Comment by joshdickson | Hacker News Reader

Comment by joshdickson | Hacker News Reader

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> The other big Tesla problem is a pure technical design error - the bumper-mounted radar is blind at windshield height. This is the immediate cause of the fatal accident involving under-running the semitrailer. It's also the cause of the parking accident with the truck with overhanging load sticking out the back.[2] Tesla's implementation has deadly blind spots. They need a radar at windshield-top height. It's quite likely, now that the NHTSA is looking into this crash, that Tesla will have to do a recall and retrofit one. (Along with hands-on-wheel sensors.)

This is just completely false. We've been putting them at bumper height for 10 years because that's where the system ends up working best with the greatest number of targets to see. NHTSA has been regulating these sensors for years and designing the tests for them; they are not new to this. Tesla is not going to have to do a recall on these, and spare me the idea that they are going to "retrofit a sensor at windshield height." This is just mindless speculation you made up.

Volvo has placed radars at the top center of the windshield. They had a blind spot at bumper level, so later Volvo systems added a second radar down there. And a LIDAR. [1] One radar at bumper level is just enough to keep from rear-ending the car in front. That's not enough for a hands-off "autopilot". You need at least two, or beam steering in elevation, like the Fujitsu unit.[2] (Although that has only ±9° of elevation, not enough at bumper level to eliminate the need for a higher sensor.)

[1] http://www.pcworld.com/article/2025386/volvo-v40-watches-the... [2] http://www.fujitsu-ten.com/business/technicaljournal/pdf/38-...

I had not seen some of that Volvo tech, thanks for the link. Ultimately the radar portion is going to be more three dimensional tech still in the bumper. It's a struggle financially to get a single one of these sensors on a commodity vehicle, so the tech is focused on how to do more with that. Still, what Volvo is doing with the technology available is very interesting transitional technology.

> because [the bumper is] where the system ends up working best with the greatest number of targets to see

Do you have a source for this? It was my understanding Google went with their roof-mounted approach because of the blind-spot issue. (They also went with Lidar over cameras because of the white-truck-in-bright-daylight problem.)

I worked on the radar systems personally and we tested them with the Lidar hardware that Google uses. When the systems are raised they become more difficult to engineer (Caterpillar uses similar sensors on its large trucks, which are raised). Ultimately we solve this with more capable radar hardware in the bumper, not multiple mounting points, though Volvo's innovation in this area is significant and commendable.

This is just completely false. We've been putting them at bumper height for 10 years because that's where the system ends up working best with the greatest number of targets to see

Who's "we"?

Based on Josh's past comments he appeares to work for tesla on their radar systems.

I do not work at Tesla or for Tesla, just have experience with the radar systems.

Sorry for the mistake.

Nope, sorry on my part for not wording things better.

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