AEB simply won't work

[Tam]

...As long as your speed is below 25 MPH you have a shot at accident avoidance. Above 25 MPH braking could be too little too late...

If you read several sentences before that, it says:

"Automatic Emergency Braking is designed to apply the brakes to reduce the severity of the impact,"

Tesla AEB never claims that its goal is to avoid an impact.

Tesla AEB has a different design: to reduce the severity and not to avoid an impact, which is a different philosophy than Cadillac AEB which is to avoid an impact as a goal.

 

[vandacca]

If you read several sentences before that, it says:

"Automatic Emergency Braking is designed to apply the brakes to reduce the severity of the impact,"

Tesla AEB never claims that its goal is to avoid an impact.

Tesla AEB has a different design: to reduce the severity and not to avoid an impact, which is a different philosophy than Cadillac AEB which is to avoid an impact as a goal.

Very true, Tesla AEB is currently designed to reduce accident severity.

I'm hoping that in the future, that will change to reduce accident collisions.

 

[lunitiks]

Tesla AEB has a different design: to reduce the severity and not to avoid an impact, which is a different philosophy than Cadillac AEB which is to avoid an impact as a goal.

"Different philosophy"...? Isn't Teslas system just inferior to Cadillacs? I mean, even if Cadillacs AEB failed to come to a complete stop (impact unavoidable), wouldn't it also reduce severity - i.e. be on par with Teslas system? It seems to me that Tesla simply lacks the 'avoidance' feature of AEB

 

[animorph]

If you read several sentences before that, it says:

"Automatic Emergency Braking is designed to apply the brakes to reduce the severity of the impact,"

Tesla AEB never claims that its goal is to avoid an impact.

Tesla AEB has a different design: to reduce the severity and not to avoid an impact, which is a different philosophy than Cadillac AEB which is to avoid an impact as a goal.

So in a 12 MPH collision it still waits until it's too late and reduces the collision speed by only 10 MPH? That seems unlikely to me, but I'm not counting on AEB to save me either. We know it should be able to shed 25 MPH before a higher speed collision. Why can't it shed 25 MPH and avoid a low speed collision?

I haven't seen any data one way or the other, hence my interest in this thread.

 

[McRat]

"Different philosophy"...? Isn't Teslas system just inferior to Cadillacs? I mean, even if Cadillacs AEB failed to come to a complete stop (impact unavoidable), wouldn't it also reduce severity - i.e. be on par with Teslas system? It seems to me that Tesla simply lacks the 'avoidance' feature of AEB

I only have experience with GM AEB systems, and GM ABS systems (both street and closed course). Of one thing I'm certain, the GM AEB system will apply maximum possible braking effort on the 2017 models, both frontal and reverse emergency braking (yes, it will hammer the brakes in reverse if there is a pedestrian, car, or shopping cart). You can feel the high frequency ABS and hear the tires complain. It also kicks in at speeds over 50 mph. Best guess? Perhaps it cannot stop an impact all the time past 50 mph on all configurations in all weather? The minimum range of the ACC is 1.5 seconds, which is about 160 ft at 70 mph. The stopping distance on dry pavement at that speed is can be as high as 175 ft.

Using the 2.0 or 3.0 second following distance settings, with a sport sedan, on dry pavement, with summer tires, will probably yield better results than the SUV model on all season tires with 5 people on a rainy day set to 1.5 seconds.

 

[Tam]

...just inferior to Cadillacs...

NHTSA says "AEB systems help prevent crashes or reduce their severity by applying the brakes for the driver."

So to claim AEB you don't need BOTH prevention AND reduction. You can claim AEB just by choosing either prevention OR reduction.

Tesla chooses reduction option.

GM Cadillac chooses prevention option.

I think with Tesla reduction option. the system can work in a greater range of speed between 5 mph (8 km/h) and 85 mph (140 km/h).

With prevention option, 2015 technology limitation was evidenced in low speed 12 and 25 mph crash tests and no higher speed tests.

Current TV advertisements from different cars don't show high speed AEB, they show very effective stop at very low city speed.

It is best for AEB to brake to a complete stop at any speed, but that is not what NHTSA demands, and I am not sure whether the technology can do that because it is no longer 2015 but 2017.

 

[Tam]

....Why can't it shed 25 MPH and avoid a low speed collision?...

Mathematically it should. If you drive 20 mph, you should be able to subtract 25 from that number and get -5 mph.

But the manual has 2 different statements to clarify its principle.

One with a reduction of 25 mph

The other says it's "designed to apply the brakes to reduce the severity of the impact"

When you have 2 statements: One positive and one negative, the negative will negate the positive one.

 

[Mrcook4590]

I am wondering if Tesla also doesn't say that it will prevent an accident due to the liability if it does not prevent an accident. Our AEB worked yesterday, and we were not what I considered close the the vehicle in front of us. It chimed and started braking when two cars ahead of us slammed on their brakes. We were going maybe 50 mph. No driving assists were on at the time.

 

[verygreen]

new firmare update has this:

Side Collision Warning Enhancements
We've upgraded Model S/Model X active safety capabilities by enhancing Side Collision Warning. In addition to warning you when it detects an object close to its side, Model S/Model X now steers away from the object if a collision is likely.
Note: This enhancement is available when Model S/Model X is traveling between 48 km/h and 140 km/h/30 mph and 85 mph

This is in addition to lifted speed limit on the AEB.

 

[Jeff-6293]

Why in the world would AEB not be implemented to PREVENT collisions (if physically possible)? I want my Tesla enclosed within a bubble (whose size varies depending on road type, speed, etc.) that the car will do everything possible to safeguard.

 

[Tam]

Why in the world would AEB not be implemented to PREVENT collisions (if physically possible)? I want my Tesla enclosed within a bubble (whose size varies depending on road type, speed, etc.) that the car will do everything possible to safeguard.

My guess is you can use Autopilot for that purpose.

Current TACC can brake to a complete stop to avoid a collision and if it fails, AEB is a last ditch effort to reduce the force of collision.

 

[FlatSix911]

My guess is you can use Autopilot for that purpose.

Current TACC can brake to a complete stop to avoid a collision and if it fails, AEB is a last ditch effort to reduce the force of collision.

Not everyone uses AP all the time ... AEB should be improved to cover all other scenarios

 

[McRat]

You will know if true AEB kicks on in a car by the violence of it. It's not gently progressive. It's not like ACC, and is not ACC. Your seat belt locks, the car vibrates, and the tires howl a little. Get going 25 mph and slam the brake pedal completely to the floor. If your foot doesn't vibrate, harder and faster. That's what AEB feels like. Full maximum braking effort applied.

I watched a person at a defensive driving school take 4 tries before they could actually floor the brake pedal. They had never done it before. She was about 40 years old. Only 1/2 the parents could max out the brakes the first try.

 

[Tam]

Not everyone uses AP all the time ... AEB should be improved to cover all other scenarios

Both statements are true.

I was trying to explain Tesla's rationale which might be reasonable according to their stand point but as you point out: that is not helpful as Autopilot is not used all the time.

I also think AEB will eventually be improved because sensors are not the problem anymore but writing algorithm is still a challenge.

Issue: Will Tesla change its position in any near future and to state that its AEB's goal will be to avoid a collision?

 

[rush6410]

I am not sure what system helped me avoid an accident. I was following a car in front of me at 55mph. My X suddenly slammed on the brakes. An intent later the car in front of me swerved to the right violently to avoid a car in front of it that came to a complete stop. The X applied the brakes really hard slowing me enough to be able to avoid the stopped car. Not sure if that was AEB. If it was, it clearly helped me avoid an accident. Maybe technically that is another system and feature that helped to avoid. While AEB might have been reserved as an extra precaution if the accident of unavoidable. Anyhow, it saved me from an accident.

 

[stopcrazypp]

Why in the world would AEB not be implemented to PREVENT collisions (if physically possible)? I want my Tesla enclosed within a bubble (whose size varies depending on road type, speed, etc.) that the car will do everything possible to safeguard.

False positives and liability. If a AEB system braked unnecessarily and causes the car behind to rear end your car, the automaker is liable. If the AEB system didn't brake, or didn't brake sufficiently to prevent the collision, the automaker is not liable since the feature is a last resort. Using milder braking significantly reduces the risk of rear ending in a false positive.

There's also a psychology part of it. By not saying it's capable of preventing collisions (even if in some cases it does), it avoids setting a reliance in the users in expecting it to do so. Even if Tesla does update their system to be more capable, they may keep the wording the same for this reason.

 

[Tam]

...My X suddenly slammed on the brakes...

If AEB is activated, you would see a message on your dashboard:

Most likely, it was your Autopilot that saw the car beyond the lead car in front and reacted accordingly by giving out quick rapid emergency alarm and braking:

 

[Shock-On-T]

Mathematically it should. If you drive 20 mph, you should be able to subtract 25 from that number and get -5 mph.

But the manual has 2 different statements to clarify its principle.

One with a reduction of 25 mph

The other says it's "designed to apply the brakes to reduce the severity of the impact"

When you have 2 statements: One positive and one negative, the negative will negate the positive one.

That's linear mathematics. Speed and stopping distance have a squared relationship.

NHTSA says "AEB systems help prevent crashes or reduce their severity by applying the brakes for the driver."

So to claim AEB you don't need BOTH prevention AND reduction. You can claim AEB just by choosing either prevention OR reduction.

Tesla chooses reduction option.

GM Cadillac chooses prevention option.

I think with Tesla reduction option. the system can work in a greater range of speed between 5 mph (8 km/h) and 85 mph (140 km/h).

With prevention option, 2015 technology limitation was evidenced in low speed 12 and 25 mph crash tests and no higher speed tests.

Current TV advertisements from different cars don't show high speed AEB, they show very effective stop at very low city speed.

It is best for AEB to brake to a complete stop at any speed, but that is not what NHTSA demands, and I am not sure whether the technology can do that because it is no longer 2015 but 2017.

The prevention option is superior to the reduction option, even if both fall into the same broad category set by some agency of some country.

 

[Shock-On-T]

Specifically, stopping distance = (velocity^2) / (friction * gravity).
Increasing either road friction (or gravity if you have that power) will reduce stopping distance.
Increasing velocity will increase stopping distance exponentially (and that exponent is 2).

 

[Mrcook4590]

I am not sure what system helped me avoid an accident. I was following a car in front of me at 55mph. My X suddenly slammed on the brakes. An intent later the car in front of me swerved to the right violently to avoid a car in front of it that came to a complete stop. The X applied the brakes really hard slowing me enough to be able to avoid the stopped car. Not sure if that was AEB. If it was, it clearly helped me avoid an accident. Maybe technically that is another system and feature that helped to avoid. While AEB might have been reserved as an extra precaution if the accident of unavoidable. Anyhow, it saved me from an accident.

Ours did that the other day with no driving assist on. It alarmed, flashed red on the screen, and started braking well before we actually were close to the vehicles, but same scenario: one car braked and the one behind it had to brake hard and swerve. I think because we were not close to the other vehicles, it was not a hard core, screech to a halt brake, but it was clearly using AEB.