Front Assist malfunction.

[bromley]

This is the fault where the Autonomous Emergency Braking triggers for no visible or logical reason whatever, without warning, and suddenly, brakes at maximum force to a standstill.  Has anyone else experienced this on this model (or any other model), and has it been resolved, and has the reason for it been explained?   I'm getting the runaround!  

[Warrior193]

Hello bromley, I have very occasionally had ABS intervention from the front assist on my Mk3 - all but one occasion was where I was clearing an obstruction on my left front and the radar thought there wasn't enough space (there was, just) Only on one occasion was there no obvious trigger visible - I put that one down to something blowing across the road.

On none of these ABS interventions did the vehicle brake to a full stop - less than 1/2 second approx.  

Edited 11 November, 2023 by Warrior193
added information

[bromley]

Thanks Warrior193, but this is not quite in the same league!  I gather the motor trade is familiar with this defect, but most drivers seem unaware because it is an unusual, random, fault that can affect the odd vehicle of almost make or model where AEB is installed and active.  This is not ABS, BTW, but Front Assist's AEB system "seeing" an imminent - but actually non-existent - collision risk and abruptly applying the maximum available mechanical braking force.

 

Fortunately, I was only doing about 30MPH and there was no following traffic.  The way the car stopped, if there had been anyone behind I think the driver would probably have a) been very, very, angry at the clown who had, apparently just jammed his brakes on the no reason, b) rear ended my car, and c) not believed me when I said the car did it all on its own!  Definitely not an experience to repeat!  

[SurreyJohn]

I am sure you can adjust front assist sensitivity 

Infotainment, car, settings, assistance systems etc

[Warrior193]

2 hours ago, bromley said:

Thanks Warrior193, but this is not quite in the same league!  I gather the motor trade is familiar with this defect, but most drivers seem unaware because it is an unusual, random, fault that can affect the odd vehicle of almost make or model where AEB is installed and active.  This is not ABS, BTW, but Front Assist's AEB system "seeing" an imminent - but actually non-existent - collision risk and abruptly applying the maximum available mechanical braking force.

 

Fortunately, I was only doing about 30MPH and there was no following traffic.  The way the car stopped, if there had been anyone behind I think the driver would probably have a) been very, very, angry at the clown who had, apparently just jammed his brakes on the no reason, b) rear ended my car, and c) not believed me when I said the car did it all on its own!  Definitely not an experience to repeat!  

Hello @bromley -  I say "ABS intervention"  because, when the AEB system kicks in, it applies the brakes in full ABS mode - you feel and hear the brakes rapidly applying and releasing.  Fortunately, on the rare occasions mine has kicked in, it has been very brief - and there was, almost without exception, a visible explanation for it. I have never experienced a 'full AEB stop' as you describe.

Edited 12 November, 2023 by Warrior193
added information

[bromley]

3 hours ago, SurreyJohn said:

I am sure you can adjust front assist sensitivity 

Infotainment, car, settings, assistance systems etc

Yes you can, but I have no idea, in real world terms, what actually achieves, or how.  Anyone else know?  Sensitivity to what, for example?

[bromley]

1 hour ago, Warrior193 said:

Hello @bromley -  I say "ABS intervention"  because, when the AEB system kicks in, it applies the brakes in full ABS mode - you feel and hear the brakes rapidly applying and releasing.  Fortunately, on the rare occasions mine has kicked in, it has been very brief - and there was, almost without exception, a visible explanation for it. I have never experienced a 'full AEB stop' as you describe.

Understood.  Yes, I had the impression that the ABS probably kicked in with the AEB, but couldn't hear it because of the row the warning signal (which began when the braking began) was making.  Manual car, in gear, so engine stalled while by the braking, and me trying to work out what the Hell had happened.  This was from about 30 MPH on a relatively smooth, dry, road.  It was a very unpleasant experience!

[Warrior193]

It does sound as if your system is overly sensitive - have you tried adjusting the sensitivity as Surrey John suggested?

[gogo110]

Fabia Mk4 uses Continental's ARS-4B radar sensor for AEB and ACC (adaptive cruise) functions. This sensor is used on a dozen other vehicle models, not just from the VAG group.

 

It is important that the radar is correctly aligned (i.e. that it is facing directly forward). An impact to the front bumper can knock the sensor out of alignment. VAG service centers and specialist garages have tools that can check the alignment and correct it if necessary.

 

However, even with the sensor correctly aligned, false AEB interventions can still occur. This can usually be attributed to two things:

 

(1) The system "seeing" objects correctly, but misinterpreting the situation, e.g. thinking you are going to crash into something when in reality you are going to steer around it. An example can be found at mark 7:51 of this video.

 

(2) The system seeing false ("ghost") targets. This is usually either due to:

     - picking off a very strong reflection in the radar beam side lobe. To put it simple, the radar can mistake a strongly reflective object (a very large metallic object) off to the side for a weakly reflective object dead ahead (e.g. a motorcycle).

     - interference from other radar emitters (other radar-equipped cars)

 

For (2) there are special algorithms that the sensor runs to reduce the probability of this happening, however no algorithm is 100 % reliable.

 

I myself have experienced Front Assist issuing a warning once with no apparent reason. However, there was no braking intervention.

I've also used ACC extensively and found the object (other road user) detection to work very reliably.

 

As for adjusting the sensitivity via the infotainment, as I understand this will only influence how early the audiovisual warning will pop up. It does not have effect on braking interventions.

[gogo110]

Oh yeah, also, you can cancel the braking intervention by stomping on the gas or steering sharply.

[bromley]

3 hours ago, Warrior193 said:

It does sound as if your system is overly sensitive - have you tried adjusting the sensitivity as Surrey John suggested?

Thanks.  First thing I did - once I'd navigated the infotainment maze!  However, wasn't at all clear on what "sensitivity" meant.  Sensitivity to what?  I later found it was possible to turn off Front Assist, so have been doing that since.

 

From gogo110's post above, it seems the sensitivity setting doesn't adjust the intervention speed, but only that of the warnings.  If only they would give clear instructions/explanations!  😞 

[bromley]

50 minutes ago, gogo110 said:

Fabia Mk4 uses Continental's ARS-4B radar sensor for AEB and ACC (adaptive cruise) functions. This sensor is used on a dozen other vehicle models, not just from the VAG group.

 

It is important that the radar is correctly aligned (i.e. that it is facing directly forward). An impact to the front bumper can knock the sensor out of alignment. VAG service centers and specialist garages have tools that can check the alignment and correct it if necessary.

 

However, even with the sensor correctly aligned, false AEB interventions can still occur. This can usually be attributed to two things:

 

(1) The system "seeing" objects correctly, but misinterpreting the situation, e.g. thinking you are going to crash into something when in reality you are going to steer around it. An example can be found at mark 7:51 of this video.

 

(2) The system seeing false ("ghost") targets. This is usually either due to:

     - picking off a very strong reflection in the radar beam side lobe. To put it simple, the radar can mistake a strongly reflective object (a very large metallic object) off to the side for a weakly reflective object dead ahead (e.g. a motorcycle).

     - interference from other radar emitters (other radar-equipped cars)

 

For (2) there are special algorithms that the sensor runs to reduce the probability of this happening, however no algorithm is 100 % reliable.

 

I myself have experienced Front Assist issuing a warning once with no apparent reason. However, there was no braking intervention.

I've also used ACC extensively and found the object (other road user) detection to work very reliably.

 

As for adjusting the sensitivity via the infotainment, as I understand this will only influence how early the audiovisual warning will pop up. It does not have effect on braking interventions.

Thanks for your posts gogo110.  Re your "two things", (1) seems very unlikely.  There was nothing in front for about 500 yards, and nothing on the nearside pavement either, so my money is on it being (2).  It might have been a reflection of the type you describe, as there was slow, orderly, traffic in the opposite direction, so a reflection has to be at least a possibility.  However, nothing struck me as unusually large at the time.  I don't remember there being one, but a double-decker bus is a distinct possibility as it's a bus route. 

 

Equally, I guess oncoming radar interference must also be possible - though it seems odd that one system should spook another.  Does that require an alignment fault in the other system to cause it "dazzle" mine?  It would surely, in any case, be quite a problem on twisting rural roads where an oncoming vehicle rounding a (for me) right-hand bend would "spray" all cars going the other way with its beam.  Not so good as the number of cars with AEB is increasing by the minute.  On that basis, reaching ones destination will become a minor miracle - with repeated involuntary stops as we each pass each other along the way!  Bring back horses, I say.  🙃

 

Re the stamping on the gas etc. there simply wasn't time!  The audio warning was loud and the braking was simultaneous with no early warnings whatever.  I was too busy trying to understand what the Hell was going on to do either - even if I'd known (as I do now thanks to your post) that it's possible, besides which I was lurched forward into the seatbelt by the force of the braking, so had no real control at all until the car stopped and I'd extracted myself from the seatbelt!

[john1952]

You could just turn the Front Assist off.  A couple of clicks on the steering wheel "Assist Menu shorcut" buttons will do that.  I always turn off the Lane Assist every time I drive - can't see the point of that feature as I'm always crossing over white lines when manoevering around town or city roads for a genuine reason.    

[Warrior193]

1 hour ago, bromley said:

Thanks.  First thing I did - once I'd navigated the infotainment maze!  However, wasn't at all clear on what "sensitivity" meant.  Sensitivity to what?  I later found it was possible to turn off Front Assist, so have been doing that since.

 

From gogo110's post above, it seems the sensitivity setting doesn't adjust the intervention speed, but only that of the warnings.  If only they would give clear instructions/explanations!  😞 

I'm inclined to believe that adjusting the sensitivity of the front radar will also make it less liable to 'ghost' activations - the visual warning and the AEB are two elements of the same system.  

[gogo110]

2 hours ago, bromley said:

(...)  Does that require an alignment fault in the other system to cause it "dazzle" mine?  (...)

 

Well actually no. The Continental radar mentioned radiates -45° +45° left-right, newer systems have an even wider beam. (Note that the beam as a whole is composed of several smaller sub-beams, allowing the radar to differentiate objects placed at different angles. However, each sub-beam has the aforementioned unwanted side-lobes). So even when driving on a straight road, oncoming cars will spray you with radiation. Automotive radar interference is a hot topic in radar engineering these days, due to the increasing number of AEB equipped cars as you mention. However, the probability of ghost targets appearing is still considered do be very low. A bigger (more prevalent) problem is the deterioration of the quality of the received signal, making it harder for the radar to detect objects, especially weakly reflective ones. You can read up more on the topic in this article.

 

2 hours ago, Warrior193 said:

I'm inclined to believe that adjusting the sensitivity of the front radar will also make it less liable to 'ghost' activations - the visual warning and the AEB are two elements of the same system.  

 

Now Skoda's manual is rather sparse with information, but from the manual for the current-gen VW Polo, a car which uses the same AEB system, we can read:

 

"If Front Assist is switched on, you can make the following settings in the Assist systems menu of the Infotainment system (...): -Set the warning time for the advance warning"

 

The Polo manual also has a bit more info on the operating conditions and limitations of Front Assist.

[bromley]

Thank you very much gogo110, especially for the article.   I confess most of that was way over my head 🙂 , but what it seemed to say was that the radar on one vehicle can interfere with that on another, to the extent that the "victim" vehicle' radar "sees" what is not the reflection of its own signal, but the transmitted signal of the other radar, and can react to that signal, possibly "seeing" a "ghost" image, to which the AEB system may respond unpredictably.  If that is a reasonable interpretation of the article, I could well be the victim of such an event.

 

My only hesitation in accepting that reasoning is - surely someone would have thought of, and eliminated, that possibility, before mandating radar based AEB systems for vehicles to be driven on public roads by an unsuspecting Joe Public?  Under that scenario, one's only defence against the "ghost image" emergency stop phenomenon, is to disable the AEB if one is likely to encounter oncoming AEB equipped traffic which, in effect, means always!  Is that really where we are, or am I misunderstanding (again 🙂)  ?  😞 

[Paws4Thot]

1 hour ago, bromley said:

what it seemed to say was that the radar on one vehicle can interfere with that on another, to the extent that the "victim" vehicle' radar "sees" what is not the reflection of its own signal, but the transmitted signal of the other radar, and can react to that signal, possibly "seeing" a "ghost" image, to which the AEB system may respond unpredictably.

In a word, "yes".

 

As to eliminating the possibility of "your" receiver receiving someone else's transmission, I think this would require your transmitter to have a different frequency and beam polarity to theirs.

[bromley]

Thank you Paws4Thot.  With apologies, but are you comments from personal/professional experience?  Could you enlarge a bit on the circumstances, please?  🙂