck in the lane to the right, when the movement of the wheel instantly alerted me and I pretty much instinctively twisted the wheel, both correcting the car and disabling autopilot.

    IMHO, it is dangerous and irresponsible to not have a hand on the wheel. I also don't see what the point is.
     

Share This Page