We were driving on the highway from Chicago to Indianapolis this weekend traveling 70 mph on "Navigate on Autopilot" when suddenly the cars slams the brake. It happened multiple times and the worse was when we were at 70 mph, the car slammed the brake to 50 mph, it scared us and the dogs at the back. There were no cars in front and in the back but there were 2 cars in the right side of the car. Prior to that brake slamming, the car has been notifying to move to the other lane because we were at the passing lane. We were not, we were in the middle lane and the other 2 cars were in the slow lane. Has anything like that happened to you? After that we just didn't activate the "Navigate on Autopilot" and the brake slamming stopped.
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Navigate on Autopilot
- Thread starter 75Dchgo
- Start date
Had a Mercedes S63 and driving home at 60MPH and the car slams on the brakes to a full stop. Scared the S--- out of my wife. Ran my dash cam back and a squirrel darted in front of the car.
The thing is there were nothing that crossed the highway and it was in broad daylight. LOL its just scary because what if someone was behind us and hit us at that speed?
Tam
Well-Known Member
It's well known and Autopilot users should have known it and they all should have expected it.
The term is called "phantom braking" when the car just brakes without legitimate reasons.
It's a radar flaw that has not been worked out just yet since its introduction in 1935 or for the past 84 years.
Uber tried to work out that problem and it finally found the solution and implemented that solution to impress their boss:
If you turn on the radar, you would get Phantom Braking, so how about turning it off so the Boss can say Wow.... So smooth!
Report: Uber self-driving team was preparing for CEO demo before fatal crash
StealthP3D
Well-Known Member
You don't think the Model X checks what's behind it before it decides how/when to slam on the brakes? I bet it does. This is one of the advantages of a computerized driving aid, it can do many more tasks simultaneously than a human. Of course, no electronic driver aid is perfect, they are getting better every year. They are already good enough to be increasing the safety on our highways (and that includes the accidents caused by misuse of these systems).
Tam
Well-Known Member
I associate Phantom Braking with an overhead bridge, overhead sign, a car in front doing a left or right turn...
And of course, there are times I can't associate it with anything.
I just pay attention to the locations and see it would repeat again.
And of course, I have to be ready to override the Phantom Braking by pressing on the accelerator if I don't want to be hit by the car in rear.
XHabjab
TSLA Bull
I've seen this quite a bit. In my experience, there are two main causes:
- Whenever you are on a relatively "new" section of highway that was formerly under construction. The car still thinks it is in a construction or detour zone regardless of the state of the current highway, and brakes whenever it thinks you are driving off into the ditch.
- The builtin map system thinks that the road comes to an end with a phantom barricade. In my community, the main road to my subdivision used to end at a real barricade. They extended the road and removed the barricade. The maps have not caught up. If I navigate from home to the grocery store, the guidance insists on turning off the main road into a side street, then do a U-turn back onto the same main road. If I drive on EAP without navigation, the car goes into panic mode where the car says the imaginary barricade is.
NoA seems to panic when it encounters a situation that triggers traumatic memories of crashing into a fire truck stopped by the side of the road - stationary vehicles in the breakdown lane, a car at the end of a driveway, cars slowing down in the exit ramp, or large trucks moving slowly in an adjacent lane.
Slamming on brakes to stop at ~140 feet or just letting of the accelerator for full regen braking?
I was not there but from experience it was likely full regen. By the time one reacts, the speed is down to 65 mph from 70. Yet it feels like the car slammed on the brakes because it is not expected.
I still do not like it but it is not as dramatic as it feels.
And I saw full braking with ABS cycling as well - pick up truck made a left turn in front of us, we were clearly going to pass behind him but the car thought otherwise. The car is more conservative but that is preferable to hitting something.
I was not there but from experience it was likely full regen. By the time one reacts, the speed is down to 65 mph from 70. Yet it feels like the car slammed on the brakes because it is not expected.
I still do not like it but it is not as dramatic as it feels.
And I saw full braking with ABS cycling as well - pick up truck made a left turn in front of us, we were clearly going to pass behind him but the car thought otherwise. The car is more conservative but that is preferable to hitting something.
XtheGas
Member
I have experienced "phantom breaking" 8-10 times in the 2 months I have owned the car. I submit a bug report every time in hopes they can use the data to improve the system.
Corbets
Member
I experienced this a lot in my P90D rental in August, but not since the v9 upgrade, either in that car (rented agin in December) or my own 100D (picked up end of dec). I was under the impression they’d more or less fixed it, since it happened so frequently in aug and not at all since.
Seattle Tom
Member
I’ve experienced this too, most often with a high road sign or highway overpass. Every time it happens, click the Voice button and say “Bug Report Phantom Braking.” The instrument cluster/binnacle will say “Thanks for your bug report” to confirm it was sent.
One other things given the OP’s situation. NoA will slow down if it thinks you should be in the right lane (say for an upcoming exit or if it thinks you are hanging too long in the passing lane). I’ve had it slow down, but never brake hard, and I have to override the system. That could be what happened here.
Of course all of this is just more example of how NoA is NOWHERE FREAKING NEAR any kind of full self driving, despite Elon’s proclamation on the last earnings call that “we basically have full self driving on the highways now.” What a joke.
One other things given the OP’s situation. NoA will slow down if it thinks you should be in the right lane (say for an upcoming exit or if it thinks you are hanging too long in the passing lane). I’ve had it slow down, but never brake hard, and I have to override the system. That could be what happened here.
Of course all of this is just more example of how NoA is NOWHERE FREAKING NEAR any kind of full self driving, despite Elon’s proclamation on the last earnings call that “we basically have full self driving on the highways now.” What a joke.
I've experienced quite a few of these breaking situations. I own both model S AP1 and model X AP2 and have to admit AP2 so far isn't better than AP1. I'm sure they'll eventually work out the algorithm for AP2 but for now it's way too buggy and overly sensitive. The speed limit issue is also a let down.
In our AP2 vehicles, we periodically see phantom braking when the AP system incorrectly detects an object in front of the vehicle (usually due to a dark shadow or rapid change to a small area of dark pavement) or because the speed limit database incorrectly indicates the speed limit is slower than the actual posted speed limit.
The phantom braking has improved over the past year, but still happens periodically - and we're comfortable with the software being overly cautious when it believes there's a reason to slow down.
The speed limit data errors are more frequent - especially on roads which have recently completed construction projects.
When this braking happens, especially in heavy high speed traffic, it poses a safety risk, if you slow down quickly and the vehicle behind is not prepared to match your slowdown (and likely driving too close).
This software is still in beta - and to be safe, drivers should continuously monitor operations, and be prepared to take over control if/when the software doesn't operate as expected.
The phantom braking has improved over the past year, but still happens periodically - and we're comfortable with the software being overly cautious when it believes there's a reason to slow down.
The speed limit data errors are more frequent - especially on roads which have recently completed construction projects.
When this braking happens, especially in heavy high speed traffic, it poses a safety risk, if you slow down quickly and the vehicle behind is not prepared to match your slowdown (and likely driving too close).
This software is still in beta - and to be safe, drivers should continuously monitor operations, and be prepared to take over control if/when the software doesn't operate as expected.
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