# Phantom braking



## Shadow LI (Aug 19, 2018)

Anyone seeing increased phantom braking lately on autopilot? Had more than a few today, including one so bad I was incredibly close to getting rear ended. I don’t see any patterns like bridges or overpasses. Almost unusable now, especially in HOV lanes.


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## PasoWino (Jul 18, 2018)

Mine does that from time to time. I had it decide the other day that the max speed limit on the highway was 25 mph. That caused a sudden deceleration from 65. It seems that it has been doing better lately though.


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## WonkoTheSane (Nov 14, 2018)

I went on a trip from PA to FL and many times when the highway passed over surface streets the speed in EAP/NOA would drop dramatically, like it was switching to the speed of the surface street. 

Is that what you are referring to?


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## Needsdecaf (Dec 27, 2018)

No, he’s referring to at times, the car will randomly slam on the brakes in traffic when it gets freaked out. For me, it happens when a vehicle is veering toward it from a two lanes over. Car thinks a collision is going to happen and brakes for a second or two.


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## MJJ (Aug 7, 2016)

I have had this happen regularly, frequently but not always, at one specific spot on highway 99 southbound, south of Merced. It has happened at the same rate across several software versions. I’ve started filing a bug report at each event.

I drive that route 5x/week so I have a good sample size.


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## atebit (Jan 26, 2018)

It happens enough to me to be a PITA. If it would only start slowing down sooner approaching a line of stopped traffic. I guess the two behaviors average out.


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## Tophoos (Jul 10, 2018)

Mine started to act up after 50.6 a few weeks ago.

Happens from time to time. No overpasses, no shadows, no car even 200ft in front.

Previously posted about my experience


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## TheHairyOne (Nov 28, 2018)

My car used to beep when I backed into my steep drive way, stopped after last update. I get phantom brake checks but have learned to quickly override by pressing accelerator. Once I noticed it,was due to a crack in the freeway at the start of a hill.


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## MJJ (Aug 7, 2016)

I noticed yesterday that the phantom braking at “the spot” coincided with another error, that being NoA suddenly insists I must change lanes to follow the route. Well, it’s a wide open 2 lane freeway right there which I stay on for 40 more miles.

I’d bet anybody an entire United States dollar there’s a map glitch there.


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## SimonMatthews (Apr 20, 2018)

Just got a "phantom" braking event today. Driving north on 680 out of San Jose, car hit the brakes as we were just about to go under a bridge. 

*"phantom" in quotes because the braking was very real. The reason for the braking wasn't.

Firmware is 5.15.


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## MJJ (Aug 7, 2016)

Braking for bridges is a thing, but I thought it was a thing of the past.


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## nonStopSwagger (May 7, 2018)

SimonMatthews said:


> Just got a "phantom" braking event today. Driving north on 680 out of San Jose, car hit the brakes as we were just about to go under a bridge.
> 
> *"phantom" in quotes because the braking was very real. The reason for the braking wasn't.
> 
> Firmware is 5.15.


I'm on the same build, I had a similar event happen last weekend.

Honestly my guess is everyone who uses AP gets these every few days, and has become numb to it.

Anybody own other cars with similar capability to AP with this issue? My wife has a Volvo she bought in July 2016 with "pilot assist", we have 32k miles on it, lots with the car driving itself. Never any phantom braking, not even once.


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## Bernard (Aug 3, 2017)

nonStopSwagger said:


> I'm on the same build, I had a similar event happen last weekend.
> 
> Honestly my guess is everyone who uses AP gets these every few days, and has become numb to it.
> 
> Anybody own other cars with similar capability to AP with this issue? My wife has a Volvo she bought in July 2016 with "pilot assist", we have 32k miles on it, lots with the car driving itself. Never any phantom braking, not even once.


Tesla clearly prefers to be safe than sorry ;-) Hence phantom braking...
I get a lot of that from sharp-ish right-hand curves -- the car does not know it's about to turn right, so whenever it "sees" a car emerging from the curve in the opposite direction, it assumes it's crossing our path and decides to brake... But I've had it with overpasses too, along with a dozen other sources, the most annoying being shadows cast across the road. Firmware releases over these last 10mos have slowly reduced the overall incidence (and may even have eliminated the "I brake for shadows" problem), but it's still pretty common.
(And it's not even EAP or AP or FSD: it's part of the basic car software, since it's a safety feature.)


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## nonStopSwagger (May 7, 2018)

What's shocking to me is the issue doesn't get any press from the big YouTube channels. I enjoy watching them, but I feel it's not an accident they are not bringing it up.

I did find one YouTuber who reported on the issue last month. His channel is pretty small, my guess is he wasn't worried about his free roadster getting pulled 😃


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## SimonMatthews (Apr 20, 2018)

MJJ said:


> Braking for bridges is a thing, but I thought it was a thing of the past.


There was a car in the lane next to us and slightly forward, it's possible that it thought the car was going to intrude into our lane, although I didn't see any reason it should. I have experienced other phantom braking events where I think the cause was vehicles in the next lane.


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## nonStopSwagger (May 7, 2018)

Most of my recent incidents are due to cars on side roads, these roads are near the highway, separated by a small grassy median and fence. My guess is my Tesla thinks these cars are going to somehow hit me, and it brakes. But they are not even on the same road....


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## Tombolian (Sep 27, 2018)

Don't you wish there was a simple way of asking the car the reason for whatever it just did? Imagine if it kept a log of said actions (or, gasp, displayed a warning message) that one could review to derive important things like 'my car sees shadows as other cars' instead of 'what the hell did my car just do and why?'
Wishfull thinking?


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## ateslik (Apr 13, 2018)

This happens everytime I use autopilot. I stopped using all beta features. They're just too dangerous.


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## nonStopSwagger (May 7, 2018)

ateslik said:


> This happens everytime I use autopilot. I stopped using all beta features. They're just too dangerous.


I'm hoping they fix this issue completely with the hardware 3 cars. Supposedly they are already making them.


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## Scubastevo80 (Jul 2, 2018)

Lots of autopilot issues for me. I still use on my commute to/from work, but I have to monitor it like a hawk and 50% of lane changes require me to take over to complete them. Some are bouncier than others in terms of going back and forth between the target lane, others are about 75% complete and then the car wants to abort back to the original lane.


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## Bernard (Aug 3, 2017)

Tombolian said:


> Don't you wish there was a simple way of asking the car the reason for whatever it just did? Imagine if it kept a log of said actions (or, gasp, displayed a warning message) that one could review to derive important things like 'my car sees shadows as other cars' instead of 'what the hell did my car just do and why?'
> Wishfull thinking?


Sadly, yes, I fear that's indeed wishful thinking.
Deep neural networks, as (presumably) used by Tesla for the autonomous driving programs, are really good at learning, but they do so by tweaking coefficients at tens to hundreds of thousands of nodes, none of which has a clear connection to a specific type of data. So these networks can learn well and make good predictions, but cannot explain/justify anything. There is a lot of research going on in AI to modify these networks (for example by adding specialized collections of nodes, called "attention layers," that do not participate directly in the learning, but are trying to correlate changes in the other nodes with specific data inputs) in an attempt to label at least some of the network nodes with the type of data they are most closely tied to, but so far the results are unconvincing.

This occurs with humans too -- many times, someone will do something unexpected and be unable to explain why or how they did it -- athletes after a particularly good performance, chefs after developing a great new recipe, etc. (Unsurprising, really, as our brains seem to be just enormously larger and more complex versions of these neural networks.)


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## WonkoTheSane (Nov 14, 2018)

"Better safe than sorry" is not valid here. "Safe" would be to realize that point A is 65mph, point C, 500 feet away is 65mph, let's make the assumption that point B is 65mph, not 35mph.


Bernard said:


> Tesla clearly prefers to be safe than sorry ;-) Hence phantom braking...
> I get a lot of that from sharp-ish right-hand curves -- the car does not know it's about to turn right, so whenever it "sees" a car emerging from the curve in the opposite direction, it assumes it's crossing our path and decides to brake... But I've had it with overpasses too, along with a dozen other sources, the most annoying being shadows cast across the road. Firmware releases over these last 10mos have slowly reduced the overall incidence (and may even have eliminated the "I brake for shadows" problem), but it's still pretty common.
> (And it's not even EAP or AP or FSD: it's part of the basic car software, since it's a safety feature.)


"Better safe than sorry" is not valid here. "Safe" would be to realize that point A is 65mph, point C, 500 feet away is 65mph, let's make the assumption that point B is 65mph, not 35mph.


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## Bernard (Aug 3, 2017)

WonkoTheSane said:


> "Better safe than sorry" is not valid here. "Safe" would be to realize that point A is 65mph, point C, 500 feet away is 65mph, let's make the assumption that point B is 65mph, not 35mph.
> 
> "Better safe than sorry" is not valid here. "Safe" would be to realize that point A is 65mph, point C, 500 feet away is 65mph, let's make the assumption that point B is 65mph, not 35mph.


The "safe" part has to do with what the cameras are sensing.
On a straight stretch of road, what if it is something falling onto the road in front of the car (e.g., something blown by the wind, like a large carboard box, or a tree branch)?
For the right-hand curves, it's clearly because the car does not "know" that it will soon to turn to the right and so views a car coming into view from the right some way ahead as a potential collision risk.
Sure, there is a risk in braking in such cases, but the risk is small compared to the potential damage of not braking if the worst-case scenario materializes (get hit by the tree branch, collide with the oncoming care coming from the right, etc.) It's not a matter of speed limits or even of safe driving speeds.


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## WonkoTheSane (Nov 14, 2018)

Bernard said:


> The "safe" part has to do with what the cameras are sensing.
> On a straight stretch of road, what if it is something falling onto the road in front of the car (e.g., something blown by the wind, like a large carboard box, or a tree branch)?
> For the right-hand curves, it's clearly because the car does not "know" that it will soon to turn to the right and so views a car coming into view from the right some way ahead as a potential collision risk.
> Sure, there is a risk in braking in such cases, but the risk is small compared to the potential damage of not braking if the worst-case scenario materializes (get hit by the tree branch, collide with the oncoming care coming from the right, etc.) It's not a matter of speed limits or even of safe driving speeds.


The situation was driving on a highway which passes over a surface street. I understand the need for safety features, but none of those conditions were present. Just me, alone, on a highway.


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## mswlogo (Oct 8, 2018)

Sorry I didn't read the whole thread and this might be already stated but I think I've seen it false on cars passing by at night and I think it sees the headlights bleeding into my lane in front of me.
Possibly it's aggravated by cars with auto high beam and their headlight flipped as they passed (maybe another Tesla  ) and it looked like an object to my car in front of me.


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## nonStopSwagger (May 7, 2018)

Now that cars are shipping with the new autopilot HW 3 computers, will we see any improvements eliminating phantom braking? My guess is the algorithms being used in the new cars are similar, but they have way more processing power.

At some point down the road these HW3 cars will get way better AP software, that the AP2.5 computers don't have the processing power to handle.


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## Jpickensok (Apr 10, 2019)

I have had at least 2 instances on the interstate, where my car braked unexpectedly, with a semi truck behind me. Anxious about using autopilot in heavy traffic. I hope future software updates will address the traffic behind your car as well.


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## mswlogo (Oct 8, 2018)

nonStopSwagger said:


> Now that cars are shipping with the new autopilot HW 3 computers, will we see any improvements eliminating phantom breaking? My guess is the algorithms being used in the new cars are similar, but they have way more processing power.
> 
> At some point down the road these HW3 cars will get way better AP software, that the AP2.5 computers don't have the processing power to handle.


I tend to agree. Question is how long before everyone is updated to HW3 that's due to get it and how long will it be before mainstream updates focus on HW3 capabilities. I'm concerned it could be a couple years.
1 year for HW3 upgrades to complete and a year of new, debugged and released code that works. Along with what ever new NN learning it might need to get there.


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## nonStopSwagger (May 7, 2018)

Any new owners with HW3 experience phantom breaking? I'm hoping with the new FSD computer this is no longer a thing.

If it's still happening to hw3 owners, most likely needs software/NN upgrades too.


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## kort6776 (Apr 30, 2019)

while rare sometimes the car will see ghosts


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## FogNoggin (Mar 19, 2019)

nonStopSwagger said:


> Any new owners with HW3 experience phantom breaking? I'm hoping with the new FSD computer this is no longer a thing.
> 
> If it's still happening to hw3 owners, most likely needs software/NN upgrades too.


My car was built April 2019 and has HW3. Phantom braking is an issue for me, too. It's mostly a problem when met with oncoming traffic. It's so bad that I'll only use autopilot on divided multi-lane highways. It's left me very glad I didn't buy FSD.


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## nonStopSwagger (May 7, 2018)

FogNoggin said:


> My car was built April 2019 and has HW3. Phantom braking is an issue for me, too. It's mostly a problem when met with oncoming traffic. It's so bad that I'll only use autopilot on divided multi-line highways. It's left me very glad I didn't buy FSD.


Phantom braking is a real bummer alright. I don't use autopilot on back roads anymore when there are other passangers, even TACC does it. I still turn it on now and then when its just me in the car to see if its improved. Nope!

My wish list for improvements with autopilot for 2019 with HW3 cars. Get rid of the nag like the 2015 AP1 cars when they were first released. Also fix Phantom braking. Everything else (Traffic lights, stop signs, FSD on city streets, Advanced summon), they can put on the back burner.

Worst case if tesla cannot fix the issue, they should at least give us the option to turn on regular old cruise control. I have used regular cruise for years to keep my speed in check.


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## kort6776 (Apr 30, 2019)

nonStopSwagger said:


> Phantom braking is a real bummer alright. I don't use autopilot on back roads anymore when there are other passangers, even TACC does it. I still turn it on now and then when its just me in the car to see if its improved. Nope!
> 
> My wish list for improvements with autopilot for 2019 with HW3 cars. Get rid of the nag like the 2015 AP1 cars when they were first released. Also fix Phantom braking. Everything else (Traffic lights, stop signs, FSD on city streets, Advanced summon), they can put on the back burner.


I agree, the original AP 1 was a pleasure compared to the incessant nagging we have to suffer with now. you really shouldn't be on AP on most back roads, the AP can get wonky on them


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## nonStopSwagger (May 7, 2018)

kort6776 said:


> you really shouldn't be on AP on most back roads, the AP can get wonky on them


TACC does the phantom thing too unfortunately


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## DocScott (Mar 6, 2019)

FogNoggin said:


> My car was built April 2019 and has HW3. Phantom braking is an issue for me, too. It's mostly a problem when met with oncoming traffic. It's so bad that I'll only use autopilot on divided multi-lane highways. It's left me very glad I didn't buy FSD.


That actually sounds like a substantial improvement. AP isn't really "supposed" to be used outside of divided multi-lane highways yet. So phantom braking there is par for the course for now. Once they fix it, Tesla can officially endorse the use of AP on other roads.

But before a lot of people were reporting phantom braking even on interstates. If that's gone away, that would be really good. I'd like to see interstate driving become true L3-level, and this brings us closer...


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## nonStopSwagger (May 7, 2018)

DocScott said:


> That actually sounds like a substantial improvement. AP isn't really "supposed" to be used outside of divided multi-lane highways yet. So phantom braking there is par for the course for now. Once they fix it, Tesla can officially endorse the use of AP on other roads.
> 
> But before a lot of people were reporting phantom braking even on interstates. If that's gone away, that would be really good. I'd like to see interstate driving become true L3-level, and this brings us closer...


I'd need to do some more interstate trips. It did do it 3 weeks back on the highway.

Honestly, just give me regular cruise control on back roads. Tesla can take their time fixing Phantom braking with TACC and AP. And I'll be happy.


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## kort6776 (Apr 30, 2019)

nonStopSwagger said:


> I'd need to do some more interstate trips. It did do it 3 weeks back on the highway.
> 
> Honestly, just give me regular cruise control on back roads. Tesla can take their time fixing Phantom braking with TACC and AP. And I'll be happy.


you can engage tacc without engaging full eap


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## nonStopSwagger (May 7, 2018)

kort6776 said:


> you can engage tacc without engaging full eap


I know. And just like AP, TACC phantom brakes on back roads around me. It's annoying as all get out. I tend to speed around town, cruise control kept me honest for years

TACC makes it look like I'm drunk, randomly braking as I drive 35 mph.


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## kort6776 (Apr 30, 2019)

nonStopSwagger said:


> I know. And just like AP, TACC phantom brakes on back roads around me. It's annoying as all get out. I tend to speed around town, cruise control kept me honest for years
> 
> TACC makes it look like I'm drunk, randomly braking as I drive 35 mph.


you must be aware that the AP was not meant to be used on back roads, even though it will work on some of them it still doesn't function well


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## nonStopSwagger (May 7, 2018)

kort6776 said:


> you must be aware that the AP was not meant to be used on back roads, even though it will work on some of them it still doesn't function well


Correct. AP is not for back roads.

Tesla's version of Cruise control, "traffic aware cruise control" or TACC for short, is what I have issues with. More so than AP. It phantom brakes on quiet backroads near me, with light traffic and clear lane markings.


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## kort6776 (Apr 30, 2019)

nonStopSwagger said:


> Correct. AP is not for back roads.
> 
> Tesla's version of Cruise control, "traffic aware cruise control" or TACC for short, is what I have issues with. More so than AP. It phantom brakes on quiet backroads near me, with light traffic and clear lane markings.


FWIW: TACC is nothing new nor unique many of the luxury brands have had it for years.


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## garsh (Apr 4, 2016)

kort6776 said:


> FWIW: TACC is nothing new nor unique many of the luxury brands have had it for years.


What does that have to do with TACC on a Tesla having issues with phantom braking?


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## nonStopSwagger (May 7, 2018)

My wife has a Volvo she bought in 2016 with TACC, zero phantom braking in the last 3 years.

My Tesla does it every single time I use it to go to the gym 5 miles away.


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## racekarl (Jul 31, 2018)

My wife's 2017 GMC Acadia has phantom braking events triggered by the AEB system even when not using any sort of cruise control. These systems are clearly immature, and I can understand why the designers would rather err on the side of responding to a false positive vs. ignoring a signal.


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## zosoisnotaword (Aug 28, 2017)

Credit to @nonStopSwagger for being patient with people who aren't actually reading his posts before responding.

TACC and its phantom breaking are the reasons I didn't purchase the full package when it dropped to $5k for everything. It works great situationally, but when traffic is light, vanilla cruise control is the superior option even without the phantom breaking. There should be a toggle option for people with EAP.


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## DerFips (Mar 11, 2019)

I do not have complete proof for this, but I noticed, that, at least in Germany, when the street has a new paving, the amount of phantom breaks are more then on older streets. It's funny, because the lines are very bright and the paving is very dark so the car should see the line very good. I'll try it a few more times to update my statistics.


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## DocScott (Mar 6, 2019)

DerFips said:


> I do not have complete proof for this, but I noticed, that, at least in Germany, when the street has a new paving, the amount of phantom breaks are more then on older streets. It's funny, because the lines are very bright and the paving is very dark so the car should see the line very good. I'll try it a few more times to update my statistics.


It wouldn't surprise me if this were the case. Phantom braking isn't about not seeing things that are there; it's about seeing things that aren't there (phantoms!). Shadows on a freshly paved street will have different characteristics then on a more weathered surface. I'm guessing the shadows will tend to be sharper and more distinct on the new surface, and thus more easily mistaken for an actual object in the road.


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## TomT (Apr 1, 2019)

I have noticed a number of occasions when dark shadows on the road from nearby objects in bright sunlight have triggered a phantom braking episode...


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## Madmolecule (Oct 8, 2018)

My fantom breaking had disappeared for about 3 months. I did a 400 mile day trip this week and had phantom breaking about 3 times, due to showdown on the road late in the afternoon. Not sure if it is software or time of year related to longer shadows.


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## Technical48 (Apr 29, 2018)

nonStopSwagger said:


> Worst case if tesla cannot fix the issue, they should at least give us the option to turn on regular old cruise control. I have used regular cruise for years to keep my speed in check.


This is why I didn't buy EAP even at the "bargain" price of 2kUSD. I pretty much hated using TACC during both of the two week trials. And was glad when both trials ended so I could get back my plain standard CC.

Until TACC becomes less glitchy, there should be a user option to disable it.


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## SimonMatthews (Apr 20, 2018)

Madmolecule said:


> My fantom breaking had disappeared for about 3 months. I did a 400 mile day trip this week and had phantom breaking about 3 times, due to showdown on the road late in the afternoon. Not sure if it is software or time of year related to longer shadows.


I had a couple of phantom braking events today. This has happened in the same place on previous occasions. It is as I come off the carpool connector from i880S to 237W in Milpitas/San Jose.


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## Nom (Oct 30, 2018)

I'm going to agree with many. I really appreciate TACC in heavy traffic ... stop and go or not quite that bad. But when it's moving fairly well and I happen to change lanes, the phantom braking is really pretty annoying. I wish I could toggle to just regular cruise control as well. 

That said, I'm noticing modest improvements .... it seems to be more smooth in slowing down when it is coming up on a car in front ... which is well done. I'm hopeful that within a year, the phantom breaking will be greatly reduced.


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## JML (Jul 26, 2018)

I find that phantom braking occurs very consistently in certain places on my commute. For example, this lower than normal overhead sign will always cause the car to brake if I'm in the left lane or the express lane. Anybody else here drive 36 between Boulder and Denver and have the same problem? Based on the number of 3s I see everyday, there must be somebody. As I've posted before, these overhead trees also cause problems.

This isn't a complete explanation, as at this particular sign the one in the east bound lane (the far sign that is readable in the picture) causes the car to brake, but the one in the west bound lane (the near sign, that you see the back of) does not cause the car to brake.


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## nonStopSwagger (May 7, 2018)

JML said:


> I find that phantom braking occurs very consistently in certain places on my commute. For example, this lower than normal overhead sign will always cause the car to brake if I'm in the left lane or the express lane. Anybody else here drive 36 between Boulder and Denver and have the same problem? Based on the number of 3s I see everyday, there must be somebody. As I've posted before, these overhead trees also cause problems.
> 
> This isn't a complete explanation, as at this particular sign the one in the east bound lane (the far sign that is readable in the picture) causes the car to brake, but the one in the west bound lane (the near sign, that you see the back of) does not cause the car to brake.


Consistent unnecessary phantom braking that doesn't go away, makes me question if tesla really is doing any meaningful fleet learning in "shadow mode" from end user data. Most likely is only being done with an approved subset of cars.

I've driven the same stretch of road now hundreds of times with my tesla, 95% of the time with TACC off due to phantom braking. I've seen other teslas on that road too. Phantom braking has never gone away in a few spots. Road lines are good, traffic is light to non existent.

Here's to hoping this all goes away when they start deploying better NN models with HW3 cars


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## bernie (Jan 5, 2018)

I’m on 12.1.2 m3 and getting phantom braking at least once or twice with each trip. Overpasses, shadows passing an on ramp and sometimes for no reason I can determine, I try to bug report when it happens and it’s particularly hard braking that could unsafe.


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## barjohn (Aug 31, 2017)

If it was being caused by false returns from the radar, then you would think that the vision recognition system should be utilized and given priority. On the other hand if it is being caused by the vision system, then the NN is inadequate to the task and maybe they need to get the HDW 3 out ASAP to solve this problem.


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## garsh (Apr 4, 2016)

The phantom braking seemed to pretty much disappear for me for several months. But it has been back with a vengeance this past week.

Does Tesla (silently) download autopilot NN updates separately from firmware updates? I'm still on 2019.12.1.2, but the AP behavior seems to have changed drastically.


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## DocScott (Mar 6, 2019)

barjohn said:


> If it was being caused by false returns from the radar, then you would think that the vision recognition system should be utilized and given priority. On the other hand if it is being caused by the vision system, then the NN is inadequate to the task and maybe they need to get the HDW 3 out ASAP to solve this problem.


Tesla recently had another fatal accident where AP did not detect a truck with a lot of clearance off the ground. It is clearly critical for them to first make sure the system _does_ recognize things that are four feet off the ground as obstacles (no false negatives). The next priority is to stop recognizing things that are ten feet off the ground (no false positives). Intuitively, that doesn't seem like it's that hard a problem.

It may in part be a limitation of the sensors, though. Can the radar distinguish the vertical position of things? At what angle above the road does the radar detect objects? This is one situation where lidar might in fact be useful, although it might just need a better scan pattern for the radar.

Does anyone have a link that explains the technical capabilities of the Model 3 radar? It would be helpful for understanding the interplay of radar and visual when dealing with objects off the ground.


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## DocScott (Mar 6, 2019)

garsh said:


> The phantom braking seemed to pretty much disappear for me for several months. But it has been back with a vengeance this past week.
> 
> Does Tesla (silently) download autopilot NN updates separately from firmware updates? I'm still on 2019.12.1.2, but the AP behavior seems to have changed drastically.


It could be a change in map data: Tesla has talked about having a "geocoded whitelist" to cut down on phantom braking. If they gained confidence in the sensors and removed a lot of stuff from the whitelist, and your car downloaded a map update with the new (smaller) whitelist, that could explain the sudden change without a firmware update.


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## Scubastevo80 (Jul 2, 2018)

3 instances on the way to work this morning for me - I'm not sure if its the position of the sun at that time in the morning, but I don't want to use autopilot if I'm going to get jolted every 3 miles on the highway for a 10 mile highway commute.


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## JML (Jul 26, 2018)

Another thing I've noticed, is that the car is much less likely to phantom brake if I'm in heavy traffic. That of course means a car in front of me, and traveling at lower speeds. The worst, of course, is when it is medium traffic, so there is nothing ahead of me, and I'm going at full speed, but there are cars behind me.


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## Bokonon (Apr 13, 2017)

DocScott said:


> It could be a change in map data: Tesla has talked about having a "geocoded whitelist" to cut down on phantom braking. If they gained confidence in the sensors and removed a lot of stuff from the whitelist, and your car downloaded a map update with the new (smaller) whitelist, that could explain the sudden change without a firmware update.


Yup, definitely possible. Since now have the ability to see the map data version on the new Software tab, we should know when the map data gets updated. Mine hasn't been updated since February (version number 2019.6.x), though.

Since Autopilot assigns probabilities and confidence levels to its sensory inputs and calculations, it's possible that relatively small environmental variations (e.g. in the position or intensity of the sun) or situational differences (e.g. current speed or traffic density) could be the difference between the car perceiving a faraway object as harmless or an obstacle that needs to be avoided. Broader trends in these variables (e.g. the changing position of the sun from one season to the next, or seasonal traffic patterns) could therefore cause phantom-braking incidents to increase or decrease over time without any change in firmware, neural network, or map data.

For example, there's a 50-mph stretch of highway by my office that passes over a small, ~100-foot hill. On the other side of the hill, just as it bottoms out, there is an overpass with a couple of green highway signs, and as you crest the hill and start heading back down, those signs visually appear to be at your current elevation. Every so often, when there is no other traffic on the road, my car seems to perceive the signs as an obstacle directly in its path and starts braking. The location where it starts braking is always the same (as is the lack of traffic, i.e. a clear view to the signs), but some combination of ambient light and/or other factors seem to be what leads Autopilot to one conclusion or the other... after encountering only one or two braking incidents all winter, they seem to be back on the rise now that the sun is higher in the sky and out more often. With all that said, phantom brakes in this location are still a relatively uncommon occurrence (maybe ~5% of the time?), and all I have to do as a countermeasure is keep my foot by accelerator as I crest the hill. So, in the event that they do occur, it doesn't bother me too much...


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## Scubastevo80 (Jul 2, 2018)

Scubastevo80 said:


> 3 instances on the way to work this morning for me - I'm not sure if its the position of the sun at that time in the morning, but I don't want to use autopilot if I'm going to get jolted every 3 miles on the highway for a 10 mile highway commute.


And zero instances this morning... it's as if the software fairies came out overnight and provided a little helping hand


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## SimonMatthews (Apr 20, 2018)

On 12.2 here.

There is a location where my M3 suffers from phantom braking about once out of very 3 times I drive there. Sunny or cloudy.

It's coming off the carpool connector from i880S to 237W.

https://www.google.com/maps/embed?p...0!3m2!1sen!2sus!4v1558757304548!5m2!1sen!2sus


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## Old Geezer (Jun 28, 2019)

MJJ said:


> I noticed yesterday that the phantom braking at "the spot" coincided with another error, that being NoA suddenly insists I must change lanes to follow the route. Well, it's a wide open 2 lane freeway right there which I stay on for 40 more miles.
> 
> I'd bet anybody an entire United States dollar there's a map glitch there.


When on I 15 between San Diego and Riverside and using autopilot, I received numerous automatic lane change commands, which I had to override. There were no route changes for the next 47 miles. I have driven this route several times since taking delivery in March (2019) and it has not happened before. I am thinking this has something to do with the latest software upgrade.


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## barjohn (Aug 31, 2017)

From my viewpoint, there is no worse AP/FSD behavior than phantom braking, which I would call a false positive for an imminent collision. In real life driving there are very few times that we as humans have to suddenly slam on the brakes. These are usually conditions caused by other drivers engaging in unexpected behavior or by our own lapse of attention and following too close when traffic abruptly and unexpectedly comes to a stop or near stop.

The thing that makes the false positive braking so unnerving is that we as humans cannot see anything that should cause the vehicle to brake in 99% of the cases. Tesla fails to give us a clue as to what is happening but it has certainly gotten much worse since version 9. I drove 2,500 miles last summer with only 2 or 3 occurrences and at least 1 of those was possibly triggered by bicyclists that we passed and that may have been too close. Since version 9 the frequency has increased to the point that I hesitate to use TACC or AP or NoAP because it freaks my wife out every time and in heavy SOCAL traffic I worry about being rear ended or causing a road rage incident.

As a software developer, I don't understand how the system can have such a high incidence of false positives. It has both radar and cameras to detect obstacles that might be in the vehicles path. It can detect range to the obstacles using doppler for the radar and a sequence of images for the camera. Before brakes are applied, the two should nominally agree that there is an obstacle within a range and at a closing rate that requires braking. It should do the equivalent of removing your foot from the accelerator pedal or reducing the pressure on it to assess the situation further and only applying the brakes to avoid a collision due to the closing rate with the object. We have a collision alarm that seems to be set off in many cases by a vehicle in front of you slowing down faster than you are but this alarm never goes off in the phantom braking situation.

Tesla should put whatever resources are needed to solve this problem. I would rather have a reliable TACC or NoAP than a driver game or enhanced white board. This just tells me that Tesla has its priorities wrong in the area of software development. Look at the big effort for enhanced summons. If the car can't identify stop lights and traffic signs, something much more important in everyday use than navigating a parking lot, why the emphasis on this? I suspect that other than showing it off a few times to friends, it (enhanced summons) will get very little use. How many people want to risk their $50K plus car being in an accident in a parking lot to save walking 50-150 feet? Having, even assisted, self driving in a non highway environment is eminently more valuable and useful.

I just hope someone at Tesla reads these forums to have a feel for our frustration and concerns in this area. From what I have read, AP1 cars do not exhibit this unpredictable and erratic behavior. I can't seem to learn whether hardware 3 cars are having this issue or not.


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## DocScott (Mar 6, 2019)

barjohn said:


> From my viewpoint, there is no worse AP/FSD behavior than phantom braking, which I would call a false positive for an imminent collision. In real life driving there are very few times that we as humans have to suddenly slam on the brakes. These are usually conditions caused by other drivers engaging in unexpected behavior or by our own lapse of attention and following too close when traffic abruptly and unexpectedly comes to a stop or near stop.
> 
> The thing that makes the false positive braking so unnerving is that we as humans cannot see anything that should cause the vehicle to brake in 99% of the cases. Tesla fails to give us a clue as to what is happening but it has certainly gotten much worse since version 9. I drove 2,500 miles last summer with only 2 or 3 occurrences and at least 1 of those was possibly triggered by bicyclists that we passed and that may have been too close. Since version 9 the frequency has increased to the point that I hesitate to use TACC or AP or NoAP because it freaks my wife out every time and in heavy SOCAL traffic I worry about being rear ended or causing a road rage incident.
> 
> ...


I agree that addressing phantom braking should be a top--probably _the_ top--priority.

But it comes in more than one variety.

I've never experienced the variety you're talking about, which amounts to _panic_ braking without visible (or rational) cause. Based on the reports I've read where that has happened, I'd guess Tesla is struggling with the problem of things off the ground. The radar can't detect them, because it's not aimed right. So that leaves just visual. Tesla _knows_ the two won't confirm each other in that case, and that if relies on them to do so, it ends up with people dead from trying to drive under big rigs. It's only happened twice, but it makes big news when it does. So they trade off a bzillion phantom braking episodes while they try to handle that edge case. But if I'm right, the problem is, as its heart, a design problem: there should be radar (or lidar or whatever) pointed a little up as well as straight, and there isn't, and that turns a relatively easy problem in to a very hard software problem.

On the other hand, there's also the more mild "take your foot off the accelerator" version. Not a panic stop, but a considerable drop in speed where a person would not. Those, I've experienced, usually with something (e.g. a car in the breakdown lane) that is a visual trigger, but not always.

I had an interesting case today of the more mild version. I was going around a weird interchange (for those who know Westchester, NY, it's the area in front of the Kensico Dam). That interchange is very confusing for human drivers; it feels like you're always in the wrong lane. And although several of the options in what amounts to a big messy traffic circle are divided limited-access highways, some are regular surface streets. So when I was new to the area I often was applying the brakes when I found I was in the wrong lane or when someone cut in front of me trying to get to the right one. Today, on AP (not NOA), the car kept changing speeds as I went through the interchange. The spots where it suddenly slowed weren't when there was a curve, and I don't think it was losing lane markers because AP didn't disengage. My guess is that it's just taking data from previous drivers and that so many of them have had a "sh*t! I'm in the wrong lane" moment at certain spots that it thinks you're _supposed_ to slow down at those spots. Either that or the map data is really dodgy there, which is also quite possible.


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## mswlogo (Oct 8, 2018)

DocScott said:


> I agree that addressing phantom braking should be a top--probably _the_ top--priority.
> 
> But it comes in more than one variety.
> 
> ...


I agree it should be number one priority.

What it's even more concerning there is zero acknowledgement there is even a problem. The answer is often, "it's beta".

Some stuff is hard and takes time. Just let us know your working on it. Don't really want to hear about games or advanced summon when something so fundamental is broken and dangerous.

Even a work around to give us an option to turn off traffic aware, or lower it.


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## barjohn (Aug 31, 2017)

We know the radar can't detect stopped objects due to the filtering that has been applied to eliminate those from detection. We also know that Elon has stated that enhanced or high resolution maps will not be part of the solution. Finally, Elon has stated that the goal is to ultimately use visual only. This implies several things. The frame rate must be very high and the ability to recognize objects and predict their behavior in real-time must be very good. As good or better than human vision. It should make mistakes less often than a human would under similar conditions. If it can't do that, then it will never be safer than a human driver.

I suspect, that this implies that HDW 3 is the minimum essential required hardware. If I can see the lag between what is happening in front of me and what the car is displaying, the processing is too slow. That should not be happening and it is. Tesla should be rolling out HDW 3 upgrades to all FSD purchasers as quickly as possible in order to move to a more unified NN capable of meeting these requirements.

I have seen all variants of the phantom braking but the abrupt ones are the worst. I suspect that the action is caused precisely because of the lag in real-time processing. It thinks it detects an obstacle in the path and rather than wait until it is certain (or at least more certain), it slams on the brakes and then it realizes there is no object so just as suddenly, it stops applying the brakes. Because the programmers know there is a lag between the time it detects a possible object and the time it can ascertain for sure it does what it thinks is the safest course of action. Of course, it has no rear radar and currently doesn't appear to use the rear facing camera so it ignores whether there is anything close behind you. Personally, I would rather Tesla just say, "We cannot detect stopped objects in your path so you are responsible to brake the car if an object is in your path. The car will issue a collision warning but it is up to you to act." Those collision warnings are bad enough.

Of course if it is tracking a moving object that stops, that is a different scenario, like traffic aware cruise control (TACC). The strange thing, is that HDW 1 cars don't appear to report these problems. I am not sure this is a true statement, and I would like to hear from HDW 1 owners as to whether they have experienced this issue or not. I do know the problem has gotten worse from version 8. In all fairness to Tesla, other aspects have seen significant improvements.


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## 19Model34me (Apr 5, 2019)

The solution is to be able to turn off TACC and just have regular cruise control. That would satisfy the mass market and allow the Beta testers to play. I hope it happens soon because my wife will no longer drive in the car from getting sick from the constant braking and I’m considering selling it. I’ve been almost rear ended multiple times with horns blaring and fingers waving because there were tree shadows on the road. It’s definitely a safety issue for me, I don’t trust the car one bit.

Every other company with adaptive cruise let’s you turn it off, that’s all I ask.


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## SalisburySam (Jun 6, 2018)

19Model34me said:


> The solution is to be able to turn off TACC and just have regular cruise control.


Not sure this is THE solution, but it certainly is A solution. I've many times wished I just had regular cruise control functionality instead of TACC, including when engaging cc while at a speed different than the shown speed limit. I do like TACC, but not always.


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## undergrove (Jan 17, 2018)

SalisburySam said:


> Not sure this is THE solution, but it certainly is A solution. I've many times wished I just had regular cruise control functionality instead of TACC, including when engaging cc while at a speed different than the shown speed limit. I do like TACC, but not always.


If you set the speed assist offset slider to -20 it will maintain the speed at which you are travelling when you engage TACC or Autopilot. You can change this speed with the right thumb wheel, but it will not adjust automatically to speed limits. The disadvantage is that you have to continually adjust the max speed as speed limits or conditions change.


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## SalisburySam (Jun 6, 2018)

undergrove said:


> If you set the speed assist offset slider to -20 it will maintain the speed at which you are travelling when you engage TACC or Autopilot. You can change this speed with the right thumb wheel, but it will not adjust automatically to speed limits. The disadvantage is that you have to continually adjust the max speed as speed limits or conditions change.


Yeah, I've tried that solution, recommended on a different forum, and you're right: big disadvantage with much too much babysitting required as speed limits change, and for me defeats the "autoness" of the provided services. I'd still rather have a quick one button/tap way to disable the TA part of TACC when wanted, and equally simple way to re-engage, at least until the TACC oddities are better resolved.


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## nonStopSwagger (May 7, 2018)

undergrove said:


> If you set the speed assist offset slider to -20 it will maintain the speed at which you are travelling when you engage TACC or Autopilot. You can change this speed with the right thumb wheel, but it will not adjust automatically to speed limits. The disadvantage is that you have to continually adjust the max speed as speed limits or conditions change.


If I do this, will the car no longer phantom brake? If so, this will be my default setting, as most of my driving is around town, with sometimes a month going by before I do a highway trip.


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## DocScott (Mar 6, 2019)

nonStopSwagger said:


> If I do this, will the car no longer phantom brake? If so, this will be my default setting, as most of my driving is around town, with sometimes a month going by before I do a highway trip.


It depends on the variety of phantom braking you're talking about.

Emergency braking because the car thinks it's about to hit something that isn't there would still happen.

But rapid drops in speed because, e.g., it thought you were on the low-speed surface street under your high-speed elevated highway would not.


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## nonStopSwagger (May 7, 2018)

DocScott said:


> I've also been in situations when I wished I could disengage TACC (by tapping the brake) and leave AutoSteer operating.
> 
> It depends on the variety of phantom braking you're talking about.
> 
> ...


Bummer. Almost all of my issues are on rural backroads, with shadows, curves or cresting a hill. Generally zero traffic when it happens, and no bridges or overpasses.

If tesla would allow for normal cruise control, I'd be happy. Then I would only use TACC on the highyway.


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## M3OC Rules (Nov 18, 2016)

barjohn said:


> I suspect, that this implies that HDW 3 is the minimum essential required hardware.


Minimum essential hardware for what? Several people on this forum report that other cars they own don't have the same degree of phantom braking issues. Do you think they have better sensors or processors than HW2.5? Tesla can and needs to fix this on HW2.5. They will never get to zero phantom braking and they will never make it prevent the car from running into things so they need to find a good balance. Right now they have too many braking events causing a bad experience.


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## GDN (Oct 30, 2017)

barjohn said:


> It thinks it detects an obstacle in the path and rather than wait until it is certain (or at least more certain), it slams on the brakes and then it realizes there is no object so just as suddenly, it stops applying the brakes. Because the programmers know there is a lag between the time it detects a possible object and the time it can ascertain for sure it does what it thinks is the safest course of action. Of course, it has no rear radar and currently doesn't appear to use the rear facing camera so it ignores whether there is anything close behind you. Personally, I would rather Tesla just say, "We cannot detect stopped objects in your path so you are responsible to brake the car if an object is in your path. The car will issue a collision warning but it is up to you to act." Those collision warnings are bad enough.


I'm not arguing any real points, but one thing you might think about on the braking, perhaps it is deciding there is no object in your way so it quits braking, but the braking in these instances the way I understand it will never stop your car. From the manual page 87 - the cars braking will only slow you 30 MPH and then release the brakes - it is designed to slow you down, not stop the car. I don't know if it has slowed you 30 MPH or it could be deciding there is no object in your way now, but per p.87 it will not stop you, only slow you down, so it could be you have decelerated 30 MPH and it is a planned release of the brakes.

_"If driving 35 mph (56 km/h) or faster, the
brakes are released after Automatic
Emergency Braking has reduced your driving
speed by 30 mph (50 km/h). For example, if
Automatic Emergency Braking applies braking
when driving 56 mph (90 km/h), it releases
the brakes when your speed has been reduced
to 26 mph (40 km/h).
Automatic Emergency Braking operates only
when driving between approximately 7 mph
(10 km/h) and 90 mph (150 km/h)."_

On the next point, they never care if any one is behind you, if an object is in front of you, you should be stopping. I'm not preaching, just noting observations. If we were all travelling using proper follow distances we'd all have time to react, but I know that is not the case, not on my commute or likely yours.


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## M3OC Rules (Nov 18, 2016)

GDN said:


> I'm not arguing any real points, but one thing you might think about on the braking, perhaps it is deciding there is no object in your way so it quits braking, but the braking in these instances the way I understand it will never stop your car. From the manual page 87 - the cars braking will only slow you 30 MPH and then release the brakes - it is designed to slow you down, not stop the car. I don't know if it has slowed you 30 MPH or it could be deciding there is no object in your way now, but per p.87 it will not stop you, only slow you down, so it could be you have decelerated 30 MPH and it is a planned release of the brakes.
> 
> _"If driving 35 mph (56 km/h) or faster, the
> brakes are released after Automatic
> ...


Does this apply to Autopilot phantom braking? I don't believe I have ever had phantom braking without TACC or TACC + Autopilot on.


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## Mr. Spacely (Feb 28, 2019)

You are correct M30CRules-- I believe the 30MPH thing is emergency braking when not in TACC.


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## Bokonon (Apr 13, 2017)

M3OC Rules said:


> Does this apply to Autopilot phantom braking? I don't believe I have ever had phantom braking without TACC or TACC + Autopilot on.


Yep, phantom braking can occur when both TACC + Autosteer are engaged, or when only TACC is engaged. I'm not aware of any reports of phantom braking without some form of TACC being engaged.


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## mswlogo (Oct 8, 2018)

undergrove said:


> If you set the speed assist offset slider to -20 it will maintain the speed at which you are travelling when you engage TACC or Autopilot. You can change this speed with the right thumb wheel, but it will not adjust automatically to speed limits. The disadvantage is that you have to continually adjust the max speed as speed limits or conditions change.


I kind of ignored this post when I first saw it (he's nuts ), but now after reading some subsequent posts, I must say you may be on to something.

I never considered that the car might confuse that the speed limit on the lower speed bridge might momentarily get applied and slow down to that speed.

I never really found TACC Auto Adjusting to the current Posted Speed Limit (PSL) work very well at all (very hit or miss), except that when I engage it, it starts at the current PSL, which I do like and I have set to Offset 0.

If the car has momentary confusion of which road the car is on, is causing the bulk of (my) phantom breaking, that's incredibly scary. Because it's NOT HARD to fix.
I never do get any warning on Phantom Breaking. It just drastically slows down and then speeds up again (possible by my foot, can't recall happens so fast).

GPS's glitch, period. Every GPS report is not perfect. You need to sanitize it. The Vehicle cannot instantaneously be on highway doing 70 mph heading north and 1 second later be on a Road Heading West rated for 35 MPH.
Ever been driving alone and Google Maps suddenly says, Enter highway at ramp when your are already on the highway, and you look down and your position is on the auxiliary road next to the highway? Of course you have. I've seen in in every Nav system, doesn't happen to often. But what if your throttle is hooked to the Speed of that road !! I've never a Nav put me on the crossing bridge though. Good Nav software knows how to deal with that.

Now, I do find most phantom braking is during daylight hours (i.e. shadows from bridges, or so I thought). But I've seen it on heavy cloudy days and occasionally at night too. It could be I can't see the bridge at night (or less so).

So I plan to try your "work around" ASAP.

So to be clear, you're saying if you set offset to -20, when I engage TACC it will still use current speed, or will it use PSL -20. If it does that, it will be annoying, but still possibly worth it, if it works. But if it just goes my current speed, that would be great.

Now I'm sure TACC also false brakes, for what it sees for obstructions (that can happen on other systems too). But I'm curious why in every case it has not popped a warning. So now I'm not sure if these are all bad Speed Changes.
But even when I do hit a "Not Supported" Speed for Auto Steer, I do get a warning on that. But maybe these bridges are "Supported" for Auto Steer at the PSL, but just a lower SPL. So no warning, just drastic reduction in speed.

I also never bought, bad mapping data, because it never repeats in the same spot. At least not for me.

This -20 offset workaround would be great if it just disables Auto PSL Adjustment (possible bulk of Phantom Braking) and engages at current throttle speed.

Thanks !! Worth a shot for sure.


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## Technical48 (Apr 29, 2018)

19Model34me said:


> The solution is to be able to turn off TACC and just have regular cruise control. That would satisfy the mass market and allow the Beta testers to play. I hope it happens soon because my wife will no longer drive in the car from getting sick from the constant braking and I'm considering selling it. I've been almost rear ended multiple times with horns blaring and fingers waving because there were tree shadows on the road. It's definitely a safety issue for me, I don't trust the car one bit.
> 
> Every other company with adaptive cruise let's you turn it off, that's all I ask.


I agree 100%. Because TACC can't be user-disabled I wouldn't opt for AP even if it was free. Both times I had the AP trial I was relieved when it was finally over since I could go back to plain CC. Autosteer was nice but not nearly nice enough to put up with a crappy implementation of TACC.


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## undergrove (Jan 17, 2018)

mswlogo said:


> I kind of ignored this post when I first saw it (he's nuts ), but now after reading some subsequent posts, I must say you may be on to something.
> 
> I never considered that the car might confuse that the speed limit on the lower speed bridge might momentarily get applied and slow down to that speed.
> 
> ...


Yes. The -20 setting changes the behavior of TACC or AutoSteer to be more like other cruise controls. It sets and maintains the speed at which you engage it, unless traffic ahead of you slows down--it is still Traffic Aware. It does not change the speed setting when the speed limit changes, either up or down. You must do that manually. It is less unpredictable, but less automatic. I have very few braking episodes that are not due to surrounding traffic.


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## Long Ranger (Jun 1, 2018)

undergrove said:


> Yes. The -20 setting changes the behavior of TACC or AutoSteer to be more like other cruise controls. It sets and maintains the speed at which you engage it, unless traffic ahead of you slows down--it is still Traffic Aware. It does not change the speed setting when the speed limit changes, either up or down. You must do that manually. It is less unpredictable, but less automatic. I have very few braking episodes that are not due to surrounding traffic.


I'm pretty skeptical that this -20 setting has any effect whatsoever on unwanted phantom braking or anything related to TACC slowing the vehicle. The only thing that I believe it will do is prevent unwanted acceleration at the moment you engage TACC if you happen to be driving slower than the posted speed limit.

In my experience, TACC (without autosteer) does not adjust your speed up or down based upon posted speed limits, even with an offset of 0. It will slow for curves and interchanges, but that isn't due to speed limits. I can set TACC to 50 in a place where the car thinks I've suddenly transitioned to a 30mph road and it doesn't slow one bit. With autosteer enabled, it will slow to 35mph there, but I'm pretty sure the -20 offset won't prevent that.


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## undergrove (Jan 17, 2018)

Long Ranger said:


> I'm pretty skeptical that this -20 setting has any effect whatsoever on unwanted phantom braking or anything related to TACC slowing the vehicle. The only thing that I believe it will do is prevent unwanted acceleration at the moment you engage TACC if you happen to be driving slower than the posted speed limit.
> 
> In my experience, TACC (without autosteer) does not adjust your speed up or down based upon posted speed limits, even with an offset of 0. It will slow for curves and interchanges, but that isn't due to speed limits. I can set TACC to 50 in a place where the car thinks I've suddenly transitioned to a 30mph road and it doesn't slow one bit. With autosteer enabled, it will slow to 35mph there, but I'm pretty sure the -20 offset won't prevent that.


I haven't driven with a 0 setting for some time so some things may have changed. I also use AutoSteer much more than TACC, so I am less sure about how much the -20 setting might reduce Phantom Braking in that mode. With the -20 setting the max speed setting will not change in TACC or AutoSteer though it will adjust actual speed in reaction to curves or slowing or speeding up of traffic (up to the max speed setting).

It may be that I am just lucky and do not encounter many of the conditions that trigger Phantom Braking. I mainly use AutoSteer and occasionally TACC locally on a familiar set of 2 lane country roads, undivided 4 lane highways, divided highways, and occasionally on local city streets. I have less experience with the latest updates on longer trips into L.A. or further out.

In any case, my wife and I prefer the behavior with the -20 setting over other settings we have tried. Try it and decide for yourself.


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## Long Ranger (Jun 1, 2018)

undergrove said:


> I haven't driven with a 0 setting for some time so some things may have changed. I also use AutoSteer much more than TACC, so I am less sure about how much the -20 setting might reduce Phantom Braking in that mode. With the -20 setting the max speed setting will not change in TACC or AutoSteer though it will adjust actual speed in reaction to curves or slowing or speeding up of traffic (up to the max speed setting).
> 
> It may be that I am just lucky and do not encounter many of the conditions that trigger Phantom Braking. I mainly use AutoSteer and occasionally TACC locally on a familiar set of 2 lane country roads, undivided 4 lane highways, divided highways, and occasionally on local city streets. I have less experience with the latest updates on longer trips into L.A. or further out.
> 
> In any case, my wife and I prefer the behavior with the -20 setting over other settings we have tried. Try it and decide for yourself.


The -20 setting is working best for you, so I agree, stick with it. However, I use an offset of 0 and I'd describe my experience as nearly identical to yours. I also usually have autosteer enabled, and it does not change the set speed up or down when the speed limit changes. The exception to that is when the car enforces the +5mph autosteer speed limit on roads that aren't divided highways.

I did try the -20 offset on my commute home tonight. It was just one drive, but I went through a few scenarios and it seemed to confirm to me that there was no difference in behavior, other than the speed it sets when you initially engage TACC/autosteer.


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## mswlogo (Oct 8, 2018)

undergrove said:


> I haven't driven with a 0 setting for some time so some things may have changed. I also use AutoSteer much more than TACC, so I am less sure about how much the -20 setting might reduce Phantom Braking in that mode. With the -20 setting the max speed setting will not change in TACC or AutoSteer though it will adjust actual speed in reaction to curves or slowing or speeding up of traffic (up to the max speed setting).
> 
> It may be that I am just lucky and do not encounter many of the conditions that trigger Phantom Braking. I mainly use AutoSteer and occasionally TACC locally on a familiar set of 2 lane country roads, undivided 4 lane highways, divided highways, and occasionally on local city streets. I have less experience with the latest updates on longer trips into L.A. or further out.
> 
> In any case, my wife and I prefer the behavior with the -20 setting over other settings we have tried. Try it and decide for yourself.


I was skeptical too. I experimented tonight with various settings.

First that UI is really messed up. He's right, at -20 it seems to ignore PSL when you engage TACC. And it does go to current speed. Well, if it's ignoring PSL when you engage it, it may ignore all PSL's, which could be a really good thing !!!

I turned the Chime on to partially learn what it was doing. The UI, gives you the impression it's JUST a Speed Limit warning offset. But obviously it's not.

But what's really ironic is when you set it to "Absolute" Limit, it continues to use the "Relative" Value you last set for TACC Engagement. That's really F'd up.

Was there a shortage of input TextBoxes or something? The TACC Offset should be separate from the Speed Limit Warning. I'd love to set Speed Limit Warning Chime to +15 MPH but I don't want TACC to start at +15.
Why would I want to get speed limit warned exactly at the speed TACC initializes to !! Hello.

Should know by end of long weekend if it helps Phantom Braking. It all makes a little bit of sense that it could help.


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## M3OC Rules (Nov 18, 2016)

I'll give the -20 a try but I think most of my speed limit issues are with errors in Google Maps combined with the 5mph over limit causing me to have to turn it off. And if it doesn't get rid of the 5mph limit on it seems like it won't help the GPS issue in most cases. I noticed in the manual they talk about reading speed limit signs but I've seen no indication that they have turned that on. They better get that working before they try to turn on FSD though or it's going to be very bad.

From the manual on speed assist limitations"

_Visibility is poor and speed limit signs are not clearly visible (due to heavy rain, snow, fog, etc.)._
_Bright light (such as from oncoming headlights or direct sunlight) is interfering with the view of the camera(s)._
_Model 3 is being driven very close to a vehicle in front of it which is blocking the view of the camera(s)._
_The windshield is obstructing the view of the camera(s) (fogged over, dirty, covered by a sticker, etc.)._
_Speed limit signs are concealed by objects._
_The speed limits stored in the GPS database are incorrect or outdated._
_Model 3 is being driven in an area where GPS data is not available._
_Traffic signs do not conform to standard recognizable formats._
_A road or a speed limit has recently changed."_
They also list the GPS issue in the manual:
"_Note: GPS data is not always accurate. The GPS can miscalculate a road's location and provide the speed limit for a directly adjacent road that may have a different speed limit. For example, the GPS can assume Model 3 is on a freeway or highway when it is actually on a nearby surface street, and vice versa_."

You should be able to tell what kind of problem it is. If it's a Google Maps problem it will happen every time and you should see the speed limit changing. (You can also check on Google Maps Mobile now what the speed limit is while driving. Not on the browser version, unfortunately.) If it's a GPS issue you should see the speed limit change and change back. (I guess I don't know how fast that can happen and meanwhile you're looking to see if someone is going to rear end you..) If it's a false object detection you should see no change to the speed limit. If its a slowing for another car you should see the car highlighted on the screen. Am I missing anything?


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## barjohn (Aug 31, 2017)

As a scientist/engineer that has worked on many problems where false positives are an issue to be resolved by not having more than one in 10K or 100K events, and the fact that other cars with TACC are not exhibiting the high frequency of false positives, I think this should be a priority for Tesla to resolve. Unfortunately, they don't provide the user with enough information to help them solve the issue.

For example, one of the problems I worked on was in Chemical agent detection. We needed detectors that could detect quickly enough and at low enough levels to provide time for our servicemen to put on protective gear. It is a lot of work and very uncomfortable in high heat desert environments to put on this gear based on a false positive. People naturally start to ignore the warning after a certain number of false positives or they quit using your system and revert to the famous Kuwaitie Chickens as being a more reliable means of getting a warning (canary in the coal mine is another). In our case, we needed to develop better and more reliable ways to test the systems and keep them properly calibrated.

For example Tesla could show us what the car thought it was reacting to and ask us to confirm that the danger was real or not. Then it could learn to identify the ghosts from the real threats. Without this type of real-time driver input there is no way, just looking at the data after the fact that Tesla can identify and fix the problem.


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## MelindaV (Apr 2, 2016)

barjohn said:


> For example Tesla could show us what the car thought it was reacting to and ask us to confirm that the danger was real or not. Then it could learn to identify the ghosts from the real threats.


the issue with that though, is many drivers are not attentive enough to the surroundings to realize/understand when there was an actual threat the car was reacting to. They would end up with many replying saying there was zero threat, when in reality, there was a car coming into their lane that just failed to notice.


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## barjohn (Aug 31, 2017)

So you are thinking that having no data is better than having some erroneous data? Remember I said that the display would identify what the car thought the threat was. It would show the type of threat and location. The driver could respond with 1. No threat observed, 2. Confirmed threat observed or 3. Not sure as I wasn't paying attention at the time.

Tesla could then throw out the uncertain responses.


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## lance.bailey (Apr 1, 2019)

barjohn said:


> For example Tesla could show us what the car thought it was reacting to and ask us to confirm that the danger was real or not. Then it could learn to identify the ghosts from the real threats. Without this type of real-time driver input there is no way, just looking at the data after the fact that Tesla can identify and fix the problem.


in another thread I suggested a button that the driver could press to indicate "autonomous didn't get things correct here" which would relay the current/relevant logs/images to the mothership for analysis.

this would remove the information being incorrectly interpreted by an inattentive driver when relayed to Tesla (because the logs and images are being used for analysis, not the driver's interpretation) and gets better beta testing back to Tesla.

Step one of problem solving is understanding the problem. Often a problem can only be understood by watching it happen. After that you can solve it.


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## M3OC Rules (Nov 18, 2016)

barjohn said:


> So you are thinking that having no data is better than having some erroneous data? Remember I said that the display would identify what the car thought the threat was. It would show the type of threat and location. The driver could respond with 1. No threat observed, 2. Confirmed threat observed or 3. Not sure as I wasn't paying attention at the time.
> 
> Tesla could then throw out the uncertain responses.


If Tesla is smart there is no reason they don't have every single false positive recorded. And I don't think it would take that many resources to identify what the source was. Many could be determined algorithmically in the car I would think. I don't think user input is necessary.


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## lance.bailey (Apr 1, 2019)

M3OC Rules said:


> If Tesla is smart there is no reason they don't have every single false positive recorded ... I don't think user input is necessary .


and that is the trick. If the car is able to determine that a false positive just happened, then the car should not have reacted to the false positive. The whole point of a false positive in any system is that the system detected something that was not true and could not tell that it was not true. The system (car) truly, but incorrectly, thought there was a positive answer to the question "is there something oncoming in my path?"

False negatives are easier to determine ("nope nothing there", but wrong) because of following events (the crash, the wheel wrenching, the successive proximity alert, ...), but false positive like phantom braking are harder to confirm without another system telling you that your positive reading is false.

That's why user input is so necessary in eliminating false positives - we are that additional system, and the need for us as the additional system is the reason AP/FSD/NOA is beta and why we are told to keep the hands on the wheel and stay alert.


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## M3OC Rules (Nov 18, 2016)

lance.bailey said:


> and that is the trick. If the car is able to determine that a false positive just happened, then the car should not have reacted to the false positive. The whole point of a false positive in any system is that the system detected something that was not true and could not tell that it was not true. The system (car) truly, but incorrectly, thought there was a positive answer to the question "is there something oncoming in my path?"
> 
> False negatives are easier to determine ("nope nothing there", but wrong) because of following events (the crash, the wheel wrenching, the successive proximity alert, ...), but false positive like phantom braking are harder to confirm without another system telling you that your positive reading is false.
> 
> That's why user input is so necessary in eliminating false positives - we are that additional system, and the need for us as the additional system is the reason AP/FSD/NOA is beta and why we are told to keep the hands on the wheel and stay alert.


I disagree. At the time of the event the car thinks something is wrong. If you stop there then what you say is correct. But if you look at the data after that you can verify if that was correct. For example, if the gps gets off and thinks it's on a different road it may brake but soon after that it realizes it was wrong and jumps back to the right road. That seems pretty easy to identify after the fact. Same thing if it incorrectly identifies something in the road. You can also look at the driver response. If the car brakes and the driver immediately hits the throttle it's a good indicator something went wrong. Maybe they couldn't get all of the events but I would think they could get the vast majority of what I've experienced pretty easily. Especially the really bad ones.


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## lance.bailey (Apr 1, 2019)

GPS thinking it's on the wrong road and braking because of that, only to correct itself to the right road and then determine based on the road correction that the earlier braking issue was a false positive is a bit of a corner case.

I would be happier if phantom braking on a freeway disappeared. So no GPS error, no obstacle in front of me, nothing but open asphalt, a false positive brake and a P.O.ed wife.


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## M3OC Rules (Nov 18, 2016)

lance.bailey said:


> I would be happier if phantom braking on a freeway disappeared. So no GPS error, no obstacle in front of me, nothing but open asphalt, a false positive brake and a P.O.ed wife.


I'm torn on this. I use AP all the time. If it was braking all the time I would not use it. But at the same time, I can totally relate to the P.O.ed wife and know others in the same boat. Meanwhile, Tesla is getting kudos for their active safety and trying to catch up and/or stay ahead of everyone else.


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## Dr. J (Sep 1, 2017)

@M3OC Rules may be on the right track. From the Investor Day presentation, I surmise that Tesla gathers data from the fleet (of drivers sharing data) to help the neural net learn from false positives. I don't know whether there's a room full of minions reviewing flagged instances of behavior described in this thread--seems doubtful, but possible--but somehow they are tracking, reviewing, and presumably fixing these issues. I don't know whether crowd sourcing this would help or hurt. The suggestions here are better than the clunky bug fix procedure, but would require at least a little driver attention, which opens up liability issues. I'm ambivalent.


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## Dr. J (Sep 1, 2017)

M3OC Rules said:


> I'm torn on this. I use AP all the time. If it was braking all the time I would not use it. But at the same time, I can totally relate to the P.O.ed wife and know others in the same boat. Meanwhile, Tesla is getting kudos for their active safety and trying to catch up and/or stay ahead of everyone else.


My default is to wait on automation to catch up by not using certain features if someone else is in the car with me, and experiment with beta software when I'm alone and paying attention.


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## GeoJohn23 (Oct 16, 2018)

I agree, for the reason stated earlier, that relying solely on driver input that a braking event was unnecessary would not be a good idea. And while I agree that the car/Tesla likely has sufficient data for a re-analysis and then tweaking of the response. The trick is, not all (and probably not even that high a %) of the breaking events should be reviewed/analyzed for feature improvement... this is where I like the ideas of highlight what the car saw as the issue (like it does for collison warning) and provide for driver input. Perhaps this could even be Thumbs up — that’s Tesla, good catch — Thumbs down, what the H was that about? (the Thumbs down being the important input for the mothership to pull and review the data — like the VAR they do in the World Cup.... (Go ladies, awesome talent on display by all the teams).

Without some form of Thumbs down tagging, I don’t see how they could do very well at finding and thus fixing this.


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## lance.bailey (Apr 1, 2019)

Dr. J said:


> @M3OC Rules may be on the right track. From the Investor Day presentation, I surmise that Tesla gathers data from the fleet (of drivers sharing data) to help the neural net learn from false positives....


How would Tesla know that something is a false positive? If someone's car brake's unexpectedly and then drives on, what feedback is there to indicate a false positive? I suspect that as far as the car is concerned, a necessary braking was done.

Let's table top a side street squirrel incident.


car drives along
squirrel dashes out
car brakes
squirrel dashes back
driver presses the accelerator to override the braking (as the squirrel is gone)
This happens to me reasonably often (darn squirrels). Now let's table top a phantom brake.

car drives along
car "sees" something
car phantom brakes
driver swears/apologizes
driver presses the accelerator to override the phantom braking
In both cases, you have a drive, brake, accelerate sequence. In both cases, the car thought it was doing the right thing - there is no feedback to the car that the braking in the second case is imaginary and I suspect that as far as the car is concerned, a necessary braking was done. In the mind of the car there was no false positive, so there is no need to analyse and fix them. You can't fix what you don't know happened.

The reason I have suspicions about the car not being able to determine false positives is because of the ongoing phantom braking complaints that we have here on the forum. I truly do not believe that enough false positives are being fed to Tesla, giving them enough data to address what continues to be an issue in a lot of posts.


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## MelindaV (Apr 2, 2016)

lance.bailey said:


> The reason I have suspicions about the car not being able to determine false positives is because of the ongoing phantom braking complaints that we have here on the forum. I truly do not believe that enough false positives are being fed to Tesla, giving them enough data to address what continues to be an issue in a lot of posts.


for those getting the phantom braking, are you all recording a bug report with each?


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## Dr. J (Sep 1, 2017)

lance.bailey said:


> How would Tesla know that something is a false positive? If someone's car brake's unexpectedly and then drives on, what feedback is there to indicate a false positive?


from the video being recorded by the car. Someone or some machine would have to collect the video [edit: of all AP braking events] and review the evidence.

Edit:
*Dacia 12:44 PT:* We ask the fleet to send us data focused on a problem to be solved, and that's used to train the neural network further, Andrej explains. He previously mentioned "tunnel" problems as an example, here is using cut ins from cars coming from other lanes. The false positives and false negatives are then analyzed, used for retraining.
https://www.teslarati.com/tesla-autonomy-day-livestream-updates/

Final edit [everyone is hoping!]:
Not to the beat the dead horse, but it's not that the car can figure out whether a past automatic braking event was warranted or not. Clearly, the car thought the braking event was warranted. But the car is also recording all kinds of data about the event--place, time, speed, video before during and after--that Tesla can access and use for training the neural network for future improvements. Those improvements are incorporated into future firmware releases, which your car will then receive. Then, you will find out whether the flaw has been fixed.


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## lance.bailey (Apr 1, 2019)

MelindaV said:


> for those getting the phantom braking, are you all recording a bug report with each?


I thought it was established that the bug reports are stored until downloaded by the service center. or is that an urban myth.


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## lance.bailey (Apr 1, 2019)

Dr. J said:


> from the video being recorded by the car. Someone or some machine would have to collect the video [edit: of all AP braking events] and review the evidence.
> 
> ... Clearly, the car thought the braking event was warranted. But the car is also recording all kinds of data about the event--place, time, speed, video before during and after--that Tesla can access and use for training the neural network for future improvements....


are you suggesting that every single braking event be analyzed and reviewed, including video and logs?

Doing that to be able to learn about phantom braking, is a bit of needle in a haystack search. I have dozens of braking events every commute, and only a few would I consider "bad", and I am not sure that someone else (AI, deep learning or flesh/blood) would agree with the driver if the braking was warranted, and I am not sure that examining orders of magnitude of data is ... efficient.

Doctors do not stand on the street and examine each person that walks past on the chance of finding a person with an ailment. People with ailments come to the doctor and make them aware of the problem. Much more efficient.

remember - Tesla already has millions and millions of miles of data and exabytes of data being analyzed, yet the drivers are still complaining of unnecessary braking. By definition, the drivers are the best judge to determine if the driver experienced unnecessary braking, why not feed this information into the research system?


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## Dr. J (Sep 1, 2017)

lance.bailey said:


> are you suggesting that every single braking event be analyzed and reviewed, including video and logs?


I wrote "AP braking," so yes, every automated braking event. I expect this is true.


lance.bailey said:


> Doctors do not stand on the street and examine each person that walks past on the chance of finding a person with an ailment. People with ailments come to the doctor and make them aware of the problem. Much more efficient.


That is efficient for people, yes, for computers, no. It would be mind-blowing to have a computer positioned on the street corner to scan each passer-by, diagnose and refer the sick ones to physicians. That would really do a lot for preventive medicine.


lance.bailey said:


> remember - Tesla already has millions and millions of miles of data and exabytes of data being analyzed, yet the drivers are still complaining of unnecessary braking. By definition, the drivers are the best judge to determine if the driver experienced unnecessary braking, why not feed this information into the research system?


I don't have a great answer for why it's taking so long, but keeping in mind that humans are error-prone, I would respectfully disagree that drivers are by definition the best judge of anything related to driving. Eyewitnesses often identify the wrong person as a suspect in crime, people are often notoriously bad at choosing life partners, and drivers in accidents will often attribute blame to anything but their own actions.


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## bwilson4web (Mar 4, 2019)

I have a loop that reproduces the phantom braking when the Sun is low on the horizon:





"SPACE" stops/starts playback
"," back one frame
"." forward one frame
With cruise control set for 18 mph, the GPS (text in lower middle) showed a dip to 9 mph before the car resumed 18 mph. Autosteer was not engaged, only TACC was used. I captured this from a better dash cam, ignore the sound as the dash cam rattles against the car. This is a loop I've replicated phantom braking with our BMW i3-REx with 'magic eye.'

This is my test loop:














Because of the slope, in the morning I can get direct sunlight on the car as well as shadows.

Bob Wilson


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## garsh (Apr 4, 2016)

lance.bailey said:


> How would Tesla know that something is a false positive?


From the fact that the driver "takes over". In this case, by pressing the accelerator.


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## mswlogo (Oct 8, 2018)

I used the -20 trick for a 120 trip. No phantom brake. This was at night in which it tends to happen less. Need some daytime long trek to still confirm. 

One thing I did notice is it felt like it was about to phantom brake once (it was just before a bridge), and it didn’t follow through !! I’ve never felt that before. 

Second, I swear one time it actually engaged 20 mph below PSL, but I could not repeat it.


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## msjulie (Feb 6, 2018)

Bokonon said:


> Yep, phantom braking can occur when both TACC + Autosteer are engaged, or when only TACC is engaged. I'm not aware of any reports of phantom braking without some form of TACC being engaged.


Happened to me 1 time so I suspected AEB was misbehaving (no AP or TACC active) though car speed was not over 40mph I think.. service visit got scheduled, nothing came of it.. I have collision warning set to late fwiw


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## mswlogo (Oct 8, 2018)

mswlogo said:


> I used the -20 trick for a 120 trip. No phantom brake. This was at night in which it tends to happen less. Need some daytime long trek to still confirm.
> 
> One thing I did notice is it felt like it was about to phantom brake once (it was just before a bridge), and it didn't follow through !! I've never felt that before.
> 
> Second, I swear one time it actually engaged 20 mph below PSL, but I could not repeat it.


Done about 400 miles now with -20, I'm definitely heavily leaning towards I think it helps a ton. But the car has fooled me way to many times thinking something is "better" when it's not.

The first 300 miles was at night and phantom braking tended to happen less at night. Today I did 50 miles or so at 2PM (usually when it did the worst phantom braking) and it worked.

Here is the interesting part. I swear it *started* to phantom brake and then changed it's mind, 3 times. It's never done that before !! It dropped like 2 mph for just 1 second and then fine.
It's like it still got the glitch, but then looked at the weird -20 offset and thought, I'm not sure what to do and went back to speed.


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## Scubastevo80 (Jul 2, 2018)

mswlogo: I've had your scenario happen quite a bit. The "should I brake hard, nah" instance where the car drops about a mph (which is still noticable) and then resumes speed. This doesn't bother me anymore, but can be startling and is the main reason my wife doesn't want me using autopilot with her in the car. Her S doesn't have this issue.

Holy phantom braking this morning... I had two aggressive braking scenarios, both of which seemed to be when going under an overpass on a decline where shadows existed. I sent a bug report for the one that shaved about 15 mph off my speed. If this occurs again tomorrow, I'm going to quickly frustrated.


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## crazym3 (Apr 20, 2019)

undergrove said:


> If you set the speed assist offset slider to -20 it will maintain the speed at which you are travelling when you engage TACC or Autopilot. You can change this speed with the right thumb wheel, but it will not adjust automatically to speed limits. The disadvantage is that you have to continually adjust the max speed as speed limits or conditions change.


But many of phantom breaking happens at freeway. And freeway has always one speed I. Los Angeles 65 mph.


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## DocScott (Mar 6, 2019)

crazym3 said:


> But many of phantom breaking happens at freeway. And freeway has always one speed I. Los Angeles 65 mph.


We don't have "freeways" in the Northeast US. We have parkways and interstates and other things like that, but they aren't _quite_ the same thing. While there may indeed be stretches of hundreds of miles where the speed doesn't change, there are also stretches, particularly around cities, where it does.


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## MelindaV (Apr 2, 2016)

DocScott said:


> We don't have "freeways" in the Northeast US. We have parkways and interstates and other things like that, but they aren't _quite_ the same thing. While there may indeed be stretches of hundreds of miles where the speed doesn't change, there are also stretches, particularly around cities, where it does.


my commute on an interstate "freeway" has at least 3 speed limit changes each direction (all of 10 miles). So freeway's on the west coast do have speed changes.


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## mswlogo (Oct 8, 2018)

Scubastevo80 said:


> mswlogo: I've had your scenario happen quite a bit. The "should I brake hard, nah" instance where the car drops about a mph (which is still noticable) and then resumes speed. This doesn't bother me anymore, but can be startling and is the main reason my wife doesn't want me using autopilot with her in the car. Her S doesn't have this issue.
> 
> Holy phantom braking this morning... I had two aggressive braking scenarios, both of which seemed to be when going under an overpass on a decline where shadows existed. I sent a bug report for the one that shaved about 15 mph off my speed. If this occurs again tomorrow, I'm going to quickly frustrated.


Is that with the -20 Offset experiment or without. If not, try it. I can't say for sure just yet. I've not done a ton of driving when bright and sunny with shadows. But I have not had a hard phantom brake yet since try -20. I've had good stretches before as well.


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## justaute (Dec 15, 2018)

I'm on 20.2. When using AP, i noticed a lot of phantom braking on the freeway when the lanes "curve" and there are vehicles on the outer/front position; in other words, when another vehicle is in the positions of 1 o'clock, 2 o'clock, 10 o'clock, and 11 o'clock. To me, basically AP can't seem to recognize the lanes are just curving and the vehicles in the outer/front positions are in the next lane, not in front of you.


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## Bokonon (Apr 13, 2017)

About an hour into our family's day-trip to ThomasLand, we've encountered no fewer than four phantom-braking incidents and even one phantom-steering event. Oh, BTW, we're in the Subaru, with a human doing 100% of the driving. 

To the points above, at least I can smile sweetly at the driver and ask why she reacted that way, whereas you cannot do that with Autopilot. Some kind of feedback would be informative and potentially helpful for predicting future incidents.


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## Franklin L (Sep 23, 2017)

Has Elon said HOW phantom breaking and crashing into stopped cars (2 sides of the same coin) will be fixed (beyond just improving the neural net)? I know he hates Lidar but wouldn’t this address the problem? It’s going to have to be fixed if FSD is ever considered safe.


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## MelindaV (Apr 2, 2016)

Franklin L said:


> Has Elon said HOW phantom *braking *and crashing into stopped cars (2 sides of the same coin) will be fixed (beyond just improving the neural net)? I know he hates Lidar but wouldn't this address the problem? It's going to have to be fixed if FSD is ever considered safe.


it will not be lidar. Lidar is not priced competitively enough to be used on a production rollout car. at least not to date, or in the foreseeable future.


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## mswlogo (Oct 8, 2018)

mswlogo said:


> This -20 offset workaround would be great if it just disables Auto PSL Adjustment (possible bulk of Phantom Braking) and engages at current throttle speed.
> 
> Thanks !! Worth a shot for sure.


I've been running this -20 offset for like a month now. I have to say it has improved things a lot.

However, I do miss it starting off at the posted speed limit when I engage TACC, not a huge deal, but I do miss it.

It is not full proof. One thing I have learned is that when the car does say slow down aggressively, say by a *mere *20 mph, it feels like it slammed on the brakes hard, maybe it did, but I think it feels worse than it really is.

I was driving home on a 120 mile trip the other day and I *did *have a couple phantom brakes. But each one seemed, albeit overly cautious and not something I would ever do, but there were reasons for them. I'm ok with that.

In one case, I was zooming into a toll booth quicker than I normally do (I usually slow way sooner than 95% of the other drivers). I typically cancel TACC early to get good regen. But there was a car jockeying for a slot so I kept my speed up a little longer (more in line with other cars). More so to communicate to the other driver my intent for my lane choice, nothing aggressive. Out of the blue the car aggressively slowed down. Crap, I'm in a 35 mph zone doing 60. So if it's a large offset it will still change speed. Now it might have seen the toll booth as an obstacle. It was still a fair distance away. But it had good reason to slow down. Nothing on the screen, no warnings.

Another case was a Semi pulled over on the shoulder. I immediately looked down at the screen after it "Phantom Braked" and the Semi was not showing. There was no reason to brake, but I can see why it might have been cautious. Again no warning, no beep. Semi did look "out of place".

One other case was cars jockeying in lanes ahead but not in my lane.

Before the -20 Offset I used have so many cases of phantom braking with no clear reason at all, expect an overpass ahead (and sometimes not). Since doing the -20 offset that has not happened once.
I'm tempted to turn that back to normal (0 offset) to see how it's doing.


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## Madmolecule (Oct 8, 2018)

I had a couple instances of phantom braking yesterday. 2019.24. I was the first time in a few months since this has occurred. Both times were shadows under a bridge, but on a flat surface this time. It definitely frustrated the driver behind me. It wasn’t as severe as it was in the past but very noticeable. I want to get a an “autopilot on board” sign but I can’t find one for sale, It used to be on eBay. We need someway to say sorry it’s not me, being an ahold.


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## undergrove (Jan 17, 2018)

mswlogo said:


> I've been running this -20 offset for like a month now. I have to say it has improved things a lot.
> 
> However, I do miss it starting off at the posted speed limit when I engage TACC, not a huge deal, but I do miss it.
> 
> ...


I just completed a 120 mile round trip into L.A. on a familiar route, using for the first time Firmware 28.2. I experienced no episodes of phantom braking with two exceptions.

The first was the usual place in the perpetual construction zone on the I-5 around Santa Clarita where the car thinks the speed limit drops from 65 to 40 for a few hundred feet--this area has undergone so many changes in the last year that I do not drive it at night even without Autosteer, because you never know what you might encounter--no wonder the Tesla might be confused. It is only one specific spot.

The second was a brief slight slow down on a rural 4 lane undivided highway--not what I would normally call braking, but there were no other vehicles anywhere nearby. This road was being repaved for most of the last year and was intermittently under lane and speed limit restrictions. Maybe our Teslas have a memory of these things and remain extra cautious for a while ; ).

We have been using the -20 setting for about 9 months, and true phantom braking has been pretty rare and getting rarer.

On my first long drive on 28.2 in moderately heavy traffic in L.A. even caution braking seemed rarer and much smoother. Auto lane changes seemed smoother, more patient, and smarter.

This is very preliminary, but consistent with our impression that each major update gets gradually better. I am interested to see if others have similar impressions of 28.2.

It is _not_ Full Self Driving, but with TACC, Autosteer, or NOA we feel much safer with the combination of our eyes and the Tesla's.


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## Steve Martin (Jan 7, 2017)

undergrove said:


> We have been using the -20 setting for about 9 months, and true phantom braking has been pretty rare and getting rarer.


Is "-20" the AP follow distance?


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## garsh (Apr 4, 2016)

Steve Martin said:


> Is "-20" the AP follow distance?


No, it's the "speed limit offset" ("Relative", and "-20mph").
See the bottom of this image:


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## MelindaV (Apr 2, 2016)

undergrove said:


> The second was a brief slight slow down on a rural 4 lane undivided highway--not what I would normally call braking, but there were no other vehicles anywhere nearby. This road was being repaved for most of the last year and was intermittently under lane and speed limit restrictions. Maybe our Teslas have a memory of these things and remain extra cautious for a while ; ).


I think the second example (maybe your first example too) would be explained by the prior drivers slowing in those specific areas and Tesla recording that as the 'real life' speed limit for those areas. 
My freeway interchange (from a 65MPH to a 55MPH freeway) has a pretty sharp right hand curve while still within the 65MPH section and AP will drop to 50 for about 20-30 yards before jumping back up to the new 55MPH speed limit (showing on the display the correct 65/50 speed sign). Most every day, the other traffic is at or below 50MPH anyway, so it is not noticeable, but when going thru the interchange later at night or when there is little traffic, it is abrupt and wacky. (IOW, I have my foot over the accelerator ready to keep it at the cruising speed). Over the last 10+ months of driving the car, it has always dropped to 50 at that one spot, but over time, where those 20-30 yards of reduced TACC speed happens has shifted a little backwards or forwards on the interchange ramp - so does seem dynamic per historical data Tesla is collecting. (and again, in normal traffic, or when following someone that maybe isn't familiar with the ramp or someone with a less stable car it is very normal to be traveling at 50mph at that spot).


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## Madmolecule (Oct 8, 2018)

How does the relative speed limit affect Phantom Braking.


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## MelindaV (Apr 2, 2016)

Madmolecule said:


> How does the relative speed limit affect Phantom Braking.


I've always had mine set to +0 and rarely have any phantom braking. Because of my normal traffic, I am almost always going under the set speed as well - if that makes any difference.
Since some are noticing setting their relative speed significantly under the speed limit, then tapping it up to the speed they want to go, gets fewer phantom braking issues, there may be something to the set speed.


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## Madmolecule (Oct 8, 2018)

To worn other drivers I have ordered some "Autopilot on Board" signs from Alibaba. It we be a couple weeks before I have them to ship. But I listed them on ebay. I have the for $8 with free shipping
, but I am certainly willing to take less if interested.

Ebay listing


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## Madmolecule (Oct 8, 2018)

or warn other drivers


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## MelindaV (Apr 2, 2016)

using AP is not an excuse for not being in control of your car.


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## Madmolecule (Oct 8, 2018)

Its not and excuse at all. But when my car does stupid stuff, I dont want to get shot. (I live in the south - shot first ask questions later). Hopefully FSD will be an excuse, but other drivers have no idea if I had a sign that said FSD on board. Non-Tesla owners aren't aware that Elon keeps changing the definition of autopilot. But thanks for straitening that out for me.


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## 19Model34me (Apr 5, 2019)

Should have a sign that says “I break for shadows” lol


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## undergrove (Jan 17, 2018)

Madmolecule said:


> How does the relative speed limit affect Phantom Braking.


In TACC or Autopilot, with the Speed Limit set to Relative and the Offset to 0, the Tesla will adjust your speed to what it perceives to be the posted speed limit (indicated in the upper right of the area of the screen with the car avatar). If you engage TACC or Autopilot while going slower, it will immediately speed up to the perceived limit.

If you raise or lower the Offset, the Tesla will adjust speed to the perceived limit plus or minus the Offset.

The -20 setting is a special case. When you engage TACC or Autopilot it becomes like a traditional cruise control. It sets and maintains the speed at which you engage. It does not change the set speed as the speed limit changes. You have to do that manually with the right thumb wheel.

One theoretical cause of true phantom braking, which occurs when there is no traffic to cause a caution reaction, is that the Tesla briefly thinks the speed limit has changed--sometimes due to a slow surface street on an over- or underpass. If you look at your screen quickly enough, you can see it change the limit--generally only for a few seconds.

The -20 setting will generally eliminate this kind of sudden slowdown. There still seem to be a few specific locations where there is a persistent brief slowdown for no apparent reason, such as what MelindaV and I have described. These happen even with the -20 setting, but I have found them to be quite rare.

What I would call "Caution Braking," when the Tesla is clearly reacting to surrounding traffic or objects, is not affected by the -20 setting, but I think this has improved steadily with each major firmware update.

My initial impression of 28.2 is that it is significantly smoother and smarter in all maneuvers on TACC, Autopilot, and NOA. My last drive into L.A. was impressive.


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## undergrove (Jan 17, 2018)

Madmolecule said:


> Its not and excuse at all. But when my car does stupid stuff, I dont want to get shot. (I live in the south - shot first ask questions later). Hopefully FSD will be an excuse, but other drivers have no idea if I had a sign that said FSD on board. Non-Tesla owners aren't aware that Elon keeps changing the definition of autopilot. But thanks for straitening that out for me.


I think MelindaV's point is that Autopilot/NOA is _not_ Full Self Driving. It is not as good as a skilled alert human driver and is not represented as being so.

However, I feel that with my own eyes and all of my Tesla's eyes and sensors, I am much safer than driving without. It has made driving much less stressful and more enjoyable. Nevertheless, especially in complex situations, I always feel I need to be ready to take over at any time.

Autopilot/NOA is far from perfect, but it continues to amaze me how far it has come in less than a year,


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## Madmolecule (Oct 8, 2018)

I got it. I have teslas. They warned me all the time to pay attention and keep my hands on the wheel. I have driven cars before. I understand the liability. But the auto pilot does not drive the way most people drive all the time. It is too considerate sometimes and other times just stupid. When it reacts to other cars or highway conditions I find it sometimes confusing to the other drivers. I don’t know a way to react quick enough to phantom breaking at 80 miles an hour. I don’t fee, I was ever at risk of wrecking but I was concerned about the guy behind me running into me and thunking I had done it on purpose for some reason.


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## mswlogo (Oct 8, 2018)

undergrove said:


> In TACC or Autopilot, with the Speed Limit set to Relative and the Offset to 0, the Tesla will adjust your speed to what it perceives to be the posted speed limit (indicated in the upper right of the area of the screen with the car avatar). If you engage TACC or Autopilot while going slower, it will immediately speed up to the perceived limit.
> 
> If you raise or lower the Offset, the Tesla will adjust speed to the perceived limit plus or minus the Offset.
> 
> ...


That is exactly my understanding as well.

Was your 28.2 drive with -20 or not?


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## undergrove (Jan 17, 2018)

mswlogo said:


> That is exactly my understanding as well.
> 
> Was your 28.2 drive with -20 or not?


Yes. Because we live in farm country, all of our trips involve driving on winding two lane country roads to get to a city or highway. Autopilot works very well on these roads but the default speed is 55. Due to critters and farm machinery, etc. it is generally not safe to drive that fast, especially at night. When engaging TACC or Autosteer it was too annoying to have to quickly whip the thumb wheel down to keep the car from jumping to 55, so we leave it at -20.

A side benefit is that we seem to have missed out on a lot of the phantom braking that many have been experiencing.

I think on a long trip on major highways we might put the offset back to 0.


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## undergrove (Jan 17, 2018)

Madmolecule said:


> I got it. I have teslas. They warned me all the time to pay attention and keep my hands on the wheel. I have driven cars before. I understand the liability. But the auto pilot does not drive the way most people drive all the time. It is too considerate sometimes and other times just stupid. When it reacts to other cars or highway conditions I find it sometimes confusing to the other drivers. I don't know a way to react quick enough to phantom breaking at 80 miles an hour. I don't fee, I was ever at risk of wrecking but I was concerned about the guy behind me running into me and thunking I had done it on purpose for some reason.


At 80 mph reactions have to be much quicker, so it is not surprising that the Tesla might be much more jerky. I wouldn't trust my own reactions at that speed.

We almost always drive at or below the posted limits--45 to 65 mph--slower in heavy traffic. Our recent experience has been that the Tesla generally reacts pretty smoothly and intelligently at those speeds. There are still edge cases where we have to intervene.

We also have the follow setting at 6 or 7, which seems to give the Tesla more time to react. I know many people feel they can't use that setting in their driving conditions, but it has worked fine for us in Ventura and L.A. Counties.


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## DocScott (Mar 6, 2019)

Hmm...this thread is making me think: is it possible that some forms of phantom braking are more of a problem for people with EAP or FSD than AP?



undergrove said:


> In TACC or Autopilot, with the Speed Limit set to Relative and the Offset to 0, the Tesla will adjust your speed to what it perceives to be the posted speed limit (indicated in the upper right of the area of the screen with the car avatar). If you engage TACC or Autopilot while going slower, it will immediately speed up to the perceived limit.


That's not what happens for me--and I have just AP, with the offset set at +2. When I engage TACC, AP just sets the speed to whatever speed I was going. If I tap on the speed limit sign it then adjusts to the speed limit +2. If the speed limit changes, the car does not change speed unless I tap on the speed limit sign again. The only time the car changes the set speed is for things like going around curves in cloverleafs or off-ramps.

Maybe if you have EAP or FSD, TACC behaves differently?

If so, that could partially explain why some kinds of phantom braking are being experienced more by some people than others. Perhaps some of the problems (like driving under an overpass and having the speed briefly switch to the speed limit of the road above) are only a problem for people with EAP/FSD?


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## MelindaV (Apr 2, 2016)

DocScott said:


> If so, that could partially explain why some kinds of phantom braking are being experienced more by some people than others. Perhaps some of the problems (like driving under an overpass and having the speed briefly switch to the speed limit of the road above) are only a problem for people with EAP/FSD?


some have been talking about phantom braking while others dont have issues since before they re-arranged EAP to AP, so dont think it's that.


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## SimonMatthews (Apr 20, 2018)

The last few days, I have been experiencing an unexplained slowdown in the same place -- i880N in Milpitas. Today, my car was down to 20mph with nothing in front, the display showing the speed limit as 65mph, no bridges or under/overpasses. It appears to do this quite reliably.


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## Klaus-rf (Mar 6, 2019)

Summary:
Had an interesting braking event today on fwy using NoAP. The braking was expected for AP (I personally would not have slowed down at all) while TACC was soooo slow resuming speed that I had a semi less than a foot off my rear bumper. AP really needs to learn about rear traffic.

Details:
4-lane fwy and I was at Speed Limit +5 ( aka 70 MPH) in lane 3. A vehicle in front of me in lane 2 swithed on its right blinker and made a slow, smooth move across two lanes passing in front of me about 80 feet ahead, moving steadily to lane 4. TACC slowed down - not severely, more like normal regen braking, then stopped slowing, maintaining speed. Traffic (semi truck) came up behind me FAST! Then TACC/AP very slooowly began to resume previous speed. The slow acceleration is a serious problem, imho.

As soon as I saw the semi trying to collect its first Tesla bumper ornament, I added power to get out of its way.

TACC/AP needs to learn about rear coming traffic. Very dangerous how it works now.


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## garsh (Apr 4, 2016)

undergrove said:


> I think on a long trip on major highways we might put the offset back to 0.


I simply leave mine at -20 mph.
All it really means is that I need to manually accelerate up to my desired speed. I find that to be an acceptable tradeoff to having the car accelerate by itself when I'm not expecting it and don't desire it.


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## mswlogo (Oct 8, 2018)

DocScott said:


> Hmm...this thread is making me think: is it possible that some forms of phantom braking are more of a problem for people with EAP or FSD than AP?
> 
> That's not what happens for me--and I have just AP, with the offset set at +2. When I engage TACC, AP just sets the speed to whatever speed I was going. If I tap on the speed limit sign it then adjusts to the speed limit +2. If the speed limit changes, the car does not change speed unless I tap on the speed limit sign again. The only time the car changes the set speed is for things like going around curves in cloverleafs or off-ramps.
> 
> ...


If you are below PSL ( Posted Speed Limit) TACC will bring you up to that speed when engaged.

If you are above PSL it will just match your speed.

The "Offset" adjusts what TACC uses for PSL.

The problem has nothing to do with Auto Steer (AP or EAP or NoA).


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## Technical48 (Apr 29, 2018)

MelindaV said:


> (IOW, I have my foot over the accelerator ready to keep it at the cruising speed).


This right here is a major reason why I'm glad I didn't buy the EAP option. If I'm operating on cruise control I keep my right foot poised for the BRAKE pedal. Ridiculous that EAP forces you to be ready for quick accelerator applications just to avoid getting rear-ended or to avoid a road rage incident because somebody thinks you're brake-checking. I just don't see how EAP is relaxing for anybody unless you're driving on a completely empty road in the middle of nowhere. During the trials that was the only situation where I liked using EAP.


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## MelindaV (Apr 2, 2016)

Technical48 said:


> This right here is a major reason why I'm glad I didn't buy the EAP option. If I'm operating on cruise control I keep my right foot poised for the BRAKE pedal. Ridiculous that EAP forces you to be ready for quick accelerator applications just to avoid getting rear-ended or to avoid a road rage incident because somebody thinks you're brake-checking. I just don't see how EAP is relaxing for anybody unless you're driving on a completely empty road in the middle of nowhere. During the trials that was the only situation where I liked using EAP.


unless you have driven with EAP, you don't get the benefits vs the inconveniences. I don't keep my foot over the accelerator because I think otherwise Id be rear ended - but because Ive learned under specific traffic conditions, the car will slow at specific points. It is no more slowing than any other car driven by a person may do, and no where in the post you quoted from me did I say it slowed to a degree that I worried about being rear ended.


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## DocScott (Mar 6, 2019)

Klaus-rf said:


> Summary:
> Had an interesting braking event today on fwy using NoAP. The braking was expected for AP (I personally would not have slowed down at all) while TACC was soooo slow resuming speed that I had a semi less than a foot off my rear bumper. AP really needs to learn about rear traffic.
> 
> Details:
> ...


That just sounds like an obnoxious semi to me. I've had plenty of experiences like what you describe long before I owned a Tesla. Does that make me a dangerous driver?

I think part of what we'll start encountering as AP gets better is that different people drive very differently, and there's a wide range of behaviors which are consistent with safe and effective driving. "AP doesn't do what I would have done" will always be the case for the vast majority of people, because if you put any other human driver in your car it's very unlikely they'll consistently do what you would have done. But you notice it more when you're the one monitoring it, sitting in the driver's seat and holding the steering wheel.


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## MelindaV (Apr 2, 2016)

DocScott said:


> I think part of what we'll start encountering as AP gets better is that different people drive very differently, and there's a wide range of behaviors which are consistent with safe and effective driving. "AP doesn't do what I would have done" will always be the case for the vast majority of people, because if you put any other human driver in your car it's very unlikely they'll consistently do what you would have done. But you notice it more when you're the one monitoring it, sitting in the driver's seat and holding the steering wheel.


I think THIS is why some owners have different gripes about (E)AP for the last couple years. Some see it being cautious in a situation as a bug that needs to be fixed. Some see it being confident in some situations as it being a bug that needs to be fixed. 
Overall, I drive near the speed limit (when not forced by traffic to be barely moving), I let merging traffic merge, I expect adjacent cars will do something stupid and am waiting to intervene when they do, etc.... 
rarely have I had (E)AP act in a way that I thought was wrong. I think that has more to do with my driving personality being in line with how (E)AP is programed than my car or route giving different results than someone that is always having 'bugs' with theirs.


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## Mr. Spacely (Feb 28, 2019)

Other than occasional complex situations, my car works very well on NOA. It gets me there safely and normally is smooth...


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## Klaus-rf (Mar 6, 2019)

DocScott said:


> Does that make me a dangerous driver?


 Insufficient data presented so far to make that determination.


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## Klaus-rf (Mar 6, 2019)

DocScott said:


> That just sounds like an obnoxious semi to me.


 May be. But NoAP (TACC / AP) didn't even now it was there. If it brakes for something minor in front, shouldn't it then accelerate or move out of the way for something serious behind? Don't we teach human drivers to check all mirrors periodically and adjust [lane / speed / etc.] accordingly??

IMHO the design needs a rear-facing RADAR. It currently has no idea about rear facing traffic. THAT IS DANGEROUS.

Reminds me of an airplane autopilot system that could easily do automated take-offs but couldn't land. BTW - AP landing capabilities have been in commercial airplanes since at least 1977. ( Might not have been FAA Approved then, but the planes were fully capable of landing using AP alone including putting the gear down. )


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## MelindaV (Apr 2, 2016)

Klaus-rf said:


> shouldn't it then accelerate or move out of the way for something serious behind? Don't we teach human drivers to check all mirrors periodically and adjust [lane / speed / etc.] accordingly??


at least here, no. drivers ed and defensive driving doesnt tell people they should speed up because someone behind them is speeding up. get out of the way, if you are blocking faster traffic, yes. but to speed up, no.


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## DocScott (Mar 6, 2019)

DocScott said:


> Hmm...this thread is making me think: is it possible that some forms of phantom braking are more of a problem for people with EAP or FSD than AP?
> 
> That's not what happens for me--and I have just AP, with the offset set at +2. When I engage TACC, AP just sets the speed to whatever speed I was going. If I tap on the speed limit sign it then adjusts to the speed limit +2. If the speed limit changes, the car does not change speed unless I tap on the speed limit sign again. The only time the car changes the set speed is for things like going around curves in cloverleafs or off-ramps.
> 
> ...


I stand corrected.

I got the perfect chance to test this out today, because I brought by Model 3 with AP in for service and then got a Model S with EAP as a loaner. So I drove it across the same section of road...and they behaved pretty much identically with respect to TACC speed.

First off, I was wrong: on today's trips, TACC _usually_ set an initial speed based on the speed limit if I'm going slower than the limit. But for some reason, not always. And if I was going faster than the speed limit-based speed when I engaged TACC, it engaged at the faster speed.

But for both cars, when the speed limit increased on the road I was on the speed limit sign on the display registered the increase, but TACC did _not_ increase the set speed to match. It would probably do if NOA were on, but _not_ for just TACC. If the speed limit on the road decreased, it would sometimes decrease the set speed to what it thought was safe (e.g. speed limit +5), but again it wouldn't be decreasing it to speed limit plus offset; with my offset at +2, it was generally faster than that.

tl;dr: TACC set speeds behave the same whether the car has AP or EAP. When on TACC (but not NOA), TACC does _not_ adjust the set speed when the speed limit on the road changes, unless the speed limit dropped and the car would then be travelling at an excessive speed.


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## Mr. Spacely (Feb 28, 2019)

Klaus-RF said: "Reminds me of an airplane autopilot system that could easily do automated take-offs but couldn't land. BTW - AP landing capabilities have been in commercial airplanes since at least 1977. ( Might not have been FAA Approved then, but the planes were fully capable of landing using AP alone including putting the gear down. )

Not exactly. 99% of all landings and 100% of takeoffs are still done by pilots. And it was only in the last 7-8 years that planes could even attempt to self land. Basically autopilot will get you lined up and very close to the ground, but the pilot has to have a visual of the runway or he/she will abort the landing...


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## Klaus-rf (Mar 6, 2019)

Mr. Spacely said:


> Klaus-RF said: "Reminds me of an airplane autopilot system that could easily do automated take-offs but couldn't land. BTW - AP landing capabilities have been in commercial airplanes since at least 1977. ( Might not have been FAA Approved then, but the planes were fully capable of landing using AP alone including putting the gear down. )
> 
> Not exactly. 99% of all landings and 100% of takeoffs are still done by pilots. And it was only in the last 7-8 years that planes could even attempt to self land. Basically autopilot will get you lined up and very close to the ground, but the pilot has to have a visual of the runway or he/she will abort the landing...


 I agree that those are the FAA's rules. I'm saying that the AP in the planes has been fully capable of doing AP-only landings for decades. Perhaps we could call it "Beta"?

I used to work (on the technical side) at a flight training facility at LAX in the late 70's (owned by Flying Tigers). We had an old DC-8 sim and a newer Lynx 747 simulator unit. Both system were fully capable of landing the planes using AP. We used to test them in the Hong Kong airport with the mountain profiles programmed in. Fun stuff.


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## SimonMatthews (Apr 20, 2018)

SimonMatthews said:


> The last few days, I have been experiencing an unexplained slowdown in the same place -- i880N in Milpitas. Today, my car was down to 20mph with nothing in front, the display showing the speed limit as 65mph, no bridges or under/overpasses. It appears to do this quite reliably.


Didn't happen today, somewhat earlier in the day. Perhaps it is shadows of the dividers, signposts or lights on the road that is causing it. There is nothing on the screen to indicate anything that needed to be avoided.


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## SimonMatthews (Apr 20, 2018)

Mr. Spacely said:


> Klaus-RF said: "Reminds me of an airplane autopilot system that could easily do automated take-offs but couldn't land. BTW - AP landing capabilities have been in commercial airplanes since at least 1977. ( Might not have been FAA Approved then, but the planes were fully capable of landing using AP alone including putting the gear down. )
> 
> And it was only in the last 7-8 years that planes could even attempt to self land.


Go look at the history of Autoland .... it dates back to the '60s.


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## Klaus-rf (Mar 6, 2019)

MelindaV said:


> at least here, no. drivers ed and defensive driving doesnt tell people they should speed up because someone behind them is speeding up. get out of the way, if you are blocking faster traffic, yes. but to speed up, no.


 I beg to differ. Drives that are going too slow get cited for it - because it's dangerous.


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## DocScott (Mar 6, 2019)

Klaus-rf said:


> I beg to differ. Drives that are going too slow get cited for it - because it's dangerous.


Defensive driving courses suggest (here's a second link; there are many more) if someone is tailgating you to slow down slightly, not speed up. This both encourages the jerk to pass you, and gives them more room in front of you to do so.

I understand that the norms for what is safe relative to the speed limit and the flow of traffic vary by region, and that in Southern California the expectation is that most people drive well over the limit, and that driving at the limit there can be a safety hazard. But that's still different from giving in to a tailgater.


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## MelindaV (Apr 2, 2016)

Klaus-rf said:


> I beg to differ. Drives that are going too slow get cited for it - because it's dangerous.


going too slow is not the same as someone behind you coming up on you too fast.


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## undergrove (Jan 17, 2018)

DocScott said:


> Defensive driving courses suggest (here's a second link; there are many more) if someone is tailgating you to slow down slightly, not speed up. This both encourages the jerk to pass you, and gives them more room in front of you to do so.
> 
> I understand that the norms for what is safe relative to the speed limit and the flow of traffic vary by region, and that in Southern California the expectation is that most people drive well over the limit, and that driving at the limit there can be a safety hazard. But that's still different from giving in to a tailgater.


My first concern with a tailgater is to make sure I have extra distance between me and the car ahead so I won't have to brake suddenly. This often means slowing down somewhat. This may irk the tailgater, but it is the only safe thing to do. Then, if there is a lane to my right I will move over when it is safe to do so. These idiots wiil often try to push you faster regardless of speed if you aren't tailgating the car in front of you--even if you are in the rightmost lane. The only thing you can do there is keep an extra safe distance from the car ahead and watch out for them whipping around you and cutting in too fast out of spite.

California law requires a safe following distance. It used to be 1 car length for every 10 mph of speed. It is now a 3 second interval at whatever speed.


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## Dogwhistle (Jul 2, 2017)

Mr. Spacely said:


> Klaus-RF said: "Reminds me of an airplane autopilot system that could easily do automated take-offs but couldn't land. BTW - AP landing capabilities have been in commercial airplanes since at least 1977. ( Might not have been FAA Approved then, but the planes were fully capable of landing using AP alone including putting the gear down. )
> 
> Not exactly. 99% of all landings and 100% of takeoffs are still done by pilots. And it was only in the last 7-8 years that planes could even attempt to self land. Basically autopilot will get you lined up and very close to the ground, but the pilot has to have a visual of the runway or he/she will abort the landing...


Staying a bit off-topic here, but modern aircraft can conduct Category III autolands that do not require the pilot to have visual contact with the runway for the landing. The only restriction on autopilot usage (assuming all systems are functioning normally), is to disconnect the autopilot by 60 knots on landing rollout.


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## Klaus-rf (Mar 6, 2019)

MelindaV said:


> going too slow is not the same as someone behind you coming up on you too fast.


 Quickly slowing does indeed bring those behind you up on you fast. No?

The issue is the car on AP/NoAP slows too much, too quickly [when it doesn't need to] and the it doesn't resume back to normal speed - while traffic is passing on both sides and closing quickly from the rear - when the suspected reason for sudden braking has cleared. By several seconds. If it slowed then sped up again as soon as the obstacle cleared, the issue would not be so much a problem.

As many others have noted and I've stated here several times: AP/NoAp have absolutely no idea about closing traffic from behind. This is dangerous - especially when one adds phantom braking to the mix.

I don;t fault the semi driver at all. He had plenty of clearance until MY car (automagically) dropped 20MPH in 70MPH traffic and waited more than four seconds where it didn't speed up at all. That time period needs to be shortened to one second, for example.


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## DocScott (Mar 6, 2019)

Klaus-rf said:


> Quickly slowing does indeed bring those behind you up on you fast. No?
> 
> The issue is the car on AP/NoAP slows too much, too quickly [when it doesn't need to] and the it doesn't resume back to normal speed - while traffic is passing on both sides and closing quickly from the rear - when the suspected reason for sudden braking has cleared. By several seconds. If it slowed then sped up again as soon as the obstacle cleared, the issue would not be so much a problem.
> 
> ...


We now have enough numbers to work it out.

Suppose the semi were following 3 seconds behind, which Undergrove states is the minimum required by California law.

Now your car drops from 70 to 50 mph for four seconds. So for four seconds, the semi, if it didn't change its speed would be closing at a relative speed of 20 mph. If it had been 3 seconds behind at 70 mph it would now be 3 - 4*20/70 = 1.9 seconds behind at 70 mph, meaning it would have closed only a bit more than a third of the following distance.

If your car then gradually speeds back up to 70 mph, the semi would never be at any risk of rear-ending your car, even if the driver of the semi didn't slow at all in response. Of course, that would leave the semi less than the three second following distance behind, and so the semi should slow slightly for a bit to let the distance open back up. It shouldn't be a crisis or nerve-wracking for anyone involved.

If your slowing by 20 mph for four seconds really did result in the semi being right on your tail, then the semi must have been tailgating before the braking occurred.

So while I agree that AP would be improved if it took more account of the rear camera view, I don't agree that the semi driver was blameless in the scenario you described.


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## M3OC Rules (Nov 18, 2016)

DocScott said:


> Now your car drops from 70 to 20 mph for four seconds.


I think you mean 70 to 50mph.

I totally agree with your point. No excuses for the semi.


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## MountainPass (May 15, 2018)

I was cruising on an evening using AP and when it saw the long shadows across the road cast by trees it slammed on the brakes, brake checking a truck behind me. I felt like a jerk!


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## Klaus-rf (Mar 6, 2019)

MountainPass said:


> I was cruising on an evening using AP and when it saw the long shadows across the road cast by trees it slammed on the brakes, brake checking a truck behind me. I felt like a jerk!


 Obviously it's all the trucks fault.


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## M3OC Rules (Nov 18, 2016)

Klaus-rf said:


> Obviously it's all the trucks fault.


No. Its @MountainPass parent's fault for raising a kid that cares about other people.


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## MountainPass (May 15, 2018)

M3OC Rules said:


> No. Its @MountainPass parent's fault for raising a kid that cares about other people.


I feel like I represent Tesla owners when I am driving, so behaving poorly makes all of us look bad. I have seen people saying we are the new BMW driver, so let's make sure to use our turn signals.


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## Klaus-rf (Mar 6, 2019)

M3OC Rules said:


> No. Its @MountainPass parent's fault for raising a kid that cares about other people.


 Touché, Mon Amie!


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## DocScott (Mar 6, 2019)

M3OC Rules said:


> I think you mean 70 to 50mph.
> 
> I totally agree with your point. No excuses for the semi.


Thanks--fixed it!


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## ChristianZ (Nov 10, 2018)

I love AP, but the phantom breaking sucks when it happens.


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## garsh (Apr 4, 2016)

green has managed to capture autopilot data for a "phantom braking due to overpass" event.
Some of his followup comments are interesting.


__ https://twitter.com/i/web/status/1223798507234111488


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## garsh (Apr 4, 2016)

As we've learned before, the radar can't really determine vertical differences in what it sees.


__ https://twitter.com/i/web/status/1223844219355324417


garsh said:


> The issue is that the radars used by Tesla (and pretty much everybody else) only scans horizontally. They don't distinguish objects vertically. It's unable to determine if the stationary object directly in front of you is a car stopped on the road or an overpass.
> https://news.ycombinator.com/item?id=12475706
> 
> Tesla's long-term goal is to eventually have autopilot rely only on vision. Once the neural network becomes good enough, that will solve the problem. Right now, I notice too many instances where my Tesla doesn't appear to notice a car near me (it doesn't appear on the display), so I think they have a lot of work to do before we get to that point.
> ...


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## Needsdecaf (Dec 27, 2018)

garsh said:


> green has managed to capture autopilot data for a "phantom braking due to overpass" event.
> Some of his followup comments are interesting.
> 
> 
> __ https://twitter.com/i/web/status/1223798507234111488


Ah yes, but FSD is "feature complete", right?

On a serious note, Green is an amazing follow and great at engaging in Q/A about what he finds. Highly recommended if you're at all interested in how this stuff really works, not marketing fluff.


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## bwilson4web (Mar 4, 2019)

Has anyone tried an aluminum foil barrier in front of the radar to defeat radar, false signals?

Bob Wilson


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## dburkland (Nov 12, 2018)

bwilson4web said:


> Has anyone tried an aluminum foil barrier in front of the radar to defeat radar, false signals?
> 
> Bob Wilson


I had somebody reserve into my front bumper which jostled the radar and unfortunately the car did not like that one bit (car completely disabled AP, Summon, etc). I would assume if you do something that interferes with radar w/ the current software builds you will lose AP functionality.


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## FRC (Aug 4, 2018)

dburkland said:


> I had somebody reserve into my front bumper which jostled the radar and unfortunately the car did not like that one bit (car completely disabled AP, Summon, etc). I would assume if you do something that interferes with radar w/ the current software builds you will lose AP functionality.


Exactly what I was thinking...In other words; Why don't you give it a try @bwilson4web, and let us know how it goes?


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## D. J. (Apr 11, 2016)

I’ve had a good coating of ice and slush on my front bumper in the winter that presumably blocks radar - totally disables all cruise control. 2018 model so no radar heater.


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## MJJ (Aug 7, 2016)

The foil only works if you make a hat.

I'm pretty sure the radar is deprecated at this point.


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## bwilson4web (Mar 4, 2019)

FRC said:


> Exactly what I was thinking...In other words; Why don't you give it a try @bwilson4web, and let us know how it goes?


I thought I'd ask first before my tests.

Bob Wilson


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## leonhobbs (Sep 18, 2021)

I have a new 2021 Model 3 and it is horrible on phantom braking. It does it while on cruise control with or without AP on. I took it to the service center. The checked it out for 3 hours and said they found nothing wrong bit did clean windshield under front camera. Picked the car up and as soon as I got on the road same problem. I haf a 2019 model 3 and had very little problem with happening. This 2921 does it every 5 minutes or so on a two lane road and every 5 to 10 miles on a four kane riad. This needs to be fixed. Am I the only one with this problem? Bad enough. that I cant even use cruise control. Almost makes me want to get rid of this car. HELP PLEASE!!!


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## bwilson4web (Mar 4, 2019)

See if it is reproducible at specific locations. Then open a trouble ticket describing the problem and location.

In my case, it was reproducible at one point where the indicated speed jumped from 50 mph to 40 mph of the parallel access road. A subsequent software update fixed the GPS software so it would not to the access road speed limit.

Bob Wilson


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## SoFlaModel3 (Apr 15, 2017)

leonhobbs said:


> I have a new 2021 Model 3 and it is horrible on phantom braking. It does it while on cruise control with or without AP on. I took it to the service center. The checked it out for 3 hours and said they found nothing wrong bit did clean windshield under front camera. Picked the car up and as soon as I got on the road same problem. I haf a 2019 model 3 and had very little problem with happening. This 2921 does it every 5 minutes or so on a two lane road and every 5 to 10 miles on a four kane riad. This needs to be fixed. Am I the only one with this problem? Bad enough. that I cant even use cruise control. Almost makes me want to get rid of this car. HELP PLEASE!!!


Went from a 2018 where phantom braking was incredibly rare to a 2021 and I've have it for almost 3 months and 4,000 miles and I've had phantom braking once so far. Once is enough for a brief heart attack of course.

In your case, is there anything that stands out about when it happens? Also, what firmware version is your car running?


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## leonhobbs (Sep 18, 2021)

Have had my 2021 Model 3 since June. Phatom Braking is HORRIBLE. Anyone else having this problem. I owned a 2019 model 3 and hardly ever had a problem. I cant even use cruise control it is so bad. Service center said I need to wait for update. I love these cars but can not put up with this much longer. It must be something to do with removing the radar. Any thoughts?


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## garsh (Apr 4, 2016)

leonhobbs said:


> I have a new 2021 Model 3 and it is horrible on phantom braking.


What kind of roads are you using cruise control on? If you try to use it on windy, hilly roads, the car is going to brake a lot.


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## PNWmisty (Aug 19, 2017)

leonhobbs said:


> I have a new 2021 Model 3 and it is horrible on phantom braking. It does it while on cruise control with or without AP on. I took it to the service center. The checked it out for 3 hours and said they found nothing wrong bit did clean windshield under front camera. Picked the car up and as soon as I got on the road same problem. I haf a 2019 model 3 and had very little problem with happening. This 2921 does it every 5 minutes or so on a two lane road and every 5 to 10 miles on a four kane riad. This needs to be fixed. Am I the only one with this problem? Bad enough. that I cant even use cruise control. Almost makes me want to get rid of this car. HELP PLEASE!!!


I want to buy your car for cash. Please contact me through private mail.


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## aginzu (Sep 26, 2021)

I just completed a 1400 mile road trip in a 3 week old Model Y LR and had numerous phantom braking incidents. Most were just a mild slow-down on some two lane roads but some were quite violent. One particularly troubling one was on a clear stretch of I5 with autopilot engaged and no other vehicles nearby, when the car suddenly slammed on the brakes bringing the speed down from 75 to about 40 before I was able to step on the pedal and stop the deceleration. Fortunately there was no one behind me at the time. If there had been a close following semi, as had occurred frequently on the trip, it would not have had time to respond and would certainly have rear ended me. I did continue to use the autopilot features but kept my foot on the gas pedal ready to jump if it were to happen again, which it did not. I believe this is a serious safety issue. If I were in charge of QA for this version of the autopilot firmware I would have completely rejected releasing it.

I love the car, otherwise. This was my first long distance trip in an electric and I was very impressed with the car's performance and the effectiveness of the supercharger network. I sure hope that Tesla comes up with a fix for this very soon, before it causes a fatality somewhere.


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## DocScott (Mar 6, 2019)

I've experienced phantom braking from time to time, although not recently, and it certainly is disconcerting to the driver when it happens. But it occurs to me: I can't recall ever reading about a single accident caused by phantom braking, either in news accounts or in forums. There are several examples, on the other hand, of accidents caused by AP failing to brake when it should.

Does anyone have an example they can point me to of an accident that phantom braking has caused?


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## FRC (Aug 4, 2018)

DocScott said:


> I've experienced phantom braking from time to time, although not recently, and it certainly is disconcerting to the driver when it happens. But it occurs to me: I can't recall ever reading about a single accident caused by phantom braking, either in news accounts or in forums. There are several examples, on the other hand, of accidents caused by AP failing to brake when it should.
> 
> Does anyone have an example they can point me to of an accident that phantom braking has caused?


Somewhat unlikely that a Tesla driver would claim that phantom braking was the culprit. Unless the Tesla driver admits differently, the rear-end collision would be the following driver's fault.


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## CreativeGuy (Nov 4, 2021)

We have a new 2021 Model Y. Yesterday, driving on a two lane highway and using cruise control (not Auto Pilot) set between 55 & 62. Almost every time there was an oncoming high profile vehicle, school bus or semi, the vehicle would rather severely phantom break. This was rather disconcerting.


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## DeborahF (Nov 18, 2021)

I have a 2021 Model Y since Sept 22. I cannot use the adaptive cruise control at all. I don't feel safe. I also feel very stupid when i have passengers in my $80,000 car and it cannot even manage cruise control. Come on Tesla get your crap together. My Volkswagen Golf works better than this.


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## KevinTillman (Jul 19, 2021)

CreativeGuy said:


> We have a new 2021 Model Y. Yesterday, driving on a two lane highway and using cruise control (not Auto Pilot) set between 55 & 62. Almost every time there was an oncoming high profile vehicle, school bus or semi, the vehicle would rather severely phantom break. This was rather disconcerting.


Same -> Almost every time. Also seems only on non divided type highways (can't see the oncoming trucks over there). I was able to time pushing of the accelerator to get out of the breaking. Annoying but fun watching the passenger trying to nod off.


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## jdfphoto (Oct 20, 2020)

It concerns me that we are seeing an uptick in phantom braking reports. In general I don't understand why some people have phantom braking and others do not. I've have had my 2020 Model 3 LR AWD with EAP for about 12 months. I use Autopilot and Auto steering most of the time on most every type of road. I had phantom braking every day I drove the car when I first got it but not as hard as some people have described. I keep current with all software updates and the phantom braking has become less and less with each update. I now experience it at most no more than once a month. Can anyone say what is common and exclusive to the cars that are experiencing the issue?


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## Kizzy (Jul 25, 2016)

jdfphoto said:


> It concerns me that we are seeing an uptick in phantom braking reports. In general I don't understand why some people have phantom braking and others do not. I've have had my 2020 Model 3 LR AWD with EAP for about 12 months. I use Autopilot and Auto steering most of the time on most every type of road. I had phantom braking every day I drove the car when I first got it but not as hard as some people have described. I keep current with all software updates and the phantom braking has become less and less with each update. I now experience it at most no more than once a month. Can anyone say what is common and exclusive to the cars that are experiencing the issue?


Cars with Tesla Vision may have different challenges than cars using radar. 🤷🏾‍♀️

FSD Beta is a lot twitchier with brakes than the wide release Autopilot stack. So, there's that.


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## Nickt (11 mo ago)

Instead of giving us update with video games an changing the color of your car in the display, how about a fix so I can use cruise control without the car slamming on the brakes when meeting a bus or semi?


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## bwilson4web (Mar 4, 2019)

A recent benchmark navigated about 100 yards North and opposite side of road, West 15 yards. Speculation but the car GPS may be off … again. It doesn’t take much error to trigger a phantom brake event.

Bob Wilson


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## lance.bailey (Apr 1, 2019)

I read today that NHST is investigating the phantom braking issue.

https://insideevs.com/news/568182/tesla-phantom-braking-nhtsa-investigation/


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## Kimmo57 (Apr 10, 2019)

jdfphoto said:


> It concerns me that we are seeing an uptick in phantom braking reports. In general I don't understand why some people have phantom braking and others do not. I've have had my 2020 Model 3 LR AWD with EAP for about 12 months. I use Autopilot and Auto steering most of the time on most every type of road. I had phantom braking every day I drove the car when I first got it but not as hard as some people have described. I keep current with all software updates and the phantom braking has become less and less with each update. I now experience it at most no more than once a month. Can anyone say what is common and exclusive to the cars that are experiencing the issue?


Mine is a 2019 with radar and it hasn't suffered from phantom braking for ages, although it did at first.


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## Bigriver (Jan 26, 2018)

The phantom braking of yester-year was a horrible, soul jarring, unexpected and significant reduction in speed. What I occasionally experience now with vision only (no radar) is what I consider phantom hesitations - they are still random, unexpected, annoying, but only result in a speed reduction of 2 to 3 mph. For a split second it feels like an ICE misfiring or the first sputter of running out of gas. I am looking forward to Tesla eliminating this behavior, but these mild slowdowns are far from a safety issue. At least based on what I’ve experienced the past 6 month.


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## Colorado (11 mo ago)

Shadow LI said:


> Anyone seeing increased phantom braking lately on autopilot? Had more than a few today, including one so bad I was incredibly close to getting rear ended. I don't see any patterns like bridges or overpasses. Almost unusable now, especially in HOV lanes.


When they switched to all vision auto pilot (no radar) my Model 3 went bonkers for the first few weeks but it was starting to settle down. Then I traded it in for the Model Y in December (with FSD) and now I'm going through the craziness all over again. It's like the car is learning to see. Oncoming semis on a two lane highway almost always trigger a hard braking from 70MPH to 40MPH. It's ridiculous. You pay $10,000 for FSD and get software that sure seems half baked. I went to Tesla dealer and they didn't even run diagnostics, they told me it's the "software" and I just need to be patient and train it by driving a lot! I love this car but Tesla's QA has a lot to be desired in this circumstance.


Shadow LI said:


> Anyone seeing increased phantom braking lately on autopilot? Had more than a few today, including one so bad I was incredibly close to getting rear ended. I don't see any patterns like bridges or overpasses. Almost unusable now, especially in HOV lanes.


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