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AP Performance on Windy Roads

PianoAl

Member
Dec 15, 2019
802
492
Far Northern California
First, let me say

1. I'm hugely impressed with the car's ability to drive itself.
2. I realize that two-lane-road driving is still in beta.
3. I'm not criticizing the car.
4. I remain fully vigilant in the below situation with my hand on the wheel. I'm not blindly trusting the AP on this windy road.

Having said that, I wonder why my M3 has trouble keeping the lane in situations in which the road is clearly marked and the car is not going too fast to negotiate a turn.

Here's an example of a curve in which the car always fails to keep the lane, letting the wheels go over the rumble strip and the yellow line:


Here's the side view (not synchronized with the above):


The question: it seems like it would be easy for the car to stay in the lane, yet it fails here every time. Why is that?
 

Knightshade

Well-Known Member
Jul 31, 2017
11,866
16,311
NC
It's not that AP on those roads is in beta.

It's that AP isn't intended for use on those types of roads at all

You can turn it on. And it may work. Or it may not.

But intended use, per the manual, is divided roads with controlled access (freeways)

this is likely to change for HW3/FSD cars by end of year when the entirely rewritten codebase goes out though... it's unclear if it'll change for non-FSD and/or HW2.5 cars though.
 

Mash

Supporting Member
Nov 10, 2019
939
686
Prague
For me it's normally hugging outside lines to decrease centrifugal forces while maintaining speed. Here it's maybe not sure which line is the divider....
 

yyysguy

New Member
Aug 31, 2020
3
0
Orlando, FL
Thanks for sharing the videos!

When this happens, does the display indicate that the car is centered between the lines, or that it has crossed the left line? Does it show two sets of lines on the left?

My guess here is that the two sets of double-yellow lines spaced apart by a meter of so is confusing the system. This would seem to be a pretty rare and non-standard road marking scheme, and the software doesn't yet have a case to handle this, so it defaults to the left-most set of lines. Thus, it tries to center the car between the left-most and right lines, which appears to be where your car is located on the video.
 

PianoAl

Member
Dec 15, 2019
802
492
Far Northern California
Here it's maybe not sure which line is the divider....

My guess here is that the two sets of double-yellow lines spaced apart by a meter of so is confusing the system.

Yes, I think you guys are right. Yesterday I drove the same road. I slowed the speed down and let the car do its thing. It was worse than shown in the video, and It definitely acted as if it was using the wrong set of double lines.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,680
11,653
San Diego
Using Autosteer in this sort of situation is always an adventure (and usually not too pleasant an adventure. Obviously, it's not a supported use case at all, which is why it's an adventure. Notwithstanding the double lines issue in this case, it's quite common for Autosteer to do very, very poorly on curvy roads (since it's not supported for that use if it's not a highway with controlled entrance/exits!). Best to drive yourself unless you are simply playing with your toy (which is fine as long as you're vigilant and expect it to make errors!).

I'm always amazed when I take over at how good humans are at driving and making a road like this a blast to drive.
 

Gasaraki

Active Member
Oct 21, 2019
1,655
1,065
Syracuse, NY
I don't get why the car has issues with curvy roads. If I can keep a constant speed and keep my car centered in the lane, it means it's physically possible to do it. On the highway in curvy sections, it's hugs or goes over the outer lane lines. If there's a car next to me I always have to cancel AP so I don't get too close to the car next to me. Seems to be more of an issue above 70+mph.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,680
11,653
San Diego
I don't get why the car has issues with curvy roads. If I can keep a constant speed and keep my car centered in the lane, it means it's physically possible to do it

Hopefully the answer is “it is not designed to do it.”

On curvy roads it is very difficult. The car needs to be able to judge the correct speed for the curve, and it also, like a good human driver, needs to smooth the apex (steering wide then cutting the corner slightly (not crossing the line) if traffic allows to do it very safely) to make it more pleasant and faster. Lots of anticipation and judgement needed.

It’s quite a challenging problem - you can tell because a lot of humans can’t do it very well, and humans are EXTREMELY good at driving, relative to the state of the art computer driver.

I anticipate it will be a very long while indeed before Autosteer can drive such a road well. It may be harder than some aspects of city street driving.
 

Gasaraki

Active Member
Oct 21, 2019
1,655
1,065
Syracuse, NY
Hopefully the answer is “it is not designed to do it.”

On curvy roads it is very difficult. The car needs to be able to judge the correct speed for the curve, and it also, like a good human driver, needs to smooth the apex (steering wide then cutting the corner slightly (not crossing the line) if traffic allows to do it very safely) to make it more pleasant and faster. Lots of anticipation and judgement needed.

It’s quite a challenging problem - you can tell because a lot of humans can’t do it very well, and humans are EXTREMELY good at driving, relative to the state of the art computer driver.

I anticipate it will be a very long while indeed before Autosteer can drive such a road well. It may be harder than some aspects of city street driving.
You have to get something simple like this down before you can say FSD is ready. If you can't make curves without leaving the lane, FSD will never happen.
 

PianoAl

Member
Dec 15, 2019
802
492
Far Northern California
There's another place where Nick consistently touches the center line: The road goes over a rise and turns to the right. So, perhaps he can't see the lines farther ahead.

Best to drive yourself unless you are simply playing with your toy (which is fine as long as you're vigilant and expect it to make errors!).

I agree with that in theory, but here's the problem that I have: I am so used to having AP on, that on three occasions, I've thought it was on and it was not. That is, the car started to go out of its lane and I'm like, "Whoa!" That's why I almost always have it in AP and I try to pay attention all the time.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,680
11,653
San Diego
I am so used to having AP on, that on three occasions, I've thought it was on and it was not. That is, the car started to go out of its lane and I'm like, "Whoa!" That's why I almost always have it in AP and I try to pay attention all the time.

Understood.

For now, I'd suggest sticking to using AP only on freeways, as intended. It works best there, and avoids this sort of mode confusion (except on freeways - where it can still happen, but there is a lot more time to react on a freeway, and they are designed to be much safer in the event of driver error).

That way you can still get the benefits of AP (perhaps, depending on where you live), but limited possibility of a mode confusion accident.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
9,680
11,653
San Diego
If you can't make curves without leaving the lane, FSD will never happen.

My point was that driving a road like this well is much more complicated than "never leaving the lane". Perfecting the "Not leaving the lane algorithm" is certainly required, both for this task and for FSD, and is not the hard part. For FSD, you need a car that can stay in the lane, but also leave the lane strategically whenever it makes sense either for safety or for passenger comfort (just like a human). It's a lot harder!

Fortunately, what we have now has no bearing on any future FSD release and handling a road like this. What we have now is completely not designed to handle this sort of situation, so you wouldn't expect it to work at all well (it's kind of a fortunate accident that it kinda sorta works).
 
Sep 18, 2020
12
3
Indiana
Just a thought, maybe it is a case of too much information having to be processed, in those situations. As auto pilot programming learns more the better it will be.
 

PianoAl

Member
Dec 15, 2019
802
492
Far Northern California
There's one place where the road turns at the crest of a hill.

Screen Shot 2020-10-21 at 7.32.25 AM.jpg


Here's something interesting:

At 55 MPH (the speed limit), it goes a bit out of the lane, with the tires going onto the warning indicators on the center line.

But if I slow it to 40 MPH, it stays within the lines perfectly.

My guess is that at 55 MPH, it just doesn't have enough time to make the calculations that allow it to stay in the lane (which is what surprises me).

In any case, I'm usually able to make the following entire trip with only 3-5 interventions, despite many curvy sections:

Screen Shot 2020-10-21 at 7.26.24 AM.jpg
 

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