ACC quirk turns dangerous

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It sounds to me like it was probably ACC and not CMBS since although abrupt, it was not a maximum effort calling for ABS. None the less, mine has never activated on a straight stretch with a car in the adjacent lane, so I hesitate to call this normal behavior.

Perhaps the radar behind the H emblem is misaligned? I have the black under hood cover off at the moment to install an air horn and noticed that the radar has adjustment screws like the headlights. Might be worth having dealer check the alignment and would be interesting to know how they do that.
 
sniwallof said:
yea, I really did not want to sound that way. And, yes get it checked out.

even highly trained military pilots can fall into the trap of not staying on top of things, fly the plane, not the other way around is what the primary flight instructors always say.

There also seems to be some confusion (in general) about ACC slowing the car down, versus crash avoidance. As noted in that other thread about saved from the person flying out of the driveway, I think the crash avoidance response is quite fast, very different from ACC slowing down the car (for a "real" or "mistaken" reason, as geo says, which happens often).
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When the acc slows down a car, do the brake lights go on? Does the driver get a warning light first!
 
tom kirshbaum said:
When the acc slows down a car, do the brake lights go on? Does the driver get a warning light first!
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According to the manual:

"When ACC with LSF slows your vehicle by applying the brakes, your vehicle's brake
lights will illuminate."

But how would you know if it is braking or just slowing down? I can't imagine that ACC activates the brake lights anytime it slows down even slightly, but who knows what the threshold is for the amount of slowing that will activate the brake lights. As I mentioned in another thread I think all cars not just Clarity that can automatically activate the brake lights should have an indicator on the dash telling you whenever that happens. Brake lights are a signal to other drivers and here we have no clue when or if our cars are sending a signal to other drivers.

Brake lights 2 - Copy.webp
 
KClark said:
How many times do I have to say it? There was no one in front of me, my lane was empty, the car exiting the freeway was not in my lane. How much clearer can I be? And please, stop the pedantic lectures.
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Sorry you have to repeat so often to people who won't read your post! Yes I have had a similar situation several times but the car over in the exit ramp was not slamming on its brakes so it was more of a gentle braking to match what they were doing. For some reason the Clarity looks more to the right than to the left, and probably the lack of a painted lane separator also has something to do with it.

One of the times I just pushed on the accelerator and the car believed me over the automatic system, that's probably what we have to be ready to do now that we have learned this is a problem.
 
This is my wife's biggest complaint about the Clarity. The OPs exact description has happened to us several times. I think the Honda software needs some design changes. It seems as if the camera and radar are not handshaking enough. If the car knows where my lane is it should not pay attention to the car in the next lane to the right turning right to exit the freeway. Also if the car knows what lane I'm in it should not break when it sees a car coming in the opposite direction one lane to my left. The Clarity brakes under these conditions so often that I've developed habits to use the accelerator to maintain speed when the car does something stupid.

I do worry about the car behind me crashing into the back of my car because the car did something unexpected and unnecessary. I'm surprised we haven't had reports of actual accidents because of this faulty behavior.
 
KClark said:
There was a car in the lane to my right about 3 car lengths in front of me. That car exited the freeway at an off ramp and as it left its lane my car suddenly and sharply braked from 65 to less than 50 in just a few seconds. There was a car in back of me that had to slam on its brakes to avoid an accident...
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Reading down thru the thread, my guess is that David Towle probably has it right when he says:

David Towle said:
...probably the lack of a painted lane separator also has something to do with it.
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I wasn't there so I don't know the exact situation, but if there was an exit lane that wasn't separated from the main lane by a divider line -- which would be perfectly normal as the one lane widens out into two -- then it seems likely that your car's ABS system interpreted the exiting car as being in your lane and slowing, which is exactly what an ABS system is designed and programmed to respond to. Of course, if the exiting car was well over to one side and so no longer in front of your car, so there was not danger of collision, then it does seem -- as has already been said -- that the ABS system is looking too far to the left and right; it should be more narrowly focused ahead of the car. But that may be jumping to a conclusion; it's hard to know based only on what's reported by an eyewitness account. It would be better if the incident was recorded on dashcam video.

I don't know if this situation would be worth reporting it to the NHTSA, but given that others have reported in this thread that they have had the same problem, it certainly seems like something that should be reported to Honda as a recurring problem. You might talk to your local Honda service shop supervisor to see if he can offer any advice on how to contact the appropriate person at Honda.
 
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I posted this in the other thread, but have any of you with issues tried changing the range of the auto breaking system?

Settings -> System -> Driver Assist System Setup -> Forward Collision Warning Distance

Try the short setting or maybe even far and see if it detects better?
 
ACC is the favorite feature in my Clarity, except for the fact that it stays locked on vehicles ahead of me too long, when they are turning right or left. I've had my car slow suddenly and significantly during that time, so I've tried to be very aware of drivers following close behind me, and not use ACC then. I also try to anticipate the turns of vehicles ahead and just disable ACC until the turning car is well away from my path, but I'm not always able to do that. I haven't experienced it scarily tracking or reacting to a vehicle turning off the highway from an adjacent lane as @KClark experienced, especially on a straight roadway, but I will now try to watch out for that possibility.

It seems to me that the extended ACC lock on turning vehicles is a design deficiency in the Clarity ACC, but it's the first car I've driven with that feature, so I don't know how others behave in the same conditions.
 
vicw said:
ACC is the favorite feature in my Clarity, except for the fact that it stays locked on vehicles ahead of me too long, when they are turning right or left. I've had my car slow suddenly and significantly during that time, so I've tried to be very aware of drivers following close behind me, and not use ACC then. I also try to anticipate the turns of vehicles ahead and just disable ACC until the turning car is well away from my path, but I'm not always able to do that. I haven't experienced it scarily tracking or reacting to a vehicle turning off the highway from an adjacent lane as @KClark experienced, especially on a straight roadway, but I will now try to watch out for that possibility.

It seems to me that the extended ACC lock on turning vehicles is a design deficiency in the Clarity ACC, but it's the first car I've driven with that feature, so I don't know how others behave in the same conditions.
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Instead of disabling it, just manually push on the "gas" pedal and it will override it, when you take your foot off it will resume.
 
dnb said:
Instead of disabling it, just manually push on the "gas" pedal and it will override it, when you take your foot off it will resume.
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Thanks, @dnb. I'll try that. I've been reluctant to force the added drive in opposition to the braking action by the ACC, but maybe it will actually just back off on the braking when I press the gas pedal.
 
I think it is also worth a sticky post on this forum that ACC with autobraking will NOT work if the cars in front are already stopped (as opposed to slowing to a stop).

Multiple times, I have come to a traffic light where cars are already stopped for the light and the ACC continues speeding towards the cars until I hit the brakes in panic. I have tested this effect multiple times to see if the car will slow itself when it encounters stopped cars, but every time, I've had to stomp on the brakes once I realize there's no way the car is even going to slow down. This is surely a bug the needs fixing.
 
Rajiv Vaidyanathan said:
I think it is also worth a sticky post on this forum that ACC with autobraking will NOT work if the cars in front are already stopped (as opposed to slowing to a stop).

Multiple times, I have come to a traffic light where cars are already stopped for the light and the ACC continues speeding towards the cars until I hit the brakes in panic. I have tested this effect multiple times to see if the car will slow itself when it encounters stopped cars, but every time, I've had to stomp on the brakes once I realize there's no way the car is even going to slow down. This is surely a bug the needs fixing.
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It is not a bug, and it specifically tells you in the manual it won't slow down for stopped objects. Again and again and again, ACC is cruise control. A better cruise control, sure, but it is not self driving, and it never claimed to be. Stop treating it as such.
 
+1 on what @petteyg359 says.
There are 14 pages of instructions on the ACC beginning on page 400 in the manual and they should be carefully reviewed before using the ACC but unfortunately many owners will not take the time.

Of particular note is the warning that the ACC is only for use on expressways or freeways and in good weather conditions. Also the warning about not using ACC in heavy traffic and continuous stop and go traffic and when encountering toll booths. In addition it notes that vehicles cutting in front of you or high closing rates will require manual braking. These indirectly address Rajiv’s concern about the ACC not picking up on a stopped car since there are not supposed to be stopped cars on expressways and freeways. So it’s not a bug, it’s just a limitation of the sensors and algorithm since trying to pick up on non moving obstacles is too difficult and would trigger too many false braking events. Hey, we’re not at the point of AI in cars quite yet.

However I can agree with Rajiv that Honda could and should do a better job in their explanation of the system’s limitations. IMHO, they should have included a sidebar WARNING that explicitly states the ACC will not react to an already stopped car it comes upon. And while I have never been a proponent of the nanny state, I would not be averse to an elasticized red warning tag about this on the steering wheel of a new Honda that you would have to notice and remove.

Keep in mind though that’s it’s impossible to make anything completely idiot proof even if you slap warning stickers all over it. Just look at a simple ladder the next time your in a big box or hardware store. They’ve got so many warning stickers on them now days that soon it will be impossible to buy a 6 ft step ladder because there won’t be enough room for all the mandated safety warnings and notices! And I just counted 13! safety and warning stickers on the back of a U-Haul that was in front of me at a light.
Sigh...As Pogo said, “We have met the enemy and he is us.”
 
Rajiv Vaidyanathan said:
Multiple times, I have come to a traffic light where cars are already stopped for the light and the ACC continues speeding towards the cars until I hit the brakes in panic. I have tested this effect multiple times to see if the car will slow itself when it encounters stopped cars, but every time, I've had to stomp on the brakes once I realize there's no way the car is even going to slow down. This is surely a bug the needs fixing.
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The low-res Doppler radars that various auto makers use for their ABS or traffic-aware cruise control systems are not designed or intended to detect stationary obstacles. Doppler radar detects only moving objects. That's not a bug; it's just that it's outside the operating parameters of such systems. It's like expecting your dishwasher to wash your clothes.

As Petteyg359 said: this is not a self-driving system, and it's dangerous to treat it as if it was.

More info on the subject here: "Why Tesla's Autopilot Can't See a Stopped Firetruck"
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Pushmi-Pullyu said:
The low-res Doppler radars that various auto makers use for their ABS or traffic-aware cruise control systems are not designed or intended to detect stationary obstacles. Doppler radar detects only moving objects. That's not a bug; it's just that it's outside the operating parameters of such systems. It's like expecting your dishwasher to wash your clothes.

As Petteyg359 said: this is not a self-driving system, and it's dangerous to treat it as if it was.

More info on the subject here: "Why Tesla's Autopilot Can't See a Stopped Firetruck"
​
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Yep. I actually ran into this (luckly not though! ;)) today. I was coming up on a stoplight and going ~10mph and the car in front of my went into the left turn lane. The ACC showed it still saw the car, then not (so I went to break), then it did show up again for a second so I thought it noticed the car in front but then it went away again and started to accelerate, it then gave the BREAK warning light and so I manually braked.

But yes this quote from that article is spot on:

The same is true for any car currently equipped with adaptive cruise control, or automated emergency braking. It sounds like a glaring flaw, the kind of horrible mistake engineers race to eliminate. Nope. These systems are designed to ignore static obstacles because otherwise, they couldn't work at all.
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But yes, ACC is great but you have to pay attention and listen for the beeps of when it loses locks on targets.
 
petteyg359 said:
It is not a bug, and it specifically tells you in the manual it won't slow down for stopped objects. Again and again and again, ACC is cruise control. A better cruise control, sure, but it is not self driving, and it never claimed to be. Stop treating it as such.
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you should use ACC on highways only. what happens when you are the first to come to a red light? the car will go straight thru if you are not paying attention
 
LAF said:
you should use ACC on highways only. what happens when you are the first to come to a red light? the car will go straight thru if you are not paying attention
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I like it in town as well, but yes, its cruise control not automated driving. As long as its locked on a car it will speed up / slow down very well and its "STOPPED" feature is nice as well. Tapping resume once will remove the "STOPPED" message and will then accelerate as the car in front leaves (usually a 2 sec delay or so after you press resume).
 
LAF said:
you should use ACC on highways only. what happens when you are the first to come to a red light? the car will go straight thru if you are not paying attention
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Nope. I use it on small city streets all the time. I also use it correctly, with myself still paying attention and my foot ready to hit the brakes.
 
petteyg359 said:
Nope. I use it on small city streets all the time. I also use it correctly, with myself still paying attention and my foot ready to hit the brakes.
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insightman said:
Yes, and the ACC is great for avoiding tickets on country roads that have low speed limits.
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You both and @dnb provided the words and the reasons I was prepared to use to respond to the notion that ACC should only be used on the highway. ACC is as safe as the driver is competent and alert, on the highways and the byways. I keep my eyes open and hands and foot ready at all time to respond to any perceived hazards in my path. I especially appreciate ACC to be able to set my 35 mph max cruise speed through our adjacent town/speed trap that I have to traverse both ways several times a week.
 
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