Author Topic: SCBS  (Read 4374 times)

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Offline photoman

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SCBS
« on: August 09, 2018, 12:12:53 PM »
Hi,  I'm new to the world of Mazda but so far have been very pleased with my 3 Sport Nav.  I had to take my car in to have the software updated and mentioned that I thought there was a problem with the SCBS as it did not seem to be working and I didn't want to get too close to test it out.  When I picked my car up they confirmed there seemed to be a problem but couldn't find a diagnostic code for it.  Amazingly on my way home a car in front stopped quickly about a car's length from me and the word BRAKING appeared on my HUD.  A couple of days later I thought it should have kicked in and so decided to test the system and stacked up some empty cardboard boxes and drove towards them.  The brakes were not applied.  I have watched a couple of videos showing the system in action and mine was not working like those shown.  I booked my car in again and after a full day I was told there is no error code which shows a fault and there was nothing they could do.  This is not something I want to rely on and I don't drive close to other cars but I would like to know it would work  if called upon.  I'm sorry for the epic tale but does anyone else have or had this issue?

Offline Willpower

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Re: SCBS
« Reply #1 on: August 09, 2018, 02:36:55 PM »

Hi Photoman.  Welcome to the forum.
Yes I had the same concerns as yourself and went to the dealers for them to check it out. I got the same response as you but perhaps a better explanation.

Whilst I was there they set up a cardboard box and one of the mechanics drove towards it. They told me that the car needed to be travelling at greater than 10 mph for the system to work properly.
On the first attempt the car hit the box. I was not impressed
After some discussion it was considered that the box did not register on the camera properly as it was not tall enough.  So as it was a rectangular box we turned it 90 degrees and tried again.  This time the car braked and came to a halt less than 1 inch away from the box.

Two things were discussed. Firstly that in my opinion the camera should have registered the box at the lower height as this would have been at approximately the same height as the back of a sports or convertible car such as an MX5 or a Mercedes SEL .  The fact that it worked when the box was stood the other way round making it taller is fine, if the only thing in front of you is a van or a truck.

The other thing that came to light according to the workshop manager, is that the SCBS will only work  a)  If the car is travelling above 10 mph  and   b)  [and this is more important] that there is absolutely no input from the driver.

I take this to mean,  no pressure on the brake pedal , no pressure on the accelerator , no application of the handbrake  and most critical no movement of the steering wheel. 

In other words if the car senses any input from the driver then the system considers that you are still in control of the vehicle  AND WILL NOT ACTIVATE.

Just to make sure we tried it a third time and once again the gap between the car and the box was less than an inch. Far too close for my liking.

All in all, I left with one fundamental truth.....  DO NOT trust SCBS     If it works fine.  But do not rely upon it to intervene in slow speed scenarios such as behind other cars at a junction or roundabout.  1. You will be going too slow and 2. you will have been operating accelerator/clutch/steering.  In these instances it will not save you running into the back of the car in front if you fail to take the proper care.
Lastly to my mind it calls into question if it will operate in a motorway collision situation. After all you will have been in control of the car before and might even been braking. Would it assist you to stop before hitting the car in front ??   

Just a couple of final thoughts.  Is SCBS really worth it. ??  In my opinion it is really not as good as it is made out to be and could be improved.  The camera will pick up an object in front of the car, but the algorithm used to apply the brakes should be tweaked to increase the stopping distance. Something I have passed on to Mazda (UK)

And the second thing to consider is that a lot of insurance companies are now asking " Does the car have semi autonomous braking ? "  One would assume from that question that they are now considering the answer to be factored into the insurance quotation that they give you.


Discuss .....
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Offline Engineer Andy

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Re: SCBS
« Reply #2 on: August 10, 2018, 12:41:36 PM »
Sounds to me like this system is very much like many 1st gen tech - great idea, lots of glitches and problems that will only be fixed for gen 2 onwards.  I also suspect it was only included in the car's spec in order to obtain a 5 star NCAP rating (similarly in many makes for 'safety' systems).  I also not that VAG's own system apparently has problems with its sensors whereby it gives a false reading if, say, a plastic bag gets caught over the sensor and suddenly brakes, whether you need to or not.  Not good if you're doing 70mph on the motorway in heavy traffic.  I think there was also (if I recall) similar issues with some BMWs?

Whilst many proven safety systems are great, many I think encourage drivers to driver faster (especially in poor weather/road conditions), closer to other vehicles in front and brake later.  That's not what they are they're for - the driver, as Will says, is the number 1 safety system and should remain so until technology has been proven as bullet-proof to make cars completely autonomous.  I suspect that day is still several decades away, despite what the likes of Google & Co may say.

Offline moozmooz

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Re: SCBS
« Reply #3 on: August 10, 2018, 08:04:39 PM »
Willpower

Looks like you've been given a bum steer by the workshop manager - sadly not unusual for Mazda service personnel.

From page 4.144 of the bible

"The Smart City Brake Support (SCBS) system is designed to reduce damage in the event of a collision by operating the brake control (SCBS brake) when the system's laser sensor (front) detects a vehicle ahead and determines that a collision with a vehicle ahead is unavoidable. It may also be possible to avoid a collision if the relative speed between your vehicle and a vehicle ahead is less than about 15 km/h (9.3 mph).
In addition, when the driver depresses the brake pedal while the system is in the operationrange at about 4 to 30 km/h (2 to 18 mph), the brakes are applied firmly and quickly to assist. (Brake Assist (SCBS brake assist))"

There's nearly three pages after that effectively telling you not to rely on it. :)

In other words, it operates under not over 10mph.

This was the information I was given by the salesman when I bought my Gen 3. He suggested using a sheet held in the path of the car to test the system As yet, I haven't bothered.

Offline Willpower

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Re: SCBS
« Reply #4 on: August 10, 2018, 09:11:20 PM »
Whatever your interpretation is, is up to you.

I've seen it in action. And it doesn't inspire confidence.  But at least the book and I agree that you should not rely upon it.  So I stand by what I say.
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Offline moozmooz

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Re: SCBS
« Reply #5 on: August 10, 2018, 10:16:22 PM »
No interpretation. The manual's perfectly clear. ". It may also be possible to avoid a collision if the relative speed between your vehicle and a vehicle ahead is less than about 15 km/h (9.3 mph)."

What the service manager said was wrong. It only operates it the speed differential between your vehicle and the vehicle or object you're closing in on is less than about 9.3 mph. It could't be clearer.

Offline Willpower

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Re: SCBS
« Reply #6 on: August 10, 2018, 10:54:58 PM »
It may also be possible to avoid a collision if the relative speed between your vehicle and a vehicle ahead is less than about 15 km/h (9.3 mph)."

Read it again.  It might be what the manual says.   It doesn't equate with what I witnessed.  End of. 
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Offline moozmooz

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Re: SCBS
« Reply #7 on: August 10, 2018, 11:44:00 PM »
Ignore the “may”. That’s irrelevant. I think we’re both agreed that it’s a waste of space and not to be relied on.

The point I’m making is that what you were told, “SCBS will only work  a)  If the car is travelling above 10 mph” is wrong. It only works if the speed differential is less than about 9.3 mph, or, in the case of approaching a static object, an absolute speed of 9.3mph.

Absolutely no need for rudeness, so unlike you, I'll resist the tempation. If you're going to be the moderator, act like one.

Offline Willpower

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Re: SCBS
« Reply #8 on: August 11, 2018, 08:10:23 AM »
Moozmooz  you have a PM !
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Offline photoman

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Re: SCBS
« Reply #9 on: August 13, 2018, 11:44:09 PM »
Thank you to everyone who took the time and effort to respond.  Somehow I feel slightly cheated in that in Mazda's promo on the safety features it lists SCBS as a wonderful addition to all the car's desirable attributes.  I'm now wondering if I missed the section on the car being able to perform a Harrier Jump Jet manoeuvre in motorway tailbacks and wing me on my merry way looking down on the sad bastards below. ;D ;D

Offline Coypars

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Re: SCBS
« Reply #10 on: December 29, 2019, 07:15:42 PM »
This just happened  driving my 66 plate mazda 3 at 40 mph on a clear road no traffic or obstacles , alarm sounded inside the car and brake flashed up  in display. Woneeded what the heck was going on.

Offline misar

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Re: SCBS
« Reply #11 on: December 30, 2019, 07:21:05 PM »
I also have this system and like you I have found that from time to time the car will scream and flash (in the HUD) a warning to brake. Each time I can see why it is confused. Most common is when driving alongside a row of parked cars and coming to the space they are forced to leave for a traffic island. If travelling quite fast the alarm will go off as I turn into the gap to go round the island. The other one, less common, is on a bend if the car happens to be pointing directly towards a pedestrian on the pavement but near the kerb.

Unlike Willpower with his tests in an earlier post, I am relieved that at least so far my car has never applied the brakes by itself. I noticed that North American Mazda forums have many complaints that this is really dangerous. The comment in Willpower's post about sensing input from the driver may explain the difference between my examples above and Americans bombing down the freeway half asleep and  relying on radar cruise control and lane assist.

Personally I can see enough benefit from warnings not to want to remove them even if they do scare my passengers from time to time. Equally I regard the automatic part of the system as a last resort which I hope to never need. If the above explanation is correct Mazda have probably got it about right.

Edit
----
As an afterthought I decided to read the current manual!

This makes it clear that the main purpose of the system is to alert the driver to take action. It then adds "Furthermore, if a collision is unavoidable, the automatic brake control is performed to reduce damage in the event of a collision. In addition, when the driver depresses the brake pedal, the brakes are applied firmly and quickly to assist." This makes it absolutely clear that the automatic braking function is not intended to save lazy drivers using the brakes in normal driving. As before there is a long list of sensible conditions where it is not considered necessary to activate the warnings (or brakes).

There is also an interesting comment for those with higher spec models which have Driver Monitoring (DM). "When the SBS determines that the driver is not paying attention to the road using the driver monitoring camera and it determines that there is the possibility of a collision with an obstruction, the SBS activates the collision warning earlier than normal." So don't nod off or play with the sat nav!




« Last Edit: December 30, 2019, 08:08:21 PM by misar »

Offline Tomweston

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Re: SCBS
« Reply #12 on: January 04, 2020, 10:05:13 AM »
I have just bought a 2017 Mazda 3 having previously owned a Volvo V40 which also had city breaking. I could never force the Volvo city breaking to work but eventually the car demonstrated that it worked effectively whilst leaving the M6. Basically whilst travelling down the slip road in the outside lane a police car came down the same lane with lights flashing, I moved over to the inside lane to allow the police car past and was closer than expected to the car in front of me, my Volvo applied the city brakes much to my wife’s and my amazement.
Hope that helps a bit.

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Re: SCBS
« Reply #12 on: January 04, 2020, 10:05:13 AM »