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Tesla Black Box Data Collection - Hands on Wheel

I'm aware that Tesla collects data on whether or not Auto-Pilot is engaged during accidents, but this article suggests that they also collect data on whether the driver even has his/her hands on the wheel. It's not clear from the article whether that information is collected from wheel motion (tiny movements left or right), a resistive connection (sensors in the wheel), or capacitive connection (just making a tactile-electrical connection to the wheel).

Black Box Reveals Cause of 60 MPH Tesla Autopilot Crash

Does anyone know the answer?

In any case, it seems likely that many of these "auto-pilot" accidents eventually will be deemed to be from drivers neglecting to maintain contact with the wheel (e.g. the driver is at fault). I suppose a small fraction of cases could emerge where a driver is paying 100% attention with their eyes but has his/her hands off the wheel for a moment and gets falsely blamed, but it seems like a good thing on a population basis, as people may feel less likely to be able to "get away" with blaming the car.
With your hands firmly on the wheel, the car still won't know it if there's no need for steering adjustments for whatever reason (road and wind are just right). When Tesla says things like "they were warned to put their hands on the wheel six times," I believe they are being intentionally vague. More specifically, they at least sometimes do not mention how far apart those warnings were, how long it was after the last one and prior to the accident, or whether or not there was just a card (hands could easily have been on the wheel), white around the screen (more likely no hands on the wheel and some inattentiveness, at least to IC), or audible warnings (almost certainly no hands on the wheel and definitely significant inattentiveness to IC). To be clear, I've read of the audible warning, but never heard it (I've heard forward collision warning sounds and "take over immediately" sounds when autopilot wasn't even engaged, but never missed the hands on wheel warning long enough to get sound due to it).
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The hands on wheel sensor is a torque sensor from steering wheel motion. You can have your hand lightly on the wheel and the car won't know it.


So in the case above, the driver could plausibly claim she had both hands on the wheel while auto-pilot was engaged, as is advised by Tesla, but they were not bouncing around at 10&2, but rather, her thumb and forefinger at 5&7 were providing insufficient torque to register. But of course, that only stands up until plaintiff's counsel points out that the tweet of her lunch pic was sent 3 seconds before the crash!
"On more than a dozen occasions, the car is said to have registered a total absence of hands on its wheel, and twice for periods exceeding a minute in length. She then allegedly only placed her hands back on the wheel after being cued to do so by the automobile, both times removing them again after the alert went away."

I found the explanation of the events leading to the collision, and the claim of the cars' ability to sense hands-on-wheel to be completely misleading. As far as I'm aware, there is no hand sensor. Hands on the steering wheel requires a very light touch so as to not inadvertently deactivate AP. If this is accurate, this kind of misleading information is going to come back to bite Tesla.
My message yesterday got swallowed, but essentially what 5thgear said. There's a few stretches of road on my way into work where I need to actively jiggle the steering wheel to prevent it from warning or to satisfy it if it's already done so. Right near the end of the trip, there's a long, flat, well-maintained stretch near a school where quite often it scolds me and bans me for the rest of the trip.

Given my seating position (high-up, with the wheel low), I often don't even notice the flashing border since the wheel occludes the upper frame of the screen and in that particular stretch of the road I'm focused on what's going on around the street (kids crossing, cars stopping or not), not inside the car. (And, of course, then there are the occasional bugs where the car doesn't play *any* sound, including warning chimes!)

I've recently found myself using autosteering less because I find the chimes (among other aspects of the system) so annoying, which makes Tesla/Elon's claims that such-and-such wouldn't have happened were some car in autopilot feel overly sanctimonious (but that's a rant for a different thread).
I have been driving using EAP quite a bit over the past year. I have found it very easy to place one hand on the wheel (right or left) at a comfortable position that keeps EAP happy. You don't need a light touch, just use a position that puts less torque on the wheel. Something like 4-5 o'clock works fine.

Using 2 hands is different since you are normally applying equal torque in both directions which amounts to 0 torque on the wheel. In that case you will have to jiggle it a bit at times.

In the case of the driver in Utah, it would be difficult for her to claim she had 2 hands on the wheel when she admitted she was using her cell phone to find a better route. Unless she has 4 hands, this would be very difficult.


Trifecta: Solar and both cars are EVs
Mar 26, 2012
Scottsdale, AZ
I drove yesterday for 100+ miles with both hands on the wheel on a curvy road and the AP only turned off one time when I felt it to be a little close to a Semi. No warnings from AP that I didn't have my hands on the wheel.

I must admit that on long stretches of straight road, I will still get some blinking border warnings. Never heard AP audible warnings.


Jul 27, 2012
"I found the explanation of the events leading to the collision, and the claim of the cars' ability to sense hands-on-wheel to be completely misleading."
Agreed...Tesla appears to be spinning the facts to protect themselves. Autopilot does not know whether hands are on or off the wheel. Periodically, the wheel will sense whether there is tension on it, presumably due to the driver's hands on the wheel. However, we all know that you can have your hands firmly on the wheel and sometimes the sensors don't detect it. Further, and more frustrating, when your hands are on the wheel, the tension is often too much and then the Autopilot automatically kicks out of self-steering mode. So, when Tesla says that the driver in the crash repeated turned Autopilot on and off, that would actually indicate to me that her hands were on the wheel for much of the drive, and the Autopilot wasn't staying engaged because of that. I'm not saying she was paying attention when she crashed, but I just feel that in all these incidents the Tesla version of the facts is designed to protect Tesla.
Here's a second, independent statement suggesting that your Tesla does in fact collect and save data on subtle touches of the steering wheel (i.e. touches which would not turn off AP's warning, but are enough to prove you're touching the wheel).

Police in Utah said data from Tesla showed that the driver enabled Autopilot about 1 minute and 22 seconds before the crash. The report said she took her hands off the steering wheel “within two seconds” of engaging the system and then did not touch the steering wheel for the next 80 seconds, until the crash happened.

Seems likely that the driver was either/both over-trusting of the system or just not paying attention. An important takeaway for us is that it's advisable to keep a hand on the wheel if you're planning to get in an accident.

I'd sure like to understand how this system works. I keep at least one hand on the wheel all the time. But I routinely get the visual "place hands on wheel" alert. A light jolt of the wheel removes the alert. But is the wheel actually sensing my hands on the wheel beyond just the torque sensor? If it does, then why the alert? And if not, then how could Tesla and the other reports suggest that the driver's hand is or isn't on the wheel down to a two-second interval?
You're asking the right questions. We don't believe there is a pressure sensor (i.e. grip). We do know there is a torque sensor (i.e. turning). It may be that you're touching the wheel too lightly to trigger the sensor which turns off the warning alert, so you're gettign the alerts despite "touching" the wheel. I have noticed that the warning doesn't appear at regular intervals, so I suspect there's a very light torque at which the car presumes human involvement, but with super-light torque (which is easy to accomplish by more or less letting the wheel slide through your lightly touching fingertips) is not enough to forestall the warning. I would say it's the best that can be achieved given the limitations of the inputs. This also would explain how Tesla is able to say "the driver wasn't touching the wheel".

This all being said, I find AP largely useless if I have a firm grip on the wheel. All it takes is a slight difference of opinion between me and the car as to whether we should turn just-a-little-bit-more around a bend and the AP disconnects. It's definitely useless on a windy road, even at slower speeds. I wonder if people find a safe balance by letting the car do the driving and just keeping the wheel sliding below their fingertips? That would create a legal issue if Tesla said "driver was not touching" while driver was, in fact, in contact with the wheel, but it also seems far less likely that you'll crash if your fingers are touching the wheel instead of playing Fortnite.
I wonder if people find a safe balance by letting the car do the driving and just keeping the wheel sliding below their fingertips? That would create a legal issue if Tesla said "driver was not touching" while driver was, in fact, in contact with the wheel, but it also seems far less likely that you'll crash if your fingers are touching the wheel instead of playing Fortnite.

This is what I do most of the time with AP on. Often I hold the wheel as if I had just made a big turn, and were letting the wheel reset to neutral; sometimes I have a slightly tighter grip, but still nothing that trips the torque sensor (essentially the same as I would have *without* AP, in low speed, smooth, and straight roads; something that moves with a little bit of play in the wheel, but gives me time to catch any sudden jolts).
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Active Member
Supporting Member
These sort of threads are the ones that make me think eventually we'll want a non-repudiable approach to storing driving logs that could be used to show liability to one or other party. As much as I do trust Tesla to do the right thing in these cases (many don't), it still is a one-party-controls-all-data-and-can-say-whatever.
With the right architecture for logs people wouldn't have to trust. Tesla's and owner's confidential drive info could be maintained as such until consent to use for audit/legal purposes.
This is one of those cases where a blockchain-like approach can be well suited to the problem.

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