Submitted by twelveparsnips t3_1165hgv in news
razorirr t1_j96oqwi wrote
Reply to comment by bobjoylove in 1 person dies when Tesla hits fire truck on I-680, 4 firefighters injured by twelveparsnips
Your statement shows you dont know how car radar works.
Cars are using the radar to measure doppler shift. This is how they tell if the car in front of you is moving faster, or slower than you. Because the speed of the signal is a known constant, it can also give you distance.
In the conditions you have driving, you have to throw out any measurement of something not moving, such as that parked firetruck and mark it as invalid. This sounds ridiculous but its for a simple reason
Pretend you are in a car with radar and you are driving down into a valley. The car will see the bottom of the valley where you would start driving up the other hill as a static object, and the car would stop. With radar, you cant tell this valley from a police car.
bobjoylove t1_j96wdpy wrote
Your statement shows how you don’t know how software works.
You augment the camera with the RADAR. When the two diverge significantly the system will error and hand back control to the driver.
razorirr t1_j96yztn wrote
That wouldn't do anything
Like I explained, the radar in this case would give "All clear"
The camera in this case should have gave "firetruck" but gave "all clear"
Erroneous camera All Clear + radar design all clear = all clear = crash.
Camera Firetruck + all clear = stop
The radar all clear in this case is unneeded, as it will never be not all clear, and the diverging car stop is not needed because the firetruck car stop would apply.
From a QA guy telling the probably Developer guy your logic is bad, you could program the radar to always return blocked if it sees any static object. but then that causes a problem.
- If the radar says blocked, and the camera sees something, That is a stop due to agreeing.
- If the radar says blocked but the camera does not see anything, that is a stop due to divergence.
Your car would never be able to go anywhere in the system you proposed other than on an unblocked flat surface.
Love all the instant downvotes all my posts are getting. Seems a lot of people don't know what they are talking about but think they do.
bobjoylove t1_j971ijk wrote
The Radar is used for ranging. It provides a distance and a rate of change over a reasonably narrow aperture. The bottom of the valley does not get close enough to warrant emergency intervention from the braking system.
The fact that the majority of cars with dynamic cruise and automated pedestrian braking systems all using 60GHz as the detection method should tell you it is possible and it is shipping already.
razorirr t1_j9731y8 wrote
>The Radar is used for ranging
Correct
>The bottom of the valley does not get close enough to warrant emergency intervention from the braking system.
Incorrect
You are driving down the hill, its a 1 mile slope from top to bottom, then it curves and goes up the next hill.
You are right that while its far away, you can ignore the read because the range is saying "yeah i see something, but its 3000 feet off, who cares" or it just sees nothing as its not looking that far out.
But since its not moving and you are, eventually you will be 200 feet from the bottom. Radar sees this as an object blocking your path, and its now close enough the car goes "Yeah I see something, its 200 feet away, lets stop."
Since the ground is never going to move, radar will always say stop. A camera with sufficient data labeling ability can overcome this as it can tell context, radar never can as it is a binary "block / clear"
Also, https://www.chevrolet.com/support/vehicle/driving-safety/brakes/front-pedestrian-braking heres Chevy explaining how they do their pedestrian braking. Its using cameras, not the radar.
bobjoylove t1_j977j8u wrote
Ok let’s agree to disagree on the technical aspects of a know working collision avoidance system they is shipping on millions of cars including my own.
It’s good to have a secondary system to cross-check the cameras. I have noted that many (not this one) cases of the Tesla systems failing have been at night. Adding RADAR or LIDAR augments the cameras. BTW the answer in the back of the book is Tesla have realised that they actually do need RADAR and have begun adding it. https://electrek.co/2022/12/06/tesla-radar-car-next-month-self-driving-suite-concerns/
razorirr t1_j978ckm wrote
No. This is a technical conversation about how a technical system works. You cant agree to disagree on those aspects else its impossible to come to an agreement at all. The only way to prove this would be for you to prove the car would not stop forever on the hill once the radar and the camera diverged if divergence = stop or in the case of pure radar = sees blockage = stop.
I agree augmenting is good. Like the radar can see the range of an object better than camera vision can guesstimate it. But what i was talking about is a known limitation to radar. You can not "Augment" around that, you have to throw the data out, and if you are throwing it out 100% of the time, you don't need it.
bobjoylove t1_j97ch2n wrote
Do you ever think that, even when provided with a link proving me right - specifically Tesla adding RADAR to fix their issue - and you still argue that isn’t the resolution; that you might just be stubbornly wrong?
razorirr t1_j97dmf4 wrote
Did you ever think that they could be putting the radar in to augment all the other situations where radar is helpful, but due to the limitations of radar, this is not one of those situations?
Actually read and comprehend that article. The OG radar my car has was insufficient compared to just cameras. The one they are putting in has much better distance that it can see, but it still will have the issues I've explained above as that is a fundamental issue with radar.
So now instead of seeing the bottom of the valley at 200 feet, it sees it at 400 feet. All of the same problems occur and the car still can not proceed to the bottom of the hill if programmed to always stop based off a radar blockage or a radar vs camera divergence. Radar always will be not helpful for static objects in path, but it will be really helpful for letting the car know something is in motion 400 feet away.
bobjoylove t1_j97ekv4 wrote
It’s clear they have reviewed the data and made a decision. If that’s not enough to convince you, then I’m not sure what more you might need.
Have a good day.
razorirr t1_j97g29v wrote
I will freely admit radar can help in situations. This situation is not one of them because of how radar works. You have convinced yourself otherwise and now refuse to correct your incorrect opinion.
Have a good one.
TenderfootGungi t1_j97ac0b wrote
>In the conditions you have driving, you have to throw out any measurement of something not moving, such as that parked firetruck and mark it as invalid.
That should depend on where it is. Is it on the side of the road? Not an issue. In my lane? Real issue.
It is telling that no other self driving tech is having trouble with this. Everyone else has this figured out.
razorirr t1_j9an80n wrote
You would think that but no. If you consider anything in front of you not moving as reason to stop, if i put you on a hill, your radar is now pointing down the slope, so as you approach the bottom your vision will tell you "im ok to proceed, its just the hill slope leveling off." Radar will tell you "oh shit theres a stationary object, brake now". Stationary objects in path is a limitation of using radar, which cant tell what the object is.
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