Phantom braking is the biggest issue with AutoPilot.

[Fernand]

First thing to learn with any autopilot system is knowing when not to use it, and when to temporarily disengage it.

About a year ago I would treat AP like a gear shift, sometimes stay in AP for 20 minutes, sometimes go in and out several times in a 5 minute period. There are situations where it helps and others where it's best tapped off. Aside from extreme curves with too high a speed limit, there were other tricky spots like being in the right lane approaching an unwanted exit.

I've never had the car "slam on the brakes", though I've seen it slow down in strong regen, maybe 2 or 3 times in the last 12 months. It's not sure of what it's seeing, better to slow down. I expect that when the software fully takes advantage of the faster hardware, this will go away.

But I'm not sleeping, I ride WITH the system, it's no big deal to re-accelerate. It never stopped me from taking advantage of AP. People who expect to leave AP on all the time and just stand back aren't being realistic. It's as if you refused to take your glasses off at times and instead railed about the "flawed" optics and the incompetent optometrists. Or throwing out your smartphone because Bluetooth loses connectivity. A better use of time is to figure out how to get the best use out of the technology.

As of 2019.40.50.7 the system is so much improved that I can keep it in NOA on highways pretty much all the time, and in AP on and off on boulevards, and to me, anyway, it's a huge net benefit.

But I've also changed how I look at the system, from observing it to driving with it. If you're having AP issues, think about it. Hard to explain, but it's like a novice riding a horse getting bounced in the saddle (ouch), versus leaning into the motion, working with the beast. For one thing feeling the car, how the AP is driving, and being at ease in position to smoothly continue onward if you were to tap out of AP. Correcting or overriding occasional problems then becomes an easy and natural part of the flow.
.

 

[Mike Ess]

I have a theory of what is happening with the phantom braking. One time when it occurred I noticed the speed limit showed that it changed from posted (65) to 40. I suspect that this is GPS drift and it is picking up the road NEAR the freeway. (ever see your GPS show you on an adjacent road in other cars or on your phone? Same issue cept our cars will slow down to make sure you aren't going WAY over the speed limit when on AP)

Has anyone else noticed this?

 

[notAnExpert]

Not sure I understand what you’re asking?

Sorry, that was a bit cryptic. I was saying that Tesla allows us to turn off Navigate on Autopilot, but that doesn’t mean they accept failure.

Tesla continues to say their AP/FSD related features are beta. So I think it would be be just fine to allow us to toggle the unstable features off. They do allow us to do that for many features. I think the other poster’s point was that it would be nice to allow us to have some finer control with cruise control.

 

[WilliamG]

Sorry, that was a bit cryptic. I was saying that Tesla allows us to turn off Navigate on Autopilot, but that doesn’t mean they accept failure.

Tesla continues to say their AP/FSD related features are beta. So I think it would be be just fine to allow us to toggle the unstable features off. They do allow us to do that for many features. I think the other poster’s point was that it would be nice to allow us to have some finer control with cruise control.

I hear you, but it just won’t ever happen with cruise control in my humble opinion.

 

[Kitfox]

The condensed version for everybody:
It's probably not a problem.
It's likely just something that you're not used to.
However if you truly think it's an issue, contact support online and provide Teslacam video (with original filenames) within 24 hours of the event occurring.
If it isn't a problem, they won't be able to do anything about it because telling the customer it's not a problem doesn't work most of the time and they don't want to waste effort on that.
If it is a legitimate problem, it'll be fixed with an OTA update.

Onward...

It's not every overpass or semi, but maybe 1 in 50 or so. It's also obviously not a speed limit mapping issue.

My offer still stands. Grab a video of it and tag me to analyze it. So far there have been no videos brought to my attention where the braking did not have a discernible cause and was a proper slowdown or braking maneuver. Well, except one where the driver stepped on the brakes to fake it, but that was just trying to catch me out and was rather rude and a waste of time.

USB drive and a quick save, then upload it and let me know. Or let Tesla know. They like to fix things after all, so in the very rare cases that somebody is actually right about these, that issue is gone in an OTA update or two. Or they change the behavior to stop triggering sensitive people.

No I do not have footage. But there is footage online that shows this flaw. It’s more than ‘a few’ drivers having this problem.

You have a recording device on wheels. Plug in a USB thumb drive and poke the button after it happens. As for the footage online, please feel free to find... mmm... let's say 0.1% examples. 500,000 Teslas on the road, so that tiny fraction would be 500 videos of phantom braking. Let's also look for current ones, because autopilot behavior changes and improves with updates.

Alternatively, I'll let you define the bar. How many people is this happening to and how often? People are very ept at complaining on the internet and providing video (just like they are at overestimating impact). Thus you should be able to provide sources for your claims. 50 Youtube videos, perhaps? That would be a One in Ten Thousand event.

And there is no law here that states i have to slow down.

I was not aware there was a locality where it's legal to maintain speed and collide with the vehicle that just merged in front of you. Even aside from that, tailgating (failure to keep a safe following distance) and reckless driving are the two items that generally apply.

What i normally did with my ICE car, was...

1: If the Tesla is actually slowing down rapidly enough to display brake lights (which it probably isn't, by the way. You'll want to take a peek at that), then an ICE age car would need to slow down just as much and as quickly, in which case either you were performing a rapid deceleration without brake lights, or pulling too close to the just-merged vehicle for safety.
2: You can adjust the follow distance of the TACC/AP. At the shortest distance, it will meet legal requirements for avoiding reckless driving and follow distance issues but only just. At which point, again, if it's slowing more than you would, that just indicates unsafe driving behavior.

It is not a slowdown, it is a sudden braking action.

I have a 100% win rate so far on the following bet:
Without looking at the display, you would not be able to tell better than random guesses when the slowdown is a brake-engaged slowdown vs a coast or lack of acceleration force change.

Human beings invariably end up way overestimating "That was braking" in cases where the change in forces was not enough to be considered braking. I can even TACC behind an accomplice who simply does "throttle pulsing", and a passenger who does not look at the display will complain that the Tesla is braking.

I’ve experienced it several times on the highway. It doesn’t consistently happen at the same place. So it isn’t a mapping issue. It happens when there isn’t a car ahead of me. So it isn’t a slowdown to maintain proper braking distance.

So grab a video and get it checked. Tesla does OTA and fixes things. If you have me analyze it, chances are I'll spot what made it slow, and if I don't, then Tesla should be aware of it so they can correct it. USB stick and hit the save after it happens.

I’m not sure how you know that hundreds of thousands of Teslas driving under millions of overpasses on autopilot have not experienced this problem. It happens to many of us and I’ve been told by Tesla that there is nothing wrong with my car. In fact, I was told by the service center that many people have reported this issue and they don’t have an answer for it.

I don't know, any more than you know it's not the case. But Occam's Razor indicates I'm more likely to be correct. People complain. People like to post, show video that they feel is proof, and so on. With 500,000 Teslas out there, if this were a major issue, there would be hundreds or thousands of complaints. You'd see the government jumping on it if it were a safety issue, and then SAYING it's a safety issue.

As for the service center anecdote, that is wholly correct. Many people have reported it and they don't have an answer for it because it's not bad behavior and they're smart enough not to say the answer is that the customer is a bad driver and has hazardous preconceptions based on poor choices made in personal behavior, or that the customer is simply not used to vehicles with the physical dynamics of a Tesla doing things that are completely normal and legitimate.

Airlines have more complaints about "stuff that happened during landing" ("It felt like we were falling!"; "the plane was tilted way to the side."; "The plane felt like it was sliding side to side.") and they also 'don't have an answer for it', because all of that stuff is completely normal and human beings are not accustomed to it.

Ride with somebody else driving and you might be white-knuckled or bored because they don't drive the way you do. But that doesn't mean they are necessarily driving unsafely or poorly. Just differently.

Finally, the one thing I'd love to see to be able to say "this is a problem" is for ANY REPORT AT ALL of this behavior causing an accident where the Tesla was considered to be at fault (unnecessary braking is still a fault in most jurisdictions).

For anybody who made it this far, congratulations!

While humans are not generally capable of such, the option exists to decide that it's not a problem even if it's not what you expect.
If you find a genuine problem, save the video and talk to Tesla.

Take action on what you can take action on.
Complain about what you can't take action on.
But if you can take a corrective action, take that action, because complaining does nothing to help and only hinders action.

 

[Kitfox]

I have a theory of what is happening with the phantom braking. One time when it occurred I noticed the speed limit showed that it changed from posted (65) to 40. I suspect that this is GPS drift and it is picking up the road NEAR the freeway. (ever see your GPS show you on an adjacent road in other cars or on your phone? Same issue cept our cars will slow down to make sure you aren't going WAY over the speed limit when on AP)

Has anyone else noticed this?

Yes, and this is precisely what I mentioned above. It can result from GPS drift (the constellation is still dying), or more commonly from out of date mapping information, such as when a road was redirected, even months after construction. There is a section of the 5 in Washington State between Seattle and Olympia where construction is mostly completed but map data is still for the old route of the freeway. When following the freeway, the car gets very confused about the proper speed and where you are. In my case, it got gummed up enough to start by flipping between the speed limits of three different side streets that the freeway had replaced, then finally disabling AP altogether, while routing went absolutely nuts.

If the system thinks you are somewhere else with a different speed limit, it will attempt to slow to that for safety reasons.

This is why recognition of speed limit signs is being worked on and more effort is being made to swap speed limit detection from map data primarily to observation primarily with map data as a backup. I'm looking forward to that. They just have to deal with that company trying to impose patent rights on all ability to recognize speed limit signs using a computer.

 

[Kitfox]

My phantom braking issue is with AP when I want to change lane for overtaking a car.
It will brake when I'm halfway of my overtake because I got too close from the left side of the car I am overtaking. Even if the overtaking is smooth.
It's like when overtaking i have to change lane as quickly as possible instead of the smoothest action.

While the AP behavior is not what you'd do, it is what you should do for safety. Until you are fully in the next lane, you should not infringe on the safe follow distance of the vehicle you're overtaking. Engage the change sooner in these situations. You can see the vehicle you intend to overtake before the car worries about it. Plan that ahead. With some practice, you'll never slow a bit.

If you are on TACC and doing the lane change manually as opposed to letting AP perform the steering, then perhaps you should practice "police lane changes". They are a very swift, decisive, and safe lane change that doesn't leave you straddling lanes for too long. A lot of folks do lane changes as the "Vector in, straighten out to travel in, vector to follow new lane" process, which is rather slow and, while appropriate for icy or very slick conditions, has a higher risk of accident due to the way it interacts with other drivers' perceptions and the longer transit time.

By comparison, a maneuver that vectors in, then reverses vector smoothly to align in the new lane, never having a period of traveling straight at an angle between lanes is more effective and safer in normal conditions. A curve the whole way instead of a curve, straight, curve.

And if all else fails, just press the accelerator lightly and the car will complain that it's not being allowed to slow down as it doesn't slow down.

 

[Knuppe]

@Kitfox:
Do you work for Tesla?
You’re trying really hard to declare us all nuts, but I can assure you, this is a problem many are experiencing. I don’t use Autopilot, only TACC, and had the car brake twice under overpasses in different locations. Luckily I was in the slow lane, and there was no traffic nearby.

 

[Mike Ess]

Under over passes happens here in PHX. When there is a VERY heavy shadow, it appears to freak the car out, at least what I have seen. @Kitfox Thoughts on that?

 

[notAnExpert]

Under over passes happens here in PHX. When there is a VERY heavy shadow, it appears to freak the car out, at least what I have seen. @Kitfox Thoughts on that?

Duh! That’s obvious user error

 

[Kitfox]

@Kitfox:
Do you work for Tesla?
You’re trying really hard to declare us all nuts, but I can assure you, this is a problem many are experiencing. I don’t use Autopilot, only TACC, and had the car brake twice under overpasses in different locations. Luckily I was in the slow lane, and there was no traffic nearby.

Do you have a short position in Tesla? You're trying really hard to declare that the half million Teslas on the road have a huge problem and are saying "many are experiencing" without coming up with even 50 non-anecdotal people who are. <.< ^.^ (Yep, I can do that silly stuff too.)

What I am trying to say is:
1: I pass under hundreds of overpasses while on AP without problem. If your anecdotal claim that you're having a problem creates a "biggest issue with Autopilot", then my anecdotal claim cancels it out. Needless to say, neither anecdotal claim actually means anything at all other than that you believe there is a problem and I do not. Check with your SC and you'll also find out that there are many people who complain about "the car slams on the brakes when I take my foot off the gas to coast". That doesn't make the person nuts, or the slowing 'unexpected', or the slowing a big problem. It just means that settings need to be changed (with an efficiency cost) or the driver needs to get used to the different behavior compared to their old car.
2: However, if there is a problem that you're encountering, then it needs to be fixed, and without data, Tesla has no way of knowing there's a problem in specific conditions.

Which leads to... and includes somebody else's question...

Under over passes happens here in PHX. When there is a VERY heavy shadow, it appears to freak the car out, at least what I have seen. @Kitfox Thoughts on that?

Exactly, "appears". We want to determine what is definitely happening, or get a better grasp on things that might be happening from a processing and functionality viewpoint. Maybe it's something that you're not seeing on the screen because it flashed for a fraction of a second. Maybe it's the GPS getting weirded out and the car thinks you're on a frontage road for a moment so is trying to slow to the speed limit of the frontage road. Maybe the road color in that area is unlike the road color here so the shadow causes a problem. So we want to find out for certain so it can be fixed.

3: When that happens:
A: Capture a Teslacam footage clip. Or, even better, if it happens very frequently like the claims imply, also record your drive with a view from behind with a cell phone or Go Pro or something else. The goal being to have the display and the road both visible in the video. You should get a capture of the details rather quickly.
B: Immediately after it happens, press the Voice Input and say "Bug report unexpected autopilot behavior"
C: When you have a few examples (please trim the videos to the events), contact Tesla support by email and provide the information within 24 hours of the most recent event.
D: Optionally post to YouTube or something else, taking a questioning tone rather than an accusing tone with the post. Assumptions lead to errors and tribalism. Somebody who knows how the systems work or how systems like this in general work, or who are adept at troubleshooting, may note a factor that you missed or may spot the source of the issue or, if there is no discernible reason visible, be able to provide the fact that they already checked for various things as possible causes and they're not there, saving time from double-checking for that.

As I pointed out to a prior Youtube video about "phantom braking", you could see exactly why the car braked and there was nothing phantom about it. The car knew exactly what it was doing and was doing exactly what it was told to do in the particular situation it encountered. The issue there was that it "felt wrong" to the human driver, and this is a completely legitimate feeling. That video and some situation testing allowed part of the "Improved lane change behavior" code that came out.

I'm making solid offers to evaluate what's going on in videos and provide feedback and useful information so that people can take action. Your choices are as follows:
Either complain about it without getting solid information and nothing will ever be fixed, so then you can complain about it more.
Or get solid information about your experiences with objective data that can be evaluated and then something can be done about it.

 

[allanw]

Under overpasses happens here in PHX. When there is a VERY heavy shadow, it appears to freak the car out, at least what I have seen. @Kitfox Thoughts on that?

Despite @Kitfox desperate attempts to insist that phantom braking isn't a thing, I have also experienced what you're describing. My theory with the underpass is that it's applying the speed limit from the road overhead to me, so effectively going from 65 mph to say 40 mph causing the deceleration. Because it's so quick and random I haven't been able to check the displayed speed limit on the screen when it happens (and honestly it's only happened maybe 3 or 4 times in 6 months).

I have also experienced what I would consider random braking on the freeway but I'm wondering if it's the "cut in" prediction that's to blame. I know the AI will attempt to predict when a car in an adjacent lane is about to cut in front of you. I wonder if the sudden deceleration is the AI reacting to what it thinks is a car that's about to cut in front of me.

 

[Kitfox]

Despite @Kitfox desperate attempts to insist that phantom braking isn't a thing, I have also experienced what you're describing. My theory with the underpass is that it's applying the speed limit from the road overhead to me, so effectively going from 65 mph to say 40 mph causing the deceleration. Because it's so quick and random I haven't been able to check the displayed speed limit on the screen when it happens (and honestly it's only happened maybe 3 or 4 times in 6 months).

I have also experienced what I would consider random braking on the freeway but I'm wondering if it's the "cut in" prediction that's to blame. I know the AI will attempt to predict when a car in an adjacent lane is about to cut in front of you. I wonder if the sudden deceleration is the AI reacting to what it thinks is a car that's about to cut in front of me.

Are you short, apathetic, or do you want answers and fixes?
If you are short, sorry about your recent losses. Consider a long position for the time being.
If you are apathetic, then I don't care either.
If you want answers and fixes, get data. See #3 above, repeated here for your convenience:

When it happens:
A: Capture a Teslacam footage clip. Or, even better, if it happens very frequently like the claims imply, also record your drive with a view from behind with a cell phone or Go Pro or something else. The goal being to have the display and the road both visible in the video. You should get a capture of the details rather quickly.
B: Immediately after it happens, press the Voice Input and say "Bug report unexpected autopilot behavior"
C: When you have a few examples (please trim the videos to the events), contact Tesla support by email and provide the information within 24 hours of the most recent event.
D: Optionally post to YouTube or something else, taking a questioning tone rather than an accusing tone with the post. Assumptions lead to errors and tribalism. Somebody who knows how the systems work or how systems like this in general work, or who are adept at troubleshooting, may note a factor that you missed or may spot the source of the issue or, if there is no discernible reason visible, be able to provide the fact that they already checked for various things as possible causes and they're not there, saving time from double-checking for that.

 

[Kitfox]

I've also experienced this a half-dozen times in the month that I've had the car. One in particular that sticks out in memory was on the freeway in a middle lane with no cars within 100 yards in front/to the side of me.

kitfox is a troll.

I can click a thing too! XD

You're in Seattle. Have you driven the 5 southbound through that no-longer-really-construction zone in South Tacoma approaching the 16? There is a major mapping problem there that ends up effectively confusing the car about where it is. It's most easily seen when you're doing NoAP (don't do NoAP through there, by the way unless you are paying VERY close attention). The last time I went that way (several months ago, the car had a group of faulty maneuvers before I took over, cycled between braking and accelerating, and the routing directions on the map flipped between directing along the freeway and directions to get back to the freeway from nearby surface streets.

I hit the record button for Teslacam, pressed the right steering wheel roller, and said, "bug report dangerous autopilot actions". Then I cancelled navigation, looped back, went with only AP and no NoAP, and tried the same stretch of road again. Exact same problem at the exact same place. A second recording, a second bug report, and then I continued home. When I got home, my car uploaded about 3GB or so of data to Tesla.

I'm kind of curious if that's where your event occurred. I'm reluctant to ask you to check that spot on AP as it was a dangerous situation and I am not keen on specifically asking anybody else to potentially endanger themselves. But if you happen to AP through that area, I'm wondering if it's still having problems or if it's fixed, especially since i was able to get it to occur twice on two back to back AP trips along that stretch of road.

 

[PianoAl]

It's happened at this location three times, and it's passed the location without any braking about four times. I figure it's the circled thing that's causing confusion??

 

[MobileClimate]

I find cleaning all the cameras reduces phantom braking not sure if anyone mentioned that yet

 

[marksvend]

I experience phantom braking nearly every day on my commute on I-90 going under the overpasses through Eastgate in Bellevue. It seems to be worse in the HOV lane.

Then Eastbound entering Mercer Island in the HOV lane, I get the red hands take-over-immediately every singe commute home. It takes the autopilot computer about 3 minutes to reboot after that.

Thie route between Seattle and Issaquah in the HOV lane is really the worst.

 

[widodh]

I experience it as well in my S100D on the roads in western Europe.

Sometimes it’s a bridge, but sometimes it also seems to think a vehicle is in my lane while it’s clearly in the lane next to me.

The random slowdowns and hard braking of the car really annoys me.

 

[notAnExpert]

I wonder why Tesla relies on GPS and maps for speed limits rather than use its cameras for reading speed limit signs like Mobileye does with its systems.

 

[Kitfox]

I wonder why Tesla relies on GPS and maps for speed limits rather than use its cameras for reading speed limit signs like Mobileye does with its systems.

Because of the patents most likely.