TACC now locks to stopped cars?

[Matias]

Earlier TACC has not locked to cars which it sees first time when they are at full stop. This has lead to situations as this

https://www.youtube.com/watch?v=0X2ftEXG7IE

Recently this has maybe changed? At least this is my impression. Today I tested this by activating TACC when I came to my home yard. Only other car was my other car which was parked. I approached it from behind and TACC locked to it.

Edit: mods, please ad question mark to title

I don't want to cause any accident, if I'm wrong.

 

[Sogorman]

Earlier TACC has not locked to cars which it sees first time when they are at full stop. This has lead to situations as this

https://www.youtube.com/watch?v=0X2ftEXG7IE

Recently this has maybe changed? At least this is my impression. Today I tested this by activating TACC when I came to my home yard. Only other car was my other car which was parked. I approached it from behind and TACC locked to it.

What firmware version are you running?

 

[Matias]

What firmware version are you running?

Nothing fancy

2.5.46

 

[Troy]

Matias,

What happens in that video is very different than just recognizing a stationary car in front of you. In the video the Tesla is following the blue car and assumes the driver will turn the steering wheel and follow the blue car. To create the same situation again, it is not enough for just the white car to be there. You also need the blue car. It is very unlikely this problem has been solved. In fact it is much more difficult to solve than it appears.

In the video image the path the blue car was following was the only road. Assume there were no intersections at all and the blue car was driving on a one way curved road with a bunch of cars parked on the side. What would be the desired TACC action in this situation? Would you prefer if the car suddenly applied breaks while you are taking a curve at high speed just because there happens to be some parked cars on the side of the road? Of course not. That would be very dangerous.

You might say, "in the video the white car is not a parked car on the side of a curved road." I know but the TACC can not differentiate between that and what happens in the video. That's exactly why the car didn't apply the brakes.

 

[RAW84]

So in the video, TACC is working fine. It's locked into the prius, but the prius turns right and the model a driver wants to go straight, so by the time the TACC accepts that the driver is going straight and locks onto the white car, it's too late to fully stop. I see no problem with this, but this just illustrates one of the many instances which causes Tesla to say TACC is not designed for surface roads. I do think TACC works fine on surface roads as long as you have a basic understanding of how TACC operates use common sense as you use it, tho....I use it everyday on surface roads.

In my experience, TACC doesn't do a good job stopping behind a car that's already at full stop because of stopping distance. If I'm cruising along at 45 mph, the car doesn't recognize and accept the fact that the car in front of me is stopped until it's too late, but at lower speeds it can work. I don't know what that cut off point is, though

 

[Matias]

I admit, that the situation in the video is very difficult for TACC. But nevertheless I feel that it now locks better to stopped cars. Or maybe I just haven't tested it so much with stopped cars because I have seen that video : D

 

[Troy]

Here is a photo to illustrate what I said. Imagine you are following another car on this road at high speed. Would you want TACC to apply brakes because there are parked cars on the side of the road while you are passing by? Of course not. That's why it didn't apply the brakes in the video. The car can't differentiate between the two situations. Maybe Tesla could do more to educate people about the limitations of TACC. The same scenario in the video is likely to happen quite often. In fact there was a topic about somebody who wrecked a brand new Tesla within days because of the same issue.

Edit: Here is that topic: 3 day old import P85D crashed while using TACC

 

[Matias]

Troy, I understand that it is very difficult for TACC to act right in the video. Car doesn't know, if the driver is going to turn right or not. I understand that and don't have a problem with that.

 

[Max*]

Sometimes I've had TACC lock into a stopped car, usually when I get that close and I know that the car is stopped, I'd turn TACC off to let regen do it's thing.

 

[doug]

What's the forward distance range on the TACC radar? Seems to me that would be a limiting factor.

 

[Matias]

What's the forward distance range on the TACC radar? Seems to me that would be a limiting factor.

Radar has more than enough range. At least 100 meters.

 

[RAW84]

What's the forward distance range on the TACC radar? Seems to me that would be a limiting factor.

Radar has more than enough range. At least 100 meters.

Yea, I don't know the exact range, but if you're cruising along with someone very far ahead, you can note when the cruise icon goes from grey to blue....it's definitely enough distance to stop at most speeds.

 

[RDoc]

I've attempted to make a reasonable guesstimate on the radar distance based on the time between when the TACC acknowledges a car in front and how long it takes me to cover the distance. My very rough guess is about 800', but I emphasize the guess part.

 

[green1]

Here is a photo to illustrate what I said. Imagine you are following another car on this road at high speed. Would you want TACC to apply brakes because there are parked cars on the side of the road while you are passing by? Of course not. That's why it didn't apply the brakes in the video. The car can't differentiate between the two situations. Maybe Tesla could do more to educate people about the limitations of TACC. The same scenario in the video is likely to happen quite often. In fact there was a topic about somebody who wrecked a brand new Tesla within days because of the same issue.

Edit: Here is that topic: 3 day old import P85D crashed while using TACC

To start with, I want to emphasize that I agree with you 100%, however, the thought occurs to me that watching the lines on the road, and not just the car in front could help. Now to be fair, in the original blue car video there was no line delineating the turn lane, however around where I live there would usually be a dotted line across that, and in your picture above there's a solid white line, in those cases, if the car ahead crosses a lane marking, and you haven't signaled an intent to do the same, the system should assume you are following the lane and not the car that has crossed a lane marking.

 

[Troy]

the thought occurs to me that watching the lines on the road, and not just the car in front could help. Now to be fair, in the original blue car video there was no line delineating the turn lane, however around where I live there would usually be a dotted line across that, and in your picture above there's a solid white line, in those cases, if the car ahead crosses a lane marking, and you haven't signaled an intent to do the same, the system should assume you are following the lane and not the car that has crossed a lane marking.

Green1, so you are saying the car should not apply brakes when there are 1. lines, 2. a curve and 3. a parked car at the curve. That's very good but this is exactly what the car is doing anyway. It doesn't apply the brakes. In fact not only does it not apply the brakes in that scenario with lines, it also doesn't apply brakes without lines. What you said is already a subsection of what is happening now. You didn't say anything about applying brakes in a certain situation.

To summarize, the car is not doing something in all situations and you just said it should not do something in a specific situation as well but you didn't say anything about doing something in a specific situation and what that situation might be.

	Apply brakes	Don't apply brakes
Curved road + parked car + no lines		This is what the car does.
Curved road + parked car + lines		This is what the car does This is what you suggested.

 

[green1]

Not quite, look at the blue car video, imagine when the car turned off, if it had to cross a white dotted line to do so (as it would have to do in my city) In that case the car should assume you are not following that car (because it crossed a line) and assume you are in fact following the lane straight ahead, see the car in that lane, and brake.
I do not believe that it currently does that. (though we don't see a video to prove either case here, so it is possible Model S already knows to do this)

I suppose in the blue car video, we could ask that due to the left lane marking going straight, that the car could assume a straight path rather than a curve, however without markings on both sides of the vehicle I'm not sure I'd want to make that assumption.

 

[Troy]

OK, I now understand what you said. Now you have described a situation where the car should apply brakes. The situation is, TACC is following a car. There are lane markings on the side edge of the road. The car you are following takes a turn and exits lane markings. TACC should apply brakes if there is a stationary obstacle in front of you. Now what I'm wondering is whether it is possible for the car to misread a different situation as this situation and apply the brakes when it shouldn't have.

Update: The situation would be like it happens in the video but when you actually want to follow the blue car and and there are lane markings before the turn. So first the blue car crosses the lane markings. You are behind it and you want to follow the blue car. But then TACC recognizes the lane markings and sees the parked white car and applies the brakes while you are taking the turn. That wouldn't be very good. It's actually dangerous to brake while taking turns especially at high speed.

 

[green1]

OK, I now understand what you said. Now you have described a situation where the car should apply brakes. The situation is, TACC is following a car. There are lane markings on the side edge of the road. The car you are following takes a turn and exits lane markings. TACC should apply brakes if there is a stationary obstacle in front of you. Now what I'm wondering is whether it is possible for the car to misread a different situation as this situation and apply the brakes when it shouldn't have.

Update: The situation would be like it happens in the video but when you actually want to follow the blue car and and there are lane markings before the turn. So first the blue car crosses the lane markings. You are behind it and you want to follow the blue car. But then TACC recognizes the lane markings and sees the parked white car and applies the brakes while you are taking the turn. That wouldn't be very good. It's actually dangerous to brake while taking turns especially at high speed.

Shouldn't be high speed in that situation, and it would accept input from your turn signals (or even the steering wheel) to decide your intentions in that situation.

 

[Matias]

I Tested this again. I took the left turning lane.

Google Maps

There was one car stopped in traffic lights. I activated TACC at the beginning of that lane. TACC did not immediately lock on stopped car but accelerated (because my speed was slower than TACC's set speed). Rather late TACC locked to stopped car, but at that time collision warning activated and I hit the brakes.

I believe TACC would have bring the car to stop (without emergency braking) but I did not have the courage to test it

 

[Troy]

Green1,

A difficulty with making rules is they sometimes apply in unintended situations. I understand that you want the car to brake if there were lane markings before the blue car turned right in the video. My argument is, such a rule would apply in a lot of unwanted situation which would be dangerous. When making rules, it is not sufficient to imagine situations where the rule should apply. It is also necessary to imagine all situations where it shouldn't apply.

The rule you suggested would have the same outcome as "apply brakes when driving on a curved road following a car TACC is locked to if there are parked cars around me and some lane markings." In other words you are telling TACC to ignore the car you are following and apply brakes at high speed randomly just because some other secondary criteria. Here is an example:

Imagine the traffic is clogged and there are parked cars in front of you just before the turn but there is enough gap to take the turn at high speed. As you cross the lines suddenly the brakes apply with full force. Would you want that? Of course not.

When TACC is locked to the car in front of you, the assumption is you are following that car. Whether there are parked cars around you or lane markings is not a strong enough reason to invalidate this assumption. That's why Tesla doesn't apply such a rule based on secondary criteria like not using the turn signal, crossing lane markings or parked cars around you.



- - - Updated - - -

Maybe someone can recreate the situation in the video to see if anything has changed.