# Is it a mirage? Phantom braking



## tencate (Jan 11, 2018)

I live out in the desert southwest. Since we all switched to vision only, I've been plagued with totally bizarre phantom braking incidents. No surprise to most of you, but I suspect these are caused by something a bit unusual. Let me explain.

Typically, I'm on a lonely US Highway, or sometimes even an Interstate, I crest a rise, no cars anywhere to be seen for miles, and the car suddenly mashes the brakes hard. I've taken dashcam videos looking to see what on earth the vision might be seeing but there's nothing obvious to me.

Alas, I don't have a great dashcam image to show you but I've come to the conclusion that the vision system is confused by the mirage of water shimmering across the road. Do an image search on "road mirage image" in Google if you don't know what it looks like on the road.

Hypothesis: methinks the car sees the mirage and decides the road suddenly ends. I've been keeping track and the "mirage" hypothesis seems to be most likely for a large number of my phantom braking incidents in the middle of nowhere.

Anyone else noticed this? And how the heck do you train the vision/AI to ignore mirages?? Good luck with _that_ Tesla engineers.


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## Luvtordrive (7 mo ago)

tencate said:


> I live out in the desert southwest. Since we all switched to vision only, I've been plagued with totally bizarre phantom braking incidents. No surprise to most of you, but I suspect these are caused by something a bit unusual. Let me explain.
> 
> Typically, I'm on a lonely US Highway, or sometimes even an Interstate, I crest a rise, no cars anywhere to be seen for miles, and the car suddenly mashes the brakes hard. I've taken dashcam videos looking to see what on earth the vision might be seeing but there's nothing obvious to me.
> 
> ...


Tencate, interesting theory and sounds plausible. I live in NJ and experienced this same phantom braking this week. While driving north from the southern most part of the Garden State Parkway, my MYP did the same thing with no cars around me (it was very light week day traffic). This was during evening dusk time and there was no “road mirage” around. 
As if I didn’t have enough things for my wife to complain about my driving ( mostly too fast) in my new Tesla 🤷🏻‍♂️


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## garsh (Apr 4, 2016)

tencate said:


> Since we all switched to vision only...


I think our cars are still using radar if your car is old enough to have the hardware and you didn't sign up for FSD Beta,


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## tencate (Jan 11, 2018)

garsh said:


> you didn't sign up for FSD Beta,


Alas, I was one of the first ones. Anyway, would _love_ to be in on discussions about phantom braking within Tesla though. It's gotta be driving them nuts. And yes, it drives me nuts because I get grief from the wife every time it happens too.


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## RhoEps (6 mo ago)

tencate said:


> I live out in the desert southwest. Since we all switched to vision only, I've been plagued with totally bizarre phantom braking incidents. No surprise to most of you, but I suspect these are caused by something a bit unusual. Let me explain.
> 
> Typically, I'm on a lonely US Highway, or sometimes even an Interstate, I crest a rise, no cars anywhere to be seen for miles, and the car suddenly mashes the brakes hard. I've taken dashcam videos looking to see what on earth the vision might be seeing but there's nothing obvious to me.
> 
> ...


Agreed. I just completed a round trip from Colorado Springs to Santa Fe and saw the same sort of phantom braking that mostly correlated with heat mirages. This happened frequently on long flat stretches with little traffic and was pretty annoying, but didn't usually happen in cities. 
I have a 2020 M3 with radar, but I believe the radar is unused even if present since the switch. I'm running FSD 10.12.2.


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## Tombolian (Sep 27, 2018)

Was going to start this post but found it already exists! Just completed a round-trip from CA to ID and had about 100 of these each way. I believe it happens when there is a car about a mile ahead of you on a long straightaway and when the mirage suddenly appears causing the car in the distance to immediately become twice as large (reflecting in the mirage). I didn't notice any phantom braking from the mirage alone. It has to reflect something that Autopilot already sees and has identified as a car. I think I managed to catch it in the act with my phone camera and will post here after I have time to go through my thousands of pictures if so.


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## Tombolian (Sep 27, 2018)

Tombolian said:


> I think I managed to catch it in the act with my phone camera and will post here after I have time to go through my thousands of pictures if so.


Golly my footage sucked! Just going to put this here instead...


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## Klaus-rf (Mar 6, 2019)

BTW - Mirages are not required to get Phantom Braking. in my experience.


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## RhoEps (6 mo ago)

Tombolian said:


> Golly my footage sucked! Just going to put this here instead...


In the comments section of Dr. Know it All's video someone suggested reducing the following distance to 2 and the Forward Collision Warning to a lower setting to mitigate this. For those long empty stretches of road where this is a problem that sounds like a good idea, I'll give it a shot the next time I'm in that sort of driving situation.


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## RhoEps (6 mo ago)

Klaus-rf said:


> BTW - Mirages are not required to get Phantom Braking. in my experience.


Agreed. I see it in the same spots on I-470 in Denver, every time I drive there. (I usually just turn it off for those sections). It's not phantom braking per se, but it thinks the speed limit has changed from 65 to 40 and slows down quickly to match what it now thinks the limit is. I don't know if it's a map problem or if it's picking up the exit ramp speed limit signs, but it's consistent.


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## tencate (Jan 11, 2018)

I think there are _lots_ of reasons for phantom braking, mirages, sudden detected drop in speed limit---I've seen it read a speed limit sign on an off ramp and think the interstate speed suddenly dropped to 40---dark shadows across the road, etc. I expect each one of these root causes require Tesla engineers to find training sets to teach the AI that what it "sees" on the images isn't cause for mashing on the brake pedal in the middle of nowhere or at 75 mph on the middle of an Interstate. I wish them luck in their endeavors (and wish they'd fix the mirage one soon, if indeed that's what really is going on.)


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## Tombolian (Sep 27, 2018)

Klaus-rf said:


> BTW - Mirages are not required to get Phantom Braking. in my experience.


You couldn't be more right, but that's the title of this thread.


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## Tombolian (Sep 27, 2018)

RhoEps said:


> In the comments section of Dr. Know it All's video someone suggested reducing the following distance to 2 and the Forward Collision Warning to a lower setting to mitigate this. For those long empty stretches of road where this is a problem that sounds like a good idea, I'll give it a shot the next time I'm in that sort of driving situation.


Good suggestion. Did they happen to also say that it worked?


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## RhoEps (6 mo ago)

Tombolian said:


> Good suggestion. Did they happen to also say that it worked?


They said it was considerably improved (but not totally eliminated) for the rest of the trip.


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## francoisp (Sep 28, 2018)




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## PanTerra (5 mo ago)

francoisp said:


>


This is definitely interesting, but my 2021 M3 LR phantom that was delivered in late June of 2021, and is confirmed to be a vision only car, experiences much harsher and drastic phantom braking than this--even on cloudy days when there is no change in the coloration of the highway and with nobody around. It is absolutely the most infuriating part of owning this car and discourages the use of basic adaptive cruise control let alone Autopilot on long trips for me. It has become way too nerve wracking.


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## Mrp911 (Nov 18, 2018)

tencate said:


> I live out in the desert southwest. Since we all switched to vision only, I've been plagued with totally bizarre phantom braking incidents. No surprise to most of you, but I suspect these are caused by something a bit unusual. Let me explain.
> 
> Typically, I'm on a lonely US Highway, or sometimes even an Interstate, I crest a rise, no cars anywhere to be seen for miles, and the car suddenly mashes the brakes hard. I've taken dashcam videos looking to see what on earth the vision might be seeing but there's nothing obvious to me.
> 
> ...


I 100% agree with you mirages are playing a part I also thing rolling up and downs do as well. We make the trek up to Mammoth Lakes on the 395 and if in day light we may get 15 phantom brakes per hour. It is brutal. Definitely takes down the 100% love this car down some notches. 
I think I caught a mirage show up as a car or truck once on the screen. There was no car in front at the time. Maybe thinks the road ends or is surprised a vehicle all of a sudden has showed up.
I am in FSD Beta. 10.69.2.1 on the drive yesterday amd 10.69.2.2 with an update last night. This used to not be a problem on the drive. 2018 M3. Dual Motor so it has Radar but it sounds like the FSD is only Vision.
Anyone figure out a way to reduce the problem? Once the sun gets closer to dusk the problem goes away.


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## francoisp (Sep 28, 2018)

Mrp911 said:


> I 100% agree with you mirages are playing a part I also thing rolling up and downs do as well. We make the trek up to Mammoth Lakes on the 395 and if in day light we may get 15 phantom brakes per hour. It is brutal. Definitely takes down the 100% love this car down some notches.
> I think I caught a mirage show up as a car or truck once on the screen. There was no car in front at the time. Maybe thinks the road ends or is surprised a vehicle all of a sudden has showed up.
> I am in FSD Beta. 10.69.2.1 on the drive yesterday amd 10.69.2.2 with an update last night. This used to not be a problem on the drive. 2018 M3. Dual Motor so it has Radar but it sounds like the FSD is only Vision.
> Anyone figure out a way to reduce the problem? Once the sun gets closer to dusk the problem goes away.


This is where a lidar/radar device would normally complement vision and eliminate that kind of artifacts.


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## Tombolian (Sep 27, 2018)

francoisp said:


> This is where a lidar/radar device would normally complement vision and eliminate that kind of artifacts.


How do you do it as a human without radar/lidar? I can't understand why people think radar is the solution. It's kinda like god-of-the-gaps; If they can't imagine such technology is possible, they think it isn't and need to resort to fanciful solutions.


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## francoisp (Sep 28, 2018)

Tombolian said:


> How do you do it as a human without radar/lidar?


Hum, maybe because people have a brain that is a little bit more complex than Tesla's neural network?


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## Klaus-rf (Mar 6, 2019)

francoisp said:


> Hum, maybe because people have a brain that is a little bit more complex than Tesla's neural network?


 Most of the humans have 20+ years of "training".

However sometimes humans get confused by mirages too.


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## francoisp (Sep 28, 2018)

Klaus-rf said:


> Most of the humans have 20+ years of "training".
> 
> However sometimes humans get confused by mirages too.


Seriously? I think that someone on a learner's permit might get confused once and that someone will learn from the experience and deal with it going forward. Tesla? Not so much and that's the challenge isn't it.


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## Klaus-rf (Mar 6, 2019)

One thng for sure: RADAR never gets confused by mirages or shadows.


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## garsh (Apr 4, 2016)

Klaus-rf said:


> One thng for sure: RADAR never gets confused by mirages or shadows.


Radar will confuse a coke can for a semi truck.


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## francoisp (Sep 28, 2018)

garsh said:


> Radar will confuse a coke can for a semi truck.


That's why a fusion of radar/lidar and vision is best. AI can then figure out what's happening.


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## SalisburySam (Jun 6, 2018)

Tombolian said:


> I can't understand why people think radar is the solution.


Maybe not a solution, but we do know vision-only doesn’t eliminate phantom braking. Possibly it will someday…not today.


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## francoisp (Sep 28, 2018)

garsh said:


> Radar will confuse a coke can for a semi truck.


Lidar wouldn't be. It would see as it is, i.e. a tiny piece of something in the middle of the road.


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## garsh (Apr 4, 2016)

francoisp said:


> Lidar wouldn't be. It would see as it is, i.e. a tiny piece of something in the middle of the road.


Vision handles that already.


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## francoisp (Sep 28, 2018)

garsh said:


> Vision handles that already.


But not mirages and other situations of unexpected slowdowns. That's where a fusion of lidar/radar with vision would add data points that the AI can use to eliminate artifacts.


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## Mrp911 (Nov 18, 2018)

Yesterday i shot some video of aggressive Phantom braking which occurred directly after a pickup truck and trailers shadow was cast across my lane. From 70 to 50 in 2 secs. This and Mirages are making these rural trips significantly painful. FSD Beta 10.69.2.2. Maybe Tesla can turn my 2018 M3 radar back.


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## richrosenblum15 (2 mo ago)

Klaus-rf said:


> BTW - Mirages are not required to get Phantom Braking. in my experience.


I agree. Since I started using FSD Beta I have experienced phantom braking in all kinds of situations. It’s the one biggest problem I’ve had. The car will slow or try to stop for no reason that I can figure out. I have to accelerate or disengage, and I still get the horn from following drivers often.


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