# Special Road Signs for Self-Driving



## John (Apr 16, 2016)

3M developing road signs with barcodes that self-driving cars can recognize.

http://www.businessinsider.com/3m-h...-help-general-motors-self-driving-cars-2017-8


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## PNWmisty (Aug 19, 2017)

That seems backwards to me. Since self-driving cars rely on GPS, why not just put the "signs" in the GPS maps?


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## John (Apr 16, 2016)

For the time being, local signs will continue to be the authority, since people without networked cars will still need them. And sometimes ad hoc signs (e.g. Construction) are needed.


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## JWardell (May 9, 2016)

This doesn't make much sense. The whole point is self-driving cars can just read the text on signs. No need for bar codes. Even better, they can read multiple languages. There are plenty of cars on the market right now that do this. Download the World Lens app on your phone if you want to see how well this works yourself.

Can you imagine the cost to cities and towns and states to replace every single sign out there?


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## Model34mePlease (Jun 3, 2017)

JWardell said:


> This doesn't make much sense. The whole point is self-driving cars can just read the text on signs. No need for bar codes. Even better, they can read multiple languages. There are plenty of cars on the market right now that do this. Download the World Lens app on your phone if you want to see how well this works yourself.
> 
> Can you imagine the cost to cities and towns and states to replace every single sign out there?


I can hardly wait to see how the excuse "my AP didn't see the speed limit sign" works with cops.


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## John (Apr 16, 2016)

I think the idea would be to have "non ambiguous" indications. In other words, it would allow codes that confirm that the content is a set of valid instructions to the car, versus an example sign in an ad for an accident lawyer. It would also allow for denser, more information-rich displays, such as location info, an IP address for further info, etc.


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## SSonnentag (Mar 30, 2017)

I just had to shake my head when I read, "But if the GPS is off by even half an inch, it can cause chaos." Seriously?

GPS is only good for 4 meter RMS (7.8 meter 95% Confidence Interval). Where do these guys get this stuff?
Some devices/locations reliably (95% of the time or better) can get 3 meter accuracy. For a technical document on that specification you can go here: (http://www.gps.gov/technical/ps/2008-SPS-performance-standard.pdf)
For more general GPS accuracy information, head to GPS.gov's website (http://www.gps.gov/systems/gps/performance/accuracy). That website also includes data and information on WAAS-enabled systems and accuracy levels depending on location. It's a great resource.

Basically, you can't get 2 meter accuracy reliably without some form of correction.


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## John (Apr 16, 2016)

SSonnentag said:


> Basically, you can't get 2 meter accuracy reliably without some form of correction.


GPS solutions have come a long way in just the last couple of years. Newer solutions now use multiple bands-not just L1-which helps them resolve various types of interference, as well as inertial sensor fusion to achieve cm-level accuracy without a dedicated land-based network. You may recall Elon's recent comment about upgraded GPS in the latest AP versions. That's what he's talkin' about.


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## garsh (Apr 4, 2016)

John said:


> I think the idea would be to have "non ambiguous" indications. In other words, it would allow codes that confirm that the content is a set of valid instructions to the car, versus an example sign in an ad for an accident lawyer. It would also allow for denser, more information-rich displays, such as location info, an IP address for further info, etc.


Unnecessary.

Each car in the Tesla fleet can upload encountered signs to the Tesla Brain (TM). Offline processes can figure out exactly what the sign is saying. Human intervention could be used for newly-encountered, and potentially ambiguous/unknown signs. Then this fleet-sourced & updated data can be accessed by every other car that drives on that section of road - they won't even have to read the sign, just confirm that it looks pretty much the same as before.


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## SSonnentag (Mar 30, 2017)

John said:


> GPS solutions have come a long way in just the last couple of years. Newer solutions now use multiple bands-not just L1-which helps them resolve various types of interference, as well as inertial sensor fusion to achieve cm-level accuracy without a dedicated land-based network. You may recall Elon's recent comment about upgraded GPS in the latest AP versions. That's what he's talkin' about.


IMU and INU is a form of correction. I didn't see either of these mentioned. I work with GPS, carrier phase ambiguity, INU and IMU data all the time and know their limitations. Under ideal circumstances the data can be amazingly good, but in uncontrolled situations it can't be depended upon to consistently provide good data. So a 1/2" error causing chaos is something you can definitely depend on.


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## John (Apr 16, 2016)

SSonnentag said:


> So a 1/2" error causing chaos is something you can definitely depend on.


Yeah, the 1/2" part is silly.


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## Thomas Mikl (Jun 26, 2017)

Do not worry the rest of the world already has easy to read signs for automated cars for centuries, it is just in North America that road signs actually spell things out.


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## JWardell (May 9, 2016)

I thought of this thread when this tweet was made yesterday. It will be a while before autonomous driving is not confused driving around Boston.


__ https://twitter.com/i/web/status/900011209281425408


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## mkg3 (May 25, 2017)

It seems to me that fixed signs are not the issue. They can be known in advance and recorded. Its the unexpected temporary signs that go up here and there. This is where AI has to adapt more and make some type of rational decision - which is what us humans do.

If a painting a bar code helps, so be it. If embedding some sensor on the signs help so be it too.

You could easily have solar powered w/battery sending out BT/RFID signal about the sign anywhere that autonomous systems can pickup near proximity based on some industry standards.


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## JWardell (May 9, 2016)

Does anyone remember the SWS Safety Warning System employed in many radar detectors? I's a similar idea that went nowhere and was never used.

The idea was that a transmitter could be placed in a construction sign, for example (like one of those variable message signs saying lane closed), that could transmit a signal over radar, and a good mile ahead, your detector would relay that message to you. Bridge Closed, Right lane closed, 10 minute delay, etc.

In fact, many of the electric signs DO have radar transmitters. But they don't carry any message or information. And of course you don't see this installed in more useful permanent areas like RR crossings. Why? Extra unnecessary cost and time.

http://www.radarauthority.com/what-is-safety-warning-system-sws-1/

The car must have the intelligence to read signs, lines, and signals and make the correct decision on its own, just like human drivers do. The cloud will be there for advanced pre-warning, but that's only icing on the cake.


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## Guest (Sep 17, 2017)

No need to invent a bicycle. A sign is there for everybody to see. 
In case of sticky snow, 3M solution solves nothing.
In case of sign degradation, 3M solution solves nothing.
In terms of money, 3M solution makes things worse.
In terms of sign meaning, 3M solution offers nothing extra.


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