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Comment by Qworg | Hacker News Reader

I'd love to see the convincing data RE: radar - they're using the same radars as every other car that has emergency braking from the car in front of the car that's in front of you. I've not heard of many "phantom braking" sessions from these other vehicles - I may have missed something.

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Allow me to take you for a drive in my Volvo V90. I turned the auto-braking feature off entirely because it spits false positives like crazy. Parked cars, signs, birds, cars travelling through roundabouts across my nose, nothing at all - they all trigger it, and the car stomps the brakes extremely hard. The 2017 VW Golf it replaced was FAR better - maybe two false positives in 5 years. The Volvo? Daily.

Model 3 vision only does the same.

How often would you say you get false positives with your Model 3?

I have a model X raven (2019) and model 3 awd (late 2021), both have radar and hw3, and both have the update that has disabled the radar.

Pre-patch there was maybe a phantom brake (hard brake) every six months, but lots of small slowdowns where you could almost sense the car got conflicting input (once pr 100 km maybe).

The latter is gone and I have not had any phantom brakes yet, but I've had a slow down where a bus went into my lane. The cars behaviour in stop and go traffic is also much better now.

The only regression I've found is that it's a bit more confused in a local spot where the road splits in two in a turn to the right. In the past it went into the right lane without much fuzz, but now it is confused for a second or two before it decides on the right lane.

Tbh, as a daily user of these cars I think the no radar update was an improvement.

  > The only regression I've found is that it's a bit more confused in a local spot where the road splits in two in a turn to the right.

Since the issue is reproducible, you should find a bug on it. Tesla is responsive and this will help everybody.

Every single time I use autopilot. I stopped using it.

Where do you drive? I feel at least some of it depends of driving style and culture... Rental MB I had in Spain had phantom braked few times a day until I eased off. Other cars in LT and NZ - maybe once a month or less.

And by phantom braking I mean emergency braking a bit too early - i.e. I am perfectly aware I am too close to a car in front, I have foot on brakes and I see how traffic flows, yet the car brakes.

How much time would you have to brake, if the car ahead came to a sudden stop (for example, due to a crash)?

If less than one second, you are almost surely tailgating.

In Sydney, Australia. I’d say I’m quite a conservative, safe driver (I have kids). I don’t tailgate, and actually I’ve never had it false positive on a car driving in front of me. It’s typically on stationary objects, or small moving objects. Or on nothing at all shrug

> birds

Birds you're about to hit with your car? That sounds like a great feature.

But we already have a deal with the birds...

Birds flying across the nose of the car half a dozen or more metres away. Not a chance of hitting them.

Also, my experience with the Volvo one (on XC90 tho) was that it would happily plough into cars standing at a red light in front of me if I would let it.

TM3 has never had this issue for me.

Karpathy covered it during a conference keynote here: https://youtu.be/g6bOwQdCJrc?t=1368

It also is pretty common with other vehicles, they just don't get as much press as Tesla:

https://www.rivianownersforum.com/threads/phantom-braking-an...

https://www.fox43.com/article/news/feds-try-to-determine-why...

However phantom breaking still happens regularly (and perhaps more often) with their vision system. Shadows really mess with it.

So I’m not sure that’s very compelling that radar is somehow making things worse for them.

I get phantom forward collision warnings on my car quite often, a 2015 VW Jetta TDI SEL. There are a few places where it triggers ~1/3 of the time while driving on a clean road with no other cars around in either direction.

The system doesn't trigger breaking just a warning alarm beep and dash screen warning message, but all these systems are unreliable at this point, even the newer ones have these same false positives and false negatives.

It does make sense to err a bit on the side of caution for warnings. With warnings, a false positive is better than a false negative. It’s better to occasionally annoy the driver (within reason) than fail to warn for an accident.

This isn’t the case with braking. You want to have a high degree of confidence in that scenario because you don’t want to cause an accident. It’s better to react later to an impending collision than it is to cause an accident that would have never happened.

Hypothetically, Tesla would spin this story differently in no time if they are making great strides in a cheap solid-state radar.

For now, though, it looks like Tesla is building a case after they decided to do away with radar. I recall EM saying that it looks ugly and expensive too. I really got confused when Telsa came up with this patent though https://twitter.com/iamkellex/status/1534240730633236480?s=2...

No one sensor will work for all use cases; each has pros and cons. Radar really shines with depth sensing; it can cut through rain, fog, and snow like a hot knife through butter, much better than pure vision-based systems. At the same time, it seems to fail during harsh breaking and maybe a few other scenarios.

The ability to cut through rain, fog, and snow is precisely why so many companies use radar based systems - that's arguably when they are the most important and useful.

Leaning further into their vision systems when their vision systems cause their cars to slam into emergency vehicles that aren't even in travel lanes, and to rear-end tractor trailers, isn't encouraging. Musk is placing the rest of us at risk and I'm sick of it.

Have you seen a recent video of their most recent vision stack in use by a customer?

Nope! Why do you ask?

I got a ton of phantom braking just two weeks ago when I rented a 2020 Toyota Corolla with this feature. I've also gotten it in a 2019 Tesla Model 3, of course.

Anecdotally I've been driving a 2020 Toyota Corolla Hybrid for around 2 years now and haven't ever experienced phantom braking. I have driven it all around Australia (Melbourne, Sydney, Coffs, Brisbane) and the driver assist features have been nothing except rock solid reliable.

I have noticed though that it is very timid when people are leaving their lane, and it takes a few seconds to decide that a car has fully left its lane. It will brake as though the car is still in your lane well after it is gone. I'm not sure I'm going to hold it against Toyota, because I'd prefer it to be timid in case the other driver does something unpredictable like change their mind. If you press the accelerator pedal lightly when you notice someone leaving the road, the software will cancel out the braking.

I've only had phantom breaking with my 2019 Camry once or twice.

I drive a 2018 Hyundai IONIQ EV. The forward radar is hit-and-miss in heavy rain: the car will often barrel quite happily into stopped traffic when it’s raining hard, requiring a stomp on the brake pedal.

Just a couple weeks ago I was driving on the motorway around 4am, no other traffic for miles, and the forward collision alert sounded and the car slammed on the brakes for ~quarter of a second and then released as if nothing had happened and we merrily resumed our journey. Having the brakes slam on at a smidge over 100 km/h gave me a sore shoulder and quite the rush of adrenaline, quite the rush at 4am!

So yes. The radar does have a mind of its own.

Now imagine that in the snow, when going around a corner on a cliff.

Welcome to Canada 11 months of the year, with wolves waiting at the bottom of the ravine, as you crawl, injured, out of your car.

And no, wolves will not be appeased with either maple syrup or poutine, trust me I know, I've tried.

Not braking per se, but on all cars I've driven recently (ie some Seat Alteca, our BMW F10 5-series and maybe 2 more a bit longer ago) there is sometimes collision warning in situation where no collision is about to happen.

Seat was pretty bad in this, had it rented for 2 weeks in Sicily few weeks ago and first few times all screens start flashing like crazy in normal situations is very distracting (since I wasn't sure what the heck is happening, but it looked sinister). BMW is pretty subtle with this, and only happened few times in past year.

I imagine if this warning system would be also connected to breaks, bad things would be happening.

They were using the radar for lane guidance. That's why they had to have a whitelist of locations where the radar was false triggered by the roadside environment. It never actually worked properly and they just papered it over with a hack to temporarily blind their input.

Radar for lane guidance? Uh, are you sure?

How does radar for lane guidance work exactly?

I'm pretty sure all of the phantom braking events due to underpasses were vision related, given that radar is essentially blind to the road.

None of what you have said is true.

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