[akama]

I would guess you are correct about how they make sure your hands are on the wheel. I've done some car hacking and one of the things that surprised me was how sensitive some cars steering wheels are to pressure. It was impossible to keep it in the same position according to the car's internal electronic systems with my hands on it. This is car is 4 years old, so it's probably only gotten more sensitive.

[osteele]

I have a Tesla, that also requires hands on the wheel from time to time. I'd assumed it was capacitive. It hadn't occurred to me that it might be subtle movements, because the wheel is unresponsive until you make a purposeful movement, at which point it starts moving with your hands; and you can just rest your hands against it lightly to let it know they're there. But of course it could be sensing subtle forces, even if it switching modes only on larger forces.

Is there a test for whether it's capacitive? Like, does the fact that it works with gloves on mean it's not capacitive? (That's diagnostic for capacitive touch screens, but they're smaller and trying to detect finer motion and from just the fingers.)

[bri3d]

According to this article, Tesla's system is not capacitive : http://www.wired.com/2015/10/tesla-self-driving-over-air-upd...

One interesting thing to try, still, would be to stuff a full water bottle into the gaps in the steering wheel to emulate a hand, like so: https://www.youtube.com/watch?v=qi2oIRMwmZY

This definitely works for many capacitive systems, but I think this might also work for some of the movement-based systems, since it will add extra mass/inertia to the wheel and the water sloshing around could emulate small hand movements.