ACC quirk

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KClark

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On my way to work this morning I was on the freeway using ACC set at 65 with the following bars set at minimum distance. It was early and there wasn't a lot of traffic. A car in the lane to my left needed to cross my lane and go to the lane on my right. He was close but just outside of the following distance. Which meant that nothing was triggered as he got in front of me. But when he exited my lane to my right suddenly the ACC reacted strongly and braked from 65 to 55. It then quickly recovered.

Over the two months I've owned my Clarity this has happened on the freeway half a dozen times. The ACC does not trigger when the car merges into my lane but sharply triggers right after the car exits my lane and my lane is completely open. Sometimes, like this morning, the braking is severe enough to make me glad that no one was behind me.
 
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jdonalds said:
Out clarity does that often. The system could be much smarter.
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To avoid the unexpected braking im going to try regular cruise control. It could also be collision mitigation causing the braking as th
KClark said:
On my way to work this morning I was on the freeway using ACC set at 65 with the following bars set at minimum distance. It was early and there wasn't a lot of traffic. A car in the lane to my left needed to cross my lane and go to the lane on my right. He was close but just outside of the following distance. Which meant that nothing was triggered as he got in front of me. But when he exited my lane to my right suddenly the ACC reacted strongly and braked from 65 to 55. It then quickly recovered.

Over the two months I've owned my Clarity this has happened on the freeway half a dozen times. The ACC does not trigger when the car merges into my lane but sharply triggers right after the car exits my lane and my lane is completely open. Sometimes, like this morning, the braking is severe enough to make me glad that no one was behind me.
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More than likely when the car enters your lane it is going a little faster than you are so it can safely change lanes. So the acc wont brake. How ever when the car exits your lane it may not be accelerating, and it will lose some forward travel speed if they change lanes quickly. Therefore the system could detect that your car is slightly gaining and apply the brake. Im going to just use regular cruise control with Lkas and see if that helps. Collision mitigation also could cause the braking.
 
No dashboard warning that accompanies collision mitigation. I could understand if maybe the car was slightly slowing while still partially in my lane, that would make sense, but this happens when the car has just completely exited my lane, in other words, when my lane is completely empty.
 
KClark said:
On my way to work this morning I was on the freeway using ACC set at 65 with the following bars set at minimum distance. It was early and there wasn't a lot of traffic. A car in the lane to my left needed to cross my lane and go to the lane on my right. He was close but just outside of the following distance. Which meant that nothing was triggered as he got in front of me. But when he exited my lane to my right suddenly the ACC reacted strongly and braked from 65 to 55. It then quickly recovered.
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I have also observed this several times when a car in front of me was exiting the highway. The ACC seems to handle things correctly until the car leaves its field of view on the right.
 
MNSteve said:
I have also observed this several times when a car in front of me was exiting the highway. The ACC seems to handle things correctly until the car leaves its field of view on the right.
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Yep, I think the issue is that its still tracking the car and sees that it is decelerating and it doesn't realize its left your lane (right or left turn lanes), potentially due to the road itself curving (seem to notice it more if the road is curving), so it thinks "oh **** its still in my lane" so breaks. I've only had it happen a few times and is usually fine, so my guess is it thinks you are still following it for a second or two so adjusts speed incorrectly.
 
I've been noticing lately that the ACC etc. systems make a lot fewer mistakes when I reduce my travel speed to the sixties versus the seventies or higher. Doesn't really help anything since I rarely have the patience to go that slow. the systems should work better than they do at all speeds.
 
KClark said:
I really wish the algorithm would just say “Hmmm, maybe I should ease off the accelerator for a second and see what’s up” instead of acting like a nervous spinster librarian saying “holy crap we’re all going to die!!!” while slamming on the brakes.
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Oh for sure :D
 
David Towle said:
Doesn't really help anything since I rarely have the patience to go that slow. the systems should work better than they do at all speeds.
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One option I’ve never seen is an option to just have the cruise control do the speed limit. Waze is aware of the speed limit on most roads, so the information exists in some database somewhere. It seems like linking a cruise control to make use of that info would be a handy thing to do.

Except for scofflaws, of course!
 
Fast Eddie B said:
One option I’ve never seen is an option to just have the cruise control do the speed limit. Waze is aware of the speed limit on most roads, so the information exists in some database somewhere. It seems like linking a cruise control to make use of that info would be a handy thing to do.

Except for scofflaws, of course!
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Some vehicles have automation packages which read speed limit signs and feed that into the software; the Tesla sales guy who demoed a Model 3 to me said it did with the full navigation software package, for example.
 
KClark said:
I really wish the algorithm would just say “Hmmm, maybe I should ease off the accelerator for a second and see what’s up” instead of acting like a nervous spinster librarian saying “holy crap we’re all going to die!!!” while slamming on the brakes.
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A kinder, gentler cruise control that isn't so erratic that "engine mode" gives up and unlocks?
After emergency braking for no reason, then ACC has to floor the accelerator to resume.
Yeah.
 
Fast Eddie B said:
One option I’ve never seen is an option to just have the cruise control do the speed limit. Waze is aware of the speed limit on most roads, so the information exists in some database somewhere. It seems like linking a cruise control to make use of that info would be a handy thing to do.

Except for scofflaws, of course!
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Could be an issue if the known info is wrong or the info changes depending on time of day. The Accord can read traffic signs for that info. I've also been in a Dodge minivan that speaks the speed limit to you if you're going too fast.
 
ab13 said:
I've also been in a Dodge minivan that speaks the speed limit to you if you're going too fast.
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KClark said:
acting like a nervous spinster librarian saying “holy crap we’re all going to die!!!”
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I like the idea of combining these two items - instead of simply telling you the speed limit, what if the car yelled out "holy crap we’re all going to die!!!"
 
dnb said:
Yep, I think the issue is that its still tracking the car and sees that it is decelerating and it doesn't realize its left your lane (right or left turn lanes), potentially due to the road itself curving (seem to notice it more if the road is curving), so it thinks "oh **** its still in my lane" so breaks. I've only had it happen a few times and is usually fine, so my guess is it thinks you are still following it for a second or two so adjusts speed incorrectly.
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That's consistent with what I'm observing. LKAS isn't very helpful on badly maintained roads (large parts of I-880 in SF Bay Area). Combine that with curving roads such that the car ahead of me in a parallel lane is directly in front of my car, which doesn't actually know where the lane is going, and I'm not surprised that ACC gets extra-cautious.

This stuff is definitely nothing more than an occasionally useful assist, not a self-driving feature or anything close to it. Maybe Tesla can do better, but Honda isn't going to get to full self-driving in the next generation of their tech - maybe the one after that.

I'm not convinced that putting a car with these features in the hands of an inattentive driver won't make things worse, by giving them a false sense of self-confidence.
 
Like oddhack said, this is not even a basic self driving system. It's cruise control plus automatic braking. If your foot isn't over the pedal to take control at all times, you're using it wrong. If your foot is over the pedal, all it takes to "reset" ACC and make it recalculate what is in front of you is hitting the accelerator for a second.
 
oddhack said:
Some vehicles have automation packages which read speed limit signs and feed that into the software; the Tesla sales guy who demoed a Model 3 to me said it did with the full navigation software package, for example.
Click to expand...

Perhaps this has been addressed since, but when I drove a Model S two years ago, when passing through a school zone it changed the displayed speed limit accordingly not knowing the lower limit applied only during certain hours. That might be a tad irritating if it influenced cruise control.
 
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