Robots sharing information

[techhelpbb]

Originally Posted by Alan Anderson

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.

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.

Originally Posted by cgmv123

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.

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.

[FrankJ]

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.

[techhelpbb]

Originally Posted by FrankJ

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.

[dave1027]

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.

[Nate Laverdure]

Originally Posted by techhelpbb

...light based communications...

Along the same lines

[dave1027]

To get the topic back on track, let me refocus the conversation with a question (or two): wouldn't it be great to have the x,y coordinates and heading of each robot reported globally for all robots to access? Perhaps with 3 or 4 additional user definable bytes

Transmitting an additional 10-16 bytes per robot (perhaps 10 times a second) would likely not bring down the FMS. Forget about trying to share video (I doubt that would be very productive anyway)

Would you use them?

[yash101]

Originally Posted by techhelpbb

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.

Building on, you could use a wide-range, moderate-power infrared LED/sensor with a coprocessor. You could possibly create some sort of PPtP tunnel over this if treated like a serial port!

Two robots:

PHP Code:

} >=====[PPTP]======> ]
[ <=====[PPTP]======< {

Robot 1:        Robot 2:
Tx } >=======[PPTP]======> ] Rx
Rx [ <=======[PPTP]======< ] Tx 


Basically, you can treat this like an opto-isolator. This can potentially give a very high speed with very low latency. However, I would use some modulation, say 100kHz to filter out the noise! Make sure that is much higher than the baud you want to use!

[Chief Hedgehog]

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.

Oh goodness - what a blessing that would be! Or a curse! However, the way I see it working for our current 2014 robot it would allow the driver to abandon the driver functions in order to allow for the most optimal truss pass. And for our 2013 robot it could place us in the most optimal position for interfering with the opponent's FCS or optimal cycler.

[techhelpbb]

Been thinking about this some more...

When it comes to the idea of sharing video between teams which is less complicated?

1. Sharing or worse duplicating the video over the network to the other teams.
2. Offering them to look at your display of that video?

Obviously 2 is far less complicated!

If FIRST really wanted to allow this all they would have to do is allow teams to put an extra monitor on their driver's station which the other alliance members could see. Or they could let users transfer their images to Android devices as mass storage over USB from their driver's station and simply run a slideshow against that storage to the display in the same manner. Put that up against the barrier and the team immediately next to you can see your video with no field network load. Just some additional COTS device and some cables.

Also it occurs to me that when I helped propose an alternative to the cRIO we suggested that we send the FMS packets down a separate slower lower frequency radio link and let the teams use any other WiFi however they like. This would of allowed teams to share as they like as WiFi would be completely irrelevant to the FIRST field operations and it would dramatically remove the spectrum competition for the radio. Course it also would have made it the teams headache to deal with the consequences if it went terribly wrong or was interfered with.

I am personally of the opinion that the field's use of WiFi in this manner is actually more annoying to the people that want to use WiFi and TCP/IP for things like video and sharing than if the field only sent the FMS packets on a lower frequency. It puts FIRST in the position of stifling innovation to protect the field operations for business reasons. It also also gives the students trying to use TCP/IP less opportunity to be exposed to the entire operational aspect because they simply can't control what the current fields impose on them. What the current field does now is not truly analogous to real time video over most of the Internet so that is not a salvageable counterposition.

[Greg McKaskle]

I attend a good number of FIRST events, and I have a few tools that I use to look at the wifi spectrum. I've attached a few screenshots from Michigan State Champs last year.

The first is a bit fuzzy, but shows that on the campus, there were lots of other access points. Venues differ ALOT, and some are wifi-crowded. The field doesn't show up because it doesn't broadcast its SSIDs.

The second photo is the wifi usage on the channel(s) that the field was using. It is shown three ways. The lower one is total packets per second for each 100ms period. The middle one shows bytes transmitted per second. The top shows airtime being used, and is on top because this is the best indication of how much more you can transmit before you hit the ceiling.

The stacked colored bands are the traffic caused by each robot, and the external stuff is gray. There is a white line plotted over the rest that is the retransmissions.

To summarize what this says ... The robots in these matches were typically using 10% of the wifi spectrum. The spikes due to a radio momentarily shifting to slower speeds caused a momentary spike to 25%. If this had hit the ceiling and caused other radios to slow, it would have been a Xmas tree event. I logged the entire weekend and never saw a tree.

Another factoid? There were 1217 unique MAC addresses that showed up on the 5GHz wifi channel on Saturday -- a few of those are even robots. But most of those devices are simply looking to see what wifi networks are available. They build the list and go dormant again.

I have never been at an event where wifi was stressed to its limits. I have heard stories, and I believe it has happened. I do not believe it is common, and FIRST is diligent at using the wifi that is available to run the best matches possible.

By the way, I have also seen matches where individual robots are sending 20Mbps HD video. The sky didn't fall. The team was asked to change camera settings. No big deal. The wouldn't be nearly as simple without usage guidelines.

I'm not claiming that things can't be made better, but before we try to fix the problem, we need to measure quantitatively what is actually going on.

As for the original topic. The field controls whether robots can communicate with each other over its AP. It cannot happen without the field specifically allowing it and coordinating it.

Greg McKaskle

[techhelpbb]

Originally Posted by Greg McKaskle

...
To summarize what this says ... The robots in these matches were typically using 10% of the wifi spectrum. The spikes due to a radio momentarily shifting to slower speeds caused a momentary spike to 25%. If this had hit the ceiling and caused other radios to slow, it would have been a Xmas tree event. I logged the entire weekend and never saw a tree.

Were the robots involved during this sample sending video and if so how?
As CSA we are not usually asked to find this out.
Perhaps the Robot Inspectors know?

I have never been at an event where wifi was stressed to its limits. I have heard stories, and I believe it has happened. I do not believe it is common, and FIRST is diligent at using the wifi that is available to run the best matches possible.

On this I give FIRST credit. They have acknowledged there can be an issue and they do make an effort to limit the potential. It is hard however, as noted, to get everything in the field area to comply with these desires.

By the way, I have also seen matches where individual robots are sending 20Mbps HD video. The sky didn't fall. The team was asked to change camera settings. No big deal. The wouldn't be nearly as simple without usage guidelines.

I agree the presence of the load balancing does restrict the consequences of a robot operating outside of the reasonable expectations FIRST offered.

I'm not claiming that things can't be made better, but before we try to fix the problem, we need to measure quantitatively what is actually going on.

I have long given up on attempting to catch something like this myself because simply put everyone that tries is doing so at a disadvantage. The field venues change. The field settings could change. The robots can change.

For the purpose of sending the tiny amount of data FMS really needs the WiFi is just fine. Unfortunately with so many people sending video to driver's stations FMS is just plain drown out. Hence the increasing issues noticed the more people have sent video to the driver's station since FIRST started using WiFi. The result at the moment is usually an impact on just the team that needs to adjust their vision system and for that I am grateful because I do not believe it was previously the case before the load balance (call it a gut feeling - I can't go back in time - and now it does not change anything).

In the end WiFi is way more bandwidth than is really needed for FMS. So even compromised quality WiFi would work out if it wasn't for the video demands being put in competition. Even more so if the programmers of the robots make their code keep the robot moving in the last instructed direction/speed/operation until new instructions arrive. Then unless enough FMS packets are missed to disable the robot the robots can still maintain control performance even if FMS is missing some packets here and there. I think that example of dropping 5,000 of 7,000 FMS packets for a team with such software is adequate (this is an example from RampRiot 2014 I presented in another topic).

[Greg McKaskle]

The thicker bands in the attached image used video to the DS, the thinner ones didn't use it or used very little. There were matches with lots of cameras.

Greg McKaskle