Phantom braking description

[Robocop]

Planning on getting a Tesla next year. I think I can wrap my head around the autopilot limitations, but I often see phantom braking mentioned. This is the only thing that gives me anxiety, but I don't' know exactly what it is like. Can anyone provide a pretty detailed explanation of scenarios where it occurs, what it feels like, has it caused damage, etc?

Looking to get a Y, but I imagine the phantom braking happens equally across models with the new hardware?

 

[TresLA]

Yes, it happens across all models, but it would seem most (including myself) don’t see phantom braking as that big a deal once you learn the potential situations it can happen. You eventually get pretty quick at reacting on the accelerator pedal to compensate for any phantom braking. YMMV of course, but I’d guess I experience it maybe once every few weeks (not often). Shadows (sun up, sun down, overpasses, etc.) seem to be the problem spots, but it’s only some of them in certain situations.

 

[LowlyOilBurner]

Some crests of hills on rural roads cause it, some are worse than others.

 

[Tiger]

All cars with TACC do phantom breaking, the only difference is that Teslas might do it in more unsuspecting situatons, as they "see things". However, I would expect the phantoms to reduce significantly with the new 3-4D processing algo.

https://twitter.com/elonmusk/status/1294724702967984128

 

[jerry33]

There is far less phantom braking with the latest release. I've had it happen two or three times in the last 9K road trip miles. (2020 X LR+). It's not something I worry about.

 

[webbah]

In my case it happens primarily with entry and exits to tunnels on the highway (autoroute) here in Europe. Easy to plan for as I just feather my foot on the accelerator to be ready in case it triggers and a car is behind me. That said, it is getting better with each release.

 

[serendipitous]

There are a few things that get lumped into "Phantom Braking":

1) When operating in TACC or TACC+Autosteer (Autopilot), the car panics and slows down fairly rapidly out of a belief that there's an obstacle ahead. This appears to be due to overly sensitive code, likely in response to the crash into a semi across the highway a few years ago - difficult to differentiate when it's just a broad flat obstacle, not well detected by radar. It often happens near overpasses or under road signs where a combination of shadows and the horizon causes enough uncertainty in the AP neural net to decide if there's something real there. In my experience, this is very specific, so some people get it frequently in a certain spot on their daily commute, and others rarely see it. I have only had this happen maybe 8-10 times in 18k miles but it is definitely real. You can touch the gas and speed back up normally. Recently, the car gets "nervous" after this happens and refuses to return to your set speed for some time - not sure if that's intentional or a bug but it'll hum along at 50MPH even though it's set to 75 and there's nothing around you. You can disengage and re-engage to get it back to normal.

2) When operating in TACC or TACC+Autosteer, the car decides that speed limit is lower, and so the cruise set speed drops suddenly and the car slows down for seemingly no reason. This should get better as they build up their database with real, visually spotted speed limit signs rather than the fairly hit-or-miss database they used to use. You can tell when this happens because your TACC set speed changes. There are a few stretches of road where this happens consistently for me and it's annoying, although I'm pretty sure it got better in the last few releases.

3) Regardless of TACC, the car detects an imminent collision and triggers Automatic Emergency Braking. This is violent, maximum deceleration with full brakes. It will come to a complete stop unless you really try hard to override it. I've had this happen once or twice on city streets when it thinks a pedestrian is about to walk into the street for example.

 

[sbhawkins]

I have a 2017 Model S - phantom braking began occurring with a software release 2 or 3 back (sorry, don’t know the version number). Never occurred prior to that time. Som since it began it has occurred once or twice a week. The first time it happened, was very frightening - very. And as noted above, it takes some effort to overcome the programmed response. My experience is it seems to happen on the freeway when approaching a curve. I think - but this is pure speculation - that one of the sensors “sees” the short concrete highway divider and mistakes it for an object in the road - which it would be if the road didn’t curve. Fortunately, when it has happened to me no one has been close behind me. If they ever are, the likelihood of being rear-ended is high.