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Autopilot slammed on breaks in middle of highway
- Thread starter Zybd1201
- Start date
My car did the same thing a few times. It just slammed the brakes on the way back home earlier. The car stopped so hard in the 25 mph traffic it threw me forward into the seat belt. Luckily I was able to react fast enough and step on the accelerator as soon as it happened, but this time was a close call. If I get into an accident because of this, Tesla will have to be responsible. Because it happened so fast, I am not even sure if i can save the car from being rear ended if it happens again.
I notice it only happens when there's a semi truck on my right side. Maybe my sensors are messed up or maybe there's some glitch in the AP itself. Either way it is another reason to be watching the road when you're using AP.
I notice it only happens when there's a semi truck on my right side. Maybe my sensors are messed up or maybe there's some glitch in the AP itself. Either way it is another reason to be watching the road when you're using AP.
My collision alert was indeed set to "early" as well when it happened. My instinct told me I should change to medium after my car stopped on freeway. Then I saw your post. I hope this solves the issue. Regardless, the car shouldn't be doing this even when forward collision is on "early". This is a serious safety issue
That setting has no effect on braking. Mine is also set to off because of too many false positives. Alarm fatigue - Wikipedia
are you still experiencing "ghost car" and brake slamming when you set it to "off"?
sakimano
Active Member
Even with it off I've had it beep and start to take action. However, I'm used to it trying to do this so my foot is already on the throttle stopping it.
Also, there are 2 other types of rapid deceleration (not AEB). One is false radar pings, and another is misdetection of roads. This often happens when there are overpasses, tunnels, or highways parallel to side streets. The car will go from unlimited highway cruising speed to being limited to 30mph instantly, and it pretty much feels like slamming on the brakes.
I HATE this. I don't know if it's a software bug or something. It really has to be fixed. Also the ghost braking is getting ridiculous.
Autopilot also SPEEDS up when a car is stopped at a red light. Makes no sense, you'd think the car could detect the car is stopped. Many times I've had to slam on the brakes because the car would've kept going and end up crashing to the car in front.
Autopilot also SPEEDS up when a car is stopped at a red light. Makes no sense, you'd think the car could detect the car is stopped. Many times I've had to slam on the brakes because the car would've kept going and end up crashing to the car in front.
While it seems like the issue has improved over the last 6 months, TACC still gets periodic false readings causing the car to rapidly slow down for now apparent reason. On a 35 MPH surface street near our house, there's a section of the road where TACC quickly slows down - every time - the only thing I see different in that section is a short stretch of pavement where they repaired it - and the new pavement is a slight different color than the rest of the road.
It's likely the software is being overly conservative - and if it thinks there is an obstacle in the road - it's slowing down, just to be safe. And as they get more data and refine the algorithms, hopefully they'll get this fixed.
The other major problem is the many errors in the speed limit database. While this doesn't impact TACC once TACC has the speed set, it does have an impact while AutoSteer is enabled - causing the car to rapidly break if the software believes the speed limit has dropped below what AutoSteer supports - something that can surprise other vehicles that are driving at full highway speeds...
It's likely the software is being overly conservative - and if it thinks there is an obstacle in the road - it's slowing down, just to be safe. And as they get more data and refine the algorithms, hopefully they'll get this fixed.
The other major problem is the many errors in the speed limit database. While this doesn't impact TACC once TACC has the speed set, it does have an impact while AutoSteer is enabled - causing the car to rapidly break if the software believes the speed limit has dropped below what AutoSteer supports - something that can surprise other vehicles that are driving at full highway speeds...
In an effort to avoid more bad publicity i.e. the Joshua Brown death, they've made it's every-day performance objectively worse
sakimano
Active Member
My 2015 P85d is AP1 and it has hit the breaks several times with no car in front while using TACC and Autopilot. Several times it picked up cars stopped on the side of the road but it has also happened in the middle of nowhere with no cars or anything in site. This did not occur during the first two years of ownership so I assume it's a software update. I agree they are probably trying to be more safe but slamming on the breaks for no reason is dangerous if there is a car following you.
ucmndd
Well-Known Member
Mine did this today for the first time too - 2017.50.3 AP2. On the freeway, nothing around anywhere - collision alert and full hard braking out of nowhere. Scary... glad nobody was behind me.
mdk1a
Member
My biggest fear when driving is getting rear-ended, likely stemming from the fact that all but one of the accidents that I've been involved in has been exactly that. These accidents have mostly occurred not during a 25 mph stop-and-go traffic variety (which I have minimal concern about as even a very average driver should be able to brake safely in that condition), but rather slower (i.e. 45-55 mph average) highway speeds with periodic stopping. The latter tends to introduce enough opening between cars such that drivers immediately and excessively speed up that they then have a hard time braking for.
It's to the point where I'm being a bit OCD about paying attention to cars behind me. My anecdotal observation is that 80% of drivers these days simply don't know how to keep a safe distance with the car in front of you. Basically, I not only judge the braking distance in front of me, but also how likely the cars behind me will be able to similarly brake. I factor in things like how close they are behind me, what their speed is, how aggressive they've been driving, and even observable condition of their cars. If I determine that I'm at risk of being rear-ended, and I'm usually a bit conservative in my estimation due to my history, I would brake early and soft so as to "calm" the traffic behind me. (Sometimes this results in them passing me over, which is just fine with me as it's one less car I'd have to worry about from my perspective.)
The point is, there's more to braking safely than simply being able to stop your car behind the one in front of you (and even more so these days), which seems to be what AP2 is mostly concerned about based on what I've experienced using it so far. It just doesn't seem to be capable of determining the rest of equally important factors yet that requires proper judgment, so I'd say don't rely on it for that and instead use our own.
ishareit
Member
Pentium2004
Former Vendor
This type of behavior is not abnormal. I've experienced it with my MS and my F-150 with adaptive cruise. My F-150 use to do it on occasions when I would be passing a semi on the freeway. Not sure if air coming off the truck caused something to happen with the radar but it almost always happened as the nose of my truck was passing the nose of the semi. It would really scare me and anyone with me because it would go from 75mph to 30mph near instantly. It's difficult to develop a system that actively tries to avoid a collision because it's always going to encounter false positives at some point. Until cars can communicate with the cars around them I believe we will always have that issue from time to time because a lot of people are bad drivers and it's hard to account for every situation.
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