Phantom braking (TACC/AP) [Not AEB]

[Drew57]

I don't use AutoPilot other than on motorways. I do occasionally get the shrill beeps from the Forward Collision Warning, it's a bit jumpy. I'll value it the one time I'm not paying full attention some day.

So had the cars speed limit changed to the 30mph road underneath? A mapping error? I'm not sure if that's what's called Phantom Breaking. Also a dual carriageway rather than a motorway, maybe that makes a difference.

We're not discussing the definition of phantom braking here, the car braked unexpectedly & that should not happen. There are various causes, either shadows, lorries, road mapping or other & all have the same potential for disastrous consequences.

 

[GRiLLA]

We're not discussing the definition of phantom braking here, the car braked unexpectedly & that should not happen. There are various causes, either shadows, lorries, road mapping or other & all have the same potential for disastrous consequences.

Why not? Seriously if anyone is at all interested in identifying why some people have a different experience to others the starting point is to understand what people actually mean. Some people are saying that this happens every time they make a motorway journey, others including myself simply don't see that. Might be interesting to find out why there's a difference.

If all people want is to vent go and find a DM article to comment on.

 

[Yachtsman]

There's something odd about this, lots of you seem to act like it's a daily life threatening experience, I've had is maybe 3 times in 21 months and it was no big deal. I use AP a lot, because of where I live every journey is on the M40 and I use it all the time. Either we drive differently or different cars react in different ways. I certainly don't hover over the accelerator.

I drove M40 - M25 - M3 -M27 on AP to Dorset last week with absolutely no excitement.

I regularly drive the M6/M5/M42 during rush hour, possibly the busiest sections of motorway outside of the M25 & literally jammed with hgv's of all shapes & sizes, almost always using TACC. I've only had a phantom (sudden sharp decellaration) happen once in 5k miles but slight hesitation probably 20-30 times particularly when in the centre lane & going faster than lanes either side. I think it doesn't like to under take, slight pressure on the go pedal & it continues.
I'm as confused as many others as to why there's a wide difference.

 

[browellm]

I think the car knows how often you’ve been worshipping at your Elon shrine and reacts accordingly.

 

[Drew57]

I think the car knows how often you’ve been worshipping at your Elon shrine and reacts accordingly.

Oh dear... mine would have been totalled long ago then.

 

[MrBadger]

Apart from driving conditions, weather, driving style and the car (such as cleanliness of windscreen), there are a number of personal preferences that may affect the vehicles behaviour. I suspect that some of these will have at least some bearing on the different experiences.

Off top of my head, follow distance, forward collision warning, automatic emergency braking and obstacle aware acceleration are likely suspects in the car reducing power or braking that are to varying degrees associated with phantom braking.

Maybe its worth mentioning these, or other similar settings, if describing issues or non issues?

 

[hgmichna]

One thing is for sure—phantom braking will never go away entirely for the simple reason that the car will always misidentify some possible obstacles. Until cars have human-level intelligence (which would create much bigger problems for us lowly humans), we will have the occasional phantom braking.

My hope is that the frequency will be lowered by better image processing and fewer programming mistakes, like using speed limits of a road or lane I'm not driving on.

 

[Tinca]

Off top of my head, follow distance, forward collision warning, automatic emergency braking and obstacle aware acceleration are likely suspects in the car reducing power or braking that are to varying degrees associated with phantom braking.

Maybe its worth mentioning these, or other similar settings, if describing issues or non issues?

Good point. At the moment I have all of these turned on and the follow distance set to 5. In my recent phantom braking experience, there were no cars in front of me in my lane (lane 3 on the A1) and the only car in lane 2 was the one I was passing. No bridges, overpasses or junctions nearby.

I'll be driving the same road tomorrow, so depending on the traffic conditions, I may try TACC in the same area to see if there is a GPS/location link.

 

[Rooster6655]

I only use AP/TACC on motorways now, I find even TACC alone is pretty useless on non motorway driving with constant random behaviour. Let us not even talk about a road without a line in the middle

 

[Tinca]

only use AP/TACC on motorways now, I find even TACC alone is pretty useless on non motorway driving with constant random behaviour. Let us not even talk about a road without a line in the middle

TACC was well behaved on a run from Lincolnshire to Guildford and back yesterday. Only a couple of unexpected slow-downs and no full braking events.

I did find TACC in a long M25 traffic jam to be really good. First time I've used it in that way, and it worked well with good distance between the car in front (I'm set on 5), good response when moving off and slowing down. I did try AP/TACC for about 2 minutes, but the motorcyclist coming between the lanes didn't appreciate the road position!

 

[Drew57]

Below are the settings on my car, zero phantom braking yesterday on Autopilot - 165 miles continuous M6 J16 to A14 Bury St Edmunds (software 2021.4.18 & 2021.8 map). Bright sun, plenty of lorries, shadows on bridges, contraflows & roadworks.

By far the most impressive journey I have used Autopilot - bongs to change lane, nags from the wheel but none from my wife (well, not about driving this time)

 

[Adopado]

I did try AP/TACC for about 2 minutes, but the motorcyclist coming between the lanes didn't appreciate the road position!

Good point. It's always worth keeping an eye open for bikes (legitimately) splitting the lanes in slow moving traffic. A human driver can make a judgement about nudging a few inches one way or the other to keep it safe for everyone.

 

[MrBadger]

Moderator comment - various posts moved to UK - Transitioning to Tesla Vision - removal of Radar

 

[Drew57]

Can I make a suggestion...

Maybe it would be good for any further posts about this subject to include a screen shot as in my post #231 above so we can understand if part of this is related to individual Autopilot settings rather than a global issue.

I've now had several journeys where earlier in the year the car braked at certain points but since 4.18, now 4.18.2 and the 2021 map it hasn't happened again. The only time my car has braked (gently-cautiously) in the recent 220 AP miles was when a mid-distance lorry crossed the median on a dual carriageway today and was waiting to join the side I was travelling on at 60mph. In my opinion that was correct anticipation of a potential incident.

I'm not saying Tesla phantom braking isn't a concern (otherwise why are Tesla looking at removing radar?) but it's never been that common or severe for me and I see wildly different reports about severity among owners. Maybe 'settings' have a significant impact?

 

[Cloggie]

Can I make a suggestion...

Maybe it would be good for any further posts about this subject to include a screen shot as in my post #231 above so we can understand if part of this is related to individual Autopilot settings rather than a global issue.

I've now had several journeys where earlier in the year the car braked at certain points but since 4.18, now 4.18.2 and the 2021 map it hasn't happened again. The only time my car has braked (gently-cautiously) in the recent 220 AP miles was when a mid-distance lorry crossed the median on a dual carriageway today and was waiting to join the side I was travelling on at 60mph. In my opinion that was correct anticipation of a potential incident.

I'm not saying Tesla phantom braking isn't a concern (otherwise why are Tesla looking at removing radar?) but it's never been that common or severe for me and I see wildly different reports about severity among owners. Maybe 'settings' have a significant impact?

@Drew57 I would love to have the time to take a photo when my car decides to throw the ankers out, but I am quite preoocupied with speeding up, checking for other cars and/or apologetically holding up my hand to the car behind me. I am not aware of a way the car can take a screenshot to save later. Is there one?

 

[Drew57]

...this is a screenshot using my camera when the car is parked & these are the fixed Autopilot settings applicable to every drive until I choose to change something.

 

[Pagemakers]

It’s not the settings. It’s a bug and Tesla needs to fix it.

 

[Obliter8]

I'd just like to echo the sentiments previous - it seems the frequency varies wildly across individuals. Fundamentally, we all drive the same car so there's likely a lot of the individual in the report.

I'm in the 'it happens every now and again, but it's usually an annoyance rather than a danger' camp.

I'll get the settings screen next time I'm in the car, but here's my human settings baseline - only really enable TACC/EAP on the motorway, then it's on 95% of the time, usually do long drives, in normal circumstances ~20k miles/year.

 

[Rustybkts]

I did a 450 mile drive yesterday from the Midlands to Newcastle and return.
Started off using TACC as usual on the M1 but was soon driving manually.
I had numerous small and large episodes and upon watching the visualisation (when driving manually) I could see why.
Trucks one lane away on four lane parts of the motorway (Smart) were jumping in to the lane next to me so clearly upsetting the software. Cars were smooth on the visualisation but trucks next to my lane didn't pass smoothly either and jumped forwards and backwards as I passed them. The lane markings were solid on screen.
The sunny side was the other side and although must have been dazzled, was working perfectly with cars and vans passing.

One really bad episode was when I indicated and pulled in to the clear empty lane to my left with a truck on the inside lane. Wow, I decelerated sharply and was surprised that the following car didn't give me the bird or brake check me as I certainly did to them.

WTF is going on and was nothing to do with radar as the problem seems to be at the side with just the camera's causing it. I did check that the camera's were clear when topping up at Scotch Corner.

 

[CaptFish2003]

There is a video by a German youtuber that suggests to recalibrate the radar to reduce Phantom braking. Can be done via the Service tab on the screen. If the actual radar has been misaligned or changes to the suspensions were made, one might need to compensate the re-calibration process by putting an additional load in the trunk or frunk.
They realised that when they changed the suspension the car was undrivable on the Autobahn using AP, but recalibration solved this.