Robots sharing information

[dave1027]

So during competition the robots and driverstations for each team are segregated by individual vlans corresponding to the team number. Is it possible for cross VLAN communication to occur? I an not a network engineer but i work with equipment on several VLANs and as long as there is no firewall between them, i can access information on the other VLANs as long as i know the IP i am looking for.

Specifically: If i have an IMU with its own controller and network interface at say IP 10.10.27.8, connected to my wireless bridge, could a member of team 256 (whos IP is something like 10.02.56.1) go to that IP and determine my location on the field? If so, all six robots could know the position of the other robots on the field.

Or could i go to team 256's onboard IP camera and pull images?

If there is a firewall between the VLANs, what do you think is the possibility of the Field Technical Authorities opening specific IP tunnels to allow this? As long as the IPs do not conflict with the communication path between the roboRIO, Driverstation, and field i would not think it is a problem.

[Monochron]

I was wondering about this a while ago and I don't even think you would need to know the IP of partner robots. Your protocol could start off with broadcast messages and each robot could start an election process or something similar to select a master. Unless I am missing the limitations of how the VLANs are setup it sounds like a really interesting case study for students to get some ad-hoc network programming done.

Ideally someone could put out a single API that teams could hook into to establish communications. Then sending could be as simple as calling the API and letting it take care of the networking.

[Jon Stratis]

Check out the FMS whitepaper:
http://www.usfirst.org/sites/default...Paper_RevA.pdf

It seems to indicate that communication between VLANs is not possible, although it doesn't go into sufficient technical detail to explain why.

The FRC competition field is configured such that each team has its own virtual local area network (VLAN) within which all data is passed. The characteristics of a VLAN ensure that the command packets from one team’s DS do not cause a response on another team’s robot. These VLANs exist on both the wired and wireless side of the playing field’s network; this is why for example, it’s necessary for a team in Blue Player Station #1 to connect their DS into the corresponding cable for that station. On the wireless side of the network, the VLANs are configured in the field access point by broadcasting an individual network (SSID) for each of the six teams on the field, each with its own encryption passkey. These VLANs are configured prior to the start of each match so that only the six teams assigned in FMS may operate on the field.

[techhelpbb]

Let me propose something else to achieve this result...

In previous years I asked in the official questions if a team was allowed to place a light source in the driver's station area anywhere for their alliance. In other words...if you are in 1,2 or 3...I asked if we could put say a flashlight in our other alliance member's windows. The answer was yes at the time as long as they agree and it does not require a power source or extra interconnecting cables.

So that would sort of indicate that there is a chance that FIRST would allow you to send data between robots or driver's stations using light. Maybe by modulating the low power laser we have in the past been allowed as well.

There are lots of ways to send data using light: modulation and encoding for example. You could take a picture of a QR code: there's a bunch of bytes and if you do that over and over there's a lot of bytes. You could watch an LED toggle between ON/OFF or change color. You could AM modulate a laser. You could use IrDA transceivers.

You could potentially exploit the fact that some cell phones have a camera that faces the user.
You could potentially use NFC.

So this is solvable without exploiting the field.
There is a way to actually communicate across the VLANs but it is a hack and very ungracious to your competitors.
So please - do not put yourselves or your team in the position to get in trouble with FIRST.

[FrankJ]

The Crios are on a different subnet from everything else. You would not be able to easily talk to other than your own even without the VLAN present. The competition FMS uses smart switches so DS computer only routes to the FMS computer & their robot. Without the smart switches the Driver Stations can see & talk to each other via ethernet.

[Tungrus]

FMS is secured, external access is not possible (as far as I know). Robot to Robot communication sounds interesting and great potential, however I am concerned with other robots taking up my bandwidth and other resources or the worst opponent rogue bot making our robot dance to their tune!

[scca229]

Originally Posted by dave1027

So during competition the robots and driverstations for each team are segregated by individual vlans corresponding to the team number. Is it possible for cross VLAN communication to occur? I an not a network engineer but i work with equipment on several VLANs and as long as there is no firewall between them, i can access information on the other VLANs as long as i know the IP i am looking for.

Specifically: If i have an IMU with its own controller and network interface at say IP 10.10.27.8, connected to my wireless bridge, could a member of team 256 (whos IP is something like 10.02.56.1) go to that IP and determine my location on the field? If so, all six robots could know the position of the other robots on the field.

Or could i go to team 256's onboard IP camera and pull images?

If there is a firewall between the VLANs, what do you think is the possibility of the Field Technical Authorities opening specific IP tunnels to allow this? As long as the IPs do not conflict with the communication path between the roboRIO, Driverstation, and field i would not think it is a problem.

This would only work if routing is allowed between the VLANs on the router that the switch is connected to which houses the VLAN subnets. As far as I know from seeing the router config during a field troubleshooting session 2 years ago, that isn't the case.

[Jared]

It's not possible with the current FMS setup.

The only device that can communicate with your robot is the laptop plugged into the correct slot. Even the enable/disable state and robot stats (battery voltage, dropped packets...) are sent through your driver station laptop. No other robots or laptops can communicate with the robot.

It is also not possible to get driver station laptops to communicate with each other.

[techhelpbb]

Originally Posted by Jared

It is also not possible to get driver station laptops to communicate with each other.

Through the field network you mean.

http://www.chiefdelphi.com/forums/sh...21&postcount=4

Of course to do what I proposed above you should verify by asking in the official Q&A after kick off.
There is no hard and fast rule I have seen that would prevent inter-team electronic communication as long as it honors the field requirements and does not present a safety hazard.

[Jared]

Originally Posted by techhelpbb

Through the field network you mean.

http://www.chiefdelphi.com/forums/sh...21&postcount=4

Of course to do what I proposed above you should verify by asking in the official Q&A after kick off.
There is no hard and fast rule I have seen that would prevent inter-team electronic communication as long as it honors the field requirements and does not present a safety hazard.

Fair point. I saw a cool electronics demo where the audio output of a ipod was amplified to drive a small laser pointer. This laser pointer shined onto a photodiode, which was used to drive a speaker. It worked very well over a distance of about 10 feet.

[techhelpbb]

Originally Posted by Jared

Fair point.

For a few years I've been joking with Team 11 when we split into Team 11/193 that if we split again we can own a whole side of the field.

Then integrate light based communications into all 3 robots and make them electronically cooperative. If it wasn't for some of the rules maybe make them join into a bigger robot after the match started.

The trick is not really finding a way to communicate in a way FIRST might approve and may not even realize you have been doing. The trick is getting everyone involved on the same page to leverage it. Any team with a camera and a light source right now could strobe that light source and read that with the camera off the retro-reflective tape allowing the robots to communicate. FIRST already approves the cameras and the light sources. So really what can they do about this in the absence of a new rule?

You could actually code this at the competition and probably wire it up if you can get all the people involved to cooperate.

[RyanShoff]

What rules would prevent adding a second ethernet port on the driverstation laptops (usb dongle) and setting up a private alliance network?

[techhelpbb]

Originally Posted by RyanShoff

What rules would prevent adding a second ethernet port on the driverstation laptops (usb dongle) and setting up a private alliance network?

I would ask in the official Q&A.

The larger issues I see is that such a device would appear in your local network routing table. This could cause you some grief if your default route goes to the wrong place (though the field should see that as a lost connection to your driver's station).

This would also result in a wire not related to the field going from one or more of the teams to others. That might be considered an issue but that is not for me to say.

[Alan Anderson]

Originally Posted by techhelpbb

Any team with a camera and a light source right now could strobe that light source and read that with the camera off the retro-reflective tape allowing the robots to communicate. FIRST already approves the cameras and the light sources. So really what can they do about this in the absence of a new rule?

First, I don't see how using retroreflective tape would do anything special to allow communication. You could blink your light at the tape and see that you did it, but other robots wouldn't notice anything. They'd have to be looking at your light directly.

Second, the existing rules already disallow active robot-to-robot communication:

Originally Posted by <R55>

One (1) D-Link Wireless Bridge (P/N: DAP-1522), hardware revision B, is the only permitted device for communicating to and from the ROBOT during the MATCH.

They also prohibit any signalling between operator consoles:

Originally Posted by <R95>

Other than the system provided by the ARENA, no other form of wireless communications shall be used to communicate to, from, or within the OPERATOR CONSOLE.

However, <R95> was judged not to apply to waving at cameras, so the blinking light option might still be viable there.

[cgmv123]

Reminder that 2014 rules are not 2015 rules and the FMS is undergoing revisions for the new control system.

Originally Posted by RyanShoff

What rules would prevent adding a second ethernet port on the driverstation laptops (usb dongle) and setting up a private alliance network?

T22Ei says any special equipment can't connect or attach to the OPERATOR CONSOLE(s). The laptop is part of the operator console, but I'd have a hard time believing cabling that links multiple consoles is.

R94 could also come into play, since the cables would extend beyond the 60" x 14" footprint and aren't worn/held by drivers.