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Thoughts on why AEB is designed to only reduce speed by 25mph?
- Thread starter viet658
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JeffK
Well-Known Member
The primary goal is to begin the braking process and the human will take over thus mitigating the severity of the crash.
Brake too fast to a stop and someone will slam into you from behind. The keywords here are "When a frontal collision is considered unavoidable..."
If you've ever had a frontal collision, you'll know that, eventually, you do get to 0 mph.
Brake too fast to a stop and someone will slam into you from behind. The keywords here are "When a frontal collision is considered unavoidable..."
If you've ever had a frontal collision, you'll know that, eventually, you do get to 0 mph.
I think it's best explained with an example
Like lets say you're traveling down the freeway at 70mph, and there is a false detection with the AEB system. With a 25mph reduction it brings you down to 45mph. It's going to be unnerving, and you'll be irked. But, odds are no one is going to crash into you. Unless they're on your butt where they don't give the proper following distance.
If you went from 70 to 0 with as much braking power as the car could give you'd likely end up with some SUV on your back.
The 25mph was picked because that's enough of a reduction in speed to be life saving.
In the end it's just a way of managing imperfect technology.
Like lets say you're traveling down the freeway at 70mph, and there is a false detection with the AEB system. With a 25mph reduction it brings you down to 45mph. It's going to be unnerving, and you'll be irked. But, odds are no one is going to crash into you. Unless they're on your butt where they don't give the proper following distance.
If you went from 70 to 0 with as much braking power as the car could give you'd likely end up with some SUV on your back.
The 25mph was picked because that's enough of a reduction in speed to be life saving.
In the end it's just a way of managing imperfect technology.
Cheburashka
Active Member
While this could be the reasoning from Tesla, does this mean that their technology is subpar compared to other car brands?
As always, I recomend everyone to check out Euro-NCAP’s reviews and videos were they test AEB as a part of the safety rating. AEB counts toward the rating, so it’s becoming quite common in Europe.
Here’s from the latest test of the Volvo XC60:
«The autonomous emergency braking system scored maximum points when tested at highway speeds, with collisions avoided at all test speeds and in all scenarios.»
Official Volvo XC60 safety rating
The Toyoya Prius also avoids the crash completly.
Official Toyota Prius 2016 safety rating
Had to do some digging to find a car that has AEB and does not avoid the crash in all scenarios, like Tesla:
Official Mazda CX-5 safety rating
The Mazda CX5 only reduces the severity of the crash if following a car at short distance and the car in front brakes harshly.
If being rear ended was a common occurance due to faulty AEB on other car brands, surely we would have heard about i more often?
Thanks for bringing this up... I was under the impression that AEB could bring the car to a complete stop... I doubt I'm alone in this misconception. TACC/EAP is fully capable of bring the car to a complete stop (and starting off again)... so the system is fully capable... I'm not understanding this -25 mph limitation.
Shock-On-T
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JeffK
Well-Known Member
JeffK
Well-Known Member
Let's take a closer look at the Volvo manual for details:
Basically, if you're in stop and go traffic, it'll stop, just like a Tesla. If you're going highway speeds, then it will not necessarily stop the vehicle in time without driver intervention.
DR61
Member
I own a 2017 XC60 with this system. The manual says it only operates at 50 mph and below. For pedestrians and cyclists it suggests 30 mph and below. It does not say if it brakes to zero mph.
Matt_CRNA
Member
Definitely in place to reduce or mitigate front collision damage. Perhaps the AEB algorithm really only applies when Autosteer is off and a human has control of the vehicle?
I think it is simply the risk of being rear ended.
Some year, these systems will provide some sort of gap management... decide if it is worth running into the car in front to make more space for the car coming in fast from behind..
The automotive talk show guys on the radio in Dallas are always saying how AEB reduces injury BUT constantly harping on how manufactures don't explain that it will not come to a complete stop in many cases... They were not talking about Tesla, they were talking about AEB in general.
Some year, these systems will provide some sort of gap management... decide if it is worth running into the car in front to make more space for the car coming in fast from behind..
The automotive talk show guys on the radio in Dallas are always saying how AEB reduces injury BUT constantly harping on how manufactures don't explain that it will not come to a complete stop in many cases... They were not talking about Tesla, they were talking about AEB in general.
AEB designed to reduce the severity of the impact? So if it detects a crash and starts applying the brakes does that mean it’s too late and there’s going to be a crash no matter what? Like even if the driver takes over and steps on the brakes as hard as they can, is it too close to the object already and there’s not going to be enough braking distance?
Sounds like AEB reduces impact and cannot avoid it.
Sounds like AEB reduces impact and cannot avoid it.
JeffK
Well-Known Member
Yes, that's exactly what it does. If the object you're going to crash into speeds away or if you're able to maneuver around it then you'll avoid the collision, but, for the most part, AEB should only go off if the collision is imminent.
Because
1) false positives are dangerous
2) it's not an autonomous car
1) false positives are dangerous
2) it's not an autonomous car
And just to add to this:
3) Liability.
If they go out saying it's going to 100% stop a car, and you smack into the back of someone, chances are you would hold Tesla liable. And given they can't even stop / move for fixed inanimate objects I would hold my breath for full stop AEB anytime soon.
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