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Ghost Braking Danger on Cruise Control

Knightshade

Well-Known Member
Jul 31, 2017
14,088
24,646
NC
It's on Tesla's own forums, so if they're not aware of it by now, I don't know what to say.

Again- everybody using radar cruise is aware of this- in every brand of car.

I even cited a bunch with links to owners manuals mentioning this.

This. Is. Not. A. Tesla. Specific. Issue.

It's an inherent limit of the technology.


Bugs are normal, but this is serious.

Is it?

Last time you insisted it was dangerous and would cause accidents- so I asked for any examples of it having done so in a Tesla- since TACC has been around for ~8 years now, surely you could provide some.

You couldn't.


Tesla has the advantage of they're trying to solve vision- which if they actually manage to do it should GREATLY reduce the chances of the car braking incorrectly compared to, say, a Toyota that only has the single front radar sensor to rely on.



But even that won't eliminate it 100%- because even humans sometimes brake incorrectly because they misunderstood what they saw for a second.

The great news though is as more and more cars have some sort of radar cruise and emergency braking tech, the cars BEHIND you will immediately notice your car slowing even on a false positive, and themselves slow to insure safety.
 

Fernand

Active Member
Mar 22, 2019
1,645
1,849
Northern california
Or all the other cars will ALSO be phantom slowing together, in response to that particular something in the roadway.

And then one day someone will actually stop, and take down that bible thumper's cardboard sign about "666 the mark of The Beast". Kind of confusing for the car's Artificial Intelligence vision system ;-)

Did I say "Navigate to The Beast"?
.
 
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I’ve owned my Model 3 for 24 days now and put just under 2800 miles via a 1300 miles road trip and a 900 mile road trip. My previous car was a 2017 Subaru Outback Touring Edition with Subaru’s Eyesight, their version of adaptive cruise control. I do not know if Subaru uses LIDAR or not. My results are anecdotal but they are my experience. Phantom Braking Incidents with the Subaru, none in 61,000 miles of 75% highway miles, often 1,000 mile road trips that required me to go through Atlanta each way. Atlanta has overpasses out the wazzoo. In 2200 road miles in my Tesla, I’ve had at least 10, probably more, five alone on a 600 mile run Monday. Monday, 2 of the incidents were on open stretches, not an overpass in sight, in traffic. I have started doing a bug report every time. I’ve noticed the overpass incidents tend to be where the overpass is descending or at some type of angle to the road with “high contrast” shadows on the road. Anyway, just my experience. My thoughts are, if everyone did a bug report every single time the data base would get so large that someone will say, “Here’s a problem and let’s fix it!” They’ll make said person a Vice President and promote them to their level of incompetence and we’ll have it fixed.
 

Knightshade

Well-Known Member
Jul 31, 2017
14,088
24,646
NC
My thoughts are, if everyone did a bug report every single time the data base would get so large that someone will say, “Here’s a problem and let’s fix it!” They’ll make said person a Vice President and promote them to their level of incompetence and we’ll have it fixed.


Bug reports don't get sent anywhere- so not so much. The only time anyone sees them at all is the local service center, and only if you make a service appointment to fix a problem- if you do they can access the logs saved locally on your car as part of the bug report when you made it.



Amusingly, the first google hit on subaru phantom braking is this:

Phantom Braking is Growing Problem - Wall St. Journal | Tesla

Which includes a WSJ article listing a slew of car companies with phantom braking complaints, and a new model 3 owner mentioning his experience with such braking on his Subaru specifically.
 
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GoergeJetson

Member
Aug 26, 2019
53
67
Florida
Again- everybody using radar cruise is aware of this- in every brand of car.

I even cited a bunch with links to owners manuals mentioning this.

This. Is. Not. A. Tesla. Specific. Issue.

It's an inherent limit of the technology.

I agree that's true, however, I want to add that I have another car with adaptive cruise and lane keep assist that doesn't "phantom brake" nearly as much as the Tesla. My wife's car has randomly braked 3 times in the 3 years of ownership, my Tesla has randomly braked 3 times in the same day. Huge difference in the number of unnecessary braking events.
 
Again- everybody using radar cruise is aware of this- in every brand of car.

I even cited a bunch with links to owners manuals mentioning this.

This. Is. Not. A. Tesla. Specific. Issue.

It's an inherent limit of the technology.

I agree with you. It just seems, in my personal experience, to have happened a lot with my car. Fortunately, I have adapted and am prepared at overpasses. FSD is a beta product after all. BTW, to somewhat correct myself, the Subaru hated me backing up in tall grass and frequent slammed on the brakes to save me from the fescue! Different system however. Also, the Automatic Emergency Braking on my Subaru prevented me from causing a serious accident. I responded quickly but the AED was a split second quicker and it saved us. And, I absolutely love my car! I was going to buy a Porsche but just happened to test drive a Model 3 and that was all she wrote!
 

Knightshade

Well-Known Member
Jul 31, 2017
14,088
24,646
NC
I agree that's true, however, I want to add that I have another car with adaptive cruise and lane keep assist that doesn't "phantom brake" nearly as much as the Tesla. My wife's car has randomly braked 3 times in the 3 years of ownership, my Tesla has randomly braked 3 times in the same day. Huge difference in the number of unnecessary braking events.


Dunno if you saw it- bit it was mentioned upthread you can try setting your emergency brake warning to medium or late, and that often significantly reduces phantom braking
 

GoergeJetson

Member
Aug 26, 2019
53
67
Florida
Dunno if you saw it- bit it was mentioned upthread you can try setting your emergency brake warning to medium or late, and that often significantly reduces phantom braking

Thanks for the advice. My emergency brake warning has been set on Late since day 1. I've also checked the setting periodically after updates since some settings seem to change after an update.
 
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nayr14

Member
Mar 18, 2019
107
100
Chicago, IL
And an Infiniti problem...

Infinity is Nissan

Here's a link where they mention it being a problem on Hondas too...
Automatic braking coming, but not all systems are equal

That's CMBS, not TACC.

So when you tell us this is primarily a Tesla problem- or that this SAME issue doesn't exist for virtually EVERY radar cruise system out there.... that appears to be... factually untrue

It's readily evident that brands, in general, experience this issue far less than Tesla. I'm not sure if it's a hardware of software issue, but Tesla phantom braking is extreme compared to other brands you cite (even though some of your references aren't related to the very point you're arguing). Manuals (your Mustang example) warn about everything that can go wrong, that isn't at all indicative of actual system performance. It's a legal requirement to help prevent lawsuits.

Stop defending Tesla's implementation. Acknowledge that it's behind the curve - if we don't, it will not get any better. You're contributing to the problem with these desperate posts that grab at any material you can find to justify a weak point.
 

ElectricIAC

Devil’s Advocate
Dec 31, 2019
2,966
1,989
DFW
Just drove around on the freeways, through many
scary exchanges and it never did anything odd. It
did slow down a bit to squeeze in on a lane change,
and that was perfectly done, only way to do it. The
2020.24.6.4 software is looking good so far.
.
An interesting thing. The phantom brake I see daily at 75-85mph (120-140kph) is severely mitigated at 55-65 (90-105kph) — If it’s a shadow, should this make a difference?
 

Fernand

Active Member
Mar 22, 2019
1,645
1,849
Northern california
We don't often get a chance to drive 75-85 MPH in NorCal, especially in typical traffic, I didn't test that today.

But you mean your car doesn't phantom brake as often at lower speeds, or by as much?

I don't remember your case, does it slow down or apply brakes? By how much? Always the same spot(s) or random? If it's reacting to something specific, it would make sense that it would panic harder at higher speed. It would also make sense to briefly disable AP there at least until you figure out the "why".

I've just never been troubled with phantom slowing on this car w/ HW2.5. Less than a handful in 18 months. The limited testing I've done w/ HW3 so far doesn't look different. I wonder if some cars have specific issues.

Is yours in NOA or Plain AP/AS or TACC Cruise? Do you have a speed limit set? Have you inspected all your sensors, meaning have you wiped the non-optical ones, and made sure your camera lenses are all intact, no cracks, and perfectly clean/clear? The side post cameras are susceptible to fogging and condensation, and there's some foam that could get dislodged. Do you do a check/wipe walk-around before starting out?

Do you see all the side warnings when you get near things, the same on left and right sides? Does the front alert on nearing say a fence when parking seem to work consistently?

I would think that people who are plagued with this problem at random every day should take the car in for service.

P.S. FWIW I always have the collision detect, or whatever it's called, set to Early, and I have all the safety stuff ON, lane departure to Assist. Driving to Normal (not Chill), Steering to Standard or Sport, Default speed set to 5MPH below limit. Lane change to Mad Max, Regen to Normal. Stop mode to Hold. No slip start. What else?
.
 
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john5520

Active Member
Mar 3, 2020
1,132
980
Florida
We don't often get a chance to drive 75-85 MPH in NorCal, especially in typical traffic, I didn't test that today.

But you mean your car doesn't phantom brake as often at lower speeds, or by as much?

I don't remember your case, does it slow down or apply brakes? By how much? Always the same spot(s) or random? If it's reacting to something specific, it would make sense that it would panic harder at higher speed. It would also make sense to briefly disable AP there at least until you figure out the "why".

I've just never been troubled with phantom slowing on this car w/ HW2.5. Less than a handful in 18 months. The limited testing I've done w/ HW3 so far doesn't look different. I wonder if some cars have specific issues.

Is yours in NOA or Plain AP/AS or TACC Cruise? Do you have a speed limit set? Have you inspected all your sensors, meaning have you wiped the non-optical ones, and made sure your camera lenses are all intact, no cracks, and perfectly clean/clear? The side post cameras are susceptible to fogging and condensation, and there's some foam that could get dislodged. Do you do a check/wipe walk-around before starting out?

Do you see all the side warnings when you get near things, the same on left and right sides? Does the front alert on nearing say a fence when parking seem to work consistently?

I would think that people who are plagued with this problem at random every day should take the car in for service.

P.S. FWIW I always have the collision detect, or whatever it's called, set to Early, and I have all the safety stuff ON, lane departure to Assist. Driving to Normal (not Chill), Steering to Standard or Sport, Default speed set to 5MPH below limit. Lane change to Mad Max, Regen to Normal. Stop mode to Hold. No slip start. What else?
.

I'm pretty confident this has nothing to do with the car needing service. And, IMO, it seemed to have gotten worse with the recent updates. I'm not getting it with overpasses lately, so I think that may have improved, however, the braking for speed limit changes is real and can happen randomly. If your freeway reported
speeds are accurate and you're not having it change suddenly from 55 to 45 or 35, then there's a good chance you'll hardly encounter it. AP can also get finicky when approaching larger vehicles and different lighting conditions. And yes, sometimes the braking can be a lot more than necessary. Enough so someone behind you would panic.

This is definitely not a rare occurrence.

Phantom braking with shadows | Tesla
Phantom braking | Tesla
[URL="https://forums.tesla.com/forum/forums/phantom-braking-question"]Phantom Braking Question | Tesla[/URL]
Phantom braking! Let’s talk about it : teslamotors
UPDATE: Was Tesla Phantom Braking The 'Cause' Of This Multi-Car Crash?
Phantom Braking when GPS and Google Map have an error
Phantom Braking - Better or worse since v10? - Tesla Owners Online
Phantom braking - AEVA Forums

BTW, this list is not even close to exhaustive. It is well known, documented and has been around for a while. The severity is not the same for everyone mainly because of location differences it seems (assuming everyone has the same hardware and software version).
And yes, it seems to happen to some degree with other manufacturers, but IMO, that's not a good excuse.
 
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electrongeek

Metrology Fanboy
Nov 1, 2019
69
74
Maine
I've made three 3600 mile round trips in my M3 since September of last year, 98% was on Interstate Highway between Maine and Texas. Phantom braking is a real PITA and always startles me and my passenger. No accidents, but I'm sure following vehicles wonder WTH. I would say it occurred about every 300 miles on average.

Not quite as bad, though still very irksome, is Navigate on Autopilot. So many poorly timed lane changes that the normal human would not even consider. The worst of these are cutting back into the right hand lane a mere 15 feet in front of a semi tractor trailer at 75 mph. This doesn't happen all the time, but enough to wonder. Using the car in standard Autopilot mode is what I have finally defaulted to. Still have to be alert for phantom braking though!
 

ElectricIAC

Devil’s Advocate
Dec 31, 2019
2,966
1,989
DFW
I've made three 3600 mile round trips in my M3 since September of last year, 98% was on Interstate Highway between Maine and Texas. Phantom braking is a real PITA and always startles me and my passenger. No accidents, but I'm sure following vehicles wonder WTH. I would say it occurred about every 300 miles on average.

Not quite as bad, though still very irksome, is Navigate on Autopilot. So many poorly timed lane changes that the normal human would not even consider. The worst of these are cutting back into the right hand lane a mere 15 feet in front of a semi tractor trailer at 75 mph. This doesn't happen all the time, but enough to wonder. Using the car in standard Autopilot mode is what I have finally defaulted to. Still have to be alert for phantom braking though!
Yes most of the time I stick to autopilot.
 

Fernand

Active Member
Mar 22, 2019
1,645
1,849
Northern california
But then what we're talking about right now is not "phantom", it's due to specific map issues, contradictory speed limit changes, those sorts of things. Of course, unbeknownst to the driver. And the terrified rear seat crew ;-)

It makes sense, as Musk says, that the cars are regionally optimized. The routes that I drive are well traveled by Tesla staff. It makes sense that the whole AP system behaves best where it's been most tested, and maybe that explains my "good luck".

This also says that with more data, more accurate maps, the performance will get better all over. In the meantime, stay alert, and if you can, learn where it's most likely to get confused, and override it.

We're on the same side here. I don't know how to best get this point across. As someone who uses the NOA a lot, I observe that using the automation requires a mental set that's different from manual driving, and also different from the SciFi scenario of treating it like a chauffeur. It's more like artificial limbs, that you wire into your brain. You don't have to control the low level muscle impulses, but you do have to ride it. We're right at the gradual addition of more and more self-determined functions with every OTA upgrade. Maybe some people don't like that, they want all or nothing NOW. Personally, I'm OK with this stepwise development, and find using it far far less work and stress than manually handling the whole stack. The chauffeur mode as Elon says, is a matter of 9's. How much better/safer than a human does it have to be?


They REALLY should have a reporting system to help correct mapping problems. I have one interchange nearby where the advisory speed is 45 and Nicki apparently doesn't read the sign and takes the plunge at the default 65. I just dial it down a bit, it's not a big deal, but I don't know how/where to scream at Tesla to fix the bloody map. They should be automatically receiving all AP disconnect events, maybe it's better to just kick it into manual?
.
 

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