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Why Tesla removed radar and ultrasonic sensors [video]

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Re: Why Tesla removed radar and ultrasonic sensors [video]

#181

Earlier quoted context omitted.

The dynamic range is the reason Tesla know counts photons rather than use traditional camera processing. They basically remove the concept of exposure entirely and simply pass the sensor photon counts to the neural net. This approach not only simpler as it removes photo processing/encoding but the result is that the NN can operate with a very high dynamic range similar to the human eye and in many cases can be sensit…

> They basically remove the concept of exposure entirely and simply pass the sensor photon counts to the neural net. That sentence does not make sense. There's no such thing as a count without a corresponding interval that count occurred over. That interval is the exposure. You can of course do lots of (very) short exposures to avoid sensor saturation. That's "just" a movie at a very high frame rate. And then you can…

Yeah that's fair. A CCD sensor basically converts individual photons to electrical charges. What Tesla has said they've done is thrown away all the traditional image signal processing & post-processing which often includes a lot of exposure-related averaging.

You're right though that we don't typically use real-time neural networks that operate based upon spike rate, so an interval needs to be chosen for photon counting which could be considered a kind of exposure and it is critical that the interval be short enough to avoid saturation.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#182
post #77

Earlier quoted context omitted.

I see surprisingly little discussion of overall statistics on safety of self drive vs humans, and what I do see is often self reported by companies or by equally potentially biased sources in the media. I’ve searched many times and a straightforward stat seems hard to find.

It's certainly not straightforward. You know how 90% of crashes occur within whatever many miles of home? People don't use autopilot while they're cruising around their suburbs or cities. Companies would have to disclose not just their accidents, but also how much driving is done in different places. Then all those places would have to be compared or at least categorized. Its complex enough that there would definitel…

This does spark a thought in me - at some point Telsa could create a proper test, with a portion of their drivers being asked to not use self-driving for a month, say. Or a free trial for a month that only half of Tesla users not already subscribed (randomly chosen) are eligible for.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#183

I thought it was telling that Andrej immediately "reframed" the question because Lex asked the "wrong question". This is a classic evasion technique one learns from experience and/or media training. Lex's comment immediately after was a clever and gentle dig at Andrej's response. It seemed like all the "full cost" negatives Andrej mentioned were related to Tesla's ability to execute, and not what would actually produ…

> In other words, the results are better, but not enough to make up for the fact that Telsa can't support additional sensors without incurring a prohibitive amount of additional risk to Tesla. Risk to passengers doesn't appear to be a consideration. You may be right about the actual decision process Tesla went through, but Karpathy is right in principle. One of the first things he says is "there can be problems with…

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Re: Why Tesla removed radar and ultrasonic sensors [video]

#184
post #132

Earlier quoted context omitted.

> In other words, the results are better, but not enough to make up for the fact that Telsa can't support additional sensors without incurring a prohibitive amount of additional risk to Tesla. Risk to passengers doesn't appear to be a consideration. You may be right about the actual decision process Tesla went through, but Karpathy is right in principle. One of the first things he says is "there can be problems with…

Taking his point to the extreme why use 8 cameras? just use 4? 1? One photo-diode? Cameras can also fail at run-time there can (and is) be variability in how they're mounted, in the lenses, in the sensors. They can get blinded or not get enough light. Their cabling can fail random components can fail. Tesla has claimed that vision outperforms vision+radar but anecdotal reports don't seem to support that conclusion. I…

> Is Tesla really optimizing for best performance at any cost or are they optimizing making more money and selling that to us as an improvement?

More likely they had a fixed budget and optimized with that constraint, if they made a rigorous decision at all. But this is guesswork.

I'm not speculating about how Tesla made the decision, just commenting on Karpathy's answer. His answer is correct even if it isn't true, i.e. even if it isn't what Tesla actually did.

There are plenty of well-known analogs, like the mythical man-month. We all know that throwing more x at a problem is routinely counterproductive, even without cost as a constraint.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#185

Earlier quoted context omitted.

If the safety delta was low after removing them, as 'tis with Lidar, absolutely.

It's also possible their LIDAR implementation was poor. Waymo uses LIDAR and has fewer incidents per mile.

Good point. I'm pretty sure it was poorer, Waymo really goes all-in on Lidar, they still top-mount it don't they? Waymo is also solving a much more constrained problem, with far fewer vehicles, so fewer accidents doesn't surprise me.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#186
post #88

Earlier quoted context omitted.

The video has a more reasonable answer. The sensors are unreliable and expensive in terms of R&D. Having marginal parts which takes money from a finite R&D budget can easily result in a worse product. “They contribute noise and entropy into everything.” … “you’re investing fully into that [vision] and you can make that extremely good. You only have a finite amount of spend of focus across different facets of the syst…

> Having marginal parts which takes money from a finite R&D budget can easily result in a worse product. "Less sensors can be more safe/effective if that allows us to focus on making effective use of the sensor information we do have, which is the result we're aiming for with this descision." would be a reasonable answer (if true), but that doesn't seem like a fair interpretation of what he actually said.

That was exactly his point. I listened earlier today. (It being his point doesn’t mean he is necessarily right.)

Re: Why Tesla removed radar and ultrasonic sensors [video]

#187

Earlier quoted context omitted.

Andrej refused to answer the question about why, and instead gave whole speech about how change management and supply chain is hard. What else is there to expand on? And of course other companies encounter it. But this has very strong vibes of “no one knew health care can be so complicated”. And what should they do? Change management. Yeah, it’s hard, and costs money, but it’s a hard industry to be in. What they shou…

Andrej did answer, he said that the delta was tested and found wanting, then detailed a number of risks that came with keeping Lidar. Positive but small. Risks larger. That exactly answers "don't you want all the help you can get." (paraphrase, from memory.) Securing supply chains is hard period. Tesla and SpaceX have gone to heavy vertical integration because ensuring quality seemed to insist upon that. What specifi…

Change management has nothing to do with people management.

It’s about managing changes to your product. It’s extremely important part of any safety critical system. And something that most new companies ignore, as it’s costly.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#188
post #132

Earlier quoted context omitted.

Taking his point to the extreme why use 8 cameras? just use 4? 1? One photo-diode? Cameras can also fail at run-time there can (and is) be variability in how they're mounted, in the lenses, in the sensors. They can get blinded or not get enough light. Their cabling can fail random components can fail. Tesla has claimed that vision outperforms vision+radar but anecdotal reports don't seem to support that conclusion. I…

> Is Tesla really optimizing for best performance at any cost or are they optimizing making more money and selling that to us as an improvement? More likely they had a fixed budget and optimized with that constraint, if they made a rigorous decision at all. But this is guesswork. I'm not speculating about how Tesla made the decision, just commenting on Karpathy's answer. His answer is correct even if it isn't true ,…

It's like the joke about the mathematician in the hot air balloon ... His answer is correct but it's not useful. It is correct there is some optimal solution short of an infinite number of sensors/technologies and larger than no sensors. The argument that Tesla is converging on the optimal solution vs. the more or less known reality that they couldn't get the components they needed to build enough cars is weaselly. But hey, necessity is the mother of invention. Also he can't actually share anything from his work in Tesla because presumably he's under NDA but he's gotta say something.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#189

Earlier quoted context omitted.

Andrej did answer, he said that the delta was tested and found wanting, then detailed a number of risks that came with keeping Lidar. Positive but small. Risks larger. That exactly answers "don't you want all the help you can get." (paraphrase, from memory.) Securing supply chains is hard period. Tesla and SpaceX have gone to heavy vertical integration because ensuring quality seemed to insist upon that. What specifi…

Change management has nothing to do with people management. It’s about managing changes to your product. It’s extremely important part of any safety critical system. And something that most new companies ignore, as it’s costly.

And maintenance etc. But if you don't gain significant benefit, it's reasonable not to take on the risks of managing changes to a product you can do without because it doesn't, itself, significantly reduce risk.

Re: Why Tesla removed radar and ultrasonic sensors [video]

#190
post #72

I thought it was telling that Andrej immediately "reframed" the question because Lex asked the "wrong question". This is a classic evasion technique one learns from experience and/or media training. Lex's comment immediately after was a clever and gentle dig at Andrej's response. It seemed like all the "full cost" negatives Andrej mentioned were related to Tesla's ability to execute, and not what would actually produ…

> I thought it was telling that Andrej immediately "reframed" the question because Lex asked the "wrong question". This is a classic evasion technique I agree with this assessment. However: > Telsa can't support additional sensors without incurring a prohibitive amount of additional risk to Tesla. Risk to passengers doesn't appear to be a consideration. This is a stupidifying take. Of course when you work in a line o…

> risks to passengers will absolutely affect your bottom line and if are rational you will take them into consideration

percieved, not real risks to customers. PR matters more than reality

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