Invisible QR Code Navigation for Robots 2020

looks like some one started working on using invisible IR inks to make a invisible machine readable QR code

https://news.mit.edu/2022/invisible-labels-identify-track-objects-0128

using IR is great but there is an expensive cost, however we found that UV ink can accomplish the same goal indoors without the expense, outdoors however the IR ink is better because of the high amount of light that would interfere with UV. That being said I will keep IR for outdoor only.

Updated Fun stuff. I have moved to Noodlers Ghost ink only as it works really well for general purposes and 1.4 the cost of the IR, the IR is still an option though much more expensive if we needed it for the application.

Here is Rovio 2.0 back together after 2018s tear down. This has certainly been a long term project.

There are two cameras here, one ceiling facing and  another forward. I do think I will add one pointing down with a focal point at about 2 inches away. The "jewel" on top is a focusing UV led illumination, and there is no forward UV illumination YET, but it is coming, I will 3D print the add on and paint it for match.

Refining the sensors. I feel that a sensor dedicated to reading codes in any lighting is more useful than one that can also do full color video. Video and Sensor data should likely be separate for best performance and video processing. I am going to get some speacialized filters to test out how this works with cameras with no IR filter and a bandpass UV / IR filter. 

https://midopt.com/filters/db475850/

Today I am home mid day when it is very bright in my home. The great room has 17 windows and floods with natural light. I used the 3 watt led and the focal lense to create a consistent dot on the ceiling. SUCCESS , the QR code illuminated with great intensity and is easily read by the cam. Agian the naked eye intensity is a soft purple glow , but through the reading cam it looks perfect. So this is perfect for indoor office setups as well. Even in the event there are a great deal of fluorescent lights, a filter could easily cut their light, but in this case we are golden! Yay Version 2 QR sensor setup. I made a short video as well in the excitement.

Here is the QR code printed on paper in normal lighting of my home,  the ink is completely invisible until it is hit with the UV and IR lighting.

This is a normally lit room but the violet shows so bright through the camera that the brightness auto adjust darkens the surrounding area. The QR is certainly readable with this newer light source.

Wow , so this single led much outperforms the 5mm led versions. I brought it up to the advertised 3 watts , using the recommended current and voltage only brought the led up to 1 watt. In either case the results are interesting because this light is NOT very bright, a dim violet color to the naked eye , but through the camera eye it might as well be the blazing sun, this is great because I need to make sure the version 2 reader works will in all lighting conditions and can be adjusted on the fly by reading a simple light sensor. Version 1 was a static 3.2 volts at a set brightness level. The lens on top of the illuminator focuses the light into a usable dot on the ceiling 6 -10 ft away.

Hello judges, this project has been ongoing for a while and continues to grow as more concepts are added. At first this project had a goal of finding a way to make physical markers for navigation and the QR code reading on the ceiling was born.  This started in 2012 when I built the first hacked roomba platform with modded camera to test out the concept. Then from there I had push back that no one really wants QR codes all over their house or apartment ect. This makes perfect sense as we all have to deal with other humans that may not like the digital decor. So this set me on the completely secondary task of making invisible QR codes that can be read with any camera without an IR filter AND be used in both the home and office environment without being visually invasive.  The project was a success! I did just that. A combination of one upshift ink and one downshift ink printed on the same label, you create a QR code that is invisible in normal light , but easily read by the camera when exited by 780-850nm IR  and/or 365-405nm Violet UV light. As you can see this is a fantastically bright QR code, but it also works in a bright room because of the second pigment that shows as a grey color which is printed as the background. To do this I tested 14 different ink types and eventually decided on Noodlers ghost ink and Maxmax.com IR upshift ink. I modded existing ink cartridges and filled them with the modified inks and they now print perfect through the Epson printer with piezo style print head.  The only shame is that there was a great deal of work put into this project to make a whole solution simple for everyone else to use, I hope the effort is appreciated by the community. Further I realize not everyone will want to go this far to make invisible QR tags ( they can be printed on clear stickers). So I am also going to offer printing them for my fellow hackers to make this project even easier for everyone else to reach.

My previously hacked roomba kicked the bucket so I started hacking a wowwee rovio , but due to the hurricane damage and flooding , I was required to put in a lot more work at the fiber optics company here and didnt have time to make a particularly interesting video with the new platform. However I posted the first video showing the use of the QR codes on the ceiling until that one is made and posted. I will still do one, but all the documentation, trials and error ect easily prove the process and out to make it work. :)

Fresh printed QR code invisible to the eye other than the paper is still wet.

After illumination with an led..

Three sets of holes made for ultrasonic SR-04 distance sensors and a quick coat of Matt black so the spacer sorta matches the body.