| | sweden on March 31, 2018 | parent | context | favorite | on: An Update on Last Week’s Accident
It's widely known that RADAR systems are not able to detect stationary objects, only moving ones. Actually, they are are to detect them but just not where they come from, so a barrier in the middle of the road and a traffic sign on the side of the street, they would look like the same to the RADAR system. But to be honest, I am more worried with the markings of the road rather than the inability of the autopilot of not foreseeing the accident: https://imgur.com/a/hAeQI What's wrong with the US road administration? Why is this even look like a driving line? Where are the obvious markings? It's a very misleading road layout, I am curious the amount of accidents that happen there every year. This is how I expect this kind of thing to look like: https://i.imgur.com/dfZehmd.gif Given on how the road looks like, it makes more sense why Tesla is reinforcing the fact that the driver wasn't paying attention to the road. Edit: Since people are curious about the limitations of the RADAR, the manual of the car mentions this limitation: "Traffic-Aware Cruise Control cannot detect all objects and may not brake/decelerate for stationary vehicles, especially in situations when you are driving over 50 mph (80 km/h) and a vehicle you are following moves out of your driving path and a stationary vehicle or object is in front of you instead." You can also read here that Volvo's system faces the same problem: https://www.wired.com/story/tesla-autopilot-why-crash-radar/ |  | | bufferoverflow on March 31, 2018 | next [–]
> It's widely known that RADAR systems are not able to detect stationary objects, only moving ones. Actually, they are are to detect them but just not where they come from That doesn't make any sense. Radar systems do detect stationary objects just fine. In fact, from the point of view of the moving car, almost nothing is stationary. I wouldn't be surprised if you're correct about the markings on the road, I almost crashed into a temporary barrier driving at night, because there were two sets of lane markings - the old ones, and the ones going around the barrier. Construction workers simply didn't bother to erase the old ones. | | | | sweden on March 31, 2018 | parent | next [–]
It is mentioned in the manual of the car: "Traffic-Aware Cruise Control cannot detect all objects and may not brake/decelerate for stationary vehicles, especially in situations when you are driving over 50 mph (80 km/h) and a vehicle you are following moves out of your driving path and a stationary vehicle or object is in front of you instead." You can also read here that Volvo's system faces the same problem: https://www.wired.com/story/tesla-autopilot-why-crash-radar/ | | | | saalweachter on March 31, 2018 | root | parent | next [–]
This is not a RADAR problem, it’s a world modeling problem. So you’re sending out pulses and listening for echos, which tells you how far away something is in a particular direction. You correlate subsequent pulses to say whether the object is moving toward you or away. If you have a car 50 m ahead of you every time you ping, everything is good. Now that car suddenly swerves around a car stopped in front of it, and your ping off that object says 60 m. A crash is less likely, your model thinks! The object in front of you is rapidly speeding away! By the time it realizes it isn’t, boom, crash. | | | | adamlett on March 31, 2018 | root | parent | next [–]
That’s not how it works in my limited understanding. Radars don’t just detect the positions of object, but also their relative speed. For this, they take advantage of the Doppler effect. When a pulse gets reflected, its frequency rises if the object is moving towards the radar, and falls if it’s moving away. | | | | saalweachter on March 31, 2018 | root | parent | next [–]
You could be right, either in this case or other cases. I'm entirely inferring what autos are doing based on their failure case (not detecting stationary cars when the car in front of you swerves around them); that sounds a helluva lot like mistaking the new car for the old. Again, not saying it's a limitation of RADAR; it sounds like a deficiency in the way they're using it. | | | | hexane360 on March 31, 2018 | root | parent | prev | next [–]
Although there's an inherent trade-off between detecting position and speed. Longer pulses give more accurate frequency/speed detection, while short pulses give more accurate time/position detection. This is the same phenomenon that underlies Heisenberg uncertainty. | | | | gus_massa on March 31, 2018 | root | parent | prev | next [–]
IIRC the radar can detect the object but it has too many false positives, like a small soda can that has a lucky alienation and shape that make it appear as a big object. So the system ignores the static signals of the radar, because randomly stopping each time an small object is confused with a big object is also dangerous. And the system uses other signals to identify and avoid static objects. | | | | random4369 on March 31, 2018 | parent | prev | next [–]
> It's widely known that RADAR systems are not able to detect stationary objects What the f*ck? That's not at all how radar works. It has no such limitation. | | | | pja on March 31, 2018 | root | parent | next [–]
My understanding is that RADAR systems can detect stationary objects just fine: What's going on is that in-car radar systems can't differentiate between, say, a metal sign on a gantry or at the side of the road and a parked car on the road, because their spatial resolution is poor to non-existent. Hence in-car RADAR systems (often) ignore radar returns that are non-moving relative to the road surface. Otherwise the car would panic brake every time you went past a road sign. The effect of this is that current in car RADAR systems are great at avoiding collisions with vehicles that suddenly brake to a halt in front of you whilst at the same time will happily let you drive a full speed straight into the back of a parked car. This is why I believe current self driving vehicles (apart from Tesla) are all using LIDAR for object detection. (The above is my interpretation of my reading on the current state of the art. If anyone knows more detail, please correct me.) | | | | URSpider94 on March 31, 2018 | root | parent | next [–]
The problem for all self-driving car systems is modeling the road. Let’s say you are climbing a gentle hill, and there’s an overpass ahead. The nose of the car is aiming up, so it will see the overpass dead ahead and not moving. This looks the same to the car as driving down a flat road with a semi perpendicular to the travel lanes and dead stopped. This is true for all imaging systems - RADAR, LIDAR and camera. Same if you are about to enter a right-hand sweeper, pedestrians standing on the sidewalk in front of you would look as if they are directly in your path. Musk mentioned this in one of his blog posts. Tesla is attempting to build a database of obstacles like this and geotag them, so that the car can filter them out. | | | | fake-name on March 31, 2018 | prev | next [–]
> It's widely known that RADAR systems are not able to detect stationary objects, only moving ones. Uh, what? I think you're thinking of Doppler radar systems. You can do static scene imaging with radar, no problems (I've written the code to do it, even!). There's no way in hell a car is going to be using a Doppler radar. In all likelyhood, they're using a plain-old FMCW system, and it can absolutely detect stationary stuff. | | | | maxerickson on March 31, 2018 | parent | next [–]
| | | | sweden on March 31, 2018 | parent | prev | next [–]
Answered here: https://news.ycombinator.com/item?id=16722617 | | | | mickronome on March 31, 2018 | prev | next [–]
While I find it deplorable that several companies are essentially using people, although in this case apparently willing, participants in testing auto pilot or autonomous driving software. I also find the lack of prominent road markings, signage, or any significant shock absorbing zone simply astonishing! It makes me wonder, is that layout actually on purpose?I truly find it hard to believe that a road or traffic authority in this day and age could design that on purpose!It's quite well known that human attention is a tenous thing, and that the attention given to an object is primarily proportional to its size. But here we have a barrier end that is signed as being about as dangerous as a a bit of debris. | | | | _pmf_ on March 31, 2018 | parent | next [–]
What irks me is that they think it's OK for them to advertise it as auto-pilot, with an asterisk pointing to the fine print that says "aw shucks, not actually, haha". | | | | s17n on March 31, 2018 | root | parent | next [–]
Well all that an actual autopilot (on a plane) does is maintain your velocity and heading, so if anything the name is underselling it. | | | | ineedasername on March 31, 2018 | root | parent | next [–]
autopilots do a bit more than maintain course, they can basically execute the entire flight-plan in between takeoff & landing, which includes plenty of heading adjustments. They also increasingly do a fair bit of heavy lifting on landings as well. | | | | emn13 on March 31, 2018 | root | parent | next [–]
A plane is much easier to navigate because there aren't things like lane-dividers floating about. That's handy, but alas it does not apply to driving a car. Just because an in-air navigation aid that allows for essentially pilot-free navigation deserving of the name "autopilot" happens to be relatively trivial to build, does not mean any navigation aid of similar complexity for other modes of transport should be called autopilot simply because they're at least as complex. If you're not automatically piloting, the name autopilot is pretty disingenuous, is it not? Also, planes have a bunch of other navigation aids, including collision avoidance systems and ground-based air traffic control, and pretty obvious stuff like predictable flight paths and huge safety margins between nearby aircraft. An autopilot for an airplane works in that context. I kind of doubt it would work if there were thousands of planes nearby, many of which are on paths separated by distances the vehicles in question cover in tiny fractions of a second, and some of which follow almost invisible rather unpredictable paths (that drunk guy without lights over there...). Context matters. | | | | ineedasername on April 1, 2018 | root | parent | next [–]
I think what I'm taking issue with isn't anything about comparing them to self driving cars, it's that you characterize them as "trivial to build". They are not. They coordinate a significant number of life-critical systems, react to minute perturbations in the air stream with microsecond precision, and do so with such a high level of precision that human pilots are often forbidden from overriding them outside of specific situations. I don't know what gave you the impression that these systems were basic or trivial, but they have been at the cutting edge of systems automation for decades. | | | | emn13 on April 1, 2018 | root | parent | next [–]
Compared to a self-driving car system, they are trivial. Your assertion that "they have been at the cutting edge of systems automation for decades" kind of indicates that - this stuff is simple enough to make that it was feasible to do even that long ago. Trivial is good mind you because it actually works, and works reliably. The same is not yet clear of self-driving cars. | | | | s17n on April 1, 2018 | root | parent | prev | next [–]
Well my kap 140 sure doesn't do any of that stuff. | | | | SerLava on March 31, 2018 | root | parent | prev | next [–]
Absolutely. It's a marketing term, and they are intentionally committing murder by the act of not calling it "LaneAssist" or some other similarly boring name. | | | | cowkingdeluxe on March 31, 2018 | prev | next [–]
I think at least 50% of the blame should be placed on the maintainer of the road. The crash attenuator was 'used up' from a previous accident and might have prevented death if it was in working condition. I see this all the time where I live. Crashed attenuators or disfigured guard rails go months and months without repair. | | | | kneel on March 31, 2018 | parent | next [–]
If we are moving towards a future with self driving cars there needs standardization of road markers so that cars can recognize what's going on. This crash is looking to be the autopilots due to the strange lane markings. Have you ever driven down a road the lines grinded away and replace by new ones? Sometimes you can still see both sets, it can be pretty confusing for a human. | | | | InternetOfStuff on March 31, 2018 | root | parent | next [–]
Won't help. There will always be surprises. Debris on the road, or snow drifts, or something. Any system that works by not interpreting the world outside is bound to encounter nasty surprises. | | | | kd5bjo on March 31, 2018 | prev | next [–]
Radars do just fine detecting stationary objects, what they can't do is tell whether the stationary object is blocking the road, overhead, or to the side of a curve in the road. As most radar reports of stationary objects fall in the latter two categories, the adaptive cruise control system filters them out of consideration. | | | | cotillion on March 31, 2018 | prev | next [–]
Yeah, there is so much wrong going on with that road.The divider warning sign is also lower than a standard car. | | | | freeone3000 on March 31, 2018 | prev [–]
They're marked 'optional' on your diagram. Optional things can be excluded. | | | | jstanley on March 31, 2018 | parent [–]
"Optional" doesn't mean "exclude it if you feel like it". It means "think about it and decide whether it's worth adding". They can be excluded if doing so doesn't present a danger (e.g. it's a small road). From the one photograph we've seen of the slip road in question, I'd say the lack of chevrons poses quite a serious danger. It looks just like a normal lane. I've never noticed a slip road branch off like that in the UK, i.e. a big crash barrier up the middle but no chevrons. (I'm not saying whoever designed this section of road is guilty of some sort of crime, or is somehow responsible for the crashes, I'm just saying it should have been designed better). | | | 
