Phantom Braking

[LastGas]

You don't likely live in an area where 2 lane non-divided highways are the only available roads.
I am learning that purchasing my model Y was a mistake as it lacks a usable cruise control on 2 lane highways with on coming traffic. I have had my model Y for 2 weeks.

...

Right now I am leaning toward selling the car once I get the title in the mail. I otherwise love the car, but I paid a lot for a car that is lacking such a basic feature that has been commonplace since the 1980s.

I live in a semi-rural area where all the connecting roads are 2-lane highways too. I get what you're saying.

My perspective is a little longer, since I drove the former Autopilot Convenience Feature on a HW1 Model S, Enhanced Autopilot with the NVIDIA HW 2.5 computer on a 2018 Model 3, EAP on HW 3 with radar and now the FSD Beta on vision only.

What I can say is that phantom braking is not an inherent flaw in the product, but rather a software version related one; that is, not all versions of HW 3 Autopilot/FSD have the problem, and not all have it to the same degree. I don't know why phantom braking occurs, but I know that it hasn't been a problem in some firmware releases. It gets better and it gets worse. Now it's worse.

I'm just saying that it is very unlikely that you're stuck with the problem over the long term.

And I would remind you that if you had a car with 1980's cruise control, you wouldn't have phantom braking, or real braking either. That old car would just run into the back of slower traffic without hesitation.

 

[Goose66]

And based on the way many people describe their "phantom braking", this is my personal take on what is happening.

Then you are just not trying to understand what (many, many) people are posting. Phantom braking has NOTHING to do with changes in the detected speed limit. Traveling down the highway in bright sunlight with no other cars around and pass under an overpass and the car sheds 10 mph in .5 sec. No speed limit change there. Just braking for no reason. Driving on a curvy road with double-yellow line and an unchanging 35 mph speed limit for miles, and the car will brake and accelerate and brake and accelerate several times per mile for absolutely no reason other than the object recognition neural network is seeing and then losing something that was never there in the first place. In my experience it's worse in bright sunlight with harsh shadows then at other times, but others have posted that doesn't seem to make a difference. Regardless, it has nothing to do with speed limit changes.

 

[AndreP]

Maybe we can pressure the regulators, municipalities, etc to add speed limit changes wherever phantom braking problems are flagged so it seems more like the vehicles complying rather than generating false positives

 

[Bouba]

Maybe we can pressure the regulators, municipalities, etc to add speed limit changes wherever phantom braking problems are flagged so it seems more like the vehicles complying rather than generating false positives

Perhaps instead we just need to get our message out to the public...so next time any driver on the road sees a Tesla suddenly slow down they think, it must be the correct speed because the Tesla slowed down

 

[SalisburySam]

What I can say is that phantom braking is not an inherent flaw in the product, but rather a software version related one; that is, not all versions of HW 3 Autopilot/FSD have the problem, and not all have it to the same degree. I don't know why phantom braking occurs, but I know that it hasn't been a problem in some firmware releases. It gets better and it gets worse. Now it's worse.

I'm just saying that it is very unlikely that you're stuck with the problem over the long term.

Maybe, maybe not. For some of us phantom braking has already been long term…almost four years for me since I got the car. We can quibble about definitions, but for me, that’s long term. Worse, I’ve seen nothing to indicate it will be going away quickly if at all. Like you I don’t know why it occurs but it does.

And I would remind you that if you had a car with 1980's cruise control, you wouldn't have phantom braking, or real braking either. That old car would just run into the back of slower traffic without hesitation.

…and after my TACC experiences I’d love that, the first part anyway. Incredibly I know, I was able to use dumb cruise control since my first car had it in 1968 and did so without running into the back of anything. It was dependable and I knew all it did was keep a set speed allowing my foot to rest on trips. My role was the “traffic awareness” part. Oh yeah, and after disengaging for whatever reason I could easily resume my set speed. Now, I have to hover over the go pedal just waiting for TACC to have an infarction, or not use it. Mostly, I don’t, and not at all with passengers/pets.

 

[JustJohn]

Then you are just not trying to understand what (many, many) people are posting. Phantom braking has NOTHING to do with changes in the detected speed limit. Traveling down the highway in bright sunlight with no other cars around and pass under an overpass and the car sheds 10 mph in .5 sec. No speed limit change there. Just braking for no reason. Driving on a curvy road with double-yellow line and an unchanging 35 mph speed limit for miles, and the car will brake and accelerate and brake and accelerate several times per mile for absolutely no reason other than the object recognition neural network is seeing and then losing something that was never there in the first place. In my experience it's worse in bright sunlight with harsh shadows then at other times, but others have posted that doesn't seem to make a difference. Regardless, it has nothing to do with speed limit changes.

I can repeat both behaviors on my commute home. One is a highway interchange ramp onto another highway. The car will adjust the speed limit 3 times with no signage present.
The other behavior I can experience anywhere. All I have to do is use AP.
It is still astounding to me the number of opinion holders who are adopting a form of moral relativism to excuse a product with *flaws*. One particularly outspoken chap actually blocked me because I continued to disagree.

 

[buyleonard]

For example lets say I'm about to pass a semi at differential of 5mph, and suddenly the car decides to slow because it incorrectly locks onto it. That slow down is likely not that remarkable aside form being annoying. But, lets say the speed differential is 10 or 15mph. That slow down is going to be a lot more aggressive.

I've been wondering how much relative speed factors into it. I drive pretty sedately, and (at least since 10.8.1 FSD Beta), PB has been very rare for me

 

[VanGuy]

Then you are just not trying to understand what (many, many) people are posting. Phantom braking has NOTHING to do with changes in the detected speed limit. Traveling down the highway in bright sunlight with no other cars around and pass under an overpass and the car sheds 10 mph in .5 sec. No speed limit change there. Just braking for no reason. Driving on a curvy road with double-yellow line and an unchanging 35 mph speed limit for miles, and the car will brake and accelerate and brake and accelerate several times per mile for absolutely no reason other than the object recognition neural network is seeing and then losing something that was never there in the first place. In my experience it's worse in bright sunlight with harsh shadows then at other times, but others have posted that doesn't seem to make a difference. Regardless, it has nothing to do with speed limit changes.

Maybe you quoted the wrong part.

Regardless, yes I still think the root of the majority of what people are terming phantom braking is speed limit mismatch.

 

[TeedOff]

It seems odd to me that these reports are popping up just now. While I agree that FSD Beta phantom braking is still pretty atrocious, on the highway it almost never happens to me anymore. The vision-based approach has definitely improved with time.

“It almost never happens to me anymore”? It should NEVER happen. Happened to me yesterday on a snowy road with no one in front of me and no oncoming traffic at 35mph and no Autopilot. If it had happened 500 yards later I would have been off the road. I loved the car, until yesterday.

 

[S4WRXTTCS]

I've been wondering how much relative speed factors into it. I drive pretty sedately, and (at least since 10.8.1 FSD Beta), PB has been very rare for me

You're from Oregon so I don't know what sedately even means in Oregonian terms. On the freeway I always drive 10 over if traffic isn't in the way, but once I hit the Oregon border I'll see people passing me doing at least 10 over what I'm doing with no concern at all.

I'm going to start putting "Do I not mean anything to you" signs on speed limits in Oregon.

 

[S4WRXTTCS]

On my 200 mile trip down to Portland on Saturday I experienced around 4 phantom braking events.

One was moderate enough that it was more than annoyance. The other three were mild, but they were still take over events. They are take over events as you are quickly losing speed, and you don't know why.

Only one of them could I immediately tell was a maps issue where it suddenly thought I was on a different road.

All in all there are fundamentally wrong things that impact AP.

Doesn't always read the speed limit correctly.
Doesn't have any awareness of the type of road its one
Still to this day re-centers when the lane widens which is really annoying
Has mild to moderate pb that varies depending on where its at. I noticed most of it occurs near Tacoma even after the latest map update

 

[COS Blue]

Regardless, yes I still think the root of the majority of what people are terming phantom braking is speed limit mismatch.

I have experienced several times where the car thinks the speed limit has been reduced, when it actually hasn't. This generally happens in the same locations. In one case it sees a Speed Limit 65 sign and thinks it says 45... same sign, every time, and the sign very clearly says 65. Other times, it must be using map data or something, because it'll slow down even though there's no sign -- but I can see that it has reduced the set speed so I assume it's because it thinks the speed limit reduced. There are a couple spots on C-470 outside of Denver, speed limit 65, where it suddenly thinks the speed limit is 35... this happens near a couple of off-ramps, so maybe it's registering the speed limit sign from the off ramp.

However, when this happens, this is merely annoying. In my experience it does not slam on the brakes when this happens. At some point I realize "hey, the car is slowing down, what's up with that," and then I realize what happened (in fact most of the locations I drive frequently enough that I know it's coming).

But this is not what I mean when I talk about Phantom Braking. The hard braking happens in other situations, like when it saw the shadow of a bridge, or it mistakenly thought a car in the oncoming lane wasn't in its lane, stuff like that. Those are the times when it has scared me, and where I have felt fortunate that there wasn't anyone right behind me.

 

[Yelobird]

“It almost never happens to me anymore”? It should NEVER happen. Happened to me yesterday on a snowy road with no one in front of me and no oncoming traffic at 35mph and no Autopilot. If it had happened 500 yards later I would have been off the road. I loved the car, until yesterday.

”On a snowy road”. You don’t think Maybe that might be an issue for a car Looking for white lines on the road??? Lol

 

[sleepydoc]

Maybe you quoted the wrong part.

Regardless, yes I still think the root of the majority of what people are terming phantom braking is speed limit mismatch.

Still not trying to understand, I see.

Speed limit mismatch would mean that the car slows down to what it thinks is the 'correct' speed limit. That's not what people are talking about. (that would also be readily evident on the screen as the incorrect speed limit will be displayed.

please go back and read the comments and then come back when you actually understand.

 

[sleepydoc]

I totally agree with you, and that was the premise and learning that came about, about tolerances and deviations, what is to be acceptable and what is to be not. The human factory ran on the pride of making everything perfect, and to their personal satisfaction. The automated system did not and was not designed to be that but designed to be reliable and acceptable within the tolerances of the application the equipment and parts were designed for.
The autopilot is similar. Everytime I hear you (and others like you) express that the autopilot did something that you wouldn’t have in the same circumstances. That is also why I asked you if you ever had a chauffeur drivern car. For 25 years of my life, I was fortunate enough to have a personal chauffeur driven vehicle for my daily work. Did the chauffeur drive the way I would have? No. But then I learnt I am not there to sit and analyze his driving skills. I have that chauffeur drivern vehicle so that I can even make my commute more productive. As long as the chauffeur did not drive like a drunken driver and/or did not cause any accidents, I learnt to accept his driving and focus on my work.

I hope this perspective helps.

No, it doesn't help at all because it's not a matter of perspective. It's a matter of a flawed system.

Tell me what 'perspective' I'm missing when I'm driving down an empty road in broad daylight and the car suddenly slows down 3-5 MPH then speeds back up. Tell me what 'perspective' I'm missing when I'm on a straight interstate under similar conditions, with minimal traffic and no one in front of me for 3-400 feet and the car suddenly drops its speed by 10+ MPH causing the cars behind me to flash their brights.

If I had a chauffeur that randomly stepped on the brakes and slowed the car 5 MPH then accelerated again to the speed limit I'd fire him. "not causing accidents" is an incredibly low bar. Like I've repeated 100 times, my bar is the standard that every other car with adaptive cruise control has achieved. It's not that low.

Please stop making excuses for a flawed system. It's incredibly tiring to have people keep saying "you're driving it wrong" when the real problem is "they're programming it wrong."

 

[Goose66]

I have experienced several times where the car thinks the speed limit has been reduced, when it actually hasn't. This generally happens in the same locations. In one case it sees a Speed Limit 65 sign and thinks it says 45... same sign, every time, and the sign very clearly says 65. Other times, it must be using map data or something, because it'll slow down even though there's no sign -- but I can see that it has reduced the set speed so I assume it's because it thinks the speed limit reduced. There are a couple spots on C-470 outside of Denver, speed limit 65, where it suddenly thinks the speed limit is 35... this happens near a couple of off-ramps, so maybe it's registering the speed limit sign from the off ramp.

However, when this happens, this is merely annoying. In my experience it does not slam on the brakes when this happens. At some point I realize "hey, the car is slowing down, what's up with that," and then I realize what happened (in fact most of the locations I drive frequently enough that I know it's coming).

Exactly! There is a place on the Interstate here where 75 splits off from 285 where the car thinks the speed limit drops to 55 regardless of what the dynamic speed limit signs say. And yes, it does slow down here, but as COS said, it's a gradual slow down and it takes me several seconds to realize its even happening. This is nothing like phantom braking, however, that is a severe braking (most often) followed by a somewhat less severe acceleration to get back to speed.

It's very clear to me that phantom braking is the neural networks identifying something that's not really there and the path planning slowing down to avoid a collision. Everything with neural nets is probabilities, right? If the probability of a detected obstacle is, e.g., 42% and has been 42% or less for the last 5 iterations, then the obstacle is not there and the car can proceed. If the probability of the detected obstacle jumps to 43% for two iterations in a row, then the obstacle is there and the car needs to avoid it. That's how the neural networks "think" and that tiny jump in probability is the cause of phantom braking, IMO. I'm sure there is some hysteresis designed into the system, but I am fairly certain it is something along these lines.

 

[Ramphex]

I think we need to separate phantom braking into multiple terms/categories. What I usually refer to as phantom braking is random 1-4mph pump down and back up for no reason, creating a nauseating rocking as if you’re driving with two feet. Seems like other people have moderate cases and other issues.

 

[drtimhill]

I think we need to separate phantom braking into multiple terms/categories. What I usually refer to as phantom braking is random 1-4mph pump down and back up for no reason, creating a nauseating rocking as if you’re driving with two feet. Seems like other people have moderate cases and other issues.

Agreed. Suggestion:

-- Mild Small decrease in speed (<5mph), annoying/surprising but presenting no significant danger of collision/accident or occupant discomfort.
-- Medium Significant decrease in speed (5-15mph), causing significant surprise/discomfort, but unlikely to cause a collision/accident.
-- Severe Major and rapid decrease in speed (15mph+), with shock to occupants and potential to cause an accident/collision.

I'm concerned that some people are seeing sever events, but then assuming everyone who reports ANY PB event is also reporting a sever event, while in fact they are mild or medium.

 

[buyleonard]

I have experienced several times where the car thinks the speed limit has been reduced, when it actually hasn't.

When it is really foggy or dark, mine will pick up the lower speed limit that is for trucks only, super annoying.

 

[Ramphex]

Agreed. Suggestion:

-- Mild Small decrease in speed (<5mph), annoying/surprising but presenting no significant danger of collision/accident or occupant discomfort.
-- Medium Significant decrease in speed (5-15mph), causing significant surprise/discomfort, but unlikely to cause a collision/accident.
-- Severe Major and rapid decrease in speed (15mph+), with shock to occupants and potential to cause an accident/collision.

I'm concerned that some people are seeing sever events, but then assuming everyone who reports ANY PB event is also reporting a sever event, while in fact they are mild or medium.

Most of mine are mild and annoying. Had a severe one for a flashing yellow the other day, the car behind me almost ended up in my back seat , luckily I was paying enough attention to floor the accelerator