Annoying braking on TACC - is this normal?

[richyrich]

I've had some long-running issues with my car braking suddenly for vehicles in other lanes, sometimes when they are two lanes over. Every time it happens the screen shows the "offending" vehicle(s) as a darker gray on screen - I'm guessing that means it's a vehicle the car is tracking/avoiding? In no cases are these vehicles encroaching or even looking like encroaching on my lane but the car brakes, often heavily. I typically drive on TACC with my foot hovering over the accelerator ready to override when it happens because it's really unpredictable and uncomfortable.

I finally managed to get a pic of it happening today - pic below. It happens at all speeds but this was very slow moving traffic. I was rolling along on cruise+auto-steer, going slightly faster than the lane on the left when it suddenly slammed on the brakes because of the blue car. That car had been behind/in-front/next to me constantly for a long while, was well in its lane and showed no sign of moving into my lane (nor did it). For whatever reason my 3 decided it needed to emergency brake for it and you can see it's showing on screen as dark-gray and coming over the line (which in reality it's not - you can clearly see that from the road markings). I'm doing 21km/h because I'm pressing the accelerator to override it after the braking so I don't cause a pile-up.

This is wrong right? Ranger told me it's normal. I feel like the car is maybe mis-judging distance or location on other vehicles - could I have a faulty sensor? Could some kind of calibration be off? Thoughts appreciated.

 

[Az_Rael]

That, unfortunately, is pretty normal right now. It gets better (and sometimes worse) on various software updates. One recent one made it worse for me. Used to be you could avoid it by using TACC only and not Autosteer, but a few updates ago they added this behavior into TACC as well.

 

[richyrich]

Thanks for the reply. Not what I wanted to hear - I was hoping I had something faulty. It definitely seems to have gotten worse recently. As you can clearly see in the photo it's hugely mis-calculating where the blue car is even with decent conditions, low speed and very clear road markings. It just doesn't make sense. Ugh.

 

[Az_Rael]

Thanks for the reply. Not what I wanted to hear - I was hoping I had something faulty. It definitely seems to have gotten worse recently. As you can clearly see in the photo it's hugely mis-calculating where the blue car is even with decent conditions, low speed and very clear road markings. It just doesn't make sense. Ugh.

What software is your car currently on? Mine got a bit better on the latest software, 2019.20.4.2. It had gotten a lot worse on one of the 2019.16 releases I recall.

 

[Telstar]

I recently finished my free trial of autopilot and also experienced this. My free trial is over and I can now relax and enjoy standard cruise control. Hope they get this worked out soon. Also, the "hands on the steering wheel intermittently" was also a deal-breaker. I'll definitely get it when I can just get in the car and tell it where I want to go.

 

[richyrich]

What software is your car currently on? Mine got a bit better on the latest software, 2019.20.4.2. It had gotten a lot worse on one of the 2019.16 releases I recall.

I'm on that same version. It just seems so odd that it has no problem seeing the lines and showing them on screen, but somehow it thinks the blue car is well over that line and into my lane?

 

[IraB]

This same problem got worse for me on 2019.4.2. It happened far less often on the previous version. It is annoying and I hope it will improve in the next release.

 

[Phugoid]

So annoying. I love the M3 on road trips except for this overly-cautious braking. I used to spend like 75% of my highway driving on TACC and AP when I first got the car last Nov (and the same with the Model S I had before), but now I’m down to more like 25% with this constant pulsing of gas/brake from every tiny shadow and every miscalculation of where other cars are located. Also really hoping for some improvement.

 

[Midway99]

This same problem got worse for me on 2019.4.2. It happened far less often on the previous version. It is annoying and I hope it will improve in the next release.

Same here. Also, now on a road that never had issues, the car will not changes lanes while on AP when wanting to move from the left lane to right. Right to left still works fine.

When I turn on blinker, it never changes lanes and a message comes up ‘auto lane change unavailable’. Only started with update 2019.4.2. Anyone else ever get this?

 

[richyrich]

I wonder if they even know there's an issue? Like I said the ranger told me it's normal. Something is very definitely not right and it's got worse. Yet again yesterday my car broke hard for another vehicle that was two lanes to the right of me on perfectly marked, non-busy highway in broad daylight. Something is very f'ed up and I'm kinda sick of it. Hovering my foot over the "gas" pedal is making AP driving a lot less enjoyable and relaxing than it should be.

 

[tyseft163]

I wonder if they even know there's an issue? Like I said the ranger told me it's normal. Something is very definitely not right and it's got worse. Yet again yesterday my car broke hard for another vehicle that was two lanes to the right of me on perfectly marked, non-busy highway in broad daylight. Something is very f'ed up and I'm kinda sick of it. Hovering my foot over the "gas" pedal is making AP driving a lot less enjoyable and relaxing than it should be.

There's this thread also: AP2 / TACC Still slowing when passing freeway offramps

 

[MMBTUS]

I would be ecstatic for a toggle to turn on/turn off TACC separately from “standard” cruise. Why not? Super easy.

 

[Octo]

I’m pretty sure Tesla knows it’s an issue.

My Model 3 also shows cars in adjacent lanes coming closer than they do in reality. Some people on this forum discount this as a rendering problem but it looks like this is the actual data that the car uses to make its decisions. I think it’s “normal” right now in the sense that that’s the accuracy of processing images from the side and front cameras with their distortions and field of view. Almost every vehicle in adjacent lanes is rendered with a curve towards the Tesla when it approaches and away from it as it pulls further ahead.

I’d expect this to eventually get fixed.

 

[cleveland97]

I'm on 20.4 and having the same issue far too frequently. Seems to have gotten worse in recent updates, not better. I had a situation last night with my family in the car where we almost got rear-ended because the car (while on TACC) slammed the breaks for no apparent reason. The nearest car was 2 lanes over, no overpasses, no shadows, no exit coming up. The only thing I can guess might have caused it is that the freeway was going from 4 lanes to 3 lanes (I was in the left-most lane and the right-most lane was going away) and the car somehow thought that it needed to allow space for people to merge from 3 lanes away??

 

[Octo]

I'm on that same version. It just seems so odd that it has no problem seeing the lines and showing them on screen, but somehow it thinks the blue car is well over that line and into my lane?

The screen shows the blue car touching the line but in reality it’s well within its lane, some three feet to the left of the line.

The TACC SW probably “thinks” that the blue car is drifting into your lane based on the flawed data it gets from the cameras and image processing + vision AI.

 

[IraB]

I updated to 20.4.4 a few days ago. Since then I have not had the issue with cruise control slowing when passing slower vehicles. Hopefully, this is one of the things that got fixed "silently."

 

[BM3B]

I call this "phantom braking" and it got a lot worse with 2019.20.2.1, it's still a problem.

 

[alexGS]

I haven’t got my Model 3 yet (arrives next month), but riding in a Model X with TACC active, I observed a couple of situations where a car in front pulled over into a right-turning bay (we drive on the left, so the car in front pulled to the right) and the symbol of that car disappeared from the Model X’s display. A moment later, the brakes were applied hard, as we reached the place at which the (previously slowing) car would have occupied.

Therefore, I hypothesise (guess) that the TACC errs on the side of caution when it loses sight of the vehicle in front; it seems to extrapolate where that other vehicle would now be (based on the previous data) and applies the brakes just in case the other vehicle is still there.

This problem should be solved by more accurately tracking the surrounding vehicles and not losing sight of them? Hoping that the camera system doesn’t have significant blind spots that prevent this.

OR - am I completely wrong and does the TACC use only a radar ‘fix’ to the vehicle ahead?

-Alex

 

[richyrich]

I'm on 20.4 and having the same issue far too frequently. Seems to have gotten worse in recent updates, not better. I had a situation last night with my family in the car where we almost got rear-ended because the car (while on TACC) slammed the breaks for no apparent reason. The nearest car was 2 lanes over, no overpasses, no shadows, no exit coming up. The only thing I can guess might have caused it is that the freeway was going from 4 lanes to 3 lanes (I was in the left-most lane and the right-most lane was going away) and the car somehow thought that it needed to allow space for people to merge from 3 lanes away??

Yeah this is why I always have my foot hovering over the accelerator now, it's just too dangerous otherwise. I drive 50,000km a year and get this braking at least once a day usually. It sucks because TACC and Auto-Steer make driving so much more relaxing.

 

[richyrich]

The screen shows the blue car touching the line but in reality it’s well within its lane, some three feet to the left of the line.

The TACC SW probably “thinks” that the blue car is drifting into your lane based on the flawed data it gets from the cameras and image processing + vision AI.

I don't have an issue with it just "showing" vehicles being in the wrong position. I do have an issue for it braking (hard) for them.