Wifi on Robots

[mogunus]

I'm aware that rule <R59> says that custom circuits may not be used for wireless communication, such as sending signals to and from the alliance base station.

It is perfectly reasonable to rule out wireless control other than IFI devices, anything else would be unsafe. However, I've worked out a method of interfacing wifi to our robot. Would using approx. five wifi-access points with known locations to "triangulate" the robot's position with a great degree of accuracy in a gps style be against this rule? This is much more of a passive sensing thing than a "communication" thing, really. I'm almost finished developing this system and I'd very much like to use it in competition. What do you people think the judge's/inspector's reactions would be? Is this illegal or not? While it might violate the letter of the rule, I don't think it violates the spirit.

[perilous]

It still is wireless communication therefore it would still be illegal.
Would be cool for demonstrations however.

[Greg Needel]

well since i don't know the answer to legality i am going to leave that one alone but the question i have is more about how this would work. The way i figure you want to use the system you would need to know the exact positioning of each wi-fi access point. I would be concerned that every event you go to would be different because it would be impossible to determine exact relative location before hand. Sure there may be a way to calibrate it but with a few access points spread throughout the event arena they might have a tendency to move (people bumping them) which would throw off your signal.

I would be very interested in seeing this work.


On a side note this would make for a fun college project, if you mapped the location of all the access points and were able to triangulate you exact position on it you could send you robot around the campus.

[devicenull]

It would violate it.. I had always thought of using something like it.. Then you picture having 60 teams setting stuff up next to the field to do so.. and it quickly becomes bad.

It would be nice if in future fields, FIRST included something like this.

[mogunus]

The way that it works is using the exact position of the wifi access points relative to the center of the field. The tracker client on the robot downloads the list of these positions from a server. Then, using access-point-specific range and propagation information also contained on the server, it triangulates it's position based on timing differences between the arrival of packets from each access point.

Concievebly, this doesn't have to be a bad thing, with 60 teams all setting up their stuff and running into each other. A bunch of teams' programmers could work together and carpet the area in way more wifi bases than I could alone, and set up a server with their locations relative to the center of the field and propagation characteristics. The accuracy resulting from an effort like that would be very impressive, and actually better than GPS.

WARNING: Now begins the speculation

I'm considering implementing DWPS. The rest of this stuff is mostly coded and working, while this whole section is just theory. DGPS works by setting up one gps station rather close to the mobile one but stationary, of exactly the same kind, and using it to solve the gps equations backwards, to arrive at the timing errors for the satellites being used for triangulation. I could set up a stationary client to run the equations backwards and transmit the results to my mobile station for correction, thus eliminating a lot of error. In GPS applications, this improves the accuracy to about 12" worth of error, using cheaper DGPS hardware.

[Tomasz Bania]

Don't the rules state that you may as long as you clear it with FIRST engineering?

[mogunus]

Don't the rules state that you may as long as you clear it with FIRST engineering?

Really? Where would that be? (this is exactly the sort of response I was hoping for, I knew someone would be enough of a rules geek to know about these things) :)

[devicenull]

Don't the rules state that you may as long as you clear it with FIRST engineering?

For cameras, yes.

<R103> Any decorations that involve broadcasting a signal to/from the robot, such as remote cameras, must be
cleared with FIRST Engineering prior to use. Teams may not use 900 MHz camera systems.

<R59> Custom Circuits may not:
• Interfere with the operation of other robots
• Directly alter the power pathways between the battery, fuse blocks, speed controller/relay, and motor.
Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to
the robot’s electrical system is acceptable, because the effect on the robot outputs should be
inconsequential.
• Directly affect any output devices on the robot, such as by providing power directly to a motor, supplying
a PWM signal to a speed controller or supplying a control signal to a relay module
• Be used for wireless communication, such as sending or receiving a signal to and/or from the alliance
station
• Connect to the radio or tether ports on the Robot Controller


I can't see it being allowed.. R59 prohibits it.

[mogunus]

Sigh. Depressing. Ah, well. I'll finish it anyway, cause it's cool, and I'll just take the wifi module off my robot before competitions. I'll update everyone as I make progress. Look for me at Atlanta!

[Al Skierkiewicz]

Marco,
It holds interesting prospects. You do need to contact FIRST and see if they would pass on it. I am guessing this late in the season, the answer would be no, but it might open a round of possibilities for next year. We have often thought that a calibrated system would be ideal for robots to use in auto. Kevin Watson might be a good person to contact with particulars. Bounce ideas off Kevin and you will get some really useful info. Good Luck with your quest.