> ”The first famous autopilot crash was because a white semi-truck was washed out by the sun and confused for an overhead sign.
That's literally trivial for a car with radar to detect.”
That crash occurred on a car which was using radar. Automotive radar generally doesn’t help to detect stationary objects.
Further, that crash occurred on a vehicle with the original autopilot version (AP1), which was based on Mobileye technology with Tesla’s autopilot software layered on top. Detection capabilities would have been similar to any vehicle using Mobileye for AEB at the time.
I find very strange the claim that a moving doppler (pulsed doppler?) radar 'generally doesn't help to detect stationary objects'. I mean if the car is moving, it generates a doppler shift on all objects moving at a different speed, right?
Maybe it's difficult for reasons of false alarm detection (too many stationary objects that are not of interest) but you can get very good results with tracking (curious about these radars' refresh rate), STAP, and classification/identification algorithms, especially if you have a somewhat modern beamformed signal (so, some kind instant spatial information). Active-tracking can also be of help here if you can beamsteer (put more energy, more waveform diversity on the target, increase the refresh rate). Can't these radars do any of those 'state of the art 20 years ago' stuff?
There's something I don't get here and I feel I need some education...
Source: have worked with some of the (admittedly last-gen) automotive RADAR chips, NXP in particular.
The issue is the number of false positives, stationary objects need to be filtered out. Something like a drainage grill on the street generates extremely strong returns. RADAR isn't high enough resolution to differentiate the size of something, you only have ~10 degree resolution, and after that you need to go by strength of the returned signal. So there's no way to differentiate a bridge girder or a railing or a handful of loose change on the road from a stationary vehicle. On the other hand, if you have a moving object, RADAR is really good at identifying it and doing adaptive cruise control etc.
RADAR can have high(er) angular resolution with (e.g.) phased arrays (linear or not) and digital beamforming. I guess it's the way the industry works and it wants small cheap composable parts, but using the full width of the car for a sensor array you could get amazing angular accuracy, even with cheap simple antennas. MIMO is also supposed to give somewhat better angular accuracy, since you can perform actual monopulse angular measurement (as if you had several independent antennas). There's even recent work on instant angular speed measurement through interferometry if you have the original signals from your array.
And with the wavelengths used in car RADARs you could get far down on range resolution, especially with the recent progress on ADCs and antenna tech.
I'm not saying you're wrong, you're describing what's available today (thanks for that).
Wondering when all this (not so new) tech might trickle down to the automotive industry... And whether there's interest (looking at big fancy manufacturers forgoing radar isn't encouraging there).
In theory a big phased array of cheap antennas is cheap, in practise not because you need to have equal impedance routing to all of the antennas, which means you need them all to be roughly equidistant to the amplifier. You could probably get away with blowing it up to the size of a large dinner plate, but then you also need a super stiff substrate to avoid flexing, and you need to convince manufacturers that they should make space for this in their design language without any metallic paint or chromed elements in front.
Which car brand do you think would take up these restrictions, and which customer is then going to buy the car with the big ugly patch on the front?
Modern phased arrays can have independent transmitters (synchronized digitally or with digital signal distribution) or you can have one 'cheap and stupid' transmitter and many receivers, doing rx beamforming, and as for complexity you mostly 'just' need to synchronize them (precisely). The receivers can then be made on the very cheap and you need some signal distribution for a central signal processor.
Non-linear or sparse arrays are also now doable (if a bit tricky to calibrate) and remove the need for complete array or rigid substrate or structure.
If you imagine the car as a multistatic many-small-antennas system there's lots that could be done. Exploding the RADAR 'box' into its parts might make it all far more interesting.
I'll admit I'm way over my head on the industrial aspects, so thanks for the reality check. Just enthusiastic, the underlying radar tech has really matured but it's not easy to use if you still think of the radar as one box.
I know even for the small patch antennas we were looking at, the design of the waveguides was insanely complicated. I can't imagine blowing it up to something larger with many more elements.
If you wanted separated components to group together many antennas I suspect the difficulty would be accurate clock synchronization what with automotive standards for wiring. I'm still not sure I understand how they can get away without having rigid structures for the antennas, but this would be a critical requirement because automotive frames flex during normal operation.
Cars are also quite noisy RF environments due to spark plugs.
I guess what you're speaking of will be the next 10-20 years of progress for RADAR systems as the engineering problems get chipped away at one at a time.
There's also a legitimate harm to consumers with such a large radar array in the front bumper. Because even a minor fender bender could total a $50k car.
So the car would be very difficult to sell since few people are willing to pay much higher insurance premiums just for that.
I've heard people on the internet claim that, in automotive radar the first thing they do when processing the signal is discard any stationary objects. Apparently this is because the vast majority of the time it's a sign or overhead gantry or guard rail - any of which could plausibly be very close to the lane of travel thousands of times per journey - and radar doesn't provide enough angular resolution to tell the difference.
Personally I've never seen these claims come from the mouth of an automotive radar expert, and many cars do use radar in their adaptive cruise control, so I present it as a rumour, not a fact :)
Indeed, my VW which uses a forward looking radar has signaled several times for stationary objects. In fact, the one time it literally stopped an accident was for a highway that suddenly turned into a parking lot. People keep repeating BS said by tesla and tesla apologists for why their cars run into stopped things and others seem to have less of a problem with it.
> I find very strange the claim that a moving doppler (pulsed doppler?) radar 'generally doesn't help to detect stationary objects'. I mean if the car is moving, it generates a doppler shift on all objects moving at a different speed, right?
I’m in the same boat as to not understanding why, but from what I have read the problem indeed isn’t that it doesn’t detect them, it’s that there are too many of them, and nobody has figured out how to filter out the 99+% of signals you have to ignore from the ones that may pose a risk, if it’s doable at all.
I think that at last part of the reason is that spatial resolution of radar isn’t great, making it hard to discriminate between stationary objects in your path and those close to it (parked cars, traffic signs, etc). Also, some small objects in your path that should be ignored such as soda cans with just the ‘right’ orientation can have large radar reflections.
Especially when most car radars are FMCW radars. They not only do know the speed, they also know the distance.
Some of the newest car radars can do some beam formimg, but not all.
Most models have multiple radars pointing in multiple directions as that's cheaper than AESA.
Only just recently have "affordable" beamformer's come to the market. And those target 5G basestations.
So the spec in most K/Ka-band models starts at 24.250GHz, where the 5G band starts.
While the licence free 24GHz band that the radars use is 24.000-24.250GHz.
If this was not bad enough there has been consistent push from regulators to get the car radars on the less congested 77GHz band.
And there's even less afforable beamformers for that band.
Might be time for some state sponsorship to have the beamforming asics, fpga designs for these bands. Although I might be missing something: once you're back down in your demodulated sampling frequency, your old beamformer should suffice? Or are we talking 'adc+demodulator+filter+beamforming' asic?
Not a fan of Tesla removing the sensors but a vehicle on a highway that isn’t moving the same direction as the car is not “trivial” with radar. No AEBs that use radar look for completely stopped objects after a certain speed because the number of false positives is so high.
So, yes, cars that are programmed to have AEB: perform well at AEB and not other tasks. We are in agreement here. (I even agree with you that those cars use Radar for AEB).
Now, where we disagree is you implying that cars with AEB-level radar (literally $10 off-the-shelf parts with whatever sensor fusion some MobilEye intern dreams ups) are somehow the same as self-driving cars (the goal of Tesla Autopilot).
Every serious self-driving car/tractor-trailer out there uses radar as a component of its sensor stack because Lidar and simple imaging is not sufficient.
And that's the point I was trying to make - we agree it's trivial for radar to find things they just need sensor fusion to confirm the finding and begin motion planning. This is why a real driverless car is hard despite what Elon would like you to believe. There is no one sensor that will do it. Full stop.
And this cuts to the core of why Tesla is so dangerous. They are making a car with AEB and lane-keeping and moving the goal posts to make people (you included) think that's somehow a sane approach to driverless cars.
> Yet somehow, humans can drive cars with just a pair of optical sensors
A pair of optical sensors and a compute engine vastly superior to anything that we will have in the near future for self-driving cars.
Humans can do fine with driving on just a couple of cameras because we have an excellent mental model (at least when not distracted, tired, drunk, etc.). Cars won't have that solid of a mental model for a long, long time, so sensor superiority is a way to compensate for that.
The optical sensors are just a small part of the human (and animal in general) vision system. A much bigger component is our innate (evolutionarily acquired) understanding of basic mechanics, simple agent theory, and object recognition.
When we look at the road, we recognize stuff in the images we get as objects, and then most of the work is done by us applying basic logic in terms of those objects - that car is off the side of the road so it's stationary; that color change is due to a police light, not a change in the composition of objects; that small blob is a normal-size far-away car, not a small and near car; that thing on the road is a shadow, not a car, since I can tell that the overpass is casting it and it aligns with other shadows.
All of these things are not relying on optics for interpreting the received image (though effects such as parallax do play a role as well, it is actually quite minimal), they are interpreting the image at a slightly higher level of abstraction by applying some assumptions and heuristics that evolution has "found".
Without these assumptions, there simply isn't enough information in an image, even with the best possible camera, to interpret the needed details.
> "A much bigger component is our innate (evolutionarily acquired) understanding of basic mechanics, simple agent theory, and object recognition. ... they are interpreting the image at a slightly higher level of abstraction by applying some assumptions and heuristics that evolution has "found"."
Of course, and all this is exactly what self-driving AIs are attempting to implement. Things like object recognition and understanding basic physics are already well-solved problems. Higher-level problem-solving and reasoning about / predicting behaviour of the objects you can see is harder, but (presumably) AI will get there some day.
Putting all of these together amounts to building AGI. While I do believe that we will have that one day, I have a very hard time imagining as the quickest path to self-driving.
Basically my contention is that vision-only is being touted as the more focused path to self-driving, when in fact vision-only clearly requires a big portion at least of an AGI. I think it's pretty clear this currently means this is not a realistic path to self-driving, while other paths to self-driving using more specialized sensors seem more likely to bear fruit in the near term.
And Tesla lacks that, so therefore they ought not simply rely on cameras and ought use extra auxiliary systems to avoid danger to their consumers, they are not doing this because it reduces their profit margins, alas, this hn thread
> Yet somehow, humans can drive cars with just a pair of optical sensors (mounted on a swivelling gimbal, of sorts).
In fairness, humans have a lot more than just optical sensors at their disposal, and are pretty terrible drivers. We've added all kinds of safety features to cars and roads to try to compensate for their weaknesses, and it certainly helps, but they still make mistakes with alarming regularity, and they crash all the time.
When you have a human driver, conversations about safety and sensor information seem so straightforward. The idea of a car maker saving a buck by foregoing some tool or technology at the expense of safety is largely a non-starter.
What's weird is, with a computer driver, (which has unique advantages and disadvantages as compared to a human driver) the conversation is somehow entirely different.
> We've added all kinds of safety features to cars and roads to try to compensate for their weaknesses
This is a super important point. Whenever self-driving cars comes up in conversation it's like, "we're spending billions of dollars on self-driving cars tech, but what if we just, idk, had rails instead of roads". We're putting all the complexity on the self-driving tech, but it seems pretty clear that if we helped a little on the other end (made driving easier for computers), everything would get better a lot faster.
> In theory, a sufficiently capable AI should be able to drive a car at least as well as a human can using the same input: vision.
In theory, cars should be use mechanical legs instead of wheels for transportation, that's how animals do it. In theory, plane wings should flap around, that's the way birds do it. My point being: the way biology solved something may not always be the best way to do it with technology.
> ”In theory, cars should be use mechanical legs instead of wheels for transportation, that's how animals do it.”
Wheels and legs solve different problems. Wheels aren’t very useful without perfectly smooth surfaces to run them on. If roads were a natural phenomenon that had existed millions of years ago, then isn’t it plausible that some animals might have evolved wheels to move around faster and more efficiently?
GP was stating that "two cameras mounted 15cm apart on a swivel slightly left of the vehicle center of geometry" has proven to be a _sufficient_ solution, not necessarily the best solution.
>Yet somehow, humans can drive cars with just a pair of optical sensors (mounted on a swivelling gimbal, of sorts).
This is wrong and I was surprised to hear them say it was enough in the video.
We don't have car horns and sirens for your eyes. You will often hear something long before you see it. This is important for emergency vehicles. Once you hear it, a good driver will immediately slow down and pull to the side, or delay movement to give space for the vehicle.
Does this mean self driving vehicles can't detect emergency vehicles until they appear on camera? That's not encouraging.
>Once you hear it, a good driver will immediately slow down and pull to the side, or delay movement to give space for the vehicle.
Robotically performing an action in response to single/few stimuli with little consideration for the rest of the setting and whether other responses could yield more optimal results precludes one from ever being a "good" driver IMO.
"See lights, pull over" is not going to cut it. See any low effort "idiot drivers and emergency vehicles" type youtube compilation for examples of why these sorts of approaches fall short.
That might have something to do with the general intelligence prediction supercomputer sitting between the ears. If Tesla is saying they won't have real (not just an 80 percent solution that they then lie and say is complete) self driving until they develop an AGI, I agree
Optical sensors, an innate understanding of they works around them that they are previewing.
And most importantly, a social understanding of what other humans around them are likely to do.
Our two eyeballs plus brain is SO MUCH MORE than just two mediocre CCDs.
Our eyes provide distance sensing through focusing, the difference in angle of your two eyes looking at a distant object, and other inputs, as well as having incredible range of sensitivity, including a special high contrast mode just for night driving. This incredibly, literally unmatched camera subsystem is then fed into the single best future prediction machine that has ever existed. This machine has a powerful understanding of what things are (classification) and how the world works (simulation) and even physics. This system works to predict and respond to future, currently unseen dangers, and also pick out fast moving objects.
Two off the shelf digital image sensors WILL NEVER REPLACE ALL OF THAT. There's literally not enough input. Binocular "vision" with shitty digital image sensors is not enough.
Humans are stupidly good at driving. Pretty much the only serious accidents nowadays are ones where people turn off some of their sensors (look away from the road at something else, or drugs and alcohol) or turn off their brain (distractions, drugs and alcohol, and sleeping at the wheel).
Yes, a "pair" of optical sensors. Tesla is at a disadvantage compared to humans -- they do not do stereoscopic imaging, which makes distance of objects less reliable -- they try to infer distance from a single flat image. Humans having two sensors pointed in the same direction gives us a very reliable way of determining distance (up to a relevant distance for driving at least).
Interestingly, even people with missing stereoscopic vision are allowed to drive. We don't require depth perception to drive. The assumption is that they can compensate.
Binocular vision isn't even the only source of depth information available to humans. That's why someone missing an eye can still make reasonable depth estimations.
Isn't this a bit like saying we can do better than fixed-wing aircraft, because birds can flap their wings? With sufficiently advanced material science, flapping-wing human flight too, is possible. But that doesn't mean Boeing and Cessna are misguided.
But that's not how people drive. They use their ears, they move their head around to generate parallax, they read the body-language of other drivers, they make eye-contact at intersections, they shift position to look around pillars, or stoop to see an inconveniently placed stop light. Fixed forward cameras do none of that.
But if the radar just sees a static object and can't tell if it's an overhead sign or a car, and the camera vision is too washed out, how would sensor fusion help in your example?
Perhaps stop cheaping out on the cameras and procure those with high dynamic range. Then again those may be "expensive and complicate the supply chain with for a small delta"
A human driver slows down and moved their head around to get a better view when the glare from the sun is too strong to see well. I’d expect a self driving car to similarly compromise on speed for the sake of safety, when presented with uncertainty.
Lidar would make it pretty obvious whether it's a sign or a car, even if the camera didn't tell you. The part where the lidar doesn't bounce back at vehicle level would be a dead give away.
That's literally trivial for a car with radar to detect.
In principle that is correct… but radars in automotive application are unable (or rather not used) to detect non-moving targets ?
Asking this because I know first hand that the adaptive cruise function in my car must have a moving vehicle in front of it for the adaptive aspect to work. It will not detect a vehicle that is already stopped.
The resolution of the radar is pretty good though, even if the vehicle in the front is just merely creeping off breaks… it does get detected if it is at or more than the “cruising distance” set up initially.
My understanding is that your typical automotive radar will have insufficient angular resolution to reliably distinguish, say, an overpass from a semi blocking the road, or a pedestrian standing in the middle of the road from one on the footpath.
Radar does however have the advantage of measuring object speed directly via the doppler effect, so you can filter out all stationary objects reliably, then assume that all moving objects are on the road in front of you and need to be reacted/responded to.
So I think it's the case that radar can detect stationary objects easily, but cannot determine their position enough to be useful, hence in practice stationary objects are ignored.
Adaptive cruise control is solving a totally different problem. It is specifically looking for moving objects to match pace with. That's very different from autonomous driving systems.
Radar is quite good at finding stationary metal objects, particularly. Putting it in a car, if anything, helps, because the station objects are more likely to be moving relative to the car...
That's literally trivial for a car with radar to detect.
Amazing how people talk about stuff they have no idea about when it comes to Tesla.