Robots sharing information

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.

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.

Check out the FMS whitepaper:
http://www.usfirst.org/sites/default/files/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2013/FMSWhitePaper_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.

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.

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.

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!

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.

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.

Through the field network you mean.

http://www.chiefdelphi.com/forums/showpost.php?p=1407421&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.

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.

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.

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:

They also prohibit any signalling between operator consoles:

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

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

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.

Line of sight or reflected line of sight.
It’s just a bank shot and the focus of the goals is usually where the tape is.
Cooperative targeting.

Even without the retro-reflective tape a laser spot in a predictable spot could send a signal other robots, drivers or driver’s stations could collect (speaking practically - not saying the rules allow that).

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

You mean other than pushing each other out of the way, assisting a partner via contact or tossing a game element cooperatively?
FIRST has a lot of full contact robot to robot communications going on every match.
We have sensors that could detect objects on the field that the robot might interact with and with that information one could determine the proximity of other robots which would communicate position information between robots.
There is no rule I see that says that we can’t build a sensor package that locates other robots or react to that information.

If this rule applies then this is a poorly enforced rule.

Also between the robot and the driver’s station there’s the FIRST supplied RSL light.
That’s a visual indicator that can instruct the driver’s to change the state of their driver’s station.
There have also been several visual examples over the years of teams visually signaling their operators from the robot both to the field (in the form of a spot light) and indicators.

So this is also questionably enforced.

They also prohibit any signalling between operator consoles:

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

I will look up later where the official Q/A question I asked previously is.
Basically I wanted to put lights in the driver’s station window that the robot could visually lock onto to locate itself on the field. It was effectively one time passive communication and these lights could have been seen by all the robots on the field looking at that end.

Obviously visual targets like this are plentiful on the game fields but I liked the idea of simply controlling the target ourselves. This ends up being communication between control systems if 2 or more teams choose to use it. The robots will react and the information to control the robots will come from each driver’s station indirectly.

Perhaps but there have been several boards floating around that could be connected to the driver’s station.
Though I have never actually done this so maybe there is a rule against it somewhere?

If someone is really serious about using this they really should propose it and ask in the official Q/A.
By the time that can happen the game will be set, the rules will be there and the consequences will be more clear.

The rules say the FMS ethernet cord most connect directly to the driver station computer. (IE not via a team supplied switch) The robot enable commands most originate from the approved driver station software. Other than that, what you can physically attach to the driver station is pretty open as long as it doesn’t violate other robot rules. The cypress board is an example of a board connecting to the driver station.

So then I guess the question is why can’t one Cypress board blink an LED and the other monitor that LED through the barrier with a photo-transistor? Again FIRST could cry foul over this but why? It leads to cooperation? If it is a safety concern I would like to understand that concern. Right now teams can easily communicate themselves within hearing distance of those driver’s stations. We can’t really stop them from verbalizing to each other.

Am trying to figure out when this question about using lights in the driver’s station was answered by FIRST.
Anybody have the 2011 Q&A? The link in the archive seems to be broken.
I have e-mails from 2011 and 2012 pondering this so somewhere in that range.

A side from the vague reference to rules that disallow robot to robot communication, does anyone know the actual rule that does not allow this? I am pretty good with rules and regs and do not remember it specifically being against the rules. Infact in the spirit of co-opertition I would think this would be encouraged.

I am proposing an open hardware/software solution for a standardized protocol for sharing information between robots,

While light based applications could technically function the bad part is that they require line of sight to work, the nice thing about the field based network is that it already exists and would require very little effort to make it work.

Personally I am of the opinion that the field network is already stressed to the max by multiple teams using TCP based real time video back to the driver’s stations.

These TCP flows can be so large that the video actually starves the UDP FMS packets to the robots and can often end up with your robot disabled and your control performance compromised. These show as missing packets on the field display and in the driver’s station DS logs. FIRST made a serious investment in load balancing for the fields to keep this problem bottled up.

I would be concerned that opening the door to bi-directional inter-team communication on a network that can be so heavily saturated could lead to headaches where one team could inadvertently swamp their own alliance.

In this regard reducing that protection might not improve things for your alliance.

The other solutions (though line of sight) at least move this extra load off the field making the proof of concept a little less likely to result in unpleasant surprises. So in this regard I think the amount of effort for FIRST to actually QA this on their field network is way bigger than anyone realizes.

This also, in my mind, falls back into the idea that such communications should be simple and short lived.
The alternatives to the field are slower and will encourage brevity and simplicity.
Why send full video to your alliance peers when you can send messages like ‘ready to shoot’?
TCP/IP is too often used like a hammer and every communications problem becomes a vastly more complicated nail.
(Ironic I wrote this because I have been writing Ruby HTTP functions all day that can do Windows Authentication without using the existing work which tends to mask exceptions I need to see for security reasons. So I make this post and then get back to my POST / HTTP/1.1).