[Honda2019]

Have had the Break Alert message and audible beeping occur when I drive under a bridge on my way to work when it is sunny out. I suspect this is due to the radar thinking the shadow of the bridge is an object in the road. Not a big issue but something I find interesting in that it is probably a limitation of the "artificial intelligence" baked into the programming of the radar safety features. You can view it happening on this Youtube video I uploaded:

 

[hasarad]

Have had the Break Alert message and audible beeping occur when I drive under a bridge on my way to work when it is sunny out. I suspect this is due to the radar thinking the shadow of the bridge is an object in the road. Not a big issue but something I find interesting in that it is probably a limitation of the "artificial intelligence" baked into the programming of the radar safety features. You can view it happening on this Youtube video I uploaded:

https://www.youtube.com/watch?v=r0z4Tou4U5k&feature=youtu.be

I have had this happen as well. Not only for overpasses, but for close guardrails as well. Nothing is foolproof.

 

[hasarad]

Several of us had noted about the CMBS flashing brake while driving when no risk was seen. Mine did it when I passed underneath a few highway signs. Well, last night it went a bit further. I passed under a sign I have been by many times. It is right near my exit. This time, the "BRAKE" warning lit up on the dash. This happens from time to time. This time, however, the brakes were automatically applied, and my daughter and I were thrown forward unexpectedly for about a second until we got passed the sign.

Not sure what to do next. I guess I'll need to adjust the setting to shorten the distance.

Thoughts?

 

[insightfully]

Scary... Hopefully no one was following too close behind you!

Do you pass this sign at different times of day? Have you noticed the incidents happen when the shadows are a particular size/direction? Wondering if the sudden response was triggered by a "bigger than usual" shadow...? Or any unusual obstructions or issues noticed on your camera area or bumper-mounted radar?

 

[JK919]

Can you turn off the auto-braking and keep it off?

 

[insightfully]

Can you turn off the auto-braking and keep it off?

CMBS can be turned off, but turns back on with each drive. There are some Honda Sensing features (like RDM, ACC) that can be turned off and stay off, but CMBS is not one.

Depending on hasarad's answer, I was wondering if maybe there are certain lighting/shadow conditions where one should proactively turn off CMBS, knowing it can't do a good job at distinguishing shadows from cars.

 

[hasarad]

Scary... Hopefully no one was following too close behind you!

Do you pass this sign at different times of day? Have you noticed the incidents happen when the shadows are a particular size/direction? Wondering if the sudden response was triggered by a "bigger than usual" shadow...? Or any unusual obstructions or issues noticed on your camera area or bumper-mounted radar?

It happened at 9 o'clock at night. No sun/shadows to speak of. I did dial back the sensitivity from normal to short today to see if it helps in the future.

Question - does the CBMS use radar, camera or both to determine if an obstacle exists?

In reviewing the attachment you posted, I indeed needed to immediately "deeply press" the accelerator to keep speed up so the guy behind me didn't run into me.

 

[hasarad]

After reviewing the video from my dashcam, I believe it may be the streetlight that caused it. Listen for the CMBS beeps right before I dive for the right exit lane.

https://drive.google.com/open?id=1srVkKayZ5ZOCFNwO68cIt9lLr_MbliQI

 

[andrew28]

I have my CMBS set to short. I have experienced false alerts(2 times) but the car has never actually activate the brakes by itself.

It happened at 9 o'clock at night. No sun/shadows to speak of. I did dial back the sensitivity from normal to short today to see if it helps in the future.

Question - does the CBMS use radar, camera or both to determine if an obstacle exists?

In reviewing the attachment you posted, I indeed needed to immediately "deeply press" the accelerator to keep speed up so the guy behind me didn't run into me.

Does the brake lights come on if CMBS activates the brakes?

From what I read on that article from last year about Honda outsourcing the safety package to companies like BOSCH. The different safety tech like radar, camera, etc don't communicate with each other like autopilot does on a Tesla.

 

[insightfully]

Does the brake lights come on if CMBS activates the brakes?

Yes - when since the braking is triggered by Honda Sensing for full physical stop, the rear brake lights come on to alert drivers who are behind. This is different from regen (engine) braking, which is meant for slowing rather than full stop.

(I read this in a Pilot forum, where a Honda Engineer called a forum member back advising that when any Sensing feature applies the brake, the rear lights work as if YOU put your foot to the brake pedal. Our Insight manual only calls out that the rear brake lights illuminate for ACC/LSF - pg 492.)

 

[andrew28]

Yes - when since the braking is triggered by Honda Sensing for full physical stop, the rear brake lights come on to alert drivers who are behind. This is different from regen (engine) braking, which is meant for slowing rather than full stop.

(I read this in a Pilot forum, where a Honda Engineer called a forum member back advising that when any Sensing feature applies the brake, the rear lights work as if YOU put your foot to the brake pedal. Our Insight manual only calls out that the rear brake lights illuminate for ACC/LSF - pg 492.)

That's good to hear so it should help mitigate a crash from occurring even with a false alert unless the driver behind is tailgating.

 

[insightfully]

Question - does the CBMS use radar, camera or both to determine if an obstacle exists?

CMBS uses both the radar and camera.

For a visual these working together, check out this (non-Honda) video which shows how radar and camera look individually AND when used in "fusion" together. The combined systems improve detection BUT also requires more programming choices from Honda to tune the inputs.

To share some thoughts / observations for further input from this group:

1. LKAS, RDM, and Sign Recognition use ONLY the Camera.
2. CMBS and ACC/LSF rely on BOTH Radar and Camera (like the "fusion" method shown in video).
3. CMBS has the highest number of 'conditions and limitations' among Honda Sensing options, and most of the limitations relate to camera (lighting, pedestrian detection).

Taking the CMBS 'heavy camera reliance' together with the 'outsourcing to improve pedestrian detection' article andrew28 shared - could CMBS/"Brake Alert" be oversensitive because Honda tuned the system to favor camera input (pedestrian risk detection) instead of radar input (physical object detection) - ?

===
If helpful, below is a topline summary comparison from re-reading the Honda Sensing section of Manual. CMBS is the only one that is "multi-tiered" by speed, object direction, and specifically calls out pedestrian detection.

CMBS = Radar + Camera, starting at speeds >3 mph
- for 3 to 62 mph: monitors for stationary, oncoming, OR same direction
- for 62+ mph: monitors same direction only
- turns on every time power system starts, regardless of prior selection
- camera is designed/used for pedestrian detection (p484)
- 47 'conditions and limitations' listed, with more than half (~30) being camera-specific (e.g. temperature, pedestrian) or lighting-related (e.g. shadow, contrast)

ACC/LSF = Radar + Camera, for speeds up to 90 mph
- retains "off" setting if selected during prior drive
- 23 'conditions and limitations' listed, of which majority are radar-related (only ~4 camera related ones, so less dependence/risk on camera)

LKAS = Camera only, for speeds 45-90 mph
- system suspends when turn signals or brake pedal are activated, or wipers are continuously running
- 26 'conditions and limitations' listed, of which most (~22) are camera-related

RDM = Camera only, for speeds 45-90 mph
- system suspends when turn signals or wipers are continuously running, or when there's active acceleration, braking or steering
- remembers "off" setting if selected during prior drive
- 27 'conditions and limitations' listed, of which most (~22) are camera-related

Sign Recognition = Camera only
- camera needs to be recalibrated after windshield is replaced
- 30 'conditions and limitations' listed, almost all of which are camera-related

 

[AMCooper63]

I personally believe that the crack in the road is what tripped up your CMBS. I can't tell how uneven the crack is, but but it pops up out of nowhere and it sounds to me that the CMBS reacts as soon as it is visible.

 

[andrew28]

I have my CMBS set to short. I have experienced false alerts(2 times) but the car has never actually activate the brakes by itself.

2 days after I wrote that, I received my first CMBS false alert where the brakes did engage(I was going probably 50mph and it felt like a max setting regenerative braking to me). Just got the chance to pull the footage off my dashcam. I think it might be the shadow from the bridge column.


https://drive.google.com/file/d/1JRH1bdkw2RtjFgZXHvBWcigpjPLIU4cB/view?usp=sharing

 

[hasarad]

2 days after I wrote that, I received my first CMBS false alert where the brakes did engage(I was going probably 50mph and it felt like a max setting regenerative braking to me). Just got the chance to pull the footage off my dashcam. I think it might be the shadow from the bridge column.


https://drive.google.com/file/d/1JRH1bdkw2RtjFgZXHvBWcigpjPLIU4cB/view?usp=sharing

That, or the pothole on the left.

 

[maynyrd150]

I have experienced CMBS working the way it probably should have when someone was taking their time making a right turn. It was an unwelcome surprise. Afterwards I turned down the sensitivity, but have since experienced a dip in the road that pumped the brakes momentarily. I really wish it would turn off and stay off. I'm not so sure that a failure of this system is less likely than an actual event in which CBMS would prevent an accident.

I could actually do without any of the Honda Sensing features. None of them work great. ACC is just OK. LKAS just enables you to screw off and fights you when you are paying attention. They are all susceptible to less than ideal road and weather conditions. Thanks Honda, for burying the radar unit inside a pocket at the bottom of the bumper where it immediately is covered with snow and ice.

 

[Verdier]

I have made many comment on these systems in the past but I've been working in my mind a point by point comparison video between my Ford fusion energi and my Honda insight, and as much as this pains me, the insight's safety tech is considerably less reliable and accurate than the Ford fusion's. As far as I'm concerned the fusion is significantly safer with it's tech than the insight. The fusion is a more mature platform and I'm wondering if that along with the general price difference is why the system seems more reliable. Perhaps the system uses a higher end camera it more expensive sensors. Either way as much as I gush about the insight I like to try to be as honest about the problems as much as the triumphs of the car. End of rant.

 

[andrew28]

I have experienced CMBS working the way it probably should have when someone was taking their time making a right turn. It was an unwelcome surprise. Afterwards I turned down the sensitivity, but have since experienced a dip in the road that pumped the brakes momentarily. I really wish it would turn off and stay off. I'm not so sure that a failure of this system is less likely than an actual event in which CBMS would prevent an accident.

I could actually do without any of the Honda Sensing features. None of them work great. ACC is just OK. LKAS just enables you to screw off and fights you when you are paying attention. They are all susceptible to less than ideal road and weather conditions. Thanks Honda, for burying the radar unit inside a pocket at the bottom of the bumper where it immediately is covered with snow and ice.

I think I found you a solution for turning the CMBS off permanently. Just need to get something to cover the radar sensor. :wink:

The CMBS should have an alert only option instead of engaging my brakes. I really don't like it when the car can overrule my decision making especially when Honda tells us that the system is not perfect.

 

[insightfully]

2 days after I wrote that, I received my first CMBS false alert where the brakes did engage(I was going probably 50mph and it felt like a max setting regenerative braking to me). Just got the chance to pull the footage off my dashcam. I think it might be the shadow from the bridge column.

I have a couple questions, hoping to learn from your experience. (I'm using default settings and haven't had CMBS brake for me; I've only seen the brake warning when I was in process of applying brake anyhow):
- Does the car brake more sharply with the 'short' distance setting, or is it about the same braking effect regardless? Do you plan to leave the setting on 'short'?
- Your car seemed to keep moving forward without lurching. Did you accelerate through the CMBS, or was the CMBS effect just minor/temporary once the issue (shadow or pothole) passed?
- How long in the video did it take for the CMBS / Brake message to clear? Did the dashboard alert stop when the beeping stopped?

 

[mgldan]

I have experienced CMBS working the way it probably should have when someone was taking their time making a right turn. It was an unwelcome surprise. Afterwards I turned down the sensitivity, but have since experienced a dip in the road that pumped the brakes momentarily. I really wish it would turn off and stay off. I'm not so sure that a failure of this system is less likely than an actual event in which CBMS would prevent an accident.

I'm not entirely sure how I feel yet. I have experienced more than my share of CMBS warnings on teh DII, but only once have the brakes actuated without my command, and there really was a car there. Wouldn't the Honda engineers have preferred false positives to missed positives (can't think of the right term)?

That said I am totally using the lowest sensitivity of CMBS, given how often the visual warnings activate.

ACC is just OK.

I wish ACC were far less aggressive about matching the speed of the car in front of me. It would be more fuel efficient to very, very incrementally approach the car I'm trailing instead of to try to get there quickly.