Tried testing SCBS & SBS today

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Virginia
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2021 CX-5 White
Keep in mind In the US we gets Advanced Smart City Brake Support with Pedestrian Detection only since 2019 CX-5 MY (expect 2019 CX-5 Sport). And both ASCBS and SCBS are for driving at low speeds (approximately 2.5 ~ 19 mph or 4 ~ 30 km/h on SCBS) only. The objects intended to detect are very different between the two.
This is one of the issues I have with Mazda, and all other car companies is the alphabet soup they create with different sub systems....

Note that in 2021, SCBS no longer exists as it did in our 2014 CX-5, which was a low speed system that only worked below 30 kph (18 mph) and at relative speeds below 15 kph (9.3 mph) based on a laser sensor in the windshield, which in newer generations has been replaced by the Forward Sensing Camera (FSC). As you can see below, there are variations of SCBS, but none are the " "original" SCBS. As an aside, our SCBS only kicked in twice to our knowledge, each time with my wife, as she was approaching either a hedge near a shopping or low hanging branches (rain soaked crape myrtles that were drooping downwards 6+ feet).

ASCBS: Advanced Smart City Brake Support
SCBS: Smart City Brake Support
SCBS-F: Smart City Brake Support (Forward)
SCBS-R: Smart City Brake Support (Reverse)
SBS: Smart Brake Support

ASCBS:
The Advanced SCBS alerts the driver of a possible collision using the display and a warning sound when the Forward Sensing Camera (FSC) detects a vehicle ahead or pedestrian and determines that a collision with the object is unavoidable while the vehicle is driven at a vehicle speed of about 4 to 80 km/h (2 to 50 mph) if the object is a vehicle ahead and about 10 to 80 km/h (6.2 to 50 mph) if the object is a pedestrian. In addition, the system reduces damage in the event of a collision by operating the brake control (Advanced SCBS brake) when the system determines that a collision is unavoidable. In addition, when the driver depresses the brake pedal, the brakes are applied firmly and quickly to assist.

SCBS-F: The SCBS F system alerts the driver of a possible collision using an indication in the display and a warning sound when the Forward Sensing Camera (FSC) detects a vehicle ahead and determines that a collision with a vehicle ahead is unavoidable while the vehicle is being driven at a vehicle speed of about 4 to 80 km/h (2 to 50 mph). In addition, the system reduces damage in the event of a collision by operating the brake control (Smart City Brake Support (SCBS) brake) when the system determines that a collision is unavoidable while the vehicle is being driven at a vehicle speed of about 4 to 30 km/h (2 to 18 mph). It may also be possible to avoid a collision if the relative speed between your vehicle and the vehicle in front of you is less than about 20 km/h (12 mph). In addition, when the driver depresses the brake pedal while the system is in the operation range at about 4 to 30 km/h (2 to 18 mph), the brakes are applied firmly and quickly to assist. (Brake Assist (Smart City Brake Support (SCBS) brake assist))

SCBS-R: The SCBS R is a system which is designed to reduce damage in the event of a collision by operating the brake control (SCBS brake) when the system’s ultrasonic sensors detect an obstruction at the rear of the vehicle while driving at a speed of about 2 to 8 km/h (2 to 4 mph) and the system determines that a collision is unavoidable.

SBS: The SBS system alerts the driver of a possible collision using a display and warning sound if the radar sensor (front) and the Forward Sensing Camera (FSC) determine that there is the possibility of a collision with a vehicle ahead while the vehicle is being driven at about 15 km/h or faster (10 mph or faster). Furthermore, if the radar sensor (front) and the Forward Sensing Camera (FSC) determines that 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. (Brake Assist (SBS brake assist))

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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
People aren't shaped like sheets either. You can't have an emergency braking system that triggers on anything and everything or it would be throwing you through the window all day with false alarms. The car's sensor is programmed to recognize the human form (which is why it won't emergency brake for animals).

This isn't an autonomous driving system but rather a simple "driver distraction" system. I think many people believe it is much more capable than it actually is. If you are manipulating the accelerator or turning the steering wheel the car assumes YOU are paying attention and driving and won't intervene. (It may warn you but not intervene). Notice on that video by @ceric that the driver had his foot off the accelerator and did not move the steering wheel during the SCBS demo.
That's to the point. It's helpful to think about what the systems do. The radar detects motion and distance. The camera detects the kind of objects in view and that is where many of the difficulties lie.

AI requires a visual system to be trained to detect specific kinds of objects. Even highly sophisticated neural networks, not likely to be found in any car regardless, have limited "self-training" abilities in inferring what an unfamiliar object might be. Even the most sophisticated humanoid robots, just reported on 60 Minutes, that can negotiate stairs and walk over rocks, have a visual field only a few feet in front of them.

The manual is fairly specific in what objects under what conditions can be detected along with numerous warnings about the kinds of conditions that might cause the systems to fail. It's worth reviewing them for a gut check if one suffers from the illusion that these systems are in any way "autonomous". Even 99% reliability would not be reassuring.

The white sheet test in the OP reminds me of the guy watching a video who plowed his "autonomous" Tesla at 70 mph into the side of a white tractor trailer against a white sky. It might be interesting to retest with the siblings shaking the sheet to see if the radar would pick up the motion/distance and engage the braking. 🙄
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
If I remember it correctly, the object has to be metal, unless the system is pedestrian capable such as “City Safety” system on Volvo.
I tend to think the system is not restricted to metal objects, at least as of 2020, when thinking about how the rear cross traffic alert works in the base system (not the 360 degree upgrade). The rear camera is dumb; it doesn't do anything but show a picture on the display. The vehicle won't warn you about backing into a stationary object. It's a radar-driven motion detector only.

Now, this system is more rudimentary than the front facing systems, yet I've seen it pick up non-metallic objects in motion, i.e., pedestrians. It would stand to reason the front-facing radar would have that sophistication. We have reports here of the front facing system engage in response to a hedge, for example. Though I would never suggest anybody try it, if one were to drive toward a brick wall in the pitch dark with the lights off taking the camera out of play, one would expect it to brake since that would involve one of the more rudimentary capabilities of a radar system.

But why not stop for a sheet? Who knows. Maybe the camera was confused about what it was seeing. Maybe the sheet was wrinkly and flapping a little in the wind, producing an inconclusive radar signal. These are backstop systems, not autonomous ones (which as yet do not exist in any meaningful way), where inconclusive signals should respond with "do nothing". Come to think of it, in the pitch dark brick wall example, if the camera was seeing nothing, a mixed signal, perhaps "do nothing" would result, like the aforementioned Tesla that slammed into a tractor trailer because evidently the camera didn't "see" it. Anyway, drive at that wall in daylight and it should brake. A friend had a salesman demonstrate that in 6 or 7 year old Accord. No metal involved. I would think current systems would handle that.
 
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Virginia
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2021 CX-5 White
What I have been told and read about the rear cross traffic alert in my now departed 2016 Mazda6, and most other vehicles with similar capabilities: The rear cross traffic function uses a very different sensor than the forward sensing camera. @HardRightEdg is correct that the rear camera is dumb, and does not play into the rear cross traffic situation.

The CX5 uses a similar system to the Mazda6 with more sophisticated software to now apply brakes for the rear automatic braking feature.

The Blind Spot Monitor (BSM) is actually a small radar unit that is in the rear bumper in the near the quarter panel, and uses a detection lobe that covers the adjacent rear area traffic lane areas for blind spot monitoring.

1617224299488.png


For Rear Cross Traffic Alert, the same radar sensor changes the shape of the detection lobe to cover a wider rear traffic area. The radar can detect objects, whether a moving pedestrian, a moving vehicle, or a stationary object you are going to back into, though not with the fidelity of the ultrasonic (sonar) sensors in the bumper.

1617224361212.png


Rear Automatic Braking uses the radar information, and if applicable, the sonar information, with software to decide when to apply the rear brakes.
 
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2017 Mazda CX-5 GT, 2016 Mazda6 iGT, 2014 Mazda3 sGT hatchback
The radar can detect objects, whether a moving pedestrian, a moving vehicle, or a stationary object you are going to back into, though not with the fidelity of the ultrasonic (sonar) sensors in the bumper.
My understanding is that RCA does not detect stationary objects. It uses Doppler effect to filter them out. Imagine in a parking lot full of vehicles. You are backing out from your space.... So many parked vehicles around you.

Pedestrians? Not reliable. It depends on how much metal objects they have on them.... Mine was able to alert me sometimes, not all the times.
 

HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
For Rear Cross Traffic Alert, the same radar sensor changes the shape of the detection lobe to cover a wider rear traffic area. The radar can detect objects, whether a moving pedestrian, a moving vehicle, or a stationary object...
A noted previously, I don't know what the upgraded 360 degree display version of the system might do or another Mazda system with auto braking, but I can tell you from first hand experience that the base version in the 2020 CX-5 does not detect rear stationary objects as discussed in another thread.

For anybody who has that base system, this is easily tested with a companion who can tell you to stop before you hit the test object.

The system is a motion detector only for lack of a better description
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
Pedestrians? Not reliable. It depends on how much metal objects they have on them.... Mine was able to alert me sometimes, not all the times.
Are you sure metal has anything to do with it? Do you think the front detection system wouldn't stop you from hitting a brick wall? It could as easily be a system glitch that manifests only under specific conditions. Maybe you're right. Maybe the front camera is not trained for "brick wall" and does not communicate confirmation of a threat. The manual only mentions "vehicles" and "pedestrians" however that isn't saying much. The manual cannot be trusted for completeness and accuracy. If this system would not stop you from hitting that wall it calls into question the intelligence of the system as a whole. Anyway, consider the following:

4 or 5 times, about once ever 500-750 miles of local driving, once just yesterday, I've had the blind spot detector squawk for no good reason as I was entering a left turn lane. Or was it a collision warning as I was angling toward on-coming cars? I had no reason to be looking in the side view mirror and had not otherwise ever activated the collision warning to know what it sounds like. The first instance was a WTF. After that I started making mental notes of what was around me. The only commonality I've detected in these situations is that I was braking at slow speed, I was first in line in the turn lane, and there was slow on-coming traffic, sometimes straight on and once with a car making a right turn toward me. I have no idea what it might be picking up or why, but in all other circumstances the blind spot detector has worked when and how it should. That too is a radar driven system.

This kind of false positive is no harm no foul. Others have reported less benign reactions to perceived threats, like over-aggressive auto braking when getting cut off, nearly resulting in a rear ender.

Further, my experience with lane keeping is that the system is very good at picking up white shoulder lines, inexplicably unreliable at picking up yellow center lines after numerous tests. I keep checking it on two-laners with no one on-coming, gradually sidling over the line, and can't for the life of me figure out why sometimes it detects and sometimes it doesn't.
 
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HardRightEdg

US 2020 CX-5 Touring AWD Soul Red
One last thought that now occurs to me: Why would you go to the trouble of building a rear cross traffic system than only detects metal ? You can go to Amazon and for less than $30 USD buy a security light with a motion detector that has a 50 foot range (about what the rear cross traffic detector has) that makes no such distinction.

You wouldn't want to run over a dog, would you? Or for our Canadian brethren, you wouldn't want to back into a galloping moose, right? And you wouldn't need to pay for the LED light array. Come to think of it, if this system is not metal-sensitive then...you get where I'm going.

It's not like I regret the purchase because of these system oddities. The same vehicle at the same price and I'd do it again. I wasn't much interested in any of this safety gadgetry except the blind spot monitor though I have come to appreciate the backup warning as limited as it may be. Other makes have their own oddities in their similar systems, of that one can be certain.
 
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Occupied Calif.
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2019 CX 5 GT-R
I always get the BRAKE signal when driving in the 1st lane on the highway and the car in front exits off.
If that is always happening you need to do one of these things:
1. Stop following so closely
2. Check the distance settings on your menu for the warning systems and/or cruise control. It may be at the minimum
3. Have the dealer check the system for proper functioning

I would start with # 2. I have only had the BRAKE graphic flash up on my HUD a few times, and that is when some idiot turns left in front of me a little too closely. In each of those cases it wasn't so close that the system activated the brakes, nor did it require me to step on the brake pedal to avoid a collision. The only action on my part was to call the other driver a 14 letter word.
 

7eregrine

The man, the myth, the legend
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Land of Cleve
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2016.5 CX5
There is no way the rear traffic alert... is detecting metal... it's certainly motion.
 
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2017 Mazda CX-5 GT, 2016 Mazda6 iGT, 2014 Mazda3 sGT hatchback
You guys are focusing much on *metal*. Metal reflects radar waves more than other materials. Human body does not reflect radar waves as much as metal does.
So, this is not black-n-white. Different amounts of radar waves bounced back.

What I meant was... if a pedestrian has more metals on him/her (watch, coins, cell phones, etc.), it would be more likely to be detected thanks to more bounced back radar waves.

A simple experiment can prove me right or wrong.... No danger involved.
I am OK to be proven wrong. :)
 
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2020 CX5 Signature
FWIW: yesterday I was backing up while turning in a small parking lot and the beeps started. I stepped on the brake and then noticed that I was less than a foot away from backing into a telephone pole. No metal. 2020 CX-5 Signature.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
FWIW: yesterday I was backing up while turning in a small parking lot and the beeps started. I stepped on the brake and then noticed that I was less than a foot away from backing into a telephone pole. No metal. 2020 CX-5 Signature.
That beeping is coming from “Rear Parking Sensors” a standard equipment only on CX-5 Signature trim.
 
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Virginia
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2021 CX-5 White
My understanding is that RCA does not detect stationary objects. It uses Doppler effect to filter them out. Imagine in a parking lot full of vehicles. You are backing out from your space.... So many parked vehicles around you.

Pedestrians? Not reliable. It depends on how much metal objects they have on them.... Mine was able to alert me sometimes, not all the times.
You are correct and I mis-spoke. The radar only detects moving objects and detects people in our underground garage or the grocery store parking lot, but it detects movng cars a lot better, almost before they are visible in the camera.
 
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2018 CX-5 Sport
It is obvious why the intelligent braking systems won't stop for a sheet. It thinks the sheet is a ghost and it knows that ghosts are already dead.
 
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Gozo

2020 Mazda6 2.5T
FWIW: yesterday I was backing up while turning in a small parking lot and the beeps started. I stepped on the brake and then noticed that I was less than a foot away from backing into a telephone pole. No metal. 2020 CX-5 Signature.
The backup sensors are ultrasonic and if you catch the pole fairly close up, it may wind up smack between the beams. Further away they’re wider. Only the front sensor (in the logo on the grill) is radar. It’s a 77Ghz unit (I checked the FCC identifier). You can Google the reflectivity of various stuff at these frequencies. That’ll give you some indication of what to use vs. a sheet to give it a go. Would be cool to test different stuff and different speeds. Not for me, but someone with more time and inclination to put in the effort. Let us know.
Edit: yup, as yrwei52 said below, the parking sensors are ultrasonic. I wasn’t clear in what I typed vs what I meant. :)
 
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yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
The backup sensors are ultrasonic and if you catch the pole fairly close up, it may wind up smack between the beams. Further away they’re wider.
Those small and rounded parking sensors are visble on the front and rear bumpers. I have rear parking sensors on my 2000 BMW 528i, and the situation you described will never happen unless you ignored the constant beeping.

Only the front sensor (in the logo on the grill) is radar.
Yes, but the ultrasonic front parking sensors are on the front bumper.
 
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Phoenix
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2020 CX5 signature
A lot of useful information, and I'm grateful for all of it. I just would have thought that in the last year at least once I would have been inattentive enough for the front braking system to work. My goal with the sheet was just to determine whether it's working at all or not. Guess I will or won't find out the hard way one day
 

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