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Tesla footage of braking before crash ahead [video]

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Re: Tesla footage of braking before crash ahead [video]

#151
post #73

Earlier quoted context omitted.

SUVs are not as stable as cars with a lower height. Think about the typical race car which is designed for turning fast, something that requires stability: light, low and wide. SUVs? Heavy, high and narrow relative to their height. Electronics can do marvels, but with the same electronics physics wins. I remember I could easily outperform a couple of BMW SUVs on a highway in a descent from a mountain pass. They had p…

I came down I-70 into Denver one time in a rented Ford Expedition. Wasn't going that fast, but when I hit the first curve, the body and frame started to really lean onto the outside suspension. I was scared to hit the brakes and cause it to pitch more, so I just barely touched them and had to let it drift into the next lane a bit. The turn went on forever!! Did I mention I was surrounded by motorcycles?

A more extreme, but related condition is a "moose test":

The dangerous Toyota Hilux:

https://www.youtube.com/watch?v=xoHbn8-ROiQ

The Jeep Grand Cherokee acting similarly dangerously:

https://www.youtube.com/watch?v=zaYFLb8WMGM

Re: Tesla footage of braking before crash ahead [video]

#152
post #67

This is great video to study on many levels beyond self-driving car. Some observations: * The car behind didn't show turn signal so probably driver wasn't paying attention. * A small car escaping with not too much damage while SUV rolls over many times * From physics point of view, the car behind produced almost perfect torque that started horizontal spin on SUV * Collisions with barrier at high speed can produce lot…

> The car behind didn't show turn signal Watch the video again; the little red car turns on their blinker and does a very slow shift to the right before clipping that stopped SUV. You're right that he wasn't paying attention, but his reaction time is incredibly slow - it looks like that car had just enough time to slam on their brakes or swerve to the right, yet they did neither.

It's odd that the turn signal is only located at the top of the car. I guess the mid height one was broken ?

I think the situation is not entirely unclear, it seemed that there was a problem ahead of the SUV, that made a bunch of cars slow down altogether. I still don't understand the smaller red car driver decisions.. maybe he didn't know what to do and hesitated and tried to swerve as a last resort. Or maybe he was just not watching. The SUV break lights were on quite a long time..

Re: Tesla footage of braking before crash ahead [video]

#153

Earlier quoted context omitted.

Quite often they're a fashion statement more than anything else.

Transporting a family takes room. Rear facing car seats don't necessarily fit into smaller cars.

Large sedans and station wagons are valid alternatives; SUVs are similarly or higher-priced.

Re: Tesla footage of braking before crash ahead [video]

#154

Earlier quoted context omitted.

Quite often they're a fashion statement more than anything else.

Transporting a family takes room. Rear facing car seats don't necessarily fit into smaller cars.

Large sedans and station wagons are valid alternatives; SUVs are similarly or higher-priced than safer options.

Re: Tesla footage of braking before crash ahead [video]

#155
post #67

This is great video to study on many levels beyond self-driving car. Some observations: * The car behind didn't show turn signal so probably driver wasn't paying attention. * A small car escaping with not too much damage while SUV rolls over many times * From physics point of view, the car behind produced almost perfect torque that started horizontal spin on SUV * Collisions with barrier at high speed can produce lot…

I'm feeling rather dumb, but can't really intuitively understand the physics here. I see a small car hitting a pretty huge one and yet spins the huge one several times. I always thought those bigger cars are safer / stronger / more resistant to hits? Is it purely because it hit it at the corner, so all the force went into the "spinning axis"? (did I say I feel dumb?)

SUV center of mass is probably higher and easier to tilt.

Both cars braking, center of mass shifting toward their front and lowering. Meaning the small car momentum was peak at the collision point, while the SUV rear end was already lifted thus lighter.

Direction of the collision helped transfer the energy into torque. The barrier provided the final help to start the car tumbles.

Re: Tesla footage of braking before crash ahead [video]

#156
post #2

I thought this an interesting video when Elon retweeted it. Basically the car is responding faster than the people do and keeping things from escalating. That said, having been on 101 when the cars in front start dancing like that I have to say my biggest worry isn't stopping in time its having someone behind me not stop.

Now if all cars had similar detection systems it would probably avoid a massive amount of escalations.

Re: Tesla footage of braking before crash ahead [video]

#157

Earlier quoted context omitted.

I wish more people followed at a safe distance.

I've actually found a really good solution to tailgaters: put very slight pressure on your brake pedal, enough to get the brake lights on, but not enough to actually cause any substantial deceleration. This will cause the tailgater to also slow down, but more than you because they have no way of telling how hard you are braking. The result is increased distance between you and them. Do that a few times and even the m…

That could just set someone off and make things more dangerous. If that's happening in the passing lane, get over and let them pass.

Re: Tesla footage of braking before crash ahead [video]

#159
post #92
post #3

Earlier quoted context omitted.

I expect an autopilot could deal with that situation much better than a human as well. It should be able to predict if the car behind won't stop. Certainly better than a human driver could (if the human would even notice the car coming from behind with that happening in front). Then, assuming there is some space open in front, as there was in this case, it could accelerate to avoid the collision from behind. Now I'm…

They are already programmed to avoid being smashed from behind. Watch these two cases [0:47, 1:54] https://youtu.be/JwknRVjUBCg?t=47 https://youtu.be/JwknRVjUBCg?t=114

Wow, that makes me want a Tesla for real :)

Re: Tesla footage of braking before crash ahead [video]

#160
post #128

Earlier quoted context omitted.

I believe it's onboard, they have an onboard GPU - cloud-assisted would have latency problems and would also have problems in tunnels and areas with bad reception.

Why do you say GPU? I'm vaguely aware that GPU is far superior at multitasking unlike a CPU.

To be pedantic, GPUs are no better than CPUs at multitasking. GPUs are best at performing one task on a moderately large set of floating-point data (SIMD).

The Tesla vehicles use cameras, ultrasonics and radar. So they are processing graphical data (a video stream) and signal data. That's exactly the kind of task that GPUs are good at.

However, this only gets you as far as perceiving the world. The vehicles also have to decide which action to take -- following the traffic laws of the jurisdiction they are in -- which is exactly the kind of branchy imperative task that CPUs are good at and GPUs are terrible at.

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