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AP/phantom braking.

so since ownership two instances that have made me weary of AP.

for perspective, whenever i use AP i am more alert/aware than when i’m driving myself.

1. driving on the the freeway in the lane next to the carpool lane. early in the morning (5AM) so scant traffic. going 80 with AP engaged. there is a semi truck two lanes over to the right ahead of me, no one in the lane directly over to the right of me. semi signals to get into the lane next to me — it is going slower so i’m slowly catching up to it. when it starts to get into the lane i am coming up to pass it. since i am traveling faster i approach the semi so the right front corner of my car is almost in line with the left rear corner of his trailer. all of a sudden AP thought it was going to hit me (which it clearly wasn’t) and swerved over to the left (thankfully no one in the carpool lane). going 80 during that was unnerving.

i can’t remember if this maneuver put me in the carpool lane or not.

2. today on the freeway going 70 with AP with a normal amount of surrounding traffic and everyone going a predictable speed. all of a sudden the car breaks for no reason, slows down about 10mph suddenly and i took over right away. thankfully the car behind me was not following close.

i am now afraid to just use AP all the time and will only use it in certain circumstances. just glad my senses have always been heightened when it is engaged.
 
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so since ownership two instances that have made me weary of AP.

for perspective, whenever i use AP i am more alert/aware than when i’m driving myself.

1. driving on the the freeway in the lane next to the carpool lane. early in the morning (5AM) so scant traffic. going 80 with AP engaged. there is a semi truck two lanes over to the right ahead of me, no one in the lane directly over to the right of me. semi signals to get into the lane next to me — it is going slower so i’m slowly catching up to it. when it starts to get into the lane i am coming up to pass it. since i am traveling faster i approach the semi so the right front corner of my car is almost in line with the left rear corner of his trailer. all of a sudden AP thought it was going to hit me (which it clearly wasn’t) and swerved over to the left (thankfully no one in the carpool lane). going 80 during that was unnerving.

i can’t remember if this maneuver put me in the carpool lane or not.

2. today on the freeway going 70 with AP with a normal amount of surrounding traffic and everyone going a predictable speed. all of a sudden the car breaks for no reason, slows down about 10mph suddenly and i took over right away. thankfully the car behind me was not following close.

i am now afraid to just use AP all the time and will only use it in certain circumstances. just glad my senses have always been heightened when it is engaged.
welcome to Tesla cruise control. If it helps, you're not the only one with these issues - they are well-known and abundant.

Just to play devil's advocate, if you take the view that TACC was watching all the traffic and proactively moving your car out of the way so the semi wouldn't merge into you, it should also have been watching the carpool lane to know there was no traffic and it was safe to use as an 'escape route.' Of course, it should also have been monitoring the lateral rate of movement of the truck to know it was slowing down and wouldn't enter your lane.

The apologists will say TACC is only for use on highways, but here we have another example of it failing at that. Cars merging on an highway is not an uncommon occurrence and something any system designed for highway use should be able to handle.
 
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CharleyBC

Active Member
Jun 28, 2019
1,535
1,770
Talent, OR
We drove from the Bay Area to Salt Lake City two days ago almost entirely on Interstate 80. There are long stretches of very straight freeway in Nevada and Utah. We were plagued by phantom stuff.

There were many instances of phantom braking. (I think someone also called this “whimsical slowing“.) Sometimes just a tiny twitch in speed, and right back again. But many was a sudden dumping of 10 or 15 mph before we could intervene. And there was no reason we could imagine. Not passing. No traffic ahead for a very long distance. No overpass making scary shadows. Nothing. Clear straight highway. I should mention we have 2021.44.30.21 FSD beta. Curiously, there’s a thread in the Model Y forum about how this same release has eliminated the poster’s phantom braking. Sometimes this was happening frequently enough that whoever was driving would get disgusted and switch to manual. That’s a lousy solution, of course. It’s so nice to have Autopilot do much of the work so you arrive less tired.

In my opening paragraph I said “phantom stuff“. There was another phantom behavior, and I wonder whether they both have the same root cause. Cruising along a nice straight stretch with no traffic anywhere near ahead, like half a mile or more. And it’d say “changing to faster lane”. And it would. A few seconds later it would get embarrassed and say, “changing out of passing lane”. I’ll dub this behavior phantom lane change. So what occurs to me is that both phantom braking and phantom lane change could be explained by the car perceiving a phantom car ahead. The phantom car is either very close, necessitating jamming the brakes, or not quite such a threat, motivating a pass.

Thoughts? Experience?
 
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We drove from the Bay Area to Salt Lake City two days ago almost entirely on Interstate 80. There are long stretches of very straight freeway in Nevada and Utah. We were plagued by phantom stuff.

There were many instances of phantom braking. (I think someone also called this “whimsical slowing“.) Sometimes just a tiny twitch in speed, and right back again. But many was a sudden dumping of 10 or 15 mph before we could intervene. And there was no reason we could imagine. Not passing. No traffic ahead for a very long distance. No overpass making scary shadows. Nothing. Clear straight highway. I should mention we have 2021.44.30.21 FSD beta. Curiously, there’s a thread in the Model Y forum about how this same release has eliminated the poster’s phantom braking. Sometimes this was happening frequently enough that whoever was driving would get disgusted and switch to manual. That’s a lousy solution, of course. It’s so nice to have Autopilot do much of the work so you arrive less tired.

In my opening paragraph I said “phantom stuff“. There was another phantom behavior, and I wonder whether they both have the same root cause. Cruising along a nice straight stretch with no traffic anywhere near ahead, like half a mile or more. And it’d say “changing to faster lane”. And it would. A few seconds later it would get embarrassed and say, “changing out of passing lane”. I’ll dub this behavior phantom lane change. So what occurs to me is that both phantom braking and phantom lane change could be explained by the car perceiving a phantom car ahead. The phantom car is either very close, necessitating jamming the brakes, or not quite such a threat, motivating a pass.

Thoughts? Experience?
you know how Wonder Woman had her invisible jet? Well, batman has an Invisible car now and you just found it!
 
We just got our 3rd Tesla last week - all 3 are 3's. Previous were yrs 2018-19. Picked it up last week. Turned on AP not knowing the drastic change in AP Holy cow. Totally unacceptable. I had probably 4 serious braking scenarios one almost getting me rear ended in the first 100 miles. Most were when other cars were coming head on in the other lane with them being semis or trucks.

What the heck. How is this ok? I tried turning on cruise control and just drive and hit the same thing. How we went from our first two being perfectly drivable with AP on this highway to outright dangerous to use even cruise control is mind boggling. Who approved this? Do they not test this? I had a base Nissan truck that had cruise control with traffic pacing and it never once had an issue. They went from cutting edge to worse than a 20 yr old Honda.
 

CharleyBC

Active Member
Jun 28, 2019
1,535
1,770
Talent, OR
We just got our 3rd Tesla last week - all 3 are 3's. Previous were yrs 2018-19. Picked it up last week. Turned on AP not knowing the drastic change in AP Holy cow. Totally unacceptable. I had probably 4 serious braking scenarios one almost getting me rear ended in the first 100 miles. Most were when other cars were coming head on in the other lane with them being semis or trucks.

What the heck. How is this ok? I tried turning on cruise control and just drive and hit the same thing. How we went from our first two being perfectly drivable with AP on this highway to outright dangerous to use even cruise control is mind boggling. Who approved this? Do they not test this? I had a base Nissan truck that had cruise control with traffic pacing and it never once had an issue. They went from cutting edge to worse than a 20 yr old Honda.
Are all three of your cars on the same software release? Just the new one is misbehaving? Hmmmm…
 
Are all three of your cars on the same software release? Just the new one is misbehaving? Hmmmm…
The previous two were radar based from the info I am reading. The 2022 uses vision only? Did they disable radar on the older ones in the latest software updates? I was told that's only if you have FSD beta. But yes it's only the new one. And sounds like I'm not the only one.
 
We just got our 3rd Tesla last week - all 3 are 3's. Previous were yrs 2018-19. Picked it up last week. Turned on AP not knowing the drastic change in AP Holy cow. Totally unacceptable. I had probably 4 serious braking scenarios one almost getting me rear ended in the first 100 miles. Most were when other cars were coming head on in the other lane with them being semis or trucks.

What the heck. How is this ok? I tried turning on cruise control and just drive and hit the same thing. How we went from our first two being perfectly drivable with AP on this highway to outright dangerous to use even cruise control is mind boggling. Who approved this? Do they not test this? I had a base Nissan truck that had cruise control with traffic pacing and it never once had an issue. They went from cutting edge to worse than a 20 yr old Honda.
Got my new 2022 M3 in December after driving a 2018 M3 for 2 1/2 years and am feeling the same stunned disbelief that this stuff is happening on a new vehicle. Reported it via a service request in the Tesla app and got a lengthy bunch of boilerplate that concluded with basically a sorry, nothing we can do but we promise it will get better, uh, someday. Not one to ever join in to a gripe-fest but I do agree 100% that is just not acceptable and hope that if there’s enough noise about it on the forums, that maybe a hardware fix (which I guess would mean a lidar retro-fit which I know is unlikely to happen) could be offered. At the very least to those of us early-ish adopters who *know* this a completely unnecessary safety hazard.
 
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I should mention we have 2021.44.30.21 FSD beta. Curiously, there’s a thread in the Model Y forum about how this same release has eliminated the poster’s phantom braking.
LOL, that was probably me. 30.21 did fix the only location where I was getting PB every time. And since I installed it, no new PB was encountered anywhere in my limited driving range (within a 200-mile radius of where I live). Even with the same release everyone's experience will be different I guess.
 
Since Tesla turned off my radar I've had way more phantom braking events. No matter what Elon says, vision only isn't working to fix the issue. Just today I had 4 phantom braking events. One was very abrupt and happened as I was trying to pass a truck carrying a load of new Tesla's.
Are you sure your car wasn’t just stopping to chat with its cousins?
 
I just took delivery on my Model 3 LR yesterday. I was aware of the phantom braking reports, but got to see it first hand on my drive home from the dealership. I was in the far left lane (which was a carpool lane). I was travelling approximately 110km/h (65mph) when the car suddenly braked hard. There were no vehicles in front of me and thankfully the one behind me was able to avoid rear-ending me. The only possible explanation I could come with as to why the car felt the sudden need to brake was the following:

A vehicle 2 lanes to the right of me made a lane change into the lane immediately to the right of me. It did not get anywhere close to my lane and there is even an added buffer zone between my lane and the one to my immediate right (car pool buffer zone). I like had about 15 feet to my right that was clear of any traffic.

It was a very unsafe situation and makes me very leery of the purchase I just made. My previous 4 vehicles all had dynamic cruise control and I never encountered a situation like this in any of them. I know the immediate fix is to not use AP, but that was one of the reasons I bought this car. It's not acceptable.
 
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It was a very unsafe situation and makes me very leery of the purchase I just made. My previous 4 vehicles all had dynamic cruise control and I never encountered a situation like this in any of them. I know the immediate fix is to not use AP, but that was one of the reasons I bought this car. It's not acceptable.
Sorry to hear you experienced it so quickly. It has been a constant source of disappointment since I bought my MY last summer.

However, there is reason for hope (finally!)

Several anecdotal reports of significant improvements to TACC/AP behavior in the 2022.4.5.17 update.
 
Sorry to hear you experienced it so quickly. It has been a constant source of disappointment since I bought my MY last summer.

However, there is reason for hope (finally!)

Several anecdotal reports of significant improvements to TACC/AP behavior in the 2022.4.5.17 update.
I'm doing an experiment now - I've disabled Autosteer, Navigate on Autopilot, FSD Beta, Traffic light and Stop Sign Control, Obstacle-Aware Acceleration and Automatic Emergency Braking. I'm trying to drive exclusively like this for a while and then will selectively add back features to see how it affects phantom braking.

I'm still early on and haven't driven on a ton of roads that would be a good test but it seems to have helped. My suspicion is that phantom braking is primarily an overly sensitive AEB system, but we'll see.
 
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We just got our 3rd Tesla last week - all 3 are 3's. Previous were yrs 2018-19. Picked it up last week. Turned on AP not knowing the drastic change in AP Holy cow. Totally unacceptable. I had probably 4 serious braking scenarios one almost getting me rear ended in the first 100 miles. Most were when other cars were coming head on in the other lane with them being semis or trucks.

What the heck. How is this ok? I tried turning on cruise control and just drive and hit the same thing. How we went from our first two being perfectly drivable with AP on this highway to outright dangerous to use even cruise control is mind boggling. Who approved this? Do they not test this? I had a base Nissan truck that had cruise control with traffic pacing and it never once had an issue. They went from cutting edge to worse than a 20 yr old Honda.
same here man. I had Model3 before and recently got the latest Model3 last week and had so many weird and dangerous braking during AP.
At 2-lane highways, every single time when semis or even big trucks on the opposite lane it brakes so hard.
 
I'm doing an experiment now - I've disabled Autosteer, Navigate on Autopilot, FSD Beta, Traffic light and Stop Sign Control, Obstacle-Aware Acceleration and Automatic Emergency Braking. I'm trying to drive exclusively like this for a while and then will selectively add back features to see how it affects phantom braking.

I'm still early on and haven't driven on a ton of roads that would be a good test but it seems to have helped. My suspicion is that phantom braking is primarily an overly sensitive AEB system, but we'll see.
Not criticizing your method here but have you ever actually experienced an AEB engagement? It is 100% full anti-skid braking - a significant emotional event if you're not expecting it. You instantly perceive way more than full regen, seat-belts lock, and anything unsecured goes flying, even from slow speeds.

There is also warning that displays "Emergency Braking in Progress" if that logic is being employed.

My thought is that it doesn't "partially" engage AEB, causing phantom events. It is either AEB or it isn't. Still interested to hear how your experiment goes.
 
Not criticizing your method here but have you ever actually experienced an AEB engagement? It is 100% full anti-skid braking - a significant emotional event if you're not expecting it. You instantly perceive way more than full regen, seat-belts lock, and anything unsecured goes flying, even from slow speeds.

There is also warning that displays "Emergency Braking in Progress" if that logic is being employed.

My thought is that it doesn't "partially" engage AEB, causing phantom events. It is either AEB or it isn't. Still interested to hear how your experiment goes.
I've had AEB engage a couple times - klaxons sounding, red steering wheel on the screen, full brakes. I've had other times where the alarm blares and it brakes but no red steering wheel, then I've had plenty of other times where it just brakes/slows for no apparent reason.

My thought was that it may be that there was some interaction between the AEB system and TACC. I can't rule that out, but I still experienced significant slowdowns/phantom braking with everything disabled, so if there is an interaction it doesn't explain everything.
 

CharleyBC

Active Member
Jun 28, 2019
1,535
1,770
Talent, OR
I developed a hypothesis about phantom braking as well as what I dubbed phantom lane change, where the car says, "changing to faster lane", when there's nothing close ahead. My thought is that if it sees a phantom ahead, and thinks it's going just a little slower than we are, then it changes lanes. And if it sees a phantom that is scarier, it jams on the brakes. Either way, I think it's seeing something that's not there. Sort of a "duh" so far.

Here's what I noticed toward the end of our long drive home from Salt Lake City a couple weeks ago. The freeway was straight as an arrow in the left-to-right sense, but had some gentle undulations. The result was that a car that was far ahead (maybe a quarter mile?) disappeared from view down a dip. As we and the other car moved over the terrain, the other car emerged back into view. Phantom braking occurred instantly. But there was no reason--the other car was much too far ahead to be any immediate threat to safety. So I thought, interesting, maybe anytime it first sees something ahead that it hasn't been seeing, it worries. Then with better evaluation of the situation, it figures out how far the other car is, and resumes the set speed. Meanwhile sleeping passengers awaken in abject fear.

So I tested my hypothesis. Sure enough, next time we were following a car at long distance, and it disappeared down a dip and then reappeared, we had a PB event. Alas, this didn't dawn on me until near the end of the freeway portion of our trip, so I have a shortage of data points. But I think it makes some sense.

And I blame (at least partly) Tesla removing radar from the mix. We had some PB back when the radar was in use, but it was usually the scary overpass syndrome, or something like that. Never on clear, straight freeway. Now with the radar shut off, we have this new phantom formula. And we had it a lot on our trip from OR to UT and back.

Tesla says humans do it with just vision, so cars can too. Well, yeah. Except we humans use binocular vision and parallax to judge distance, as well as other clues. As far as I know, with three forward-facing cameras of different focal lengths, Tesla isn't doing parallax computations.

Can I please have my radar back?
 

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