6 ms·

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

by sweden 9y ago

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 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 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/ https://www.wired.com/story/tesla-autopilot-why-crash-radar/

bufferoverflow 9y ago
> 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 9y ago
  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/ https://www.wired.com/story/tesla-autopilot-why-crash-radar/
  - gus_massa 9y ago
    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.
  - saalweachter 9y ago
    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 9y ago
      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.
fake-name 9y ago
> 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.
- sweden 9y ago
  Answered here: https://news.ycombinator.com/item?id=16722617 https://news.ycombinator.com/item?id=16722617
- maxerickson 9y ago
  Model S likely uses https://www.bosch-mobility-solutions.com/en/products-and-services/passenger-cars-and-light-commercial-vehicles/driver-assistance-systems/predictive-emergency-braking-system/mid-range-radar-sensor-(mrr)/ https://www.bosch-mobility-solutions.com/en/products-and-ser... (It's for sure a Bosch radar, but maybe a different one)
cotillion 9y ago
Yeah, there is so much wrong going on with that road. The divider warning sign is also lower than a standard car.
mickronome 9y ago
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_ 9y ago
  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 9y ago
    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 9y ago
      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 9y ago
        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.
kd5bjo 9y ago
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.
freeone3000 9y ago
They're marked 'optional' on your diagram. Optional things can be excluded.
- jstanley 9y ago
  "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).
cowkingdeluxe 9y ago
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 9y ago
  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 9y ago
    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.

by sweden 9y ago

bufferoverflow 9y ago

> 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 9y ago
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/ https://www.wired.com/story/tesla-autopilot-why-crash-radar/
- gus_massa 9y ago
  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.
- saalweachter 9y ago
  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 9y ago
    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.

fake-name 9y ago

> 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.

sweden 9y ago
Answered here: https://news.ycombinator.com/item?id=16722617 https://news.ycombinator.com/item?id=16722617
maxerickson 9y ago
Model S likely uses https://www.bosch-mobility-solutions.com/en/products-and-services/passenger-cars-and-light-commercial-vehicles/driver-assistance-systems/predictive-emergency-braking-system/mid-range-radar-sensor-(mrr)/ https://www.bosch-mobility-solutions.com/en/products-and-ser... (It's for sure a Bosch radar, but maybe a different one)

cotillion 9y ago

Yeah, there is so much wrong going on with that road. The divider warning sign is also lower than a standard car.

mickronome 9y ago

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_ 9y ago
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 9y ago
  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 9y ago
    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 9y ago
      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.

kd5bjo 9y ago

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.

freeone3000 9y ago

They're marked 'optional' on your diagram. Optional things can be excluded.

jstanley 9y ago
"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).

cowkingdeluxe 9y ago

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 9y ago
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 9y ago
  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.