WARNING: I rear-ended someone today while using Auto Pilot in my brand new P90D!

[AWDtsla]

That's exactly how AEB is supposed to work.

But was TACC on? And if so, why didn't it stop the car?

This is the real question.

 

[Canuck]

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

"You must spread some Reputation around before giving it to sandstruck again."

(No need to slink away -- you should proudly enjoy that drink. Cheers!)

 

[thegruf]

I'm going to buck the trend here - with the obvious caveat that I was not there so do not know what really happened and I dont have the logs from Tesla.

That said ...

If AEB kicked in - ie the car slammed on the brakes - I would be astonished if the driver didnt clearly recall this.
An attentive driver would be alert to a sudden rapid deceleration, and inattentive driver would be woken up by it.

I'm no conspiracy theorist but something doesn't stack up.

 

[WarpedOne]

The most probable reason fort things not stacking up was already given:

Probably not news, but when "exciting" things happen that cause adrenaline to kick in, your perception of time and speed changes. Everything slows down. It's normal, and nothing to be embarrassed about.

Human memory is very imperfect thing. A person may be 100% honest in his recollection and interpretations, but he has no clue about accuracy of those memories and interpretation. Human brains are an imperfect recording machines when in 'normal' state. When they jump into panic mode, it only gets worse.
Go watch some mind games documentaries. It gets interesting and scary how 'removed from reality' are our perceptions.

 

[bhzmark]

TACC was on. The OP has said this many times, and it was confirmed by Tesla. The reason it didn't stop the car was that the target car did "a rapid emergency deceleration." TACC is not designed to slow the car in that situation. AEB kicked in, and did reduce the impact of an unavoidable frontal collision, which is what it is supposed to do.

If TACC is on and senses a rapid decelerating car in front, it damn well better stop my car behind it -- or at least try its hardest. There is no reason it shouldn't. It seems to do that regularly in quickly stopping traffic. Even when making the tracked car red, but it still supplies sufficient braking to stop. I still don't see why it didn't ok in this case.

Also sandstruck didnt report that tesla said anything about TACC in this latest call. I would him to ask them this question. Why didn't TACC stop the car?

 

[davidc18]

Sandstruck thanks for sharing, it was an interesting thread. Glad you are okay.

 

[TSLA Pilot]

TESLA MOTORS: WHERE ARE YOU?

One event is an anomaly; two is a trend.

It's time to send out some engineers and start carefully inspecting hardware and reviewing vehicle logs--here is a perfect example, and the OP's new car too, of course.

Let's nip these problems in the bud before we start reading some remarkably bad headlines . . . .

Thanks.

I have not read every post, so if I'm repeating something somebody else said, forgive me.

I think AP may recognize cars faster and better than 18 wheelers. This is based on an unscientific sample size of one - me and my experience. I drive in Houston rush hour traffic 5 days a week on beltway 8, with AP engaged. The car has never come close to rear-ending another car. But today, for the first time since 7.1 came out, I almost hit an 18-wheeler. I would have hit him at about 5 or 10 mph if I had not stomped on the brake at the last second. I let it get extremely close because I wanted to see if the Model S would stop, but it didn't.

What happened was this: I was in the center lane with cruise set to 73 (distance at 7 as always) and the lane was clear in front of me. Then this 18-wheeler decides to pull in front of me from the lane to my right. (I ordered a new dashcam today, will be installed tomorrow, because my dashcam failed me) The Model S started slowing but only on regen. And it didn't start slowing until long after I was aware the truck was pulling in. (because it took it too long to recognize the truck?) I didn't feel the brakes cut in, and that really puzzles me because I know sometimes they do kick on. So, the car slowed but not enough and as I was about to smack the rear of the truck I decided to exercise the better part of valor and step in, braking just in time to keep from hitting it.

I am mystified why Tesla would program the car to let it hit an object it knows is there. Why not brake?? It was slowing quickly on its own. Why on earth did it not use the brakes and slow just a little more to avoid an accident?

The only answer I can come up with is this: I was wrong. It wasn't going to hit the truck. But I've been driving for 40 years, and all my instinct says I would have hit him. Again, I wish I had the dashcam footage, but dashcam is in trashcan now. New one on way.

- - - Updated - - -

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

Whoa. Don't be so hard on yourself.

What you've been told does not necessarily indicate what actually transpired. Yes, being an eyewitness may not mean you saw everything correctly either, but nor is the car infallible either.

What the car "reported" may not have been exact because what the logs show is simply what the car sensed--and it may not sense correctly.

Regardless, this has been a very informative thread and we appreciate your candor.

I'm going to start looking for dashcams--do we have a thread for those on here?

 

[sandstruck]

That's exactly how AEB is supposed to work.

But was TACC on? And if so, why didn't it stop the car?

He was following at 2 car length difference. If it had been four lengths AEB might have had enough time to stop. If the car in front does an emergency stop, AEB can only do so much at close range (and did what it could)

Thanks for sharing, Sandstruck.

This squares with what the Service Manager told me. At the time of the event, TACC was functioning correctly. Had my distance been set higher than two, he said I'd likely have avoided the collision (i literally needed an extra foot).

Extrapolating from this, it seems obvious that depending upon one's speed, even with the maximum setting of 7, the system's radar and cameras cannot see far enough ahead to avoid all accidents (i wonder if i'd been going sixty at the time, with a setting of 7, would the car have stopped on time? How about at seventy?).

Some on this thread have posited that tbe system reacts faster than a driver ever can. but (and this is also obvious) in many cases a driver might see brake lights ahead cosiderably sooner than TACC senses that car's rapid desceleration.

 

[msnow]

TACC was on. The OP has said this many times, and it was confirmed by Tesla. The reason it didn't stop the car was that the target car did "a rapid emergency deceleration." TACC is not designed to slow the car in that situation. AEB kicked in, and did reduce the impact of an unavoidable frontal collision, which is what it is supposed to do.

True.

 

[dsm363]

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

Thanks for sharing and glad you are ok as well. That explanation does seem more plausible as if there was a gradual deceleration to 5 mph you should have been able to stop the car easily. Memory can be a tricky thing when events like this happen. Agree dash cams seem more and more useful as time goes on.

- - - Updated - - -

TSLA pilot: there is a thread for dash cams on TMC
How about a DashCam option? - Page 19

 

[ecarfan]

If TACC is on and senses a rapid decelerating car in front, it damn well better stop my car behind it -- or at least try its hardest. There is no reason it shouldn't. It seems to do that regularly in quickly stopping traffic...I would him to ask them this question. Why didn't TACC stop the car?

Tesla does not claim that TACC will bring the car to a complete stop in every situation. At this point the system is not capable of doing that. The AEB kicked in at 40mph and significantly reduced the impact speed. The TACC setting was 2 on a scale of 1 to 7. The following distance was not enough to give the system time to react and avoid a collision.
The system is not yet perfect. You seem to think it should be at this early stage of development. I'm sure it will improve over time.
My conclusion is that at this time Tesla should not allow such low TACC settings. It can give drivers a false sense of security.

 

[dsm363]

Tesla does not claim that TACC will bring the car to a complete stop in every situation. At this point the system is not capable of doing that. The AEB kicked in at 40mph and significantly reduced the impact speed. The TACC setting was 2 on a scale of 1 to 7. The following distance was not enough to give the system time to react and avoid a collision.
The system is not yet perfect. You seem to think it should be at this early stage of development. I'm sure it will improve over time.
My conclusion is that at this time Tesla should not allow such low TACC settings. It can give drivers a false sense of security.

Agree. If someone is following that close they should be in control and responsible. Not depending on some system that isn't designed to completely protect them in every situation.

 

[Electroman]

For those who say AEB will release the brakes after reaching 5mph, have you seen the video titled: Autopilot saves the day (Tesla Autopilot saves the day - YouTube) where the car initially traveling at 45mph sees an object cut across and comes to a complete stop with inches to spare.

You will notice that the car was never locked onto anything in the front, but it still came to a complete stop when it noticed a stationary obstruction.

So this 'AEB will reduce by 25 mph and will give up after reaching 5 mph' isn't true as you can clearly see on that video

 

[pdq]

In the 4 months I've had my P90D I've used TACC as often as I can -- love it. I don't like people who tailgate me, and I don't tailgate, so I have my car set to a separation distance setting of 7 which gives plenty of time if TACC were to not respond properly.

AP OTOH still scares me. I tell people it's like being a passenger in a car with someone who has just gotten their learners permit.

 

[Pollux]

I admire your willingness to re-examine your position.

While confabulating is way more common than any of us would like to believe, I'm still struck by the variation between your memory and the report from Tesla. The engineer who used to reside within my body would want to see the actual data and/or engineering root cause analysis rather than have it filtered through a service manager. Not that I would ever doubt the chain that reliably transported data and interpretation all the way from an overworked individual contributor in a core engineering team all the way through a sequence of managers and departments until it finally reached you.

Alan

I received a phone call an hour ago from my Tesla Service manager who told me the following:

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car, thus avoiding a much worse accident. In fact, the damage to my car is negligible (broken nose cone).

As I repeatedly mentioned in my posts, I remembered something very different transpired--a gradual slowing down, synchronously, with the car ahead of me to about 5 MPH--and a surprising, last-second failure of my car to stop. That's how I remembered it, anyway (I'd have sworn on a stack of bibles). It now seems that my version of events was dead wrong. It makes me wonder how many other memories I have mistakenly fabricated.

The important thing is that I believe Tesla's interpretation of events more than my own. And I want to apologize to everyone who wasted time on this thread and on me, and who believed me at my word. To those posters who accused me of acting irresponsibly by posting before I had the full information from the logs--you were right!

I will slink away now to my basement, inebriate myself perhaps, and marvel at my fallibility, at the frailty of my memory. Mea culpa.

 

[AWDtsla]

Just trying out 7 tonight. That's really really far, at embarrassing levels even. It's like you're "that guy" with a line of cars behind you, trying to pass you over the shoulder one at a time

 

[bhzmark]

From the OP:

. . . After following this new car for a few minutes, the traffic began to slow. My car slowed as well. But when the car in front of me came to a complete stop (not a sudden emergency stop, but rather a gradual stop), [TESLA now claims that the logs show this was an rapid stop by the car in front] I expected my car to do the same (as it had been doing previously). It didn't. I slammed on the brakes in that dreadful instance before I realized my car wouldn't stop in time, but I still hit the car in front of me (while going maybe 5-10 MPH).

No one said TACC should be able to avoid a collision in all cases. But it should try. And certainly in this case. If it is following a car for a few minutes, and that car brakes hard, even screeches to a halt, there is no reason TACC shouldn't do the same. And it should be able to do it much faster than any person can.

And also, why was AEB engaged when TACC was on and functioning? Why didn't TACC do the braking (to a stop) instead of AEB braking (just reduce speed by 25mph)?

I still think something else went on. From my extensive experience with TACC (and its counterpart in other cars) I have seen auto braking very aggressively when the locked on car in front brakes hard.

Which best explains what happened?

1) Sometimes when TACC is on and functioning and following a locked on car and that car brakes hard, TACC might run into it anyway. (or just hand over the braking to AEB which won't brake to a stop).

OR

2) While TACC will normally brake hard to try to stop when the car in front brakes hard to a stop, in this case there was weird condition such as some lane-changing by cars in front, or a hill, or a curve, or sun glare, or accidentally disengaging TACC or something else that better explains the failure to brake hard to a stop.

 

[ecarfan]

Just trying out 7 tonight. That's really really far, at embarrassing levels even. It's like you're "that guy" with a line of cars behind you, trying to pass you over the shoulder one at a time

TACC set at 6 or 7 provides a safe following distance and allows the driver to react in time if the car in front slams on their brakes. A lower TACC setting is not safe.
What "embarrasses" you does not embarrass me. Your attempted comparison of TACC to someone driving with a line of cars behind them on a single lane road and no one in front of them is obviously incorrect. TACC operates by locking on to the car in front and then maintaining a fixed distance.

 

[woof]

My car had been traveling at approximately 40 MPH when it engaged the AEB. He told me that the engineers determined that the car in front of must have slammed on the brakes ("a rapid emergency deceleration"), and the AEB significantly slowed my car,

Playing armchair engineer...there are other possibilities. I'm sure the data show AEB suddenly kicked in at 40 MPH due to the rapidly decreasing distance between you and the car in front. However, there are alternate possibilities as to why TACC saw that.

Imagine this scenario:

1. You are Car T moving 60 MPH, Car B is directly in front of you moving 60 MPH, Car C is directly in front of her, slowing down from 60 MPH to come to a stop up ahead.
2. Car B sees Car C slowing down, and moves to the right lane to pass Car C, slowing down to 50 MPH, then 40 MPH.
3. Car T is tracking Car B as she moves right and slows. Car T slows as well. Car B is moving faster than Car C.
4. Car B passes Car C, which is now moving 20 MPH. Car T moving 40 MPH (because it was tracking Car B) switches to track Car C.
5. Car C is moving significantly slower than Car T.
6. Car T applies AEB as it calculates Car C is in collision path.

I'm guessing the data Tesla sees is that the tracked car suddenly slowed, thus AEB was applied. What it probably doesn't show is that Mobileye just switched which car it was tracking, which I've seen occur quite often when using the Mobileye based ACC in the BMW. I use ACC almost every day, even though every day does something "wrong" at least once, and I need to correct it. It's still a useful feature that I prefer over regular cruise control.

So have that drink, but mull over the possibility you may not be as wrong as you think.

 

[AWDtsla]

TACC set at 6 or 7 provides a safe following distance and allows the driver to react in time if the car in front slams on their brakes. A lower TACC setting is not safe.
What "embarrasses" you does not embarrass me. Your attempted comparison of TACC to someone driving with a line of cars behind them on a single lane road and no one in front of them is obviously incorrect. TACC operates by locking on to the car in front and then maintaining a fixed distance.

Lots of people do stupid things all the time and failed to be embarrassed by them.

Regardless, while it is tracking the other car, your brake lights often light up while tracking at this distance. Again I don't care if YOU are not embarrassed, but being a football field length away from the car in front of you and randomly hitting the brakes just screams "old man, should have had license revoked, steer f****** clear!"