The Tech Support is used to gather help requiring something broken or trying to use and wire something regarding electronics. This won’t include clarification on the rules on electronics, hardware, etc. In order to get an official clarification for VEX U you must go on the robotevents page, go on the VEX U tab, then click “VEX Q&A Forum” ← This should be the same Forum on the VRC tab but in case it isn’t go here.
Hopefully this helps 
also I’ve seen multi million dollar companies try to implement GPS positioning indoors and it never works out.
Bare minimum I can guarantee it would never work in freedom hall (huge stone building with a metal roof)
Ya high quality GPS will have accuracy within ±1 foot. Assuming all events were outside it still wouldn’t be a very helpful sensor. If you wanted to measure which field you were on, GPS would be the answer but within a field it wont tell you much.
I think it would be risky in most venues.
oh yeah, but as soon as I say it won’t work at any venue, someone will find an exception.
Back to the OP’s original question, though: “it is allowed” not “will it work”:
From the VEX-U appendix (my emphasis):
There is no restriction on sensors and other additional electronics that are used for
sensing and processing, except as follows:
a. Sensors and electronics MUST be connected to the V5 Robot Brain via any of the externally
accessible ports (i.e. without any modification to the microcontroller).
b. Sensors and electronics CANNOT directly electrically interface with the VEX motors or
solenoids.
c. The additional sensors and electronics may only receive power from any of the following:
i. Directly from the V5 Robot Brain via any externally accessible port.
ii. From an additional VEX 7.2V Robot Battery or from a VEX 9.6V Transmitter Battery
(only one (1) additional battery can be used for sensor power).
No radio communication is allowed between robots. However, other non-radio forms of
communication are permitted (i.e. IR, ultrasonic, etc.).
Although GPS uses radio, it is not “between robots”, so the VUR7 rule is not applicable here.
I would disagree but would need to look into it more. I think communication with parts outside the robot is already illegal or I would move all my AI computation off the robot to a server instead of onboard.
slaps PC with wheels
“this baby can hold so many autonomi”
I have onboard computer with 8GB of ram and an onboard GPU. Not having to run on the computer would be very convenient.
Just hook a 2.4 ghz wifi hotspot wireless antennae onto your PC, easy peasy. “its not another robot”
All sensors and electronic have to connect to a V5 port, and must be powered by the robot battery or extra 7.2 volt battery, so the “off-robot” processing would not be legal.
The GPS receiver, though, is just receiving (sensing) a signal, not interacting with the GPS satellite, so would still be legal.
So for indoor tracking there is a system similar to GPS that uses wifi hotspots.
If GPS is allowed than I think a series of wifi transmitters around the venue, or a series of IR beacons is legal.
https://www.researchgate.net/publication/231881715_Localization_Using_Infrared_Beacons
I do not think 1 way communication changes the legality. Hell a 1 way transmitter would allow me to drive the robot during autonomous.
But there is a difference: The GPS is a signal equally and publicly available to all teams, just like the earth’s magnetic field for a compass or the position of the stars and planets (for that outdoor nighttime event), while a series of transmitters or beacons in the venue is specific to, and set up by, an individual team for their own advantage only.
VUG4a would apply
Anyone else would be able to use them equally. They just might not be equipped to do so.
I will admit the argument about gravity is a good one. I don’t necessarily have a counterpoint to that other than G2 saying gravity is different than a man made machine.
Such devices could certainly become legal in the future, if all the specification were spelled out in the game manual. They would become no different that reflective tape or targets.
Do they have that available in 5 ghz? because otherwise you would be interfering with everyone’s 2.4ghz controllers.
RTK GPS will get that down to centimeters, but with active communication to a base station. Reach M2 | RTK GNSS/GPS modules for high-precision mapping
Wikipedia says the relative accuracy of RTK GPS against the base station is millimeters, but I don’t know if the Reach’s API exposes that, and I’m guessing it would be much worse indoors with multipath effects from the roof.
The GPS signals are traveling at the speed of light. This means an error of 1/1000 millisecond by the v5 brain will place you 300 meters away from your intended location. Don’t do it.
/s ← did you drop this?